How sustainable is PV power?

SUBHEAD: Manufacture and energy storage limit the maximum sustainable growth rate of the solar PV industry.

By Kris De Decker on 26 April 2015 for Low Tech Magazine -

Image above: Solar-voltaic electric panels at dusk. From original article.

Solar photovoltaic (PV) systems generate "free" electricity from sunlight, but manufacturing them is an energy-intensive process.

It's generally assumed that it only takes a few years before solar panels have generated as much energy as it took to make them, resulting in very low greenhouse gas emissions compared to conventional grid electricity.

However, the studies upon which this assumption is based are written by a handful of researchers who arguably have a positive bias towards solar PV. A more critical analysis shows that the cumulative energy and CO2 balance of the industry is negative, meaning that solar PV has actually increased energy use and greenhouse gas emissions instead of lowering them.

This doesn't mean that the technology is useless. It's just that our approach is wrong. By carefully selecting the location of the manufacturing and the installation of solar panels, the potential of solar power could be huge. We have to rethink the way we use and produce solar energy systems on a global scale.

There's nothing but good news about solar energy these days. The average global price of PV panels has plummeted by more than 75% since 2008, and this trend is expected to continue in the coming years, though at a lower rate. [1-2]

According to the 2015 solar outlook by investment bank Deutsche Bank, solar systems will be at grid parity in up to 80% of the global market by the end of 2017, meaning that PV electricity will be cost-effective compared to electricity from the grid. [3-4]

Lower costs have spurred an increase in solar PV installments. According to the Renewables 2014 Global Status Report, a record of more than 39 gigawatt (GW) of solar PV capacity was added in 2013, which brings total (peak) capacity worldwide to 139 GW at the end of 2013. While this is not even enough to generate 1% of global electricity demand, the growth is impressive. Almost half of all PV capacity in operation today was added in the past two years (2012-2013). [5] In 2014, an estimated 45 GW was added, bringing the total to 184 GW. [6] [4].

Solar PV total global capacitySolar PV total global capacity, 2004-2013. Source: Renewables 2014 Global Status Report.

Meanwhile, solar cells are becoming more energy efficient, and the same goes for the technology used to manufacture them. For example, the polysilicon content in solar cells -- the most energy-intensive component -- has come down to 5.5-6.0 grams per watt peak (g/wp), a number that will further decrease to 4.5-5.0 g/wp in 2017. [2]

 Both trends have a positive effect on the sustainability of solar PV systems. According to the latest life cycle analyses, which measure the environmental impact of solar panels from production to decommission, greenhouse gas emissions have come down to around 30 grams of CO2-equivalents per kilwatt-hour of electricity generated (gCO2e/kWh), compared to 40-50 grams of CO2-equivalents ten years ago. [7-11] [12]

According to these numbers, electricity generated by photovoltaic systems is 15 times less carbon-intensive than electricity generated by a natural gas plant (450 gCO2e/kWh), and at least 30 times less carbon-intensive than electricity generated by a coal plant (+1,000 gCO2e/kWh). The most-cited energy payback times (EPBT) for solar PV systems are between one and two years. It seems that photovoltaic power, around since the 1970s, is finally ready to take over the role of fossil fuels.

Manufacturing has Moved to China
Unfortunately, a critical review of the PV solar industry paints a very different picture. Many commenters attribute the plummeting cost of solar PV to more efficient manufacturing processes and scale economies. However, if we look at the graph below, we see that the decline in costs accelerates sharply from 2009 onwards. 

This acceleration has nothing to do with more efficient manufacturing processes or a technological breakthrough. Instead, it's the consequence of moving almost the entire PV manufacturing industry from western countries to Asian countries, where labour and energy are cheaper and where environmental restrictions are more loose.

Less than 10 years ago, almost all solar panels were produced in Europe, Japan, and the USA. In 2013, Asia accounted for 87% of global production (up from 85% in 2012), with China producing 67% of the world total (62% in 2012). Europe's share continued to fall, to 9% in 2013 (11% in 2012), while Japan's share remained at 5% and the US share was only 2.6%. [5]

Price of silicon solar cells wikipedia
Compared to Europe, Japan and the USA, the electric grid in China is about twice as carbon-intensive and about 50% less energy efficient. [13-15

Because the manufacture of solar PV cells relies heavily on the use of electricity (for more than 95%) [16], this means that in spite of the lower prices and the increasing efficiency, the production of solar cells has become more energy-intensive, resulting in longer energy payback times and higher greenhouse gas emissions. 

The geographical shift in manufacturing has made almost all life cycle analyses of solar PV panels obsolete, because they are based on a scenario of domestic manufacturing, either in Europe or in the United States.

LCA of Solar Panels Manufactured in China
We could find only one study that investigates the manufacturing of solar panels in China, and it's very recent. In 2014, a team of researchers performed a comparative life cycle analysis between domestic and overseas manufacturing scenarios, taking into account geographic diversity by utilizing localized inventory data for processes and materials. [13]

 In the domestic manufacturing scenario, silicon PV modules (mono-si with 14% efficiency and multi-si with 13.2% efficiency) are made and installed in Spain. In the overseas manufacturing scenario, the panels are made in China and installed in Spain.

Compared to the domestic manufacturing scenario, the carbon footprint and the energy payback time are almost doubled in the overseas manufacturing scenario. The carbon footprint of the modules made in Spain (which has a cleaner grid than the average in Europe) is 37.3 and 31.8 gCO2e/kWh for mono-si and multi-si, respectively, while the energy payback times are 1.9 and 1.6 years.

However, for the modules made in China, the carbon footprint is 72.2 and 69.2 gCO2e/kWh for mono-si and multi-si, respectively, while the energy payback times are 2.4 and 2.3 years. [13]

Carbon footprints solar cells produced in china and europe
At least as important as the place of manufacturing is the place of installation. Almost all LCAs -- including the one that deals with manufacturing in China -- assume a solar insolation of 1,700 kilowatt-hour per square meter per year (kWh/m2/yr), typical of Southern Europe and the southwestern USA. If solar modules manufactured in China are installed in Germany, then the carbon footprint increases to about 120 gCO2e/kWh for both mono- and multi-si -- which makes solar PV only 3.75 times less carbon-intensive than natural gas, not 15 times.

Considering that at the end of 2014, Germany had more solar PV installed than all Southern European nations combined, and twice as much as the entire United States, this number is not a worst-case scenario. It reflects the carbon intensity of most solar PV systems installed between 2009 and 2014. More critical researchers had already anticipated these results. A 2010 study refers to the 2008 consensus figure of 50 gCO2e/kWh mentioned above, and adds that "in less sunny locations, or in carbon-intensive economies, these emissions can be up to 2-4 times higher". [17]

Taking the more recent figure of 30 gCO2e/kWh as a starting point, which reflects improvements in solar cell and manufacturing efficiency, this would be 60-120 gCO2e/kWh, which corresponds neatly with the numbers of the 2014 study.

Solar insolation in europe
Solar insolation in north america
Solar insolation in Europe and the USA. Source: SolarGIS.

These results don't include the energy required to ship the solar panels from China to Europe. Transportation is usually ignored in LCAs of solar panels that assume domestic production, which would make comparisons difficult.

Furthermore, energy requirements for transportation are very case-specific. It should also be kept in mind that these results are based on a solar PV lifespan of 30 years. This might be over-optimistic, because the relocation of manufacturing to China has been associated with a decrease in the quality of PV solar panels. [18]

Research has shown that the percentage of defective or under-performing PV cells has risen substantially in recent years, which could have a negative influence on the lifespan of the average solar panel, decreasing its sustainability.

Energy Cannibalism
Solar PV electricity remains less carbon-intensive than conventional grid electricity, even when solar cells are manufactured in China and installed in countries with relatively low solar insolation. This seems to suggest that solar PV remains a good choice no matter where the panels are produced or installed.

However, if we take into account the growth of the industry, the energy and carbon balance can quickly turn negative. That's because at high growth rates, the energy and CO2 savings made by the cumulative installed capacity of solar PV systems can be cancelled out by the energy use and CO2 emissions from the production of new installed capacity. [16] [19-20]
A life cycle analysis that takes into account the growth rate of solar PV is called a "dynamic" life cycle analysis, as opposed to a "static" LCA, which looks only at an individual solar PV system. The two factors that determine the outcome of a dynamic life cycle analysis are the growth rate on the one hand, and the embodied energy and carbon of the PV system on the other hand. If the growth rate or the embodied energy or carbon increases, so does the "erosion" or "cannibalization" of the energy and CO2 savings made due to the production of newly installed capacity. [16]

For the deployment of solar PV systems to grow while remaining net greenhouse gas mitigators, they must grow at a rate slower than the inverse of their CO2 payback time. [19]

 For example, if the average energy and CO2 payback times of a solar PV system are four years and the industry grows at a rate of 25%, no net energy is produced and no greenhouse gas emissions are offset. [19]

If the growth rate is higher than 25%, the aggregate of solar PV systems actually becomes a net CO2 and energy sink. In this scenario, the industry expands so fast that the energy savings and GHG emissions prevented by solar PV systems are negated to fabricate the next wave of solar PV systems. [20]

The CO2 Balance of Solar PV
Several studies have undertaken a dynamic life cycle analysis of renewable energy technologies. The results -- which are valid for the period between 1998 and 2008 -- are very sobering for those that have put their hopes on the carbon mitigation potential of solar PV power. A 2009 paper, which takes into account the geographical distribution of global solar PV installations, sets the maximum sustainable annual growth rate at 23%, while the actual average annual growth rate of solar PV between 1998 and 2008 was 40%. [16] [21]


This means that the net CO2 balance of solar PV was negative for the period 1998-2008. Solar PV power was growing too fast to be sustainable, and the aggregate of solar panels actually increased GHG emissions and energy use. According to the paper, the net CO2 emissions of the solar PV industry during those 10 years accounted to 800,000 tonnes of CO2. [16] These figures take into account the fact that, as a consequence of a cleaner grid and better manufacturing processes, the production of solar PV panels becomes more energy efficient and less carbon-intensive over time.
The sustainability of solar PV has further deteriorated since 2008. On the one hand, industry growth rates have accelerated. Solar PV grew on average by 59% per year between 2008 and 2014, compared to an annual growth rate of 40% between 1998 and 2008 . [5] On the other hand, manufacturing has become more carbon-intensive. For its calculations of the CO2 balance in 2008, the study discussed above considers the carbon intensity of production worldwide to be 500 gCO2e/kWh. In 2013, with 87% of the production in Asia, this number had risen to about 950 gCO2e/kWh, which halves the maximum sustainable growth rate to about 12%.

If we also take into account the changes in geographic distribution of solar panels, with an increasing percentage installed in regions with higher solar insolation, the maximum sustainable growth rate increases to about 16%. [23-24] Although more recent research is not available, it's obvious that the CO2 emissions of the solar PV industry have further increased during the period 2009-2014. If we would consider all solar panels in the world as one large energy generating plant, it would not have generated any net energy or CO2-savings.

The Solution: Rethink the Manufacture and Use of Solar PV
Obviously, the net CO2 balance of solar PV could be improved by limiting the growth of the industry, but that would be undesirable. If we want solar PV to become important, it has to grow fast. Therefore, it's much more interesting to focus on lowering the embodied energy of solar PV power systems, which automatically results in higher sustainable growth rates. The shorter the energy and CO2 payback times, the faster the industry can grow without becoming a net producer of CO2.

Embodied energy and CO2 will gradually decrease because of technological advances such as higher solar cell efficiencies and more efficient manufacturing techniques, and also as a consequence of the recycling of solar panels, which is not yet a reality.

However, what matters most is where solar panels are manufactured, and where they are installed. The location of production and installation is a decisive factor because there are three parameters in a life cycle analysis that are location dependent: the carbon intensity of the electricity used in production, the carbon intensity of the displaced electricity mix at the place of installation, and the solar insolation in the place of installation. [16]

By carefully selecting the locations for production and installation we could improve the sustainability of solar PV power in a spectacular way. For PV modules produced in countries with low-carbon energy grids -- such as France, Norway, Canada or Belgium -- and installed in countries with high insolation and carbon-intensive grids -- such as China, India, the Middle East or Australia -- greenhouse gas emissions can be as low as 6-9 gCO2/kWh of generated electricity. [16] [20] [14-15] That's 13 to 20 times less CO2 per kWh than solar PV cells manufactured in China and installed in Germany. [25]
Sustainable growth rates of 300-460% are possible when PV modules are produced in countries with low-carbon energy grids and installed in countries with high insolation and carbon-intensive grids
This would allow sustainable growth rates of up to 300-460%, far above what's even necessary. If solar PV would grow on average at a rate of 100% per year, it would take less than 10 years to meet today's electricity's demand. If it would grow at the 16% maximum sustainable growth rate we calculated above, meeting today's electricity demand would take until 2045 -- with no net CO2 savings. By that time, according to the forecasts, total global electricity demand will have more than doubled. [26]

Of course, producing and installing solar panels in the right places implies international cooperation and a sound economic system, none of which exist. Manufacturing solar panels in Europe or the USA would also make them more expensive again, while many countries with the right conditions for solar don't have the money to install them in large amounts.

An alternative solution is using on-site generation from renewables to meet a greater proportion of the electricity demand of PV manufacturing facilities -- which can also happen in a country with a carbon-intensive grid. For example, if the electricity for the manufacturing of solar cells would be supplied by other solar cells, then the greenhouse emissions of solar PV systems could be reduced by 50-70%, depending on where they are produced (Europe or the USA). [7] In China, this decrease in CO2 emissions would even be greater.

In yet another scenario, we could dedicate nuclear plants exclusively to the manufacture of solar cells. Because nuclear is less carbon-intensive than PV solar, this sounds like the fastest, cheapest and easiest way to start producing a massive amount of solar cells without raising energy use and greenhouse emissions.

But don't underestimate the task ahead. A 1 GW nuclear power plant can produce about 11 million square metres of solar panels per year, which corresponds to 1.66 GWp of solar power (based on the often cited average number of 150 w/m2). We would have needed 24 nuclear plants -- or 1 in 20 atomic plants worldwide -- working full-time to produce the solar panels manufactured in 2013. [27]

What About Storage?
Why does the production of solar PV requires so much energy? Because the low power density -- several orders of magnitude below fossil fuels -- and the intermittency of solar power require a much larger energy infrastructure than fossil fuels do.

It's important to realize that the intermittency of solar power is not taken into account in our analysis. Solar power is not always available, which means that we need a backup-source of power or a storage system to jump in when the need is there.

This component is usually not considered in LCAs of solar PV, even though it has a large influence on the sustainability of solar power.

Storage is no longer an academic question because several manufacturers -- most notably Tesla -- are pushing lithium-ion battery storage as an alternative for a grid-connected solar PV system.
Lithium-ion batteries are more compact and technically superior to the lead-acid batteries commonly used in off-grid solar systems. Furthermore, the disincentivation of  grid-connected solar systems in a growing number of countries makes off-grid systems more attractive.

In the next article, we investigate the sustainability of a PV-system with a lithium-ion battery. Meanwhile, enjoy the sun and stay tuned.

Sustainabilty of Stored Sunlight 

By Kris De Decker on 3 May 2015 for Low Tech Magazine -

One of the constraints of solar power is that it is not always available: it is dependent on daylight hours and clear skies. In order to fill these gaps, a storage solution or a backup infrastructure of fossil fuel power plants is required -- a factor that is often ignored when scientists investigate the sustainability of PV systems.

Whether or not to include storage is no longer just an academic question. Driven by better battery technology and the disincentivization of grid-connected solar panels, off-grid solar is about to make a comeback. How sustainable is a solar PV system if energy storage is taken into account?

In the previous article, we have seen that many life cycle analyses (LCAs) of solar PV systems have a positive bias. Most LCAs base their studies on the manufacturing of solar cells in Europe or the USA. However, most panels are now produced in China, where the electric grid is about twice as carbon-intensive and about 50% less energy efficient. [1] Likewise, most LCAs investigate solar PV systems in regions with a solar insolation typical of the Mediterranean region, while the majority of solar panels have been installed in places with only half as much sunshine. 

As a consequence, the embodied greenhouse gas emissions of a kWh of electricity generated by solar PV is two to four times higher than most LCAs indicate. Instead of the oft-cited 30-50 grams of CO2-equivalents per kilowatt-hour of generated electricity (gCO2e/kWh), we calculated that the typical solar PV system installed between 2008 and 2014 produces close to 120 gCO2e/kWh. This makes solar PV only four times less carbon-intensive than conventional grid electricity in most western countries.

However, even this result is overly optimistic. In the previous article, we didn't take into account "one of the potentially largest missing components" [2] of the usual life cycle analysis of PV systems: the embodied energy of the infrastructure that deals with the intermittency of solar power. Solar insolation varies throughout the day and throughout the season, and of course solar energy is not available after sunset. 

Off-grid Solar Power is Back
Until the end of the 1990s, most solar installations were off-grid systems. Excess power during the day was stored in an on-site bank of lead-acid batteries for use during the night and on cloudy days. Today, almost all solar systems are grid-connected. These installations use the grid as if it was a battery, "storing" excess energy during the day for use at night and on cloudy days.

Obviously, this strategy requires a backup of fossil fuel or nuclear power plants that step in when the supply of solar energy is low or nonexistent. To make a fair comparison with conventional grid electricity, including electricity generated by biomass, this "hidden" part of the solar PV system should also be taken into account. However, every single life cycle analyse of a solar PV ignores it. [3, 2].

Until now, whether or not to include backup power or storage systems was mainly an academic question. This might change soon, because off-grid solar is about to make a comeback. Several manufacturers have presented storage systems based on lithium-ion batteries, the technology that also powers our gadgets and electric cars. [4, 5, 6, 7] Lithium-ion batteries are a superior technology compared to the lead-acid batteries commonly used in off-grid solar PV systems: they last longer, are more compact, more efficient, easier to maintain, and comparatively more sustainable.
Battery storage price projections

Lithium-ion batteries are more expensive than lead-acid batteries, but Morgan Stanley's 2014 report on solar energy predicts that the price of storage will come down to $125-$150 per kWh by 2020. [8] According to the report, this would make solar PV plus battery storage commercially viable in some European countries (Germany, Italy, Portugal, Spain) and across most of the United States. Morgan Stanley expects a lot from electric vehicle manufacturer Tesla, who announced a home storage system for solar power a few days ago (costing $350 per kWh). [9] Tesla is building a factory in Arizona that will produce as many lithium-ion batteries as there are currently produced by all manufacturers in the world, introducing economies of scale that can push costs further down.
Other factors also come into play when it comes to home storage for PV power. Solar panels have become so much cheaper in recent years that government subsidies and tax credits for grid-connected systems have come under pressure. In many countries, owners of a grid-connected solar PV system have received a fixed price for the surplus electricity they provide to the grid, without having to pay fixed grid rates. These so-called "net metering rules" or "feed-in rates" were recently abolished in several European countries, and are now under pressure in some US states. In its report, Morgan Stanley predicts that, in the coming years, net metering rules and solar tax credits will disappear altogether. [8]
A 5 kWh lithium-ion battery pack from Powertech Systems.

Utility companies are fighting the incentivisation of PV power succesfully with the argument that solar customers make use of the grid but don't pay for it, raising the costs for non-solar customers. [10] The irony is that the disincentivization of grid-connected solar panels makes off-grid systems more attractive, and that utilities might be chasing away their customers. 

If a grid-connected solar customer has to pay fixed grid fees and doesn't receive a good price for his or her excess power, it might become more financially savvy to install a bank of batteries. The more customers do this, the higher the costs will become for the remaining consumers, encouraging more people to adopt off-grid systems. [11]

Lead-Acid Battery Storage
Being totally independent of the grid might sound attractive to many, but how sustainable is a solar PV system when battery storage is taken into account? Because a life cycle analysis of an off-grid solar system with lithium-ion batteries has not yet been done, we made one ourselves, based on some LCAs of stand-alone solar PV systems with lead-acid battery storage.

One of the most complete studies to date is a 2009 LCA of a 4.2 kW off-grid system in Murcia, Spain. The 35 m2 PV solar array is mounted on a building rooftop and supplies a programmed lighting system with a daily constant load pattern of 13.8 kWh. 

The solar panels are connected to 24 open lead-acid batteries with a storage capacity of 110.4 kWh, offering three days of autonomy. [12] The study found an energy payback time of 9.08 years and specific greenhouse gas emissions of 131 gCO2e/kWh, which makes the system twice as energy efficient and 2.5 times less carbon-intensive than conventional grid electricity in Spain (337 gCO2/kWh). Manufacturing the batteries accounts for 45% of the embodied CO2, and 49% of the life cycle energy use of the solar system.
This doesn't sound too bad, but unfortunately the researchers made some pretty optimistic assumptions. First of all, the results are valid for a solar insolation of 1,932 kWh/m2/yr -- Murcia is one of the sunniest places in Spain. At lower solar insolation, more solar panels would be needed to produce as much electricity, so the embodied energy of the total system will increase. [13]. If we assume a solar insolation of 1,700 kWh/m2/yr, the average in Southern Europe, GHG emissions would increase to 139 gCO2e/kWh. If we assume a solar insolation of 1,000 kWh/m2/yr, the average in Germany, emissions amount to 174 gCO2/kWh.

Battery Lifespan
Secondly, the researchers assume the lifespan of the lead-acid batteries to be 10 years. For the solar panels, they assume a lifetime of 20 years, which means that they included double the amount of batteries in the life cycle analysis. A lifespan of ten years is very optimistic for a lead-acid battery -- a fact that the scientists admit. [12] Most other LCA's looking at off-grid systems assume a battery life of 3 or 5 years [14, 15]. However, the lifetime of a lead-acid battery depends strongly on use and maintenance. Because of the low load of the system under discussion, a battery lifespan of 10 years is not completely unrealistic.

On the other hand, if the batteries are used for higher loads -- for example, in a common household -- their lifetime would shorten considerably. Because almost 50% of embodied CO2 and life cycle energy use of a PV solar system is due to the batteries alone, the expected lifespan of the 2.4 ton battery pack has a profound effect on the sustainability of the system.

Lead acid battery storage
A lead-acid battery system. SuperiorSolar.

If we assume a battery lifespan of 5 instead of 10 years, and keep the other parameters the same, the GHG emissions increase to 198 and 233 gCO2e/kWh for a solar insolation of 1,700 and 1,000 kWh/m2/yr, respectively. In grid-connected solar PV systems, assuming a longer life expectancy for the solar panels improves the sustainability of the system: the embodied energy and CO2 can be spread over a longer period of time. With off-grid systems, this effect is countered by the need for one or more replacements of the batteries.

If we increase the life expectancy of the solar panels from 20 to 30 years, and keep the battery lifespan at 10 years, CO2e emissions per kWh remain more or less the same. However, if we assume a battery lifespan of only 5 years and extend the lifespan of the solar panels to 30 years, GHG emissions would increase to 206 gCO2e/kWh for a solar insolation of 1,700 kWh/m2/yr, and decrease to 232 gCO2e/kWh for a solar insolation of 1,000 kWh/m2/yr.

Made in China
Thirdly, the researchers assume that all components -- PV cells, batteries, electronics -- are made in Spain, while we have seen in the previous article that manufacturing of solar PV systems has moved to China. Spain's electricity grid is 2.7 times less carbon-intensive (337 gCO2/kWh) than China's electric infrastructure (900 gCO2e/kWh), which means that the GHG emissions of all components of our system can be multiplied by 2.7.

This results in specific carbon emissions of 353 and 471 gCO2e/kWh for a solar insolation of 1,700 and 1,000 kWh/m2/yr, respectively, which is higher than the carbon-intensity of the Spanish grid. Considering a battery lifespan of 5 instead of 10 years, emissions would rise to 513 and 631 gCO2e/kWh for a solar insolation of 1,700 and 1,000 kWh/m2/yr, respectively.
Although there are some assumptions by the researchers that are less optimistic -- such as a battery recycling rate of only 50% instead of the more commonly assumed +90% -- it's obvious that an off-grid system with lead-acid batteries is not sustainable, and definitely not when the components are manufactured in China. That doesn't make off-grid solar with lead-acid batteries pointless: compared to a diesel generator, a solar PV system with lead-acid batteries is often the better choice, which makes it a good solution for remote areas without access to the power grid. As an alternative for the centralized electricity infrastructure in western countries, however, it makes little sense.

Lithium-ion Battery Storage System
When we replace the lead-acid batteries by lithium-ion batteries, the sustainability of a stand-alone solar PV system improves considerably. At first glance this may seem counter-productive, because it takes more energy to produce 1 kWh of  lithium-ion battery storage than it takes to manufacure 1 kWh of lead-acid battery storage. According to the latest LCA's, aimed at electric vehicle storage, the making of a lithium-ion battery requires between 1.4 and 1.87 MJ/wh, [16, 17, 18] while the energy requirements for the manufacture of a lead-acid battery are between 0.87 and 1.19 MJ/Wh. [18, 12]

Bosch energy storage system lithium-ion6.6 kWh Energy management and lithium-ion storage solution in one. Bosch Power Tec.

Despite this, the higher overall performance of the lithium-ion battery means that considerably less storage is required. For a prolonged lifetime, lead-acid batteries demand a limited "Depth of Discharge" (DoD). If a lead-acid battery is fully discharged (DoD of 100%) its lifespan becomes very short (300 to 800 cycles, or roughly one to two years, depending on battery chemistry).

he lifespan increases to between 400 and 1,000 cycles (1-3 years, assuming 365 cycles per year) at a DoD of 80%, and to between 900 and 2,000 cycles (2.5-5.5 years) at a DoD of 33%. [18]. This means that, in order to get a decent lifespan, a lead-acid battery system should be oversized. For example, three times more battery capacity is needed at a DoD of 33%, because two thirds of the battery capacity cannot be used.

Although the lifespan of a lithium-ion battery also decreases when the depth of discharge increases, this effect is less pronounced than with its lead-acid counterpart. A lithium-ion battery lasts 3,000 to 5,000 cycles (8-14 years) at a DoD of 100%, 5,000 to 7,000 cycles (14-19 years) at a DoD of 80%, and 7,000 to 10,000 cycles (19-27 years) at a DoD of 33%. [18]

As a consequence, lithium-ion storage usually has a DoD of 80%, while lead-acid storage usually has a DoD of 33 or 50%. In the LCA of the Spanish off-grid system discussed above, the assumption of three days of autonomy implies that 41 kWh of storage is required (3 x 13.8 kWh per day). Because the DoD is 33%, total storage capacity should be multiplied by three, which results in 123 kWh of batteries. If we would replace these by lithium-ion batteries with a DoD of 80%, only 50 kWh of storage is needed, or 2.5 times less.

6 x Less Batteries Needed
For utmost accuracy, we should mention that the lifespan of a battery isn't necessarily limited by the cycle life. When batteries are used in applications with shallow cycling, their service life will normally be limited by float life. In this case, the difference between lead-acid and lithium-ion is less pronounced: at no-cycling (float charge), lithium-ion lasts 14-16 years and lead-acid 8-12 years.

Battery life will be limited by either the life cycle or the float service life, depending on which condition will be achieved first. [18] Nevertheless, if we focus on off-grid systems for households, the assumption of deep daily cycling better reflects reality, although there will be periods of float charge, for example during holidays.
If we also factor in the lifespan of the batteries, the advantage of lithium-ion becomes even larger. Assuming a lifespan of 20 years for the solar PV system and a DoD of 80%, the lithium-ion batteries will last as long as the PV panels. On the other hand, the lead-acid batteries have to be replaced at least 2-4 times over a period of 20 years. This further widens the gap in energy use for manufacturing when comparing lead-acid and lithium-ion batteries. [18]

 In the original LCA, a total storage capacity of about 240 kWh is needed over a lifespan of 20 years. On the other hand, the cycle life of the lithium-ion battery is 19-27 years, meaning that no replacement may be needed. Consequently, the total storage capacity to be manufactured over the complete lifetime of the system is 6 times lower for lithium-ion than for lead-acid. [19]

E3DC lithium-ion battery system. Picture: Thomas Salzmann.

If we take the most optimistic values for energy during manufacturing, being 0.87 MJ/Wh for lead-acid and 1.4 MJ/Wh for lithium-ion, and multiply them by total battery capacity over a lifetime of 20 years (248,000 Wh for lead-acid and 42,000 Wh for lithium-ion), this results in an embodied energy of 60 MWh for lead-acid (the value in the original LCA) and only 16.5 MWh for lithium. In conclusion, energy requirements for the manufacturing of the batteries is 3.6 times lower for lithium-ion than for lead-acid.

Another advantage of lithium-ion batteries is that they have a higher efficiency than lead-acid batteries: 85-95% for lithium-ion, compared to 70-85% for lead-acid. Because losses in the battery must be compensated with higher energy input, a higher battery efficiency results in a smaller PV array, lowering the energy requirements to manufacture the solar cells. In the original LCA, 4.2 kW of solar panels (35 m2) are needed to produce 13.8 kWh per day.

If we assume the lead-acid batteries to be 77% efficient, and the lithium-ion batteries to be 90% efficient, the choice for lithium-ion would resize the solar PV array from 4.2 kW to 3.55 kW. We now have all the data to calculate the greenhouse gas emissions per kWh of electricity produced by an off-grid solar PV system using lithium-ion batteries.

GHG Emissions of the Off-grid System with Lithium-ion Batteries
In the original LCA, the batteries and the solar panels (including frames and supports) account for 59 and 62 gCO2e/kWh, respectively. The rest of the components add another 10 gCO2e/kWh, resulting in a total of 131 gCO2e/kWh. If we switch to lithium-ion battery storage, the greenhouse gas emissions for the batteries come down from 59 to 20 gCO2e/kWh.

Because of the higher efficiency of the lithium-ion batteries, the greenhouse gas emissions for the solar panels come down from 62 to 55 gCO2e/kWh. This brings the total greenhouse gas emissions of the off-grid system using lithium-ion batteries to 85 gCO2e/kWh, compared to 131 gCO2e/kWh for a similar system with lead-acid storage.

While this result is an improvement, it's dependent on the assumptions of the researchers; most notably, a solar insolation of 1,932 kWh/m2/yr, and that all manufacturing of components occurs in Spain. If we adjust the value for a solar insolation of 1,700 kWh/m2/yr in order to compare with the other results, total GHG emissions become 92.5 gCO2e/kWh (assuming battery capacity remains the same).

If we correct for a solar insolation of 1,000 kWh/m2/yr, the average in Germany, GHG emissions become 123.5 gCO2e/kWh. Furthermore, if we assume that the solar panels (but not the batteries or the other components) are manufactured in China, which is most likely the case, GHG emissions rise to 155 and 217 gCO2e/kWh for a solar insolation of 1,700 and 1,000 kWh/m2/yr, respectively.

Testing a lithium-ion battery. Picture: A123 Systems.

In conclusion, lithium-ion battery storage makes off-grid solar PV less carbon-intensive than conventional grid electricity in most western countries, even if the manufacturing of solar panels in China is taken into account. However, the advantage is rather small, which effects the speed at which solar PV systems can be deployed in a sustainable way.

In the previous article, we have seen that the energy and CO2 savings made by the cumulative installed capacity of solar PV systems are cancelled out to some extent by the energy use and CO2 emissions from the production of new installed capacity. For the deployment of solar systems to grow while remaining net greenhouse gas mitigators, they must grow at a rate slower than the inverse of their CO2 payback time. [20, 21, 22]
For solar panels manufactured in China and installed in countries like Germany, the maximum sustainable growth rate is only 16-23% (depending on solar insolation), roughly 3 times lower than the actual annual growth of the industry between 2008 and 2014. If we also take lithium-ion battery storage into account, the maximum sustainable growth rate comes down to 4-14%.

In other words, including energy storage further limits the maximum sustainable growth rate of the solar PV industry.

On the other hand, if we would produce solar panels in countries with very clean electricity grids (France, Canada, etc.) and install them in countries with carbon-intensive grids and high solar insolation (China, Australia, etc.), even off-grid systems with lithium-ion batteries would have GHG emissions of only 26-29 gCO2/kWh, which would allow solar PV to grow sustainably by almost 60% per year. This result is remarkable and shows the importance of location if we want solar PV to be a solution instead of a problem. Of course, whether or not there's enough lithium available to deploy battery storage on a large scale, is another question.

Battery Production Powered by Renewable Energy?
Another way to improve the sustainability of battery storage is to produce the batteries using renewable energy. For example, Tesla announced that its "GigaFactory", which will produce lithium-ion batteries for vehicles and home storage, will be powered by renewable energy. [23, 24]

To support their claim, Tesla published an illustration of the factory with the roof covered in solar panels and a few dozen windmills in the distance.

However, the final manufacturing process in the factory consumes only a small portion of the total energy cost of the entire production cycle -- much more energy is used during material extraction (mining). It's stated that the GigaFactory will produce 50 GWh of battery capacity per year by 2020.

Because the making of 1 kWh of lithium-ion battery storage requires 400 kWh of energy [16, 17, 18], producing 50 GWh of batteries would require 20,000 GWh of energy per year.

Tesla gigafactory

If we assume an average solar insolation of 2,000 kWh/m2/yr and a solar PV efficiency of 15%, one m2 of solar panels would generate at most 295 kWh per year. This means that it would take 6,800 hectares (ha) of solar panels to run the complete production process of the batteries on solar power, while the solar panels on the roof cover an area of only 1 to 40 ha (there is some controversy over the actual surface area of the factory under construction). Tesla's claim, though potentially factually accurate, is an obvious example of greenwashing -- and everyone seems to buy it.

There are other ways to improve the sustainability of solar PV when storage is taken into account. Most of these solutions require that solar systems remain connected to the grid, even if they have a (more limited) local storage system. In this scenario, chemical batteries could help to balance the grid system, acting as peak-shaving and load-shifting devices. The electric grid has to be sized to meet peak demand, and battery storage could mean that less power plants are needed for that.

Decentralized, grid-connected energy storage could also increase the share of renewables that the electricity infrastructure can handle. Of course, this "smart grid" approach should also be subjected to a life cycle analysis, including all electronic components.

Sources & Notes:
[1] Domestic and overseas manufacturing scenarios of silicon-based photovoltaics: life cycle energy and environmental comparative analysis. Dajun Yue, Fengqi You, Seth B. Darling, in Solar Energy, May 2014
[2] Energy Payback for Energy Systems Ensembles During Growth (PDF), Timothy Gutowski, Stanley Gershwin and Tonio Bounassisi, IEEE, International Symposium on Sustainable Systems and Technologies, Washington D.C., May 16-19, 2010
[3] "Current State of Development of Electricity-Generating Technologies: A Literature Review", Manfred Lenzen, Energies, Volume 3, Issue 3, 2010.
[4] "Storage is the new solar: will batteries and PV create an unstoppable hybrid force?", Stephen Lacey, Greentechmedia, 2015
[5] "Report: Solar Paired with Storage is a 'Real, Near and Present' Threat to Utilities", Stephen Lacey, greentechmedia, 2014
[6] "Australia to pilot new power plan", Gregg Borschmann, ABC, May 2014
[7] "SolarCity Launches Energy Storage for Business Using Tesla Battery Packs", Eric Wesoff, greentechmedia, December 2013
[8] "Solar Power & Energy Storage: Policy Factors vs. Improving Economics" (PDF), Morgan Stanley Blue Paper, July 28, 2014
[9] "Tesla announces home battery system", Slashdot, May 1, 2015
[10] "Utilities wage campaign against rooftop solar", Joby Warrick, The Washington Post, March 2015
[11] "Disruptive Challenges: Financial Implications and Strategic Responses to a Changing Retail Electric Business" (PDF), Peter Kind, Energy Infrastructure Advocates, Edison Electric Institute, January 2013
[12] "Life cycle assessment study of a 4.2kWp stand-alone photovoltaic system", R. García, in "solar energy", september 2009.
[13] You could argue that you also need more battery storage, because there is a bigger chance of cloudy days. However, we assume battery capacity to remain the same.
[14] "Optimal Sizing and Life Cycle Assessment of Residential Photovoltaic Energy Systems With Battery Storage", A. Celik, in "Progress in Photovoltaics: Research and Applications", 2008.
[15] "Energy pay-back time of photovoltaic energy systems: present status and prospects", E.A. Alsema, in "Proceedings of the 2nd World Conference and Exhibition on photovoltaics solar energy conversion", July 1998.
[16] "Towards greener and more sustainable batteries for electrical energy storage", D. Larcher and J.M. Tarascon, Nature Chemistry, November 2014
[17] "Application of Life-Cycle Assessment to Nanoscale Technology: Lithium-ion Batteries for Electric Vehicles" (PDF), Environmental Protection Agency (EPA), 2013
[18] "Energy Analysis of Batteries in Photovoltaic systems. Part one (Performance and energy requirements)" (PDF) and "Part two (Energy Return Factors and Overall Battery Efficiencies)" (PDF). Energy Conversion and Management 46, 2005.
[19] The lifespan of the lithium-ion battery will probably be closer to 14-16 years (float charge lifespan) because of the shallow cycling assumption in the original LCA. However, since the assumed lifespan of 10 years for the lead-acid batteries is very optimistic, and because deep cycling is more common for household off-grid systems, we assume that no replacement of lithium-ion batteries is needed.
[20] "The climate change mitigation potential of the solar PV industry: a life cycle perspective", Greg Briner, 2009
[21] "Optimizing Greenhouse Gas Mitigation Strategies to Suppress Energy Cannibalism" (PDF). J.M. Pearce. 2nd Climate Change Technology Conference, May 12-15, 2009, Hamilton, Ontario, Canada.
[22] "Towards Real Energy Economics: Energy Policy Driven by Life-Cycle Carbon Emission", R. Kenny, C. Law, J.M. Pearce, Energy Policy 38, pp. 1969-1978, 2010
[23] "Construction of Tesla's $5B solar-powered Gigafactory in Nevada is progressing nicely", Michael Graham Richard, Treehugger 2014
[24] "Tesla's $5bn Gigafactory looks even cooler than expected, will create 22,000 jobs", Michael Graham Richard, Treehugger 2015


Low Tech living post Peak Oil

SUBHEAD: Practical solutions to living in a sustainable world that might avoid disastrous Climate Change.

By S. Alexander & P. Yacoumis on 29 July 2015 for Resilience -

Image above: Achieving a low-tech simpler lifestyle within the framework of a failing high-tech culture. The art work of Ethan Hayes on display. From (

Energy is often called the ‘lifeblood’ of civilisation, yet the overconsumption of fossil energy lies at the heart of two of the greatest challenges facing humanity today: climate change and peak oil. While transitioning to renewable energy systems is an essential ‘supply side’ strategy in response to climate change and peak oil, the extent of the problems and the speed at which decarbonisation must occur means that there must also be a ‘demand side’ response. 

This means consuming much less energy not just ‘greening’ supply, at least in the most developed regions of the world. In that context, this paper provides an energy analysis of various ‘low tech’ options – such as solar shower bags, solar ovens, washing lines, and cycling  – and considers the extent to which these types of ‘simple living’ practices could reduce energy consumption if widely embraced. We demonstrate that low-tech options provide a very promising means of significantly reducing energy (and water) consumption.[1]

1. Technology Fetishism
All problems have hi-tech solutions. This is one of the defining assumptions of our technocratic, industrial civilisation, and yet it is an assumption that seems to be failing on its own terms. As the world continues to celebrate the most ‘advanced’ and ‘profitable’ technologies, we find our ecosystems being degraded and our communities fragmented more so now than ever before.

Unfortunately, it seems that technology often just helps us get better at doing the wrong things, or the right things in unnecessarily harmful, energy-intensive ways.

Without denying the obvious benefits of many advanced technologies – such as the Internet, medical procedures, labour-saving machinery, etc. – humanity must nevertheless develop a more critical understanding of the costs of our technologies, costs that are often hidden or indirect, escaping our notice as we marvel at the latest invention. It is naïve to think that advanced technologies can solve all societal problems, and yet this naivety permeates contemporary understandings of what ‘progress’ and ‘sustainable development’ mean (Huesemann and Huesemann, 2011).

The most pernicious consequence of this blind faith in technology is that it deflects attention away from the need to rethink our lifestyles, our economic structures, or our systems of governance, because it is assumed that technology will solve our problems without the perceived inconvenience of having to change the way we live. In this light, technology becomes an ethical void, one in which our societies are expected to become just and sustainable, without us having to live justly or sustainably ourselves. Even ethical problems are assumed to have hi-tech rather than behavioural solutions. This is techno-fetishism.

But what is technology? Technology can be defined simply as any tool, invention, technique, or design that assists in achieving certain goals. It follows that even the most primitive human societies were, in a sense, technological.

The prehistoric tribes that used fragments of stone to create axes were developing technology, just as the engineers that design spacecraft today are. Technology is a broad term, therefore, and so it makes no sense to be either for or against technology without stating what types of technology are being considered. Moreover, technology can only be judged according to some goal or end that the technology is supposed to help us achieve.

A technology may be very good at achieving a certain goal, but if the goal is dubious or comes at too great a cost, then the technology’s appropriateness is questionable, no matter how effectively or efficiently it achieves that goal. In fact, when the goal is misconceived, the effectiveness or efficiency of a technology is more of a flaw than a feature.

Technology, in short, is a means to an end. This calls on us to assess the ends that our technologies are serving, and not merely get lost admiring the often dazzling means. As Henry Thoreau said: ‘Our inventions are wont to be pretty toys, which distract our attention from serious things. They are but improved means to an unimproved end’ (Thoreau, 1982: 306).

Granted, we have become very good at cutting down rainforests and emptying the oceans in the pursuit of economic growth and more affluent lifestyles, using machinery and techniques that would have amazed earlier generations. It is not clear, however, whether all such inventions have been a positive advance. Just because we can do something does not mean that we should.

Have our communities, for example, been enriched by Facebook? Or is there more alienation today than ever before? Should the development and refinement of ‘fracking’ techniques be considered progress? Or are they merely feeding an addiction to fossil fuels and hastening climate disruption? Instead of saying that all problems have hi-tech solutions, perhaps it would be closer to the truth to say that many of our greatest problems have hi-tech causes.

At least, advanced technology has allowed our misguided ethics to devastate the biosphere in unprecedented ways. As we continue to degrade our planet ever more efficiently, and live in the shadow of nuclear weapons that still threaten to turn on us, homo sapiens may come to be described as the species that was more clever than wise; the species that chose to destroy the foundations of its own existence, spellbound by its own technological power but lacking the maturity to wield it responsibly.

Despite the ominous dark side of many of our inventions, many people still think that the problems we face are not because of too much advanced technology, but too little (see, e.g., Nordaus and Schellenberger, 2011).

Entranced by the many wonderful inventions that have genuinely advanced the human situation, techno-optimists think that all our problems therefore must have hi-tech solutions (for a critique, see Alexander, 2014a).

Geo-engineering is perhaps the most perverse example of this techno-fetish – a so-called ‘solution’ to climate change that risks causing greater problems without necessarily stabilising the climate (see generally, Hamilton, 2013). But geo-engineering is merely an extreme example of a more insidious and generalised zeitgeist.

The underlying assumption, once more, is that we do not need to change our ways of living or capitalist structures to solve our environmental and social ills. Instead, it is assumed that we must simply get better at forcing nature to do what she is told through the application of technology within a market-based society.

In an age so enamoured with hi-tech thinking, any consideration of low-tech solutions – which are the focus of this essay – will immediately be dismissed by some as being ‘Luddite’.

By ‘low-tech’ we refer to things such as cooking with solar ovens, showering under solar shower bags, drying clothes on a washing line, keeping warm with a woollen jumper rather than a heater, even using a bike instead of driving.

Regrettably, it is often considered an affront to human ingenuity to think that we cannot solve all problems with technological innovation and application. Low-tech is reproached as being primitive or ‘just for hippies’.

But could it be that various low-tech options are actually more civilised, all things considered, than some of their hi-tech replacements?

Could ‘advancement’ or ‘progress’ today actually involve a move toward, rather than away from, some low-tech alternative technologies? These are some of the questions we explore in this essay by attempting to assess the potential energy savings of various low-tech options. By doing so we hope to understand the extent to which a society could reduce its energy consumption if various low-tech options were broadly embraced.

It is important to point out at once that the following review of low-tech options must not be interpreted to be a blanket rejection of appropriate hi-tech options. The key word there, of course, is ‘appropriate’ (see Schumacher, 1973). There is surely a place for hi-tech innovations like solar PV and wind turbines, and arguably computers should or could be a part of the good, sustainable, interconnected society (although let us not forget that life went on well enough without computers not so long ago).

Without doubt, many medical treatments are genuine ‘goods’ also, and the list could go on. We must not throw out the baby with the bathwater.

But this essay attempts to examine with some analytical rigour the question of whether, or to what extent, various low-tech options provide an effective and available means of reducing energy demand. In an age when the overconsumption of energy underlies some of our most pressing problems – climate change and peak oil, in particular (as outlined below) – it should be clear that this analysis is about looking forwards, not backwards.

2. Living in an Age of Limits
Before beginning the substantive analysis we wish to outline the broad context in which this analysis takes place. First and foremost, this means acknowledging that we are living at the ‘limits to growth’ (Meadow et al, 2004; Turner, 2012). If once we lived on a relatively ‘empty’ planet, that planet is now ‘full’.

There are now more than seven billion people trying to live on a planet that has declining biocapacity (Global Footprint Network, 2013). Indeed, we are living in an age frequently described by scientists as the Anthropocene, signifying the first geological epoch that has been induced by human impacts on the planet. Geological timeframes are normally measured in millions or tens of millions of years, but the Anthropocene refers merely to the last three hundred years of industrialisation.

During this geological blink-of-an-eye, humanity has degraded Earth’s ecosystems in unprecedented ways and at unprecedented speed. Among a host of other ecological aberrations, this has induced what has been called ‘the sixth great extinction’ (Kolbert, 2014). Over the last 40 years we have destroyed over 50% of Earth’s vertebrae wildlife (mammals, birds, reptilians, amphibians, and fish) (WWF, 2014).

As George Monbiot (2014) asks: ‘Who believes that a social and economic system which has this effect is a healthy one? Who, contemplating this loss, could call it progress?’ Strangely, the last few decades are in fact widely considered a time of great progress, despite this continuing holocaust of biodiversity. It seems the dominant conception of progress is deeply flawed.

Humanity’s impact has been so devastating because fossil fuels have given us extraordinary powers, at a time when our ethical vision has been narrow and short-sighted. With this one-off inheritance of dense, stored, non-renewable energy, we have been able to use machines and other technologies and techniques to do things we simply could never have done without a cheap and abundant supply of energy.

But this power has come at a devastating ecological cost. Not only is global capitalism destroying the ecological foundations of the planet’s declining biodiversity, but the vast amount of carbon being emitted into the atmosphere is destabilising the climate in ways that is threatening the viability of the planet for human civilisation.

urrent trends suggest we are facing a future 4°C hotter or more by 2100 (Potsdam, 2012; Christoff, 2013), which climate scientist Joachim Shellnhuber argues could reduce the carrying capacity of the planet to below one billion people (Kanter, 2009). This presents us with a foreseeable moral tragedy almost unfathomable in its enormity. We may try to understand this scenario intellectually, but it is doubtful whether there are any among us with the emotional capacity to truly absorb the meaning of it (Gardiner, 2011).

In international climate negotiations, it has been agreed that humanity must avoid a temperature rise of more than 2°C above pre-industrial levels (UNFCCC, 2011). For this goal to be achieved, however, it has been shown that the wealthy ‘Annex 1’ nations need to decarbonise their economies by 8-10% p.a. over coming decades, starting immediately (see Anderson, 2013).

The problem is that historically, long term emissions reductions of more than 1% p.a. have been associated with recession (Stern, 2006), and while surely greater reductions could be achieved if we seriously planned for decarbonisation, it nevertheless seems clear enough that reductions of 8-10% year on year are incompatible with continued economic growth (for the details of this argument, see Alexander, 2014b).

The basic reasoning here is that decarbonising by 8-10% p.a. will mean a significant reduction in overall energy consumption, and given the close connection between energy and the economy (Ayres and Warr, 2009), an economy cannot continue growing in terms of GDP while also reducing energy consumption so significantly.

Therefore, effectively responding to climate change means transcending the growth paradigm that has defined industrial civilisation and embracing ‘degrowth’ strategies of planned economic contraction.

Not only does this mean transitioning to renewable energy systems and producing goods and services more efficiently, which can be understood as ‘supply side’ responses. It also requires that the most developed regions of the world simply consume less energy and resources, which is a ‘demand side’ response that must supplement ‘supply side’ strategies.

As well as climate change, there is also the looming problem of peak oil (and other peak resources). Peak oil refers to the point at which the rate of oil production cannot be increased (whether for geological, economic, or political reasons, or some mixture of such reasons).

When this happens, and while oil demand continues to grow, the price of oil will inevitably increase. In fact, this is the dynamic we have seen unfolding since the mid-2000s, when the growth of conventional crude oil began to plateau (Alexander, 2015), forcing producers to extract unconventional oils that are far more expensive due to their lower energy returns on investment (Murphy, 2014).

Oil, however, is often called the ‘lifeblood’ of industrial economies, and when it gets expensive, everything dependent on oil (which is pretty much everything) gets more expensive too. This begins to suffocate oil-addicted economies, as there is less and less discretionary income to spend paying back our debts, or to consume in ways that help grow our economies. And when debts do not get paid back, and when growth-based economies do not grow, life begins to fray in undesirable ways (see, e.g., Tverberg, 2012).

Many analysts think that this process of civilisational deterioration is already underway (see Heinberg, 2011; Gilding, 2011; Greer, 2008), a process that is likely to intensify in coming years as oil becomes scarcer; as climate change worsens; and as the broader limits to growth tighten their grips on the global economy (Turner, 2012). In this broad context, the notion of ‘deindustrial’ civilisation can be better understood. It refers to an industrial civilisation in the process of deteriorating or collapsing as the supply of cheap and abundant fossil energy comes to an end, fundamentally changing the conditions of development.

Deindustrialisation can also refer to the voluntary process of building a new, low-carbon civilisation as a means of dealing with energy descent and turning crisis into opportunity. That latter definition can sit within the former, and this paper is based on the view that low-tech living will become increasingly necessary as industrial civilisation continues its inevitable decline.

There is one point deserving of further emphasis. In response to the problems of climate change and peak oil, many people naturally hold up renewable energy as the salvation of civilisation, arguing that all we need to do is transition to renewable energy and the problems of peak oil and climate change will be resolved.

The problem is that it is highly doubtful that renewable energy will ever be able to sustain a growth-orientated, industrial civilisation. Although it may be technically feasible from an engineering perspective, the problems of intermittency and storage make renewable energy supply much more expensive and problematic than most analysts think (see Moriarty and Honnery, 2012; Trainer, 2013a; Trainer, 2013b).

Even if electricity could be affordably supplied by renewables, electricity only constitutes about 18% of final energy consumption (IEA, 2012), meaning that there is still around 82% of energy to replace, including oil used for transport, pesticides, and plastics, etc. If we try to produce that remaining segment of energy with biofuels, the production of biofuels would compete with land for food production, a conflict that also seems to be already underway, despite the relatively low levels of biofuels production today (Timilsina, 2014).

Biofuels also have a very low energy return on investment – between 1 and 3 (Murphy, 2014: 12), suggesting that they will never be able to sustain an industrial civilisation, as we know it today.

What all this means is that responding to today’s energy, economic, and ecological crises is not simply a matter of transitioning to renewable energy systems, necessary though that is. It also requires that we (in the developed world) simply consume far less energy.

Given the close relationship between energy and economics, a radical reduction in energy consumption implies embracing a post-growth macroeconomic framework and materially sufficient but non-affluent ways of living (see Alexander, 2013a; Trainer, 2010).

Again, this radically new way of life should be understood in a context of deindustrialisation, which involves trying to retain the best parts of the existing civilisation, and creatively using its existing products and waste streams, while eliminating (or letting wither away) those parts that simply cannot be sustained in an energy and resource constrained world (see Holmgren, 2012; Greer, 2009).

While this will involve using the most appropriate forms of advanced technologies to help us decarbonise our economies, the equally important but neglected part of the equation involves a deep behavioural shift away from high-consumption, energy-intensive ways of living.

We do not, however, assume that mere ‘lifestyle’ responses to climate change and peak oil are enough to address those problems. The subtext of our analysis is that the revolution that is needed must begin with individuals and communities prefiguring a ‘simpler way’ to live and beginning to build the structures that support that way of life (Trainer, 2010). The relevance of low-tech living therefore goes beyond its immediate energy and water savings, significant though they are.

Low-tech living can also play a part in creating the cultural conditions needed for the fundamental structural transformation of our economies to take place (Alexander, 2013b).

For present purposes, the essential point can be summarised as follows. Addressing the world’s problems cannot simply be solved from the ‘supply side’. That is, we cannot just transition to renewable energy and more efficient productive processes and expect the growth model of global capitalism to persist more or less as usual. Rather, we also need to consume far less energy and resources – that is, we must confront our problems from the ‘demand side’ too. This is the essential framework within which the following analysis takes place.

Low-tech options are being considered in this paper as a means of reducing energy consumption from the ‘demand side’. It will also be seen that low-tech options can lead to significant water savings, which, along with energy savings, is a necessary part of a sustainable way of life (for a justification for water conversation, see Brown, 2011). We show that low-tech options are full of potential and should be receiving far more attention than they do. They also provide paths to increased resilience – the ability to withstand shocks – in ways that will be explained.

3. A Review of Low-Tech Living
Having outlined why energy consumption must be reduced, the analysis will now explore various low-tech options that have the potential to assist in that critically important societal goal. This is particularly relevant to the energy-intensive lifestyles prevalent in the most highly developed regions of the world, but they are also relevant to the poorer parts of the world.

With respect to the latter, the argument is not so much that they need to reduce energy consumption so much as they should embrace low-tech as one means of escaping the conventional development path that is in the process of ‘locking’ them into high-carbon, industrial modes of existence.

The following review will consider such low-tech options as solar shower bags, hand-washing clothes, washing lines, simple warming and cooling techniques, cycling, solar ovens, non-electric fridges, composting toilets etc., in the attempt to understand the extent to which these options could help achieve the goal of minimising energy consumption, if they were broadly embraced across a culture.

Low-tech can also refer simply to behaviour change, as opposed to relying on technological solutions of any variety. While much has been written on low-tech or alt-tech options, the following analysis represents the first attempt to quantify with some analytical rigour the potential energy savings of a range of such options. We hope that over time these tentative figures and analyses can be refined, updated, and expanded upon.

A few words on methodological issues are required. As will be seen, some of the low-tech options below are more or less effective depending on weather conditions. For example, a solar shower bag will be more effective (and much more pleasant!) in warmer months or regions, and non-electric fridges may be more effective over a longer period in cooler months or regions.

What this means is that an analysis of low-tech options is ultimately context-dependent, and this means universal statements cannot always be made with much confidence. Nevertheless, by clearly stating the assumptions of the analysis, we provide the methodological framework for this type of analysis to be applied in various contexts.

Furthermore, although this type of analysis is ultimately context-dependent, there will obviously be much overlap between contexts, insofar as most regions of the world, to varying degrees, have something resembling the four seasons. Indeed, we have chosen Melbourne, Australia, as the case study for the following analysis precisely because it is a good example of a region that has four seasons (and also because it is our home region, which means we have been able to personally test and apply the following low-tech options).

Finally, the fact that different regions of the world have different weather patterns does not mean that the final energy conclusions from the analysis are only relevant to Melbourne. This is because there is something of a balancing effect that flows from different weather patterns.

For example, a region that has more hot days each year than Melbourne might allow solar shower bags to be used more often, while this warmer region might not be able to use a non-electric fridge so effectively; similarly, a region much cooler than Melbourne may be able to use a non-electric fridge for more months of the year (or all year), but find it more difficult to use solar shower bags. Not only that, several of the low-tech options (e.g. composting toilets) are not usually linked to weather patterns at all, meaning that the analysis is more or less universally applicable.

For these reasons, we would argue that the analysis below, while often shaped by a particular context, is of more general significance. As will be seen below, each of the low-tech options considered also requires more specific methodological assumptions, which will be stated as the analysis proceeds.[2]

We begin our investigation by calculating a baseline ‘reference’ scenario for each of the technologies discussed; that is, what might be considered the ‘typical’ use of the conventional technology in the Melbourne area today. Our reference household is a unit or semi-detached dwelling situated in the inner-northern suburbs and has two occupants, the most common occupancy rate in greater Melbourne.[3]

We conduct our calculations using publicly available data on appropriate usage metrics related to each technology under consideration (discussed on a per-technology basis below). We then develop multiple scenarios representing varying levels of adoption of the low-impact technologies discussed, and calculate the energy and water consumption under each scenario. These ‘alternative’ scenarios range from moderate to radical levels of low-tech adoption, which are also described on a per-technology basis.

Finally, we compare the reference and alternative scenarios to calculate the potential water and energy savings afforded by adoption of the various low-tech options.

The following analysis is intended to be illustrative of potential solutions in a general sense. We will, however, present our assumptions and the sources used to inform them.

3.1 Showering
The conventional method of showering is to heat water with electricity or gas. But using electricity or gas is unnecessary on warm days when water can be heated directly from the sun. Most readers will be familiar with ‘solar shower bags’, often used when camping, which are black plastic or canvas bags that are filled with water and heated in the sun. After a few hours in the sun the water is warm enough to use for a comfortable shower, without requiring energy inputs other than free, zero-carbon sunlight. But why should solar shower bags only be used when camping?

In the reference scenario, based on conventional methods of showering, we assume an average shower duration of 5.6 minutes[4] and an average flow rate of 6.5 litres per minute[5] (L/min), giving us an average of 36 litres of water use per shower. In line with actual observations, we assume occupants shower 5.6 times per week on average.[6]

A reasonable estimate is that half (18L) of the water used for showering is heated.[7] Assuming the household hot water system must heat water by 45 degrees Celsius to reach the set thermostat temperature of 60 degrees,[8] and that the water is heated with a ‘task efficiency’ of 73% (using an electric storage system),[9] we estimate that the end-use energy consumption for a single shower is 1.3 kilowatt-hours (kWh).

In terms of the alternative scenarios, we also make several assumptions. We suppose, firstly, that 20L is a sufficient volume of water when using the solar shower – a reasonable estimate based on personal experience.[10]

We recognise that weather conditions can render a solar shower either uncomfortable or impossible on some days, so we consider only days between October and April (the warmer months in Australia), with a maximum temperature over 22 degrees Celsius, and with more than 4 hours of sunlight, as suitable for the purposes of solar showering. According to the Australian Bureau of Meteorology, these criteria yielded 108 suitable days for solar showering in Melbourne over the 2013-2014 period.[11] For simplicity, we assume that whenever a solar shower is possible (108 days), it will be taken.

The reference scenario yielded a result of 21,199 litres of water and 851 kWh of energy consumed by our two-person household annually. Five alternative scenarios are described as follows:
· Moderate 1: Reducing shower time to 3 minutes with no use of a solar shower.
· Moderate 2: Using a solar shower, when possible, but showering regularly otherwise.

· Strong 1: Using a solar shower, when possible, and reducing shower time to 3 minutes otherwise.
· Strong 2: Using a solar shower, when possible, otherwise reducing shower time to 3 minutes, and reducing shower frequency by one-third (equivalent of showering around 4 times per week).
· Radical: Using a solar shower, when possible, otherwise reducing shower time to 3 minutes, and reducing shower frequency by two-thirds (equivalent of showering around 2 times per week).
The results, based on a two-person household, are summarised below in Table 1:

Annual water saving (L)

Annual water saving (%)

Annual energy saving (kWh)

Annual energy saving (%)

Moderate 1





Moderate 2





Strong 1





Strong 2






< 82%


Table 1: Potential water and energy savings from low-tech showering practices

It is clear that changing our showering behaviour, in terms of shower duration and frequency, has an enormous impact on our water and energy consumption. Under the ‘radical’ scenario our two-person household is saving over 17,000 litres of water per year, and reducing shower-related energy consumption by nearly 90%.

An interesting point to note is that reducing shower time to 3 minutes, without using a solar shower, actually saves more water and energy than simply replacing conventional showers with a solar shower, when possible. Nevertheless, the low-tech solar shower bag clearly provides a way to save significantly more energy and water when combined with taking shorter and less frequent showers.

3.2 Heating
Conventional heating methods involve using gas or electricity to heat living areas. Low-tech alternatives can reduce the need for such energy-intensive heating methods by wearing woollen clothing, insulating one’s home well, and, when heating is deemed necessary, heating fewer spaces.

Our reference household is equipped with a wall-mounted gas space heater. A commonly accepted value for average household heating demand is 0.1 kW per square metre,[12] which we adopt in this paper. We assume heating is required in an area of the house with a floor area totalling 60 square metres. According to the Australian Bureau of Statistics most Victorian households use heating for more than 3 months, but less than 6 months, of the year.[13]

We take a baseline of 150 days (approximately 5 months) as our reference scenario and assume that the heater is in operation for an average of 8 hours on each of these days. In addition, based on SA government figures, we assume a heater efficiency of 75%. We acknowledge that insulation varies greatly in housing across Melbourne, as does the health status of individuals, so we leave scope for the necessity of artificial heating in times of temperature extremes.

This reference scenario sees our household consuming 9,600 kWh of energy annually for heating, a figure that aligns closely with CSIRO estimates.[14] Three alternative scenarios are described as follows, all of which assume appropriate clothing:
· Moderate: Insulating house well, and halving the amount of time each day heating is used (i.e. 3 hours instead of 6).
· Strong: Insulating house well, heating only on days between May and September (Australian winter) with a maximum temperature below 15 degrees Celsius (41 days in total for 2014, according to the Bureau of Meteorology), and halving the amount of time heating is used on these days.
· Radical: Insulating house well, heating only on the 10 coldest days, and halving the amount of time heating is used on these days.

The results are summarised in the following table:

Annual energy saving (kWh)

Annual energy saving (%)



< Strong





Table 2: Potential energy savings from low-tech heating practices

From this analysis we see that we can save upwards of 90% of our energy consumption for heating space by simply adopting the humble sweater as our modus operandi in order to keep warm, rather than relying on energy-intensive heating appliances. This would obviously require a ‘reframing’ of our attitudes to keeping warm, but if that inner work was done (see generally, Burch, 2013) then staying warm in a low-carbon world would be achievable in many climates without hardship.

Well-designed, passive solar houses with good insulation would also assist greatly. Other low-tech heating options include highly efficient rocket stove thermal mass heaters, which could be especially useful in colder regions of the world. But the best place to start is with appropriate clothing (Havenith, 1999).

3.3 Cooling
The conventional means of cooling houses on hot days is to use air-conditioners, which are energy-intensive to operate. Low-tech and low-energy alternatives exist, such as closing curtains or blinds to keep the sun out, or using simple fans rather than air-conditioners. 

Data made available by the South Australian government suggests that ducted evaporative air conditioners consume approximately 1.5 kW of energy and 24 L of water every hour on average,[15] which we take as representative of the Victorian context also. According to the Australian Bureau of Statistics almost half of all Victorian households use their air conditioners between 1 and 3 months of the year.[16] We take a point of 60 days as our reference scenario and, in addition, assume that the air conditioner is in operation for an average of 6 hours on each of these days.

For the low-tech scenarios, we assume a mid-range value of energy consumption for ceiling and portable fans based on SA governments data (0.0667 kW per hour). In calculating the use of fans, we assume our occupants require 3 rooms to be artificially cooled. We acknowledge that insulation varies greatly in housing across Melbourne, as does the health status of individuals, so we leave scope for the necessity of artificial cooling in times of temperature extremes.

The reference scenario sees our household consuming 540 kWh of energy and 8,640 litres of water annually to cool the house in hot temperatures. Three alternative scenarios are described as follows:
· Moderate: Using blinds as insulation from sunlight/external heat, and halving the amount of time each day air conditioning is used (i.e. 3 hours instead of 6).
· Strong: Using blinds as insulation and air conditioning only on days with a maximum temperature above 35 degrees Celsius (10 days in total for 2014, according to the Bureau of Meteorology).
·  Radical: Using blinds as insulation, and fans instead of air conditioning on days above 35 degrees Celsius.

The results are summarised in the following table:

Annual water saving (L)

Annual water saving (%)

Annual energy saving (kWh)

Annual energy saving (%)
















Table 3: Potential water and energy savings from low-tech cooling practices

We can see that, by significantly increasing our reliance on blinds to keep out heat and restricting our reliance on air conditioning to days when temperatures soar, we can reduce our cooling-related energy and water usage by well over three-quarters. Moreover, if we choose fan cooling instead of air conditioning on such days, we eradicate nearly all cooling-related energy and water consumption.

3.4 Drying clothes
The conventional way to dry clothes is to use an electric clothes dryer, which is very energy-intensive. A low-tech alternative is to use a simple washing line to dry clothes outside.

According to Sustainability Victoria, the average dryer use by Victorian households is 78 cycles per year, or 1.5 cycles per week.[17] Taking a mid-range approach to their energy data, we calculate an average per-cycle energy consumption of 4.6 kWh, and an annual energy consumption of 359 kWh, which represents our reference scenario.

Three alternative scenarios are described as follows:
· Moderate: Reducing electric drying to the four coldest and wettest months of the year, and using a clothesline otherwise.

· Strong: Running the dryer for only five cycles per year (say, on the wettest and coldest days), and using a clothesline otherwise.
· Radical: Using a clothesline only throughout the year (some days may necessitate indoor clothes drying racks).
The results are summarised in the following table:

Annual energy saving (kWh)

Annual energy saving (%)










Table 4: Potential energy savings from low-tech clothes drying practices

The decision to dry clothes by clothesline rather than electric dryer can save a significant amount of energy, up to 100% if adopted as a complete replacement. From experience we know this can be achieved without hardship in Melbourne. At most it requires some planning in winter to ensure that washing is done on sunny days.

3.5 Television
The conventional way to spend leisure is to watch many hours of television each day, often on large, energy-intensive plasma screens. The low-tech alternative is to turn off the TV and spend leisure in ways that do not depend on energy-intensive technologies (e.g. reading a book, playing the guitar, talking with friends, doing craft, etc.).  

Our reference scenario assumes two televisions in the household, reflecting the national average[18], both of which are 32 inch LCD screens (the most popular TV in terms of sales in 2009).[19] The average number of hours of TV each occupant watches in the house also reflects the national average: approximately 3 hours per day.17 Energy consumption for a TV in use is estimated at 0.15 kW,17 and standby energy consumption is 0.001 kW.16

We have assumed the occupants watch 2 hours of TV together, plus one hour separately each day. This equals a daily total of 4 hours of TV operation. The reference scenario energy consumption therefore totals 235 kWh per year.

Three alternative scenarios are as follows:
· Moderate: Halving TV watching time, but keeping TVs in standby mode when not in use.
· Strong: Watching only 5 hours per week, and switching TVs off at wall when not in use.
· Radical: Removing TVs altogether (or watching negligible amounts).

The results are summarised in the following table:

Annual energy saving (kWh)

Annual energy saving (%)




< 196.06




Table 5: Potential energy savings from low-tech (non-television) leisure activities  

It’s clear that reducing TV watching time is a much more effective energy-saving behaviour than simply ensuring the TV is switched off at the wall when not in use. Not only would this transition reduce energy consumption directly, it would also mean less exposure to consumerist messages from advertising that promotes energy-intensive lifestyles. This means there would likely be indirect energy savings too.

3.6 Driving
The conventional means of transporting ourselves to and from work and leisure activities is to drive in a private motor vehicle. In many parts of the world, however, there are public transport options available, as well as the option of cycling. Shorter trips could be walked.  

Perhaps the most involved analysis, the following calculations largely draw on ‘average usage’ statistics for private vehicles and public transport (PT) published by the Victorian Government Department of Transport and the Public Transport Users Association. Many of these details, while crucial to our calculations, are not vital for describing the various scenarios, and so will be included only in the Appendix.

There are several assumptions that we should note at this stage, however, to set the context for our reference scenario. We are first assuming that both our occupants are of working age, own a car each, and drive to work separately. We assume that each work trip is a 16km round trip, half of all trips made are shorter than 5km (corresponding closely with data for Melbourne published by Deakin University),[20] and of those shorter trips the average is 3km.

The total distance each occupant travels per day is 33 kilometres, 83% of which is by car and a further 12.5% by a mix of PT modes – bus, train and tram. Some trips are shared. We also assume that a greater shift to cycling and PT is feasible for the occupants of our household, which is not unreasonable for most inner-suburban residents in fair health.

The reference scenario for our household yields an annual energy consumption of 18773 kWh for transport, which is one of the largest contributors to household energy consumption.

Three alternative scenarios are described as follows:
· Moderate: Switching to public transport for all work trips.
· Strong: All trips under 5km are walked or cycled, a car is used for one trip per week (an average of 5km per week) by each occupant, public transport is used for all other trips.
· Radical: Shared car usage totalling 100km over the course of a year, all other trips are walked or cycled.
The results are summarised as follows:

Annual energy saving (kWh)

Annual energy saving (%)
< Moderate








Table 6: Potential energy savings from low-tech transport practices

We can see that even with a modest change to our travel decisions – for example, shifting from private vehicle to public transport for work trips only – we can potentially save a significant amount of fossil fuel energy. By choosing the bicycle as our preferred mode of transport we are able to realise an even greater energy benefit.

3.7 Five Other Low-Tech Options (in brief)
The above analysis has demonstrated that low-tech options can lead to huge energy and water savings, depending on the degree to which they are adopted. 

We conclude this part of the analysis with a more conceptual discussion of several more low-tech options, which in the future could also receive the same type of analysis we have undertaken above.

For present purposes, we simply highlight some of the more interesting and promising options:
· Solar ovens / parabolic solar dishes: The conventional means of cooking food is with gas or electric ovens and stoves. Solar ovens and parabolic solar dishes provide a hugely promising means of replacing those methods, on suitable days, using free energy from the sun and without hi-tech PV solar panels.
· Fridge / Freezer: The conventional means of keeping food sufficiently cold or frozen is to use a fridge and freezer, both of which are energy intensive. However, in many parts of the world, including Melbourne, the winter months are sufficiently cold to keep food from spoiling too quickly without a fridge, and there are other low-tech options that can help keep food for longer even in warmer months and warmer regions of the world (e.g. evaporative coolers). Behavioural and dietary changes (e.g. eat less meat and dairy or purchase meat on the day it is to be consumed) can also make it easier to turn off your fridge/freezer. While this low-tech option may indeed find fewer supporters than the others, we nevertheless feel this deserves to be included because the fridge-freezer is a significant category of energy consumption in the household. This also challenges us to think through whether we could cope well enough even if something as seemingly indispensable as a fridge-freezer were not available. It can be helpful to remember that the fridge/freezer is a relatively new innovation, and many of our ancestors survived without one.
· Hand washing clothes and dishes: The conventional means of washing clothes and dishes is to use an electric washing machine. Dishes can be washed by hand, and clothes can be washed in a tub with a manual agitator, especially in the warmer months when a spin-dryer is not necessary.
· Organic food: Industrial methods of food production and global distribution are incredibly complex and energy-intensive. Local, organic food production – a low-tech option which was used throughout history – is far less-energy intensive, but does require more human labour. Any transition to a low-carbon world is going to require industrial and globalised methods to be replaced by local and organic methods (Jeavons, 2012).
· Composting toilets: Following on from the last point, in order to replace the fossil-fuel dependent fertilisers used widely in industrial food production today, we are going to need a huge increase in organic fertilisers. One promising low-tech option is to compost human waste for ‘humanure’ via composting toilets (see Jenkins, 2005). Currently most people conceive of human waste as a problem, but it could be part of the solution if we compost it responsibly. This would significantly reduce or eliminate the need for fossil-fuel dependent fertilisers as well as hugely reduce or eliminate the amount of water required in flushing toilets. As these systems become universally adopted, we would also lessen the need for complex and centralised sewage infrastructure that currently depend on fossil fuels.

4. Conclusion
Although the analysis above has much room for refinement and development in context and household specific ways, it has been demonstrated that what we have called low-tech options have the potential to significantly reduce the energy intensity (and water intensity) of our ways of living. 

Our personal experience practising all of these low-tech options at times, many of them often, and some of them always, also gives us confidence that the results above are broadly correct. Indeed, when low-tech ‘demand side’ strategies are applied in conjunction with hi-tech ‘supply side’ strategies (e.g. solar PV), our personal experience confirms that people can be net-producers of renewable electricity, provided ordinary consumption of electricity is significantly reduced.

Moreover, we know that this can be done without diminishing quality of life, although low-tech practices do often demand a greater time investment than their conventional alternatives, which can call for broader lifestyle changes to accommodate this increased time commitment.

Adopting low-tech options certainly requires a rethinking of conventional practices and attitudes, but if we are serious about a ‘demand side’ response to climate change and peak oil – which is a necessary part of any effective response – then these low-tech options are likely to be a critical part of any future adaptation to an energy descent context.

Many people will resist this conclusion, no doubt, and insist that we can universalise the conventional ‘affluent’ ways of living as well as create a post-carbon world. But this is an unjustifiable assumption, which may arise in part from a blind faith in technological solutions or perhaps from a natural human aversion to change. A post-carbon world, however, means a world far less energy-intensive than developed regions of the world, and transitioning to such a world probably implies, whether we like it or not, the embrace of some low-tech options.

Importantly, these low-tech options deserve consideration not just as a means of voluntarily responding to climate change and peak oil. They can also be seen as ways of becoming more resilient in circumstances of economic shock, recession, disruption or collapse, where it may be that the conventional ways of living simply aren’t available or affordable (see De Young and Princen, 2012). In other words, the low-tech options demonstrate ways to adapt to challenging circumstances, even if they are not freely chosen in advance.

Of course, it would be far better to begin working toward these low-tech options now, because prevention of energy crises would be more desirable than dealing with them when they arrive. Accordingly, we ought to be giving these low-tech options more consideration now, because energy and economic crises are already unfolding, and deeper crises seem to be on the horizon (Friedrichs, 2013; Turner, 2012; Gilding, 2011).

This analysis sits in the broader context of a world facing social and environmental crises that cannot be solved within consumer capitalism. Low-tech options are part of an alternative vision of progress that involves rejecting affluent lifestyles for environmental and social justice reasons, and moving toward a ‘simpler way’ of life based on material sufficiency, highly-localised economies, and self-governing communities (see Trainer, 2010; Alexander, 2012; Alexander, 2013a).

Our argument must not, however, be interpreted as a blanket rejection of advanced technology, which certainly has its place. Nor have we argued that the energy crises we face have mere ‘lifestyle’ solutions. There are a great many structural issues that must be addressed too.

But we hope this analysis helps provoke a broader conversation about which technologies are ‘appropriate’ for our times. When the humble washing line is compared with the electric clothes dryer, one can certainly sympathise with Leonardo Da Vinci’s famous decree: ‘Simplicity is the ultimate sophistication.’

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Some key assumptions in calculating transport scenarios are provided below for transparency.

The public transport mix used by our household occupants is assumed to be: 10% distance travelled by bus, 40% by train and 50% by tram. This appears to be a reasonable estimation based on local usage of these transport modes. Moreover, different PT mixes yield similar results in terms of energy savings due to the vast difference between private vehicle and PT energy consumption per passenger.

We have assumed zero energy consumption for walking and cycling. Of course, this is not strictly true, as our bodies require energy to undertake these activities. However, such activities consume an essentially negligible amount of energy when compared with fossil fuelled transportation.

Furthermore, we argue that as the body requires a certain level of physical activity to remain healthy, much of the energy consumption for these ‘manual’ forms of transport could be considered necessary and even beneficial for maintaining basic human health, and thus might best be excluded from such an analysis.

Some key figures drawn from the Department of Transport’s 2009 VISTA survey:[21]

Average number of trips per occupant per day = 3.2 trips
Passenger kilometres per person per day = 33 pkm/day
Percentage of total distance travelled for the purpose of work = 32%
Distance travelled by car as a percentage of total distance = 83%
Distance travelled by PT as a percentage of total distance = 12.5%
Key figures drawn from analysis by the Public Transport Users Association:[22]
Average car occupancy = 1.5
Energy per car vehicle-km (assuming are fuel efficiency of 12 L/km) = 4.1 Megajoule/kilometre (MJ/km)
Energy per tram passenger-km (conservative estimate) = 0.6 MJ/km
Energy per bus passenger-km (conservative estimate) = 1.1 MJ/km
Energy per train passenger-km (conservative estimate) = 0.18 MJ/km

[1] While our focus herein is on the direct energy and water savings of low-tech living, it is our view that prefiguring a simpler way to live has deeper significance too, in that it helps create the cultural conditions needed for a post-capitalist politics and economics to emerge, which we maintain is a necessary part of the decarbonisation project. In this paper, however, space does not permit any sustained engagement with those underlying political or macroeconomic issues.

[2] One final general point is that we’ve chosen to ignore the embedded energy in the alternative technologies we discuss, on the assumption that the embedded energy is likely to be negligible in comparison to the potential energy savings they provide. Most of the low-tech options we discuss can be made from recycled or salvaged materials, and others, such as a solar shower bag, have low embedded energy. In any case, low-tech options have vastly lower embedded energy than their hi-tech alternatives (e.g. washing machine compared to a washing line). This means that ignoring the embedded energy does not distort the following analysis in any significant way.


[4] Average between winter and summer median duration: Redhead, M (2013), Melbourne Residential Water End Uses Winter 2010 / Summer 2012, Final Report June 2013, p24.

[5] Average between winter and summer median flow rates, ibid. p25.

[6] Average between winter and summer average frequency: Redhead, M (2013), Melbourne Residential Water End Uses Winter 2010 / Summer 2012, Final Report June 2013, p26.

[7] S.J. Kenway, A. Priestley, S. Cook, S. Seo, M. Inman, A. Gregory and M. Hall, Energy use in the provision and consumption of urban water in Australia and New Zealand, 10 December 2008, p19.

[8] Ibid. p19

[9] George Wilkenfeld & Associates Pty Ltd  (2008), Victoria’s Greenhouse Gas Emissions 1990, 1995, 2000 and 2005: END-USE ALLOCATION OF EMISSIONS, report to the Department of Sustainability and Environment, February 2008, p84.

[10] See also, Redhead, M (2013), Melbourne Residential Water End Uses Winter 2010 / Summer 2012, Final Report June 2013.


[12] SA government, ‘Energy efficient heating,

[13] ABS, ‘Heating and cooling’, 0/85424ADCCF6E5AE9CA257A670013AF89?opendocument

[14] CSIRO, ‘Zero Emission House’, available at:

[15] SA government, ‘Energy efficient cooling’,

[16] ABS, ‘Heating and cooling’, available at:

[17] Sustainability Victoria, ‘Washers and Dryers’,

[18] Energy Use in the Australian Residential Sector 1986-2020,

[19] Baseline TV Power Consumption 2009,

[20] Deakin University, Environmental benefits of cycling:

 [21] Department of Transport 2007, Victorian Integrated Survey of Travel and Activity 2007,

[22] PTUA, 2015,