Solving Climate Change

SUBHEAD: The key to this existential crisis is beneath our feet in the soil.

By Ellen Brown on 26 December 2019 for Truthdig -
(https://www.truthdig.com/articles/the-key-to-solving-the-climate-crisis-is-beneath-our-feet/)


Image above: Close-up of living soil from the original article.

The Green New Deal resolution that was introduced into the U.S. House of Representatives in February hit a wall in the Senate, where it was called unrealistic and unaffordable. In a Washington Post article titled “The Green New Deal Sets Us Up for Failure. We Need a Better Approach,” former Colorado governor and Democratic presidential candidate John Hickenlooper framed the problem like this:

The resolution sets unachievable goals. We do not yet have the technology needed to reach “net-zero greenhouse gas emissions” in 10 years. That’s why many wind and solar companies don’t support it. There is no clean substitute for jet fuel. Electric vehicles are growing quickly, yet are still in their infancy. Manufacturing industries such as steel and chemicals, which account for almost as much carbon emissions as transportation, are even harder to decarbonize. 

Amid this technological innovation, we need to ensure that energy is not only clean but also affordable. Millions of Americans struggle with “energy poverty.” Too often, low-income Americans must choose between paying for medicine and having their heat shut off. …

If climate change policy becomes synonymous in the U.S. psyche with higher utility bills, rising taxes and lost jobs, we will have missed our shot. …

The problem may be that a transition to 100% renewables is the wrong target. Reversing climate change need not mean emptying our pockets and tightening our belts. It is possible to sequester carbon and restore our collapsing ecosystem using the financial resources we already have, and it can be done while at the same time improving the quality of our food, water, air and general health.

The Larger Problem – and the Solution – Is in the Soil

Contrary to popular belief, the biggest environmental polluters are not big fossil fuel companies. They are big agribusiness and factory farming, with six powerful food industry giants – Archer Daniels Midland, Cargill, Dean Foods, Dow AgroSciences, Tyson and Monsanto (now merged with Bayer) – playing a major role.

Oil-dependent farming, industrial livestock operations, the clearing of carbon-storing fields and forests, the use of chemical fertilizers and pesticides, and the combustion of fuel to process and distribute food are estimated to be responsible for as much as one-half of human-caused pollution. 

Climate change, while partly a consequence of the excessive relocation of carbon and other elements from the earth into the atmosphere, is more fundamentally just one symptom of overall ecosystem distress from centuries of over-tilling, over-grazing, over-burning, over-hunting, over-fishing and deforestation.

Big Ag’s toxin-laden, nutrient-poor food is also a major contributor to the U.S. obesity epidemic and many other diseases. Yet these are the industries getting the largest subsidies from U.S. taxpayers, to the tune of more than $20 billion annually. We don’t hear about this for the same reason that they get the subsidies – they have massively funded lobbies capable of bribing their way into special treatment.

The story we do hear, as Judith Schwartz observes in The Guardian, is, “Climate change is global warming caused by too much CO2 in the atmosphere due to the burning of fossil fuels. We stop climate change by making the transition to renewable energy.” Schwartz does not discount this part of the story but points to several problems with it:

One is the uncomfortable fact that even if, by some miracle, we could immediately cut emissions to zero, due to inertia in the system it would take more than a century for CO2 levels to drop to 350 parts per million, which is considered the safe threshold. Plus, here’s what we don’t talk about when we talk about climate: we can all go solar and drive electric cars and still have the problems – the unprecedented heat waves, the wacky weather – that we now associate with CO2-driven climate change.

But that hasn’t stopped investors, who see the climate crisis as simply another profit opportunity. According to a study by Morgan Stanley analysts reported in Forbes in October, halting global warming and reducing net carbon emissions to zero would take an investment of $50 trillion over the next three decades, including $14 trillion for renewables; $11 trillion to build the factories, batteries and infrastructure necessary for a widespread switch to electric vehicles; $2.5 trillion for carbon capture and storage; $20 trillion to provide clean hydrogen fuel for power, cars and other industries, and $2.7 trillion for biofuels.

The article goes on to highlight the investment opportunities presented by these challenges by recommending various big companies expected to lead the transition, including Exxon, Chevron, BP, General Electric, Shell and similar corporate giants – many of them the very companies blamed by Green New Deal advocates for the crisis.

A Truly Green New Deal

There is a much cheaper and faster way to sequester carbon from the atmosphere that doesn’t rely on these corporate giants to transition us to 100% renewables. Additionally, it can be done while at the same time reducing the chronic diseases that impose an even heavier cost on citizens and governments. Our most powerful partner is nature itself, which over hundreds of millions of years has evolved the most efficient carbon sequestration system on the planet. As David Perry writes on the World Economic Forum website:

This solution leverages a natural process that every plant undergoes, powered by a source that is always available, costs little to nothing to run and does not cause further pollution. This power source is the sun, and the process is photosynthesis. 

A plant takes carbon dioxide out of the air and, with the help of sunlight and water, converts it to sugars. Every bit of that plant – stems, leaves, roots – is made from carbon that was once in our atmosphere. Some of this carbon goes into the soil as roots. The roots, then, release sugars to feed soil microbes. These microbes perform their own chemical processes to convert carbon into even more stable forms.

Perry observes that before farmland was cultivated, it had soil carbon levels of from 3% to 7%. Today, those levels are roughly 1% carbon. If every acre of farmland globally were returned to a soil carbon level of just 3%, 1 trillion tons of carbon dioxide would be removed from the atmosphere and stored in the soil – equal to the amount of carbon that has been drawn into the atmosphere since the dawn of the Industrial Revolution 200 years ago. The size of the potential solution matches the size of the problem.

So how can we increase the carbon content of soil? Through “regenerative” farming practices, says Perry, including planting cover crops, no-till farming, rotating crops, reducing chemicals and fertilizers, and managed grazing (combining trees, forage plants and livestock together as an integrated system, a technique called “silvopasture”). 

These practices have been demonstrated to drive carbon into the soil and keep it there, resulting in carbon-enriched soils that are healthier and more resilient to extreme weather conditions and show improved water permeability, preventing the rainwater runoff that contributes to rising sea levels and rising temperatures. Evaporation from degraded, exposed soil has been shown to cause 1,600% more heat annually than all the world’s powerhouses combined. Regenerative farming methods also produce increased microbial diversity, higher yields, reduced input requirements, more nutritious harvests and increased farm profits.

These highly favorable results were confirmed by Paul Hawken and his team in the project that was the subject of his best-selling 2016 book, “Drawdown: The Most Comprehensive Plan Ever Proposed to Reverse Global Warming.” The project involved evaluating the 100 most promising solutions to the environmental crisis for cost and effectiveness. 

The results surprised the researchers themselves. The best-performing sector was not “Transport” or “Materials” or “Buildings and Cities” or even “Electricity Generation.” It was the sector called “Food,” including how we grow our food, market it and use it. Of the top 30 solutions, 12 were various forms of regenerative agriculture, including silvopasture, tropical staple trees, conservation agriculture, tree intercropping, managed grazing, farmland restoration and multistrata agroforestry.

How to Fund It All

If regenerative farming increases farmers’ bottom lines, why aren’t they already doing it? For one thing, the benefits of the approach are not well known. But even if they were, farmers would have a hard time making the switch. As noted in a Rolling Stone article titled “How Big Agriculture Is Preventing Farmers From Combating the Climate Crisis”:

[I]implementing these practices requires an economic flexibility most farmers don’t have, and which is almost impossible to achieve within a government-backed system designed to preserve a large-scale, corporate-farming monoculture based around commodity crops like corn and soybeans, which often cost smaller farmers more money to grow than they can make selling.

Farmers are locked into a system that is destroying their farmlands and the planet, because a handful of giant agribusinesses have captured Congress and the regulators. One proposed solution is to transfer the $20 billion in subsidies that now go mainly to Big Ag into a fund to compensate small farmers who transition to regenerative practices. We also need to enforce the antitrust laws and break up the biggest agribusinesses, something for which legislation is now pending in Congress.

At the grassroots level, we can vote with our pocketbooks by demanding truly nutritious foods. New technology is in development that can help with this grassroots approach by validating how nutrient-dense our foods really are. 

One such device, developed by Dan Kittredge and team, is a hand-held consumer spectrometer called a Bionutrient Meter, which tests nutrient density at point of purchase. The goal is to bring transparency to the marketplace, empowering consumers to choose their foods based on demonstrated nutrient quality, providing economic incentives to growers and grocers to drive regenerative practices across the system. 

Other new technology measures nutrient density in the soil, allowing farmers to be compensated in proportion to their verified success in carbon sequestration and soil regeneration.

Granted, $20 billion is unlikely to be enough to finance the critically needed transition from destructive to regenerative agriculture, but Congress can supplement this fund by tapping the deep pocket of the central bank. In the last decade, the Fed has demonstrated that its pool of financial liquidity is potentially limitless, but the chief beneficiaries of its largess have been big banks and their wealthy clients. 

We need a form of quantitative easing that actually serves the local productive economy. That might require modifying the Federal Reserve Act, but Congress has modified it before. 

The only real limit on new money creation is consumer price inflation, and there is room for a great deal more money to be pumped into the productive local economy before that ceiling is hit than is circulating in it now. For a detailed analysis of this issue, see my earlier articles here and here and latest book, “Banking on the People.”

The bottom line is that saving the planet from environmental destruction is not only achievable, but that by focusing on regenerative agriculture and tapping up the central bank for funding, the climate crisis can be addressed without raising taxes and while restoring our collective health.


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More native shrubs are essential

SUBHEAD: Shrubs grow much faster than trees and are powerful carbon sequestration engines in their own right.

By Adrian Fisher on 27 December 2018 for Ecological Gardening
(https://www.ecologicalgardening.net/2018/12/native-shrubs-and-why-theyre-essential.html)


Image above: Sand prairie merging into shrubland in southeast Wisconsin. From The Prairie Botanist

“Shrubbiness is such a remarkable adaptive design that one may wonder why more plants have not adopted it.” (H. C. Stutz, 1989)

In light of the newest IPCC and US climate change reports, coupled with reports of the ongoing declines of wild species—birds, insects—you name them, just so long as they aren’t human, I have turned to thinking about shrubs.

It is precisely their adaptive characteristics that give shrubs their potential to be powerful players in soil carbon sequestration and ecosystem regeneration in certain parts of the world, such as the Midwest.

Although alarming, the reports are not surprising to anyone who’s been keeping track. The IPCC report says human global society has 12 years to reduce carbon emissions to 45% below 2010 levels if there is to be any hope of holding overall average global temperature rise to 1.5 degrees C (2.7 degrees F).

The US report, searchable by region, adds fairly detailed, equally dire scenarios for this country. No place on earth will be immune to the destructive consequences of our failure to act.

Since the world has already warmed approximately 1 degree C, even if we are able to keeping warming to 1.5 degrees—an almost insanely optimistic proposal, given the array of forces, from active malice to blind inertia, all backed by money, power and influence poised against success—there will still be massive, destabilized weather patterns and disruptive, destructive weather events similar to and worse than what we are already experiencing.

The resultant ecological destruction and human misery will only increase with each half a degree beyond 1 degree until large parts of the earth are literally uninhabitable by humans. We are, right now, on track to warm roughly 3.3 degrees by century’s end.

Despite the official reports’ newly grim tone, there are no new solutions. As we’ve known for decades, staving off disaster requires both cutting greenhouse gas emissions and helping earth’s biological systems regenerate, pull massive amounts of carbon from the air, and store it in biomass and soils.

For an overview of how all of this can be achieved, the book and companion website “Drawdown” remains an excellent compendium of strategies and tactics.

The IPCC report offers four scenarios by which rapid decarbonization and carbon sequestration could be achieved. Three of them rely heavily on so far non-existent or extremely small-scale technological carbon capture and sequestration methods.

Possibly the worst of these from an ecological point of view is BECCS (bioenergy with carbon capture and storage), a technique involving growing and burning massive amounts of trees, shrubs and grasses while “magically” capturing and sequestering the resultant carbon emissions.

Relying on salvation by means of a fix we don’t actually have the ability, money or time to accomplish is a distracting, destructive form of magical thinking. Practiced at scale, BECCS would require appropriating farmland, destroying forests and wrecking ecosystems.

An analogous illustration of its potential for upending ecosystems and ways of life would be the destruction palm oil plantations have wrought in Borneo, devastation turbo-charged in part by an American law meant to get us off dependence on fossil fuels and well documented in the New York Times Magazine.)

Natural carbon solutions offer the most realistic way forward
The IPCC scenario that best comports with current reality and a genuinely sustainable, resilient future describes what carbon farmers, holistic managers, scientists, environmentalists and many others have been touting and practicing for 50 years.

That is, while we ramp up renewables, increase energy efficiency, and decarbonize our life styles, we should also do everything possible to enable worldwide carbon sequestration through biological processes.

We should restore and vastly augment our forests, grasslands and wetlands and overhaul agricultural practices along agroecological lines. Here in the US, the recently published paper “Natural Carbon Solutions for the United States” quantifies how much carbon can be sequestered through improved landscape and coastal wetlands management practices.

The authors calculate potential sequestration to be about 21% of total US emissions, or enough to equal taking all cars and trucks in the US off the road.

Unlike purely mechanical carbon sequestration methods, or schemes such as BECCS, natural carbon solutions would simultaneously help get global temperature rise under control while improving and enriching ecosystems’ functioning—thus helping ease the crisis of ecological destruction now sweeping the planet.

While nearly everyone has a pretty good idea of how to cut emissions, fewer are aware of how they themselves could implement natural carbon solutions beyond planting a tree or two. But simply plopping some trees in a lawn or along a parkway is not enough.

As I’ve written previously, serious natural carbon sequestration, at whatever scale, requires regenerative landscape management practices such as putting in a biodiverse palette of native trees, flowers and grasses and stopping the use of pesticides and synthetic fertilizer.

Shrubs can be crucial to this kind of planting, especially in terms of the other ecological benefits they offer. Wherever there is a lawn, a tree and possibly a small garden, or even a tiny strip along the foundations of a building, there should be a native shrub or two, or possibly more.

Large properties and farms have nearly unlimited possibilities in the form of hedgerows, shelterbelts or even reconstituted shrub prairies.

Shrubs are a necessary part of landscaping for carbon sequestration
From a landscaping perspective, shrubs are sort of like the middle children in a very large family: necessarily adaptable, but little thought of or noticed.

This is true even scientifically. “Natural Carbon Solutions” explicitly omits shrublands from the calculations, and a 2016 review of scientific literature in “Why Be a Shrub” states that the least studied landscape types are shrublands, while the least studied plants are shrubs.

Yet shrubs flourish virtually everywhere and shrublands are increasing across the globe, possibly due in part to climate change.

In the American West the new severity of wildfires makes it difficult for forests to regenerate. The replacement is shrubland, or, to use an old term, “barrens.” Is the lack of notice and study because shrubs are so common and ubiquitous, but lack the majesty of trees and the show-offy beauty of flowering annuals and perennials?

This lack of notice carries through in our designed landscapes. The default for parks and private property alike is often faux open woodland or savanna, with widely spaced trees and plenty of grass—and few shrubs.

Farms are faux prairies where shrubs that formerly would have flourished wild and later in hedgerows and fencerows and along waterways have been largely extirpated.

What shrubs there are might be a few non-native ornamentals ranged in a row along a building foundation, kept as a low hedge along a sidewalk, or grouped in a small island of mulch.

Humans love these savanna-ish landscapes that now cover millions of acres. For us, they are comfortable and attractive. They look very green on Google Earth and from the air to migrating birds.

But for birds and other animals, they function as “death traps,” as a US Fish and Wildlife employee once told me. Birds looking for habitat in such a place find it inhospitable. There is neither ground-level shelter, nor, for some kinds of shrub-dependent birds, good nesting habitat.

Nor is there much in the way of flowers for pollinators or host plants for insect herbivores or caterpillars, which means few of the native insects and berries that birds forage for in massive quantities for their own needs and to feed their young.

Finally, what should be a complex underground web of fungal species and soil dwelling microbes is, instead, simplified and depauperate.

Because they are missing shrubby layers, what seem to humans like well structured environments are, in fact, missing the complex structure that creates the capacity for higher order ecological relationships—that is, the relationships among three or more species (including plants, animals, fungi and bacteria) that tie an ecosystem together and enable carbon sequestration.

The adaptive characteristics of shrubs
Shrubs are the woody plants with multiple stems that branch close to the ground and may be erect but might sprawl. Usually they are less than 15 feet in height; anything taller than that is usually, but not always considered a tree. In general, deciduous shrubs are spring (sometimes fall) flowering and yield small fruits such as berries, drupes or nuts.

Crucially for wild landscapes of all types, their adaptability means they can re-sprout easily after fires or other disturbances, grow to mature size much faster than trees, and have self-spreading habits such as suckering or rooting where branches touch the ground.

It’s often hard to kill a shrub without digging out the roots. Their many leaves and stems make them efficient photosynthesis factories, pulling carbon out of the air, and their roots hook up with the underground biome as contributing partners.

They share nutrients and information with other plants, engage in the carbon-sugars-for-nutrients trade with fungi, shelter microbes in return for nitrogen and other nutrients, and thus contribute to a healthy, biodiverse, carbon-sequestering soil system. Some kinds of shrubs even act as nurse species, so that young trees grow better in their company.

The Midwest was once a very shrubby place
It’s hard to visualize what the landscape in the Midwest looked like prior to the European invasion down through the first half of the 19th century.

There were, of course, towns and trade routes, especially along the rivers, but it was a land with few fences or readily marked boundaries in the sense that we know them.

A broad area of the country around the western Great Lakes and running south to Texas functioned as the transition zone between the Eastern forest and the Western prairies. It was a landscape of great diversity, an intricate mosaic of landscape types, all of them highly dependent on fire to maintain their distinctive characteristics.

Overall, the land ranged along a continuum from mostly treeless open prairie to shrub prairie to savanna to woodland to, rarely, closed-canopy forest. The native peoples used fire as a management tool and maintaining and shaping the diversity.

Yet this management was holistic, non-linear, intuitive, spiritual, and tended to enhance biodiversity, unlike most of the control-prioritizing methods we employ today.

Surveyors’ notes from the early 19th century often include mentions of shrubs such as American hazelnut. A typical comment might read, “scattering timber, principally burr and white oak, hazel and hickory undergrowth.”

That is, they were traveling through shrub prairies and savannas where shrubs intermingled with trees and prairie plants.

Other noted shrub species included New Jersey tea, four species of dogwood, wild crabapple, wild plum, sumac species, roses, prairie willow and prickly ash.

Species prevalence depended on soil type and moisture availability, but all—more than thirty species— were adapted to fire, with the shrubby adaptive ability to easily spread vegetatively and to rapidly regenerate post-fire.

In areas of very frequent fires where shrub barrens developed, even some species of oak took on a shrubby form. The vanishingly few modern examples of shrub prairie also demonstrate their value as wildlife habitat.

These remaining landscapes tend to be on moist, sandy soil and include not only some of the species listed above, but also chokeberries, huckleberries, blueberries, grasses such as big bluestem, and flowers such as prairie violet. They are home to shrub-dependent birds, pollinators and wildlife such as herptiles, amphibians and mammals, including some rare or endangered species.

Disappearing native shrubs
Our cultural landscape amnesia is so great that, during the time much of this landscape was being physically erased by farms and towns, memories of it were concurrently erased, or if spoken of, were disputed or even disbelieved.

Unless we learn otherwise, we tend to think that the current landscape is how it should be. I’ve talked with farming people who have lost their history, can’t call native shrubs and prairie plants by their names and think of them as weeds to be mown down. Conventional farming policy and practice exacerbates this tendency.

 Only very old people, mostly long dead now, have told me of hedgerows full of shrubs in bloom, and remembered homemade wild plum preserves, gooseberry pies and elderberry wine.

Today, as a result, wild native shrubs are in decline in the Midwest. To the knowledgeable eye it is odd, even jarring to see farmhouses landscaped with nursery standardized non-native barberries and privets in one of the great shrub producing regions of the world.

It is sad to realize that shrubs with scant to no ecological value are favored over the Midwest species that could be such a boon to wildlife, soil health and to the farmers themselves.

And our cities, suburbs and towns are no better for many native shrubs, which don't easily conform to the constraints imposed by extremely manicured landscapes. Luckily, this has been slowly changing as cultivars have been selected and developed.

Viburnums and hydrangeas have long been of value and these days, many residential street have their serviceberries, chokeberries, dogwoods and oak leaf hydrangeas.

Even in natural areas, often created in less desirable, less farmable land than the great open prairies, fire suppression ensured that what were shrub prairies and savannas rapidly became woodlands and sometimes forests.

Only in the late 20th century were these last two landscapes rediscovered as entities in and of themselves.

A former savanna can often be recognized by the presence of old bur oaks with the characteristically wide-spreading shape they develop when open-grown, surrounded by younger, straighter, narrower trees. In modern restoration, savannas have often been prioritized.

Conversely, shrub species such as gray dogwood, though native, have frequently been put on lists of less desirable plants in need of control. Only in this century have wild native shrubs’ value been reconsidered as necessary understory species and as major landscape components in and of themselves.

Wild native shrubs for carbon sequestration
In the Midwest (and possibly other regions in the world), reforestation and afforestation as a major carbon sequestering and ecological resilience strategy does not mean recreating the deep forests of the Eastern and Southeastern US.

What is required is figuring out how lessons from the old patchwork-mosaic, fire-dependent landscape can be relearned and applied in new ways.

Existing natural landscapes should be examined for their carbon-sequestering, water management and ecological resilience functions and the data used as inspiration for how best to conduct the necessary rewilding, recomplexifying efforts in the landscapes where humans live, work and farm.

We need to expand the army of ecologists, restorationists, landscape managers, farmers, and public and private landowners already at work and create new, potent alliances of land managers.

I believe it will be found that recreating a diversity of landscapes along the prairie to forest continuum, including shrub prairies and wetlands, in accordance with given soil types and water availability, will best make use of conditions here--even as the climate changes.

The possibilities are manifold.

• Where can gray dogwood and other spreading, suckering shrubs be encouraged in their proclivities?
  
• Where can huge wetland restorations be undertaken, where swamp roses and black chokeberries, buttonbush and swamp dogwood are allowed to run riot?
  
• Where will wild plums be allowed to form their dense, thorny thickets, or hazelnuts and bladdernuts be encouraged to grow among the oaks, their rightful companions?
  
• Who can persuade farmers that allowing these species back on their less productive land will improve the resilience of their farms—and the health of themselves and their children?
  
• How can park district and municipal officials and other urban/suburban land owners and managers learn to see native shrubs as worthwhile companions to trees?

And, though some of the needed work is ongoing even now, much more needs to be done, faster.

All of this should be possible and will be necessary as the indisputable benefits of nurturing species complexity in the service of biological diversity and soil carbon sequestration become more widely acknowledged during our climate emergency.

Shrubs grow much faster than trees and are powerful carbon sequestration engines in their own right.

They could play a huge part of the Midwest’s potential carbon sequestration and resilience strategy. It’s time for these middle children of the plant world to come into their own.

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Direct Air Carbon Capture

SUBHEAD: Combining renewable energy with Direct Air Capture for ‘Net Negative’ CO2 emissions.

By Carl-Friedrich Schleussner on November 7 2018 in Resilience  -
(https://www.resilience.org/stories/2018-11-08/combining-renewables-with-direct-air-capture-for-net-negative-emissions/)


Image above: Climeworks direct air CO2 capture plant, Zürich, Switzerland. Photo by Simon Evans. From (http://carbonalist.com/2017/06/what-is-direct-air-capture-pt-2/).

[IB Pulisher's note: Artilce authored by Jan Wohland, Dirk Witthaut , Carl-Friedrich Schleussner, originally in www.carbonbrief.org]

The recent special report from the Intergovernmental Panel on Climate Change (IPCC) has shown that limiting global warming to 1.5C is still within reach, but that it requires rapid and stringent cuts to global CO2 emissions.

Modelling pathways that achieve the Paris Agreement goals rely on swift decarbonisation of the power sector and scaling up of “negative emissions” – an array of techniques to remove CO2 from the atmosphere and store it on land or underground.

However, both tasks have challenges to overcome. Shifting away from fossil fuels and towards renewable electricity requires accommodating the variable nature of, for example, wind and solar power. Negative emissions techniques, meanwhile, face challenges of cost, scale and acceptability before being ramped up.

For example, Direct Air Capture (DAC) – a technology that essentially sucks carbon out of the air – is a process that needs heat and electricity. And, despite recent progress, DAC is still considered a niche technology prohibited by its energy demand and high costs.

But what if the dual challenges facing renewables and negative emissions could be tackled together? In a recent paper, published in Earth’s Future, we find that there is considerable potential for combining a renewables-reliant electricity system with DAC.

Renewables rise

We have witnessed a considerable expansion of renewable power generation over the past two decades. Along with increased deployment, costs have come down substantially. As of today, onshore wind energy is the cheapest source of electricity in many places – including in large parts of Europe. Photovoltaics also has seen massive price drops which have not been anticipated in the modelling community.

The variability of renewable electricity generation becomes increasingly important as renewables evolve from a niche player to the dominant contributor.

This variability leads to additional challenges and integration costs on a system level, such as for congestion management, transmission line expansion and storage.

Fortunately, solutions exist that can successfully integrate large shares of renewables into energy systems, including storage, continental-scale transmission line infrastructure, and sector coupling (the interconnection of sectors, such as transport, industry or housing, with the energy sector, allowing renewable electricity to be converted to heat or another fuel as needed).


The availability of cheap renewable energy provides an opportunity to implement negative emissions that were previously considered uneconomic.

DAC, for example, can provide some of the flexibility that is needed for system integration of renewables. This could make DAC more cost effective by using excess wind or solar power during periods of high supply, low demand and low prices.

Put simply, you can switch on DAC whenever renewable generation is high and leave it off at other times. On top of that, DAC could be deployed in a decentralised fashion, which can help alleviate local grid congestion.

Net neutral

To investigate the carbon removal potential of such an approach, we modelled a simplified European power system (based on data from the European Network of Transmission System Operators for Electricity, known as “ENTSO-E”).

We assume that the more direct solutions to mitigate renewable generation variability have been implemented – such as unlimited electricity transmission across Europe and different levels of storage – but deploy conservative assumptions related to the energy efficiency of DAC. Also, our model still includes fossil gas power plants that can be fired up on demand.

For different levels of renewable contributions, we assessed the negative emission potential of DAC and the total emissions of the whole electricity system.

We find that “net neutral” European power systems – where any CO2 emitted is balanced by CO2 taken out of the atmosphere – are achievable with a renewable penetration of just above 100% and at least 30 gigawatts (GW) of DAC.

Here, “penetration” means the ratio of renewable power generation to electricity consumption (excluding DAC). If it exceeds 100%, this means that some renewable generation has to be curtailed and/or is used for DAC.

We also find that storage technologies and DAC are not competing, but complementary. Increases in storage size allow for reductions of remaining carbon emissions and enable more efficient use of DAC.

You can see this in the charts below, which show the average annual CO2 emissions for Europe (y-axis), according to the penetration of renewables (x-axis), and the amount of DAC – from 30 GW (left-hand chart) to 300GW (right-hand). This would be equivalent to DAC matching approximately 3-30% of current generation capacity in Europe.

The charts reveal that at a low take-up of renewables, net emissions are positive (red bars), no matter how much DAC is used. However, as renewables approach 100% penetration, DAC can be used to take net emissions negative (blue bars).


Image above: Chart of CO2 emissions potential carbon capture. From original article.

European CO2 emissions versus renewable penetration for different DAC capacities at a storage size of one average load day (where the energy typically consumed in one day can be stored). Red bars denote emissions from open-cycle gas turbines that are used for backup. Blue indicates negative emissions from DAC. Green circles denote net emissions. Source: Wohland et al. (2018)
In the case of a substantially higher share of renewables and an increase in DAC capacity to 300GW, negative emissions of up to 500m tonnes of CO2 per year (MtCO2/yr) could be achieved using the excess renewable energy generated in Europe.

By way of comparison, there are 3-14bn tonnes of net negative emissions each year by 2100 in scenarios limiting warming to 1.5C and included in the IPCC’s special report.

The system properties of DAC are more important than the exact numbers in this example, which are just given as an illustration and highly uncertain. What we show is that DAC can facilitate the integration of high shares of renewables and offers co-benefits with electricity storage.

The indications are that DAC could provide a sizeable contribution to negative emissions and thereby represent a suitable option for removing carbon from the atmosphere in future power systems – if carbon storage solutions can be provided.

A closer look

There are still many uncertainties to consider, perhaps most importantly, whether or not the approach we have laid out is economically practicable.

For example, in order to be viable even when not running around the clock, DAC’s future capital costs would need to be lowered substantially and/or carbon prices would have to increase, each by at least 10-fold. It is possible both conditions could be met as the technology is scaled up and global efforts to mitigate climate change become more tangible.

On the other hand, imperfections in real-world electricity grid and energy system design – that can lead to excess electricity and negative electricity prices even today – may enhance DACs attractiveness.

An increase in the efficiency of DAC – for example, by also making use of heat from other sources, such as industrial waste or renewable heat – would strongly increase its negative emission potential.

However, it is also worth noting that other options to use excess renewables in a “sector coupled” approach exist that would be in direct competition with DAC.

These might include electric vehicles that can be charged within a particular timespan, district heating with large reservoirs that store electricity, or converting electricity to hydrogen for transport and industry.

While DAC is, thus, clearly not a silver bullet for carbon dioxide removal, it does come with system friendly features. And given the need for negative emissions, the concerns about land-based options, and the rapid technological and cost evolution of renewables, our first results indicate that it might be worth a closer look.


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