Why BECCS might not produce ‘negative’ emissions after all

Why BECCS might not produce ‘negative’ emissions after all

SOURCE: Carbon Brief DATE: August 14, 2018 SNIP: Model scenarios that limit warming to 1.5C or 2C typically rely on large amounts of “negative emissions” to extract CO2 from the atmosphere and store it on land, underground or in the oceans. Bioenergy crops with carbon capture and storage (BECCS) is, perhaps, the most prominent of the various negative emissions techniques. There are many attractive features, since this technology would provide energy – thus reducing our need for fossil fuels – and remove CO2 from the atmosphere at the same time. In our new study, published in Nature Communications, my colleagues and I find that expansion of bioenergy in order to meet the 1.5C limit could cause net losses in carbon from the land surface. Instead, we find that protecting and expanding forests could be more effective options for meeting the Paris Agreement. Removing trees to plant biofuels as a way of mitigating climate change clearly seems counterintuitive. So we looked more closely at the effectiveness of the land-use patterns in the two scenarios. Overall, we found that in a majority of the areas where forests would be replaced, more carbon was stored by keeping the forests than with employing BECCS. Forests accumulate and store carbon in vegetation and soils and this is lost when forests are converted to crops. We found that this had a very big impact on the net carbon balance of land converted from forest to bioenergy crops. In high latitudes, for example, significant losses of soil carbon meant the “payback” time for the carbon lost in replacing forests with BECCS could be more than 100...
Tree Farms Will Not Save Us from Global Warming

Tree Farms Will Not Save Us from Global Warming

SOURCE: Scientific American DATE: March 13, 2018 SNIP: The Intergovernmental Panel on Climate Change, in its Fifth Assessment Report, presented more than 100 modeled scenarios that it said had a high likelihood of keeping global temperatures within 2 degrees Celsius of preindustrial levels. Nearly all of them assumed that negative emissions technology would be viable and widely used, particularly BECCS. The idea calls for massive plantations of trees and other crops to draw carbon dioxide out of the air. The trees could then be harvested for the production of energy or biofuels, with carbon capture technology used to sequester their emissions. The whole process would be carbon-negative. This could theoretically cool the climate. But it would have to be done at a massive scale. It’s still almost an entirely hypothetical concept. But it has rapidly risen to prominence as a strategy for meeting the world’s climate targets established under the Paris Agreement. But there’s a major problem: Research increasingly suggests that the process is not feasible at the scale necessary to make a real dent in global climate goals—at least, not without causing massive environmental or social disruptions. If that’s the case, some experts worry that the models could mislead policymakers into believing there’s a definite “out” if global emissions don’t fall fast enough in the future. A study published in the journal Nature Climate Change in January is among the latest to raise doubts. It suggests that the large-scale deployment of BECCS—which calls for massive, managed plantations of trees—would likely require an unsustainable use of land, water and other resources. “Our main message is that really relying on...
Negative emissions have ‘limited potential’ to help meet climate goals

Negative emissions have ‘limited potential’ to help meet climate goals

SOURCE: Carbon Brief and European Academies’ Science Advisory Council (EASAC) DATE: January 31, 2018 SNIP: The potential for using negative emissions technologies to help meet the goals of the Paris Agreement could be more “limited” than previously thought, concludes a new report by European science advisors. Negative emissions technologies (NETs) describe a variety of methods – many of which are yet to be developed – that aim to limit climate change by removing CO2 from the air. Some of these techniques are already included by scientists in modelled “pathways” showing how global warming can be limited to between 1.5C and 2C above pre-industrial levels, which is the goal of the Paris Agreement. However, the new report says there is no “silver bullet technology” that can be used to solve the problem of climate change, scientists said at a press briefing held in London. Instead, “the primary focus must be on mitigation, on reducing emissions of greenhouse gases,” they added. The report concludes: “We conclude that these technologies offer only limited realistic potential to remove carbon from the atmosphere and not at the scale envisaged in some climate...
It’s the big new idea for stopping climate change — but it has huge environmental problems of its own

It’s the big new idea for stopping climate change — but it has huge environmental problems of its own

SOURCE: Washington Post DATE: January 22, 2018 SNIP: Widespread use of a futuristic energy technology to remove carbon dioxide from the atmosphere would create severe environmental problems, scientists argue in a new critique, casting doubt on one potential method of helping humanity escape the worst effects of climate change. The technology, known as bioenergy with carbon capture and storage (BECCS), comes in many variations. But the core idea is burning trees or other plants for energy while pulling in the resulting carbon dioxide and storing it below ground. When the plants grow back again, they would pull more carbon dioxide from the air, resulting in a net removal of the greenhouse gas from the atmosphere. [I]n the new paper, scientists argue that deploying BECCS technology on the scale needed to address the problem would use up massive amounts of water, fertilizer and land. That would probably lead to large environmental problems or even destabilize key planetary systems. BECCS at such a scale would lead to millions of square miles of forest loss and large pressures on biodiversity, the study found. Meanwhile, the huge plantations would require tens of millions of tons of nitrogen fertilizer that would alter flow of this chemical around the Earth, and huge amounts of water — over a trillion tons of it each year. “Negative emissions using biomass has great potential for removing carbon from our air,” said Rob Jackson, a Stanford University earth scientist who has also studied the environmental limitations of BECCS but was not involved in the current paper. “It can’t be done, though, without using more land, more water and more...
The Dirty Secret of the World’s Plan to Avert Climate Disaster

The Dirty Secret of the World’s Plan to Avert Climate Disaster

SOURCE: Wired DATE: December 10, 2017 SNIP: The UN report envisions 116 scenarios in which global temperatures are prevented from rising more than 2°C. In 101 of them, that goal is accomplished by sucking massive amounts of carbon dioxide from the atmosphere—a concept called “negative emissions”—chiefly via BECCS. And in these scenarios to prevent planetary disaster, this would need to happen by midcentury, or even as soon as 2020. Like a pharmaceutical warning label, one footnote warned that such “methods may carry side effects and long-term consequences on a global scale.” Indeed, following the scenarios’ assumptions, just growing the crops needed to fuel those BECCS plants would require a landmass one to two times the size of India. The energy BECCS was supposed to supply is on par with all of the coal-fired power plants in the world. In other words, the models were calling for an energy revolution—one that was somehow supposed to occur well within millennials’ lifetimes. Today that vast future sector of the economy amounts to one working project in the world: a repurposed corn ethanol plant in Decatur, Illinois. Which raises a question: Has the world come to rely on an imaginary technology to save it? “The most important of the IPCC’s projections is that we’re screwed unless we can figure out how to take CO2 out of the atmosphere, because we haven’t acted fast enough,” [Emily McGlynn] says. “I think that’s the most important part of the...