Biomass energy with carbon capture and sequestration (BECCS) combined with the growth of renewable energy could reduce emissions as much as 145 percent below 1990 levels by 2050 in western North America, according to a new study published in Nature Climate Change from the University of California, Berkeley.
Reducing greenhouse gas emissions by generating electricity from biomass is considered effective because biomass emits as much carbon dioxide as plants absorb from the atmosphere. So capturing carbon dioxide from burning biomass could, in theory, allow power plants to store more even carbon than they emit, creating negative emissions and paving the way for a zero-carbon future. Once captured, the carbon would be stored underground.
According to the authors, if climate change is worse than anticipated, BECCS would be a particularly effective mitigation strategy.
"Negative emissions are very valuable to the power sector when decarbonizing the entire economy," said study authors Daniel Sanchez and James Nelson. "These negative emissions could also be valuable to transportation sector or other sectors of the economy that emit greenhouse gases."
Total carbon storage from BECCS could offset emissions from transportation, which releases 28 percent of total greenhouse gas emissions in the United States, according to the study’s authors.
Last year, the United Nations Intergovernmental Panel on Climate Change’s fifth assessment report suggested that BECCS was an effective method for removing carbon from the atmosphere, but added that the success of carbon-capturing technologies remained speculative.
In order to quantify the role of BECCS in power systems, Sanchez and his team developed a computer model of western North America’s electric power grid and studied power generation, transmission and storage possibilities in the region. They found that the total carbon offsets produced by BECCS — even with as little as 7 percent of total power coming from BECCS — was more valuable than the electricity it generated.
Approach directed at biomass, not coal
"The conclusions of this study are consistent with a broad body of existing research that shows that while BECCS is not essential to meeting aggressive emissions reductions targets, it has the potential to significantly reduce the costs of meeting those targets," said Patrick Luckow, from Synapse Energy Economics, who was not affiliated with the study. "Scientists have thoroughly demonstrated the need for us to be thinking seriously about significant emissions reductions, and BECCS is one of many potential steps down that path."
Producing enough electricity does not require converting forests and grasslands into agricultural land for biomass production, the authors found, further reducing potential carbon emissions. Biomass from wastes and residues would provide enough electricity to make a significant difference in carbon emissions from the power sector.
Critics of carbon capture and sequestration have argued that the technology is too expensive to be economically viable. CCS can reduce a coal plant’s output by 40 percent, doubling the cost of electricity. The effect on biomass-burning plants is even worse because biomass has a lower energy density than coal (ClimateWire, April 3, 2014).
But the authors of the UC Berkeley study disagree. For them, cheaper CCS technology is in sight.
"The promise of CCS is that we already know how to do it technically [through several routes], so if carbon management becomes important, it could come down in cost dramatically through industrial-scale application," co-author Daniel Kammen said.
Reporter Christa Marshall contributed.
