We don’t hear much these days about BECCS – that’s bioenergy with carbon capture and storage – as carbon capture in general struggles to fulfill its climate-change mitigation promise. But a new study out of Sweden says BECCS could save our bacon, and actually be pretty cost-effective, even if we don’t act quickly and forcefully enough to keep the global temperature from rising more than 2°C.
“The most policy relevant implication of our study is that even if current political gridlock causes global warming in excess of 2°C, we can reverse the temperature trend and reach targets later. This means that 2°C targets or even more ambitious targets can remain on the table in international climate negotiations,” study co-author Christian Azar said in a statement.
The way things are going, that “if” sounds pretty likely, and that, if the Swedes are right, could make BECCS worth pursuing with a little more vigor.
The basic idea behind BECCS is to use biomass (crops: tree, plants, whatever) for fuel to produce electricity or for transportation. Sure, biomass emits carbon when burned – but when the plants were growing they absorbed carbon. This, advocates say, makes them carbon neutral. If you then layer carbon capture and storage onto the power plant or fuel processing plant, you end up with negative carbon emissions. That is, the whole process pulls more carbon out of the atmosphere than it puts in.
In 2011, the Intergovernmental Panel on Climate Change wrote [PDF], “Combining biomass conversion with developing carbon capture and storage could lead to long-term substantial removal of GHGs from the atmosphere (also referred to as negative emissions).”
Of course there are issues with this very nice scenario – why do you think it’s not happening on a big scale? CCS technologies are varied, new. expensive, uncertain. In addition, there are all kinds of issues related to growing and harvesting plants for fuel, from just how carbon neutral the whole process really is in life-cycle analysis to the impact on land use and thus food production and prices.
BECCS is working in some demonstration-level projects. Last November a project in Illinois backed by the U.S. Department of Energy completed its first year of taking carbon dioxide captured from an ethanol plant and injecting it into the Mount Simon Sandstone. Some 317,000 tons had been buried at a rate of 1,100 tons/day, according to MIT’s CCS technologies page.
But such small-scale projects, usually costing more than expected and taking longer than expected, only seem to emphasize how far there is to go with carbon capture. Which, in a way, makes the Swedes’ case more intriguing because, as mentioned, they allow for overshooting the 2°C target. Of course, there’s a downside to that acknowledgement, as the authors write:
The option of global negative emissions increases the possibility of meeting stringent overshoot temperature targets. This benefit of BECCS is also, somewhat paradoxically, its main political risk. The possibility of achieving negative emissions in the future may be perceived as a carte blanche for delaying emission abatement efforts.
This would be bad, they say, ticking off the reasons:
First, because of the long atmospheric lifetime of carbon dioxide, the less we emit in the near term, the more ambitious targets can be reached in the future. Second, the potential rate of temperature decline (about 0.6 ° C per century) is too slow to act as an ’emergency brake’ on short timescales, if climate damage becomes unacceptable. Third, the extent to which BECCS can be made available in the future is uncertain, due to uncertainties in land availability as well as technological constraints. Fourth, there are ecological and climate risks associated with the higher temperatures during the transient phase