Addressing the climate change challenge is of utmost importance. The atmospheric CO2 concentration is today above 390 parts per million (ppm). This is almost 50 % more than the pre-industrial levels. The level is currently increasing by 2 ppm per year. During the history of the earth, the increase in CO2 levels been has never been as rapid. This is believed to make it difficult for the ecosystems and living species to adapt or migrate, in order to cope with the increase in temperature that we can foresee. The higher levels of CO2 also change the acidity of the oceans, threatening vital components within marine life. This means that we put biodiversity at risk in the coming decades, if we do not take action.
The costs of not taking action are high, both from an environmental point of view, and also in economic terms. The financial costs for combating the threat of climate change are considerable.1 Therefore, accurate priorities have to be set and economic efficiency must be sought. With large parts of the world’s population living at or below the poverty line, this is an important factor to consider.
In order to meet both environmental and economic constraints, there must be a comprehensive mitigation portfolio that includes multiple options. This would for example mean measures that improve efficiency, favour energy conservation, renewable energy and enhancement of carbon sinks, as well as CCS (Carbon Capture and Storage).
Figure 2 Emissions
This report describes a new opportunity which is showing a great potential for CO2 abatement: geologic storage of CO2 from biomass, or BECCS (Bio-Energy with Carbon Capture and Storage).
So-called biogenic CO2 is part of the renewable carbon cycle. CO2 is extracted from the atmosphere into trees and crops as they grow, and is released when they are combusted or decompose. Therefore, biogenic CO2 does not contribute to the increase ofin the atmosphere. On the contrary, these emissions may become part of the solution to the climate problem.
When CO2 that has been captured from the atmosphere byis stored geologically, a flow of carbon from the atmosphere into the underground is created, i.e. a permanent CO2 sink. In scientific terms, this is called negative CO2 emissions. With increasing emission levels and the burden of historic emissions in the order of one trillion (1,000,000,000,000) tonnes of CO2, negative emissions may be necessary if we are to achieve climate targets such as 350, 400 or 450 ppm.
The public debate around CCS shows that the technique is both questioned and little known at the same time. The arguments against CCS cover the range of classical NIMBY-opinions (Not In My Back Yard) to opposition against the mining and combustion of coal. The concept of BECCS gives new dimensions to this debate, as it is a technique for permanent removal of CO2 from the atmosphere, as well as based on a renewable energy source.
BECCS operations are not expected to be able to mitigate global warming on their own, but the technology has become more and more important through the modelling of climate change mitigation, primarily because of the potential for negative emissions. In combination with the complete range of possible mitigation options, the introduction of BECCS technology is creating the possibility of actually decreasing the absolute level of CO2 in the atmosphere. This will enable us to move to lower CO2 concentration levels and allow us to reach the 350 ppm level.
1 Stern, 2006