Bio-energy With Carbon Capture and Storage - Negative Emission

Negative Emission

See also: Carbon sink and Negative carbon dioxide emission

The main appeal of BECCS is in its ability to result in negative emissions of CO₂. The capture of carbon dioxide from bioenergy sources effectively removes CO₂ from the atmosphere.

Bio-energy is derived from biomass which is a renewable energy source and serves as a carbon sink during its growth. During industrial processes, the biomass combusted or processed re-releases the CO₂ into the atmosphere. The process thus results in a net zero emission of CO₂, though this may be positively or negatively altered depending on the carbon emissions associated with biomass growth, transport and processing, see below under environmental considerations. Carbon capture and storage (CCS) technology serves to intercept the release of CO₂ into the atmosphere and redirect it into geological storage locations. CO₂ with a biomass origin is not only released from biomass fuelled power plants, but also during the production of pulp used to make paper and in the production of biofuels such as biogas and bioethanol. The BECCS technology can also be employed on such industrial processes.

It is argued that through the BECCS technology, carbon dioxide is trapped in geologic formations for very long periods of time, whereas for example a tree only stores its carbon during its lifetime. In its report on the CCS technology, IPCC projects that more than 99% of carbon dioxide which is stored through geologic sequestration is likely to stay in place for more than 1000 years. While other types of carbon sinks such as the ocean, trees and soil may involve the risk of negative feedback loops at increased temperatures, BECCS technology is likely to provide a better permanence by storing CO₂ in geological formations.

The amount of CO₂ that has been released to date is believed to be too much to be able to be absorbed by conventional sinks such as trees and soil in order to reach low emission targets. In addition to the presently accumulated emissions, there will be significant additional emissions during this century, even in the most ambitious low-emission scenarios. BECCS has therefore been suggested as a technology to reverse the emission trend and create a global system of net negative emissions. This implies that the emissions would not only be zero, but negative, so that not only the emissions, but the absolute amount of CO₂ in the atmosphere would be reduced.