BECCS (BioEnergy with Carbon Capture and Storage)

China, the world’s largest emitter of CO2, plans to become carbon neutral by 2060. EU, UK, Japan and South Korea have announced their intent to go carbon neutral by 2050. Many big corporations too have declared that they will be carbon neutral by middle of this century or even earlier. Amazon plans to achieve this goal by 2040. Microsoft is even more ambitious and hopes to become carbon negative by 2030.

Becoming carbon neutral means achieving “Net Zero Emission” of CO2. This requires removal of CO2 equivalent to amount emitted. One way of achieving this is to grow more forests or improve land management though better farming practices and thus enhance the natural sinks for carbon. But natural processes cannot achieve carbon neutrality and technological interventions are necessary.

The most practical and scalable technological solution consists of disrupting the carbon cycle by capturing the CO2 released while using biomass as fuel and locking it away permanently in a secure geological formation. The CO2 that is absorbed by the growing biomass thus does not get back into the atmosphere.

There are 3 techniques to capture the CO2: post-combustion, pre-combustion and oxy-combustion. The post-combustion approach uses well proven solvents like potassium carbonate and amines to scrub out the CO2 from the flue gases. In the pre-combustion approach, the fuel is subjected to partial oxidation and the resulting syngas is processed in a shift reactor to produce a mixture of H2 and CO2. The higher CO2 concentration makes the capture easier and cheaper. The oxy-combustion technique uses pure air for burning the fuel and results in flue gas that is nearly pure CO2, thus making capture simpler.

BECCS is not without critics. The land required for cultivating biomass for use as fuel is a serious limitation. Achieving carbon neutrality only via BECCS would require land equivalent to the area currently used for agriculture – 1.5 billion hectares.