Plants take in CO2 from the air and use it to grow and produce oxygen . Can we use this natural power of plants to our advantage, to generate energy AND remove CO2 from the air? Here’s an idea how :
1) Grow lots of plants 2) Burn them and use the heat to generate electricity (e.g. by using steam to turn a turbine, which runs an electric generator [12,13]) 3) Capture the CO2 emitted by the burning plants, and store it
This process is called Bioenergy with Carbon Capture & Storage (BECCS) . We get energy from a biological source (plants) and capture the carbon released . Carbon is taken out of the atmosphere by plants, and is then stored by humans after the plants are burnt . For details of how carbon is captured see yesterday’s post; for storage, see tomorrow’s post!
In theory this can generate energy whilst reducing the amount of CO2 in the atmosphere, in stark contrast to most energy sources which cause release of CO2 [1,7]! It is an example of a Negative Emissions Technology (NET) . It’s predicted that we will need to implement NETs on a large scale if we are to keep warming to 1.5°C above the pre-industrial (1850-1900) average [8,10]. However, there are no BECCS facilities currently in operation claiming to have substantial negative emissions .
A core problem with BECCS is that a huge number of plants need to be grown . To remove the amount of CO2 humans currently emit each year (~37 billion tons ), we’d need to use 100% to 320% of existing cropland . Since we need food, to grow enough plants for BECCS we’d have to make new farmland. If we cut down forests to plant crops for BECCS carbon would be released from trees, meaning it would take many years of BECCS production on that land to make up for this released carbon [7,8,11].
As a solution, some people have tried using algae (like tiny plants that live in water) for BECCS . The advantage of algae is that it grows very fast so would take up less space [5,6,9].
 https://unfccc.int/sites/default/files/resource/28_EASAC%20Report%20on%20Negative%20Emission%20Technologies.pdf See: 3.3 Bioenergy with carbon capture and storage (BECCS) (Annex 3)
 https://www.ipcc.ch/sr15/chapter/chapter-1/ See: Executive summary, introduction, paragraph 2
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