Happy new year! CDR Technique: Biochar!

Hello people!

This is my first 2015 post so I wanted to say:

HAPPY NEW YEAR!

I hope you had a good time with friends and family... 

But here we are again, trying to understand a little bit more about the new things being investigated about how to save the world. :)

Today we are going to discuss one technique, biochar.

Everyone knows plants use CO2 by photosynthesis. However when plants (and any other living organism) die, they return all the CO2 back to the atmosphere. So, a way of reducing the amount of CO2 in the atmosphere would be capturing this CO2 and avoiding it to return to the atmosphere. 

Clearly, it would be much better, instead of capturing this CO2, to stop emitting CO2 from fossil fuels to the atmosphere. However, we have discussed the political implications and complications of this, and therefore, anything that can reduce the amount of CO2 released must be considered. 

Let's discuss the process. Pyrolysis is an irreversible thermochemical decomposition with no or little oxygen, that transforms biomass into biofuel and charcoal (Shepherd et al, 2009). 

Biochar by pyrolysis. Source: Wikipedia by K.salo.85

So, this is great, because it produces energy from biomass (renewable energy), and it leaves charcoal behind. Therefore, it allows us to capture the C in this charcoal by burying it back in the soil. We would be eliminating the carbon that would have been released by the living organisms used in the process as biomass and, in the process, we would be producing energy! This process is synthesised in the following image:

Process of producing biochar and returning it to soil, by pyrolysis of biomass. Source: Lehman, 2007

I included that picture because it is a friendly representation of the process. However, it may seem like a perfect solution, and that this discovery could save the world. However, this picture does not show how much carbon would we be taking from the atmosphere and how much would we be giving back. So, what's the result? Woolf et at., 2010, found that by doing this process we could be reducing the emissions by 1.8 Gt of CO2 - C equivalent per year. This is, 12% of today's emissions. 

The following image shows the process in a less friendly way, but clearly shows the process of where is the emission of CO2 avoided and when it is not. However, it does not show the CO2 we would be preventing from being released into the atmosphere by the decomposition of plants and all biomass. 

Schematic representation of the process by Woolf et at., 2010.

It is interesting to read that Indians from the Amazones did bury charcoal into the soil. They did this, not to mitigate nor geoengineer climate, but for improving crop yields (Lean, 2008).

However, to do this at large scale, a lot of new technologies need to be created, and a risk analysis needs to be done. It is suspected that large amounts of biochar buried in the soil could generate chemichal problems but further studies on this topic have just started.

We hope in some time we will be able to understand the risks of doing this and transmit it to you!