Biochar? A silver bullet?

Biochar is created through the slow decomposition of organic matter at high temperatures in the absence of oxygen. Normally the organic matter would decompose rapidly after the vegetation/plant matter dies, releasing CO2, however, instead of allowing the plant matter to decompose, the process of pyrolysis can be used to sequester the carbon.

The use of biochar for carbon sequestration is a novel idea (I had never heard of it until I conducted this investigation!) Biochar can draw carbon from the atmosphere, locking it away for thousands of years, making it a long-term carbon sink (Winsley, 2007). Global analysis reveals that approximately 12% of terrestrial carbon emissions could be offset by biochar (Lehmann, et al., 2006). Moreover, by burying the biochar in the soil, this increases the fertility of the soil. Consequently, as with afforestation, the creation of biochar is another option that many land owners and farmers are pursuing as biochar can also be used to earn carbon credits. However, the disadvantage of biochar is that involves burning vast areas of natural habitats and ecosystems. If biochar was heavily integrated into the carbon markets then what would this mean for our natural ecosystems?

When the idea of biochar first came about, many referred to it as the ‘silver bullet’, seeing it as a method to utilise waste in a way that allows society to offset emissions. However, the extent to which emissions are offset is limited. Lenton and Vaughan (2009) suggest that by the 2060s a saturation point will achieved if biochar is fully adopted as a way to sequester carbon. Therefore, this shows that this option is difficult to scale up to a level that will make a significant impact to carbon emissions.

Overall, research shows that biochar can store large amounts of carbon, it is stable and can last a very longtime, so it can even be termed as a ‘permanent’ carbon sink. However, what worries me is the conflicting results found regarding the impact that biochar may have only soil. Some scientists argues that is beneficial and increases the productivity of soil, while others argue that it increases the pH of soil and could be damaging (see video showing experiment with biochar). There is concern that companies may start to heavily invest in biochar through conducting pyrolysis on an industrial scale in order to gain carbon credits. Before this happens we need to ensure we know the effects that biochar will have on our soils; especially since that once it is mixed with the soils, it will be there for a very long time...