Cornell University's Professor Johannes Lehmann explains that biochar -- sequestering carbon in soils -- is one of the only low-cost ways to remove CO2 from the atmosphere. The expert in soil fertility management and soil biogeochemistry calls for the launch of pilot projects that will allow us to study the real potential for scaling up the technique. Lehmann also warns that the biochar community must avoid making the mistakes shown in other renewable energy sectors.
There are very few alternatives for removing CO2 from the atmosphere. There is the idea to capture carbon from biomass power plants and to geosequester it. But geosequestration is expected to be costly and would take at least a decade or more to become technically feasible.
Other 'geo-engineering' methods to capture atmospheric CO2 or to counter climate change in a strong way, are all either very risky or extremely costly. The concept of introducing sulphur particles into the stratosphere so as to emulate the effect of the cooling blanket generated by a massive volcanic eruption, has been dismissed because the acid rain that would result from it is a serious threat to agriculture and fresh water supplies. It would also destroy the ozone layer. Iron-seeding the oceans so as to induce algae blooms has been rejected by marine ecologists and the international community: the effects of the intervention on marine biodiversity are unknown. Launching billions of tiny mirrors into space so that they form a cloud that can reflect sunlight back, away from Earth, is one of the most costly options. Finally, building large oceangoing vessels which spew salt particles into clouds so as to make them more reflective has some technical barriers to overcome.
One lower-risk strategy to capture CO2 is to erect plenty of 'synthetic trees', which withdraw the greenhouse gas from the air and store it deep into the ground. However, the method is not only very costly, it also doesn't overcome the objections raised against geosequestration.
In light of this list of difficult options, biochar seems to be the most elegant, low-cost and safe strategy. Plants are used as natural CO2 sponges. Once they have trapped the climate-destructive gas, man transforms the biomass into a stable form: biochar. This carbon-rich material is then sequestered into problem soils (like nutrient-poor tropical soils), where it has been found that adding char can improve the fertility of these soils. The char can stay locked up in the soils for very significant periods of time.
energy :: sustainability :: biomass :: bioenergy :: biochar :: atmosphere :: soil carbon sequestration :: geosequestration :: geo-engineering ::