photo: Soil Science/Creative Commons
There's been lots of back and forth in the past year on biochar, ranging from research showing it has huge potential for absorbing carbon emissions on one side, to uncertainty about its potential, to outright hostility towards the enthusiasm shown towards it--and all from people with good environmental credentials. A new report from NRDC tries to sort it all out, and comes down somewhere in the middle.Biochar: Assessing the Promise and Risks To Guide U.S. Policy arrives at the overall conclusion that there is great technical potential for biochar on a global scale, but that what we can actually achieve with it on a wide scale is likely significantly lower than that. It's just premature to claim with certainty what the impact of widespread biochar production and application will be--something which the Royal Society assessment on geoengineering also concluded.
Which is pretty much always the case with any technology. Sure, there is potential sunlight available striking the Earth to easily meet current and future energy demand many times over, but will we practically capture all that? No way. Ditto for wind power, petroleum, coal, etc etc.
The main point made about developing biochar systems with the best environmental performance is using the right feedstock. Sometimes you hear opposition to biochar on the grounds that it's futile to grow plants just to turn them into biochar, and this report echoes that, saying that "already concentrated sources of waste biomass, such as animal manures, organic municipal solid waste, and urban wood residues" are the way to go. These feedstocks offer savings in terms of energy and carbon emissions to produce them, as well as reduced environmental impact from land-use changes, compared to using primary biomass.
As for the optimum method of producing the biochar itself, the report says slow pyrolysis is best for maximizing output and creating the best, most uniform product.
At a broader perspective, the report recommends,
Instead of focusing just on carbon sequestration, our view is that considering the multiple benefits that flow from well-designed biochar systems--water quality benefits from improved nutrient management, an ability to utilize biomass waste streams as feedstocks, and to produce a variety of renewable energy resources--makes a more robust case for further developing biochar systems.
Read more: Biochar: Assessing the Promise and Risks To Guide U.S. Policy
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More on Biochar:
Biochar Alone Could Offset 12% of All Human Greenhouse Gas Emissions: Study
Biochar Offers Answer for Healthy Soil and Carbon Sequestration
Jason Aramburu on the Promise of Biochar
Author of 'The Biochar Solution' Says 'It's Not a Solution' (Video)