I’m all for offsetting more than our fair share of carbon to be carbon negative, and photovoltaics are a great way to do it. But we might also want to investigate other beneficial forms of carbon mitigation, like local, personal sequestration with biochar.
Biochar has been used by indigenous peoples to improve soil productivity in the Americas since pre-Columbian times. By heating biomass in the absence of oxygen, a stable high-carbon powder is obtained, which when mixed into the soil can sequester carbon for thousands of years. Biochar sequestration of carbon is reported to provide environmental benefits beyond greenhouse gas reductions, including prevention of soil nutrient loss, increases in nutrient availability, improvement in plant growth, increased water retention in sandy soils, decreased soil acidity, decreased bioavailability of toxins, and decreased emissions of greenhouse gases (N2O and CH4) from the soil, making it extremely attractive on many different levels.
According to a recent estimate published in Nature, if our forest litter and crop residues were pyrolyzed, along with fast-growing vegetation grown on idle cropland, the resulting biochar could sequester 10% of U.S. greenhouse gas emissions each year. The same author suggests that pyrolysis can produce three to nine times as much energy as it uses in the process (by co-producing bio-oil and bio-gas), making it a carbon-negative source of renewable energy.
Sounds like a cool thing for the green dorm to experiment with – maybe we can make use of some of our organic waste this way, and if we grow food, some of our crop residues?Â
Notes:
- This is an adaptation of part of my assignment for a class tomorrow where I was writing in support of it – Dave suggested I post it.
- If anyone can poke holes in the idea, I’d quite appreciate it, because it does seem to have a slightly “too-good-to-be-true” feel to it that I want to have fully tested.
- I’ve collected about fifteen journal articles about it so far (there are ten referenced in the document form of this post, it’s just too hard to link to them all right now). Let me know if you want to read them.
Further Reading:
