Monday, July 10, 2017

Drawing Down - 3rd World Style

If  you are the independent type, third world solutions, otherwise known as appropriate technology, can be pretty great. The Drawdown project sees the biggest benefit of small methane generating anaerobic digesters in parts of the world where wood fired cookstoves are commonplace. Distributed digesters in the Drawdown model are fed livestock manure exclusively. Paul Hawkins' group estimates that 36.5% of manure in Asia is currently being run through small digesters and that we can bring that percentage up to 52.6% for all regions of the world where agriculture is dominated by small farms. For the rest of the world, they estimate much greater savings through the use of industrial sized anaerobic digesters. Yet, in marketing their product to the first world, HomeBiogas claims, even without displacing a cookstove, that their food scrap fed digester will save as much GHG emissions as if you stopped driving a car. In my case, it would also save on electricity to run cooking appliances and electricity to cool the house from the heat of those appliances.

Everyone's situation is different, but if you don't rely on a biodigester for recycling your kitchen waste, it may still be better to consider ways to do it yourself - the "it" here being greenhouse gas reduction. Composting of manures, food, and garden refuse are all ways to reduce waste, but they can also reduce greenhouse gas emissions if done properly. The key thing is to keep compost piles aerated. The hard way to do that is by turning the pile frequently enough to avoid anoxia in the pile while also avoiding outbursts of ammonia and methane in the process of turning it. The easy way is by lacing the pile with biochar which is full of microscopic air pockets. I still do some turning and churning of my non-manure compost, but all the piles get about 5 gallons of biochar or more (much more in the case of humanure compost which needs extra pore space in the pile). Sometimes I finish off a pile by giving it time in the tumbler for a few weeks where it gets a lot of air exchange.

If you happen to be a little higher up in the food chain, adding 0.5 to 1% of biochar in the feed for poultry and livestock could reduce enteric methane emissions dramatically. Putting charcoal in feed is not new, but it is being researched more rigorously. The amount of GHG emissions that could be reduced this way is astonishing since it comes with potentially reduced N2O emissions from manure, improved animal health, accelerated feed conversion, as well as biochar's innate sequestration of carbon.

Two solutions you won't find in Drawdown's list are Bioenergy with Carbon Capture and Storage (BECCS) and clean coal. Biomass energy is included as a transitional solution, but does not include any carbon capture, which turns out, like clean coal, to be technically infeasible. If the examples of alternative approaches described above are any indication, however, at the grassroots level, we can still drawdown significant amounts of CO2 by using the means at our disposal. It may surprise many experts to see some of these turn out to be major contributors to limiting global warming.
cells by Penfold_xxx

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