Long pause....
in posting, not in working in the improved cookstove space. I'll be setting down many more thoughts in the near term future.
Life happened, and as it happened, I steadily moved closer to this issue. Here's a piece of that story
Just over 4 years ago, I was riding in the co-pilot seat of a small commercial plane, heading to Chipata in the eastern province of Zambia. We ascended to perhaps 4000 meters out of Lusaka and then descended gently down over perhaps 30 minutes to our destination. Definition of features on the ground became clearer as we descended. Across at least 150 km and 30-45 minutes, I could increasingly make out details of the landscape; A dry semi-wooded, hilly landscape, an occasional dirt road, more frequent dirt tracks, little villages, large villages, watercourses, etc. Higher up, I was puzzled by random "target lesions " on the landscape. Concentric rings with a central large white spot, each well larger than a thatched roof of a hut, smaller than a large building.
As we descended, I had an "Aha" moment when I realized these plaques were broadly associated with either villages or dirt tracks. I was seeing aerial evidence of the charcoal industry. It made a huge impression on me; kilometer after kilometer, as far to one side and the other as the eye could see, these circular zones were clearings in the scrub forest with a big ash-pile in the center. I quickly connected this with the many prior observations of piles of burlap bags packed to overflowing with charcoal along the roads, the old diesel exhaust belching trucks hopelessly overloaded with these bags, the men on bicyles perilously balancing 3 or more of these bags on a bicycle, pedaling laboriously towards Lusaka.
The concepts of deforestation, desertification, massive amounts of wood burning on a global scale began real in the image of those "lesions" on the landscape. It is said that 70% of the combustible energy in wood used to produce charcoal goes "up the smoke-stack" so to speak, only there is no smoke stack, just a hole in the top of the great big pile of wood heaped up, covered with dirt and carefully lit on fire. The objective is pyrolysis, driving wood-gas off of the fuel until only pure carbon remains. Controlling this transformation in the traditional fashion is very imprecise, as indicated by the huge ash piles littering the rural landscape.
Now; I am not opposed to using biomass as a fuel source. After all, we're dredging up carbon stores that have been buried for eons and stacking them on top of the more available carbon cycling through the biosphere on a continual basis. A very long term, stable form of carbon storage which simultaneously enriches our soils is biochar, far more durable than mulch and capable of absorbing water, providing excellent habitat for microbes of every sort that convert biomass into compost, recycling minerals and carbon back into the soil.
Even ash recycles some nutrients, largely minerals, back into the earth, but bio-char is even better as a soil builder. It is a far more durable amendment than mulch or compost. If we had an intentional and productive means to harvest the first 70 percent of the heat value of wood and use the last 30% as a soil amendment or many other secondary uses we would transform our global carbon footprint on a similar scale as would the elimination of the use of hydrocarbons to power our cars, trucks, ships and planes. Biochar can be used as fuel; after all, it is simply a form of charcoal, but far better to make it a byproduct of the primary extraction of energy from wood for gainful purposes, than the primary product for heating and cooking in the slums of large cities.
Were we to convert maximally to the pyrolysis of biomass as a source of energy, we'd divert 1/3 of the actively circulating CO2 in the atmosphere that is converted to biomass by plants and trees and sequester it in soil, while harvesting 2/3 as energy, leaving all that historically sequestered carbon in the form of oil and natural gas where it lies. The amount of petrochemical derived fertilizer required to produce our food can be reduced as soil fertility is improved.
Rather than the gas pump, the propane filling station, the electric charging station, one could pull up to the pellet elevator, pick up a load of pellets, gasify the first 70% for motive power and return the 30% as biochar to be used as a soil amendment. I wonder how far your Prius, your Honda Fit, your energy sipping compact, your fuel-guzzling SUV could travel on 100 kg of wood pellets?
This all seems a bit romantic until you examine what is now occurring in industries that create biomass waste as they install co-generation power plants, reducing their energy inputs by extracting energy from biomass byproducts of their industrial processes. We may get there incrementally, converting from fossil fuels to "fresh" biomass, but every journey starts with a single step. We need to begin to take those first steps to begin to reverse the balance of carbon entering active circulation in our biosphere. One massive source of biomass waste is the production of meat from feedlot enterprises, with massive biomass inputs and similarly massive biomass outputs in the form of urea, methane and incompletely metabolized cellulose. Digesters produce bio-gas, usable for combustion-based applications in lieu of fossil fuel gas sources. Landfills produce bio-gas. Burping cows produce bio-gas. Every colon in every living creature produces bio-gas. Harvesting this bio-gas is impractical if not impossible, but it is possible to harvest those bi-products of animal metabolism that are in non-volatile forms.
