Philip is excited again.

Crop residues, although often referred to as agricultural waste, are in fact a vital component of soil agroecosystems. Crop residues contain substantial amounts of plant nutrients (primarily C, N, K, P, Ca, and Mg), and if crop residues were harvested every year these nutrients would have to be replaced by increased fertilizer use. Many soil organisms utilize crop residues as their primary substrate, and these organisms are responsible for nutrient cycling, building of biogenic soil organic matter, and maintaining levels of soil organic C. Crop residues are critically important for building and maintaining soil structure, which facilitates root penetration and the movement of both air and water in soils. And, crop residues on soil surfaces enhance water infiltration, which increases available water to growing plants, and decreases the destructive effects of raindrop impact and surface runoff, which are the dominant causes of soil erosion. If all aboveground crop residues were removed year after year, the quality of our soils would rapidly deteriorate (Wilhelm et al., 2004). Production agriculture would require more fertilizer, more tillage, and more irrigation water to produce the same crops, and the quality of our surface and ground water would deteriorate due to increased leaching of plant nutrients and agrochemicals and higher sediment loads due to increased soil erosion. Furthermore, any C credit claimed for bioenergy production would have to be significantly discounted because of the loss of soil organic C and the substantial energy required for increased fertilizer manufacture and tillage. Much of the current scientific debate on the harvesting of biomass for bioenergy is focused on how much can be harvested without doing too much damage. I propose a fundamental paradigm shift, the scientific debate should be focused on how to design integrated agricultural biomass-bioenergy systems that build soil quality and increase productivity so that both food and bioenergy crops can be sustainably harvested.

I've said as much for a long time, though not as well and not with references of equal quality. This is from a paper by David A. Laird of the USDA, ARS, National Soil Tilth Laboratory: The Charcoal Vision: A Win–Win–Win Scenario for Simultaneously Producing Bioenergy, Permanently Sequestering Carbon, while Improving Soil and Water Quality. The ideas alluded to recently in Old Tech that loosely advocated distributed on-farm systems for management of crop residues, favoring pyrolyzing biochar systems over incineration are more than amplified by this fine article.

Processing biomass through a distributed network of fast pyrolyzers has many potential advantages relative to the cellulosic ethanol platform. Fast pyrolyzers rapidly (~1 s) heat dry biomass (10% H2O) to ~500°C and thereby thermally transform biomass into bio-oil (~60% of mass), syngas (~20% of mass), and charcoal (~20% of mass). The energy required to operate a fast pyrolyzer is ~15% of the total energy that can be derived from the dry biomass. Modern systems are designed to use the syngas generated by the pyrolyzer to provide all the energy needs of the pyrolyzer. Bio-oil is an energy raw material (~17 MJ kg–1) that can be burned directly to generate heat energy or easily shipped to a refinery for processing into transportation fuels and various co-products (Bridgwater et al., 1999). Charcoal is also a potential energy product, however, I advocate returning the charcoal to the soils from which the biomass was harvested thereby closing the nutrient cycle in a way the mimics the soil building effects of natural prairie fires.

There are many ways to configure pyrolyzing systems. The gases and oils produced can be made into fertilizer as well as fuel, or burned to drive generators to make electricity. See Post Toasties for a discussion of the Biochar Fund which is developing small scale systems for use in Africa that turn crop residues into biochar for fields and use the gasses to drive village scale generators. In my view fertilizer is the most sensible use for these gases, though some liquid fuel will result too. The Eprida system that produces nitrogen doped biochar and some fuel is attractive since it can be applied to fields to not only improve soil tilth, CEC, and water retention, it provides fertilizer in a sort of time release form. A little nitrogen goes a longer way when it is made available over time. I also like the fact that Eprida is a for-profit social-purpose enterprise, which is marketing devices and technologies that can be used on-farm to convert waste biomass into char, biofuel and fertilizer.

But I understand that pyrolyzing systems need to compete with the ethanol plague. The current disaster using grain as feedstock is defended (like other mistakes such as Kyoto) as a first step and that cellulosic ethanol technologies are coming. It is liquid fuel for use in transportation that we most desire, and it is sold as a national security issue as well as an emissions issue. It's all nonsense, but that's the political climate today.

The potential to generate large quantities of carbon negative energy in a form that can replace petroleum-based liquid transportation fuels is a major advantage of The Charcoal Vision. Extrapolating this strategy to a global scale coupled with substantial increases in energy use efficiency and greater use of nuclear and other non-CO2 generating energy sources, humanity could actually start decreasing levels of greenhouse gases in the atmosphere (Lehmann et al., 2006).

There is also a desire to seek rents.

The biggest problem is economics. If an energy company is paid only by the volume of fuel delivered, there will be no incentive to convert any of the biomass to charcoal. The charcoal will represent diverted raw material that could otherwise be turned into fuel, and hence, profits. Farmers will have a small incentive to apply charcoal to their fields, that is, long-term increases in crop yields and lower fertilizer bills. But, transportation and application of charcoal will take time and cost money with returns in future years. Hence, farmers renting land on short-term leases will have no incentive to apply charcoal. The obvious solution is some form of compensation to the owner of the pyrolyzer to make charcoal and to the farmer to apply the charcoal. The compensation could be through the sale of high value C sequestration credit contracts in the commodities markets or through direct government payments. Currently, contracts for C sequestration in agricultural soils are highly discounted because of uncertainty about the amount and the duration of C sequestered in agricultural soils, and because the United States opted out of the Kyoto treaty (Weersink et al., 2005). Contracts for C sequestration through charcoal applications to agricultural soils have the potential to be high value contracts, because the buyer would know exactly how many tons were applied and the buyer would have confidence that the C would be stable for 1000 yr. But without access to international markets, any such contracts would still be greatly discounted. Alternatively, direct government payments to farmers for charcoal applications could easily be justified, as the farmers would be providing critical environmental and ecosystem services to the rest of the nation.

I think that this is false. The profit comes from reduced inputs needed to produce better crops. Farmers aren't real dumb. When they see a neighbor out doing them they want to know why and they are pretty quick to adopt superior techniques. It might take a little longer for the system to develop without rents, but it won't be subject to a crash (like the CRP) when political and market conditions evolve. It's real, rather than just political shenanigans.

Other potential problems with The Charcoal Vision include the development of technology needed to handle, spread, and incorporate charcoal into soils. Mishandling could result in substantial amounts of dust, which could pose air quality issues and be a threat to human health. Poor engineering and/or poor management of pyrolyzers could result in emissions of NOx, CO, various volatile organic compounds, and dust, which would degrade air quality and release potent greenhouse gasses to the atmosphere. Properly engineered and managed, modern fast pyrolyzers will emit only CO2 and water vapor.

There will be a suite of technologies and techniques developed for biochar agronomic systems. John Deere and International Harvester, among many others, ought to be consulted and included in these early stages of roll out. I suspect that some of the Japanese companies might be very aggressive developers of appropriate machinery.

Laird concludes:

Assigning a monetary value to intangible benefits such as reducing the threat of global climate change and enhancing energy security, food security, water quality, and rural economies is vital to development of visionary policies.

I think that this is dead wrong. It isn't vital. This is going to happen whether governments meddle or not. The benefits are real and it's just good business to do it. I'd wager that we will see growers producing crops for cellulosic ethanol who use biochar amendments to reduce their costs and increase their profits. As ever, agronomic systems will be half crippled and bent by government interference, but they will also be half sensible.