One of the arguments against biofuels is that (like all agriculture, even organic) it is essentially soil mining. By removing plants that grow on the land, we also remove nutrients. This includes trace essential nutrients like iron and copper as well as the big ones like potassium. We can do our best to replace the nutrients with fertilizers (synthetic or organic) but will never match mother nature. So, what do we do?
Biochar is plant matter (such as corn stover) that has undergone pyrolysis (heating without oxidation). To put it extremely simply, biochar is a large quantity of biomass “condensed” into a smaller quantity of charcoal. All of the minerals in the biomass are now in the biochar. Increasing soil health in the form of microbes is another positive effect of biochar. Plants grown in biochar do better than plants in unamended soil (see picture at right, no info on a comparison to conventional or organic soil amendments.
I’ll let the International Biochar Initiative (IBI) explain:
Biochar is a fine-grained charcoal high in organic carbon and largely resistant to decomposition. It is produced from pyrolysis of plant and waste feedstocks. As a soil amendment, biochar creates a recalcitrant soil carbon pool that is carbon-negative, serving as a net withdrawal of atmospheric carbon dioxide stored in highly recalcitrant soil carbon stocks. The enhanced nutrient retention capacity of biochar-amended soil not only reduces the total fertilizer requirements but also the climate and environmental impact of croplands. Char-amended soils have shown 50 – 80 percent reductions in nitrous oxide emissions and reduced runoff of phosphorus into surface waters and leaching of nitrogen into groundwater. As a soil amendment, biochar significantly increases the efficiency of and reduces the need for traditional chemical fertilizers, while greatly enhancing crop yields. Renewable oils and gases co-produced in the pyrolysis process can be used as fuel or fuel feedstocks. Biochar thus offers promise for its soil productivity and climate benefits.
Biochar even appears in the 2008 Farm Bill, I learned on the IBI policy site, appearing just before provisions for research of and protection for pollinators. Apparently Senator Ken Salazar (D Colorado) fought to have the language on biochar included.
Biochar Research. Grants may be made under this section for research, extension, and integrated activities relating to the study of biochar production and use, including considerations of agronomic and economic impacts, synergies of co-production with bioenergy, and the value of soil enhancements and soil carbon sequestration.
Ideally, the production of biochar would be coupled to biofuel production (bioplastic, biorefining, etc) such that every molecule of the plant would be useful – while improving soil quality and sequestering carbon! Admittedly, this sounds too good to be true (some naysayers have stepped forward), but I have reason to beleive it. At the recent Breeding Lignocellulosic Crops for the Bioeconomy lecture series at Iowa State, most of the speakers seemed to think use of biochar was a given (speakers included an economist, multiple plant breeders, people from industry and from a non-profit). Their idea of biofuels doesn’t match that in the media or the doom-and-gloom environmentalists at all.
Each biofuel plant would be limited by transportation. In other words, a circle will be drawn around each plant at the boundary where transporting the feedstock becomes too expensive or too carbon positive. The grain (or beans, etc) can be used as food or feed. Some amount of lower stalk, along with the roots, will be left to retain soil. The remaining stalks and leaves will be harvested and deconstructed in a series of enzymatic and industrial steps. Compounds such as xanthan gum and lysine will be extracted (along with any profitable genetically engineered compounds), the starch and sugar will go to ethanol, and the remaining organic material will be burned for power with the charcoal going back to the farms as a soil amendment. This is, in effect, a closed system.
While I’m not quoting him directly, this model was described by Charles Abbas, the charismatic Director of Renewables Research for Archer Daniels Midland who still teaches at the University of Illinois and coined the term “biorefinery”. He believes that we need to wring every last drop of productivity out of the crops we have, becasue 1) we will not be able to depend on petroleum much longer, 2) we have a limited amount of land, and 3) demand for pretty much everything is only going to increase. Our answer is “industrial ecology”. I’ll have a whole post on his talk at the lecture series soon.
Despite the copious media coverage of biofuels lately, I had actually never heard of biochar until I read a post at the Agricultural Biodiversity Weblog which I heard of through Inoculated Mind that linked to a post titled Soil Mining at Muck and Mystery. Because of the post, I asked about biochar use in biofuel production at the lecture series and learned what the speakers thought about it. Gotta love the blogosphere!