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Johannes Lehmann is a soil scientist at Cornell University. He’s also an expert on biochar. That’s what’s created when biomass – things like leftover crops, manure, and yard waste – are heated and charred.
Johannes Lehmann: You make a resource out of your waste stream.
Charring is different from burning, Lehmann said. If something is charred, it retains its carbon, rather than releasing it. That’s why, he explained, charring can turn waste into a valuable resource for farmers.
Johannes Lehmann: One possible biochar system is, for instance, a poultry farmer who would otherwise not know where to put poultry litter.
Lehmann went on to explain that fertilizer made from chicken manure is a source of water pollution. But if the manure were converted to biochar, Lehmann said, the charring process could create enough energy to heat the farm’s chicken coop. And, the biochar itself could be used to enrich the farm’s soil. Lehmann hopes more small farmers will use biochar to create a more sustainable and localized agricultural system.
Johannes Lehmann: To deal with biomass locally, where you can take care of waste, generate electricity, and generate product that will enhance soil health locally is a smart idea.
Lehmann said biochar’s ability to return carbon to the soil – and keep it there – might help reduce carbon dioxide emissions. But, he added, this value of biochar will vary, depending on what the biochar is made from, and how it is produced. Lehmann said that biochar, buried in the soil, stores carbon longer than biomass, because it takes longer to decompose.
Johannes Lehmann: The relatively rapid return of carbon as carbon dioxide from the soil, and to the atmosphere, and the much slower cycling biochar cycle in soil, makes the difference for the emissions reductions that can be achieved by transforming by biomass into biochar.
While biochar has been touted by its advocates as carbon-negative – meaning, it stores more carbon than it releases – Lehmann said that not all biochar systems are created equal, and careful development work is needed.
Johannes Lehmann: If you take an old growth forest, and harvest that forest to produce biochar, that would be emission generation.
Basically, if there’s a change in land use for the purpose of producing biochar, it can do more harm than good. The point, said Lehmann, is to use biomass that would otherwise have decomposed in a short period of time or been burned. Lehmann sees biochar as a way to improve local agricultural productivity, while at the same time preserving nearby ecosystem services and biodiversity.
Johannes Lehmann: The trick is now to find out for a certain farmer or a certain agricultural landscape, what is the most appropriate, the most sustainable way of dealing with our scarce resources.
He said that biochar is just one of many tools that can be used to create a more sustainable planet.
Johannes Lehmann: Biochar is an approach which is unique in how it links energy and crop residue management with soil enhancement.
What is the exact process of bio-char?
Biocharrting is similar to “Coking” coal and is the same as making charcoal. Simply put, organic matter is put in ovens or kilns and heated in the absence of oxygen and converted to charcoal. It takes a lot of energy to complete this process, especially in the poultry litter example. The water must first be converted to steam and driven off before the carbonization can take place. It is probable that in the case of very wet biomass, the energy required would be greater than that ehich would be gained from the buring of the charcoal. It the case of wet material, it would be best to air and sun dry the material before initiating the process.
Problems arise when one thinks about the gathering of the material to be converted to charcoal. The collection and transportation of the material is both labor intensive and fuel intensive. One would need to apply some economic analysis to this before adopting it.
And when you have the biochar, the only purpose would be to burn it and that would produce CO2 just like buring oil, wood, and coal. Not sure why one would spend a pile of money doing this.
With all due respect, that is a very uneducated response. The over-simplification is so great that a response could take hours.
I suggest reading Dr. Lehmann’s book and some scientific articles to understand how char can be made and used. I have learned a lot, and will not profess to be an expert any time soon.
In response to Benjamin\’s questions. Yes, wet materials can require more energy to char than they produce, but drier materials will produce excess energy during the charring process which can be utilized. Secondly, \”why anyone would spend a pile of money doing this\” ; biochar has consistently delivered positive and often drastically positive crop yield increases with increased water retention, greater fertilizer efficiency and enhanced microbial activity. Biochar/charcoal is extremely stable and has been found to last in soils for thousands of years. Waste materials can be used to produce electricity, improve soils and effectively sequester Carbon using proper biochar systems. Waste management, food and fuel, global climate change = worth spending some money.
Josiah,
I am rather perplexed at the idea of taking a high moisture, high carbon, high nitrogen material and using a lot of energy to render it nearly inert to add it to soil when one could use it in a composting opertation and in that way prevent a lot of nitrogen oxides from being formed and also not producing a very positive soil amendment.
After reading your explanation, the idea still amkes no sense to me. If you have a wet, high nitrogen material, you add it to high carbon biomass and produce compost. Or, throw it in a landfill and produce methane. It makes NO sense to spend a pile of money to make charcoal and spread it on soil. Not from a waste management perspective, not from an agricultural perspective, not from an air quality perspective and certainly not from an economic perspective.
Benjamin,
I am glad you that you have the sense to think that way, you are very correct. I was just reading the comments on the USA today article covering the same subject and there was quite a bit of nonsense. A wet material high in nitrogen would be best suited for mixing with organic material high in carbon. However, that same material dry seems to make a suitable Biochar feedstock according to those who have studied it. There are many other organic material waste streams that fit the bill such as; forestry waste, lumber mill waste, corn stover, rice hulls, coconut husks, invasive plant species, and some municipal green wastes.
Biochar itself is an organic material high in carbon and could be used to mix with high moisture, high nitrogen material. In fact using biochar in composting situations seems to be synergistically beneficial to the compost and to the biochar. I speak from experience not just theory, I produce biochar and I have experimented with and analyzed biochar in compost systems. The hot, moist, nutrient rich environment of a thermophillic compost pile can improve the quality of the biochar so as to help achieve immediate positive plant growth responses, in effect the biochar becomes mature, charged and ready for action. In turn, during composting the extremely high adsorptive properties of biochar help to reduce nutrient loss (especially N) and the equally high surface area aids in microbial activity.
When applied to soil, the results can be outstanding. Strictly from an agricultural standpoint this is very exciting and worth the money. I strongly suggest that you look on the internet for articles and pictures showing results. It can cut fertilizer costs, improve yield, and last for decades (if not centuries).
Josiah, I will read on it. I must say it looks like a waste of energy. I have two college careers to base my thoughts on beyond my experience. My first major was Animal Science at Texas A&M University. We studied soils and botany as well as general biology and dendrology and forage crops. I graduated with a BS in Environmental Management with a concentration in Sopid Waste Management. That from the Rochester Institute of Technology in Rochester, NY. I taught part of the senior level class on land application of waste. I have built, run and closed MSW and hazardous waste landfills and cleaned up tens of thousands of tons of hazardous waste. I have built Petroleum Contaminated Soils compost piles and fed and stirred them until the petroleum was \”eaten\” by the bacteria. So, I am speaking from some experience and knowledge. I have also worked on construction and shutdowns at fossil and nuclear power plants. Entropy is a bear. It takes a lot of energy to char any material.
It is my experience that trying to establish growth on an area that has a lot of charcoal in and on the soil. It takes HUGE amounts of added nitrogen to cause the charcoal to become biologocally active.
Anyhow, appreciate the conversation. I will look this up and see what I learn.
Ben
The USDA’s Agricultural Research Service has estimated that if the United States were to pyrolyze 1.3 billion tons of various forms of biomass annually, it could replace 1.9 billion barrels of imported oil with bio-oil. That would represent about 25 percent of the annual oil consumption in this country. In addition, USDA estimates the country could sequester 153 million tons of carbon annually by adding biochar to soils.
Although widespread research on biochar began less than a decade ago, debate already is brewing on whether its prevailing commercial use will be for fuel or for soil and carbon sequestration.