700-year-old West African soil technique could help mitigate climate change
A high temperature LENR reactor that uses molten salt a heat transfer medium can be used to char farm wastes to produce a vigorous farm fertilizer.
Fundamentals of Charcoal Production
One of the most important outputs of the Molten Salt Oxidation Process (MSOP) is biochar. In traditional methods of biomass fast pyrolysis ,this char is used to fire the bioreactor and is turned into CO2. When LENR heat is used, biochar can be saved and reapplied back to the soil.
First off, Biochar is charcoal created by pyrolysis of biomass, and differs from charcoal only in the sense that its primary use is not for fuel, but for biosequestration or atmospheric carbon capture and storage. Charcoal is a stable solid rich in carbon content, and thus, can be used to lock carbon in the soil. Biochar is of increasing interest because of concerns about climate change caused by emissions of carbon dioxide (CO2) and other greenhouse gases (GHG).
Carbon dioxide capture also ties up large amounts of oxygen and requires energy for injection (as via carbon capture and storage), whereas the biochar process breaks into the carbon dioxide cycle, thus releasing oxygen as did coal formation hundreds of millions of years ago.
Biochar can sequester carbon in the soil for hundreds to thousands of years, like coal. Modern biochar is being developed using pyrolysis to heat biomass in the absence of oxygen in kilns and MSOP is an analogous process. However, to the difference of coal and/or petroleum charcoal, when incorporated to the soil in stable organo-mineral aggregates does not freely accumulate in an oxygen-free and abiotic environment. This allows it to be slowly oxygenated and transformed in physically stable but chemically reactive humus, thereby acquiring interesting chemical properties such as cation exchange capacity and buffering of soil acidification. Both are precious in clay and /or nutrient-pore and/or nutrient depleted soils.
Biochar can be used to hypothetically sequester carbon on centurial or even millennial time scales. In the natural carbon cycle, plant matter decomposes rapidly after the plant dies, which emits CO2; the overall natural cycle is carbon neutral. Instead of allowing the plant matter to decompose, pyrolysis can be used to sequester some of the carbon in a much more stable form. Biochar thus removes circulating CO2 from the atmosphere and stores it in virtually permanent soil carbon pools, making it a carbon-negative process.
In places like the Rocky Mountains, where beetles have been killing off vast swathes of pine trees, the utilization of pyrolysis to char the trees instead of letting them decompose into the atmosphere would offset substantial amounts of CO2 emissions. Although some organic matter is necessary for agricultural soil to maintain its productivity, much of the agricultural waste can be turned directly into biochar, bio-oil, and syngas.
Biochar is believed to have long mean residence times in the soil. While the methods by which biochar mineralizes (turns into CO2) are not completely known, evidence from soil samples in the Amazon shows large concentrations of black carbon (biochar) remaining after they were abandoned thousands of years ago.
Lab experiments confirm a decrease in carbon mineralization with increasing temperature, so ultra high temperature charring of plant matter increases the soil residence time and long term soil benefits of high temperature biochar.
Terra preta soils are of pre-Columbian nature and were created by the local farmers and caboclos in Brazil's Amazonian basin between 450 BC and AD 950. It ows its name to its very high charcoal content, and is characterized by the presence of charcoal in high concentrations; organic matter such as plant residues, animal feces, fish and animal bones and other material; and of nutrients such as nitrogen (N), phosphorus (P), calcium (Ca), zinc (Zn), manganese (Mn).
All of these elements save nitrogen will be found in the ash residuals in the MSOP process. To mitigate nitrogen depletion of the soil, cogeneration of nitrogen based fertilizer via the co-production of ammonia is possible from the gas output of the MSOP process.