Assessing Excess Carbon Emissions and Soil Toxicity as Unintended Consequences in Applying Biochar as a Geoengineering Scheme

Executive Summary In the years since the Industrial Revolution, atmospheric carbon dioxide levels have steadily risen, causing an associated increase in global warming. In an attempt to remedy some of the effects caused by global warming, various geoengineering schemes have been put forth as possible solutions in resolving the global warming problem. A large portion of these geoengineering solutions are categorized as carbon sequestration techniques, where the geoengineering schemes vary from injecting liquefied carbon dioxide into the deep ocean or fertilizing the oceans with iron to stimulate phytoplankton growth. The focus of this proposal is on carbon sequestration via biochar burial. Biochar is a form of carbon produced via pyrolysis, or combustion with no oxygen or very little oxygen. The pyrolysis process produces a high-density form of carbon, which can be used to sequester carbon through underground burial. A practical implementation of carbon sequestration via biochar would be to convert decaying plant matter into biochar, rather than to allow natural decay from occurring, which releases carbon contained in the biomass back into the atmosphere. However, being an extremely new geoengineering method, biochar still needs to be tested for unintended consequences that may surface from its global application as a carbon sequestration technique. Therefore, this proposal identifies and tests for two important unintended consequences: unintentional carbon emissions from biochar production via the use of traditional kilns and soil toxicity affecting crop productivity due to residual hydrocarbon content contained in biochar. In many parts around the world, farmers produce biochar as a supplemental fertilizer by utilizing traditional kilns often constructed of brick or clay. Although these kilns are inexpensive and easy to construct, there is no way of containing the gaseous pyrolysis byproduct (known as syngas). Syngas is rich in carbon emissions, which then 2 becomes released into the atmosphere and adds to the existing excess quantities of greenhouse gases already present in the atmosphere. A rigorous experiment needs to be conducted to assess the amount of carbon emissions emitted through biochar production via traditional kilns in order to establish a recommendation for the most eco-friendly method of producing biochar. Additionally, hydrocarbons are produced naturally during the pyrolysis process, and are released during combustion in the form of liquid, which is often harvested in commercial pyrolysis machines as fuel. However, hydrocarbons may not be completely released from the solid char during pyrolysis, and residual hydrocarbon contained in biochar incorporated into the soil …