This study presents a novel process for producing pipeline-quality biomethane by anaerobic digestion (AD) of sludge with in-situ biogas cleanup and upgrading using corn stover biochar. The biochar has high surface area (105 m2/g), high ash content (45.2% dry weight) and high concentrations of potassium, calcium and magnesium (14.2% K2O, 3.9% CaO and 4.2% MgO of the ash content, respectively). The biochar-amended digesters produced near pipeline-quality biomethane (>90% CH4 and <5 ppb H2S), facilitated CO2 removal by up to 86.3%, boosted average CH4 content in biogas by up to 42.4% compared to the control digester, close to fungibility of natural gas. The biochar addition enhanced the methane yield, biomethanation rate constant and maximum methane production rate by up to 7.0%, 8.1% and 27.6%, respectively. The biochar addition also increased alkalinity and mitigated ammonia inhibition, providing sustainable process stability for thermophilic sludge AD. The biochar-amended digestate is enriched with nutrients such as potassium, nitrogen and phosphorus, and therefore has great potential for soil applications.

Areas of Focus: Energy Markets
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Energy Markets
Well-functioning markets are essential for providing access to reliable, affordable energy. EPIC research is uncovering the policies, prices and information needed to help energy markets work efficiently.
Energy Efficiency
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Energy Efficiency
Improving energy efficiency is lauded as a promising way reduce emissions and lower energy costs. Yet, a robust body of research demonstrates that not all efficiency investments deliver. EPIC faculty...
Renewable Energy
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Renewable Energy
Lower technology costs and supportive public policies are driving an increase in renewable energy in markets around the world. EPIC research is assessing the costs, benefits, and efficiency of policies...
Environment
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Environment
Producing and using energy damages people’s health and the environment. EPIC research is quantifying the social costs of energy choices and uncovering policies that help protect health while facilitating growth.