Roeslein Alternative Energy partners with Argonne National Lab to improve biogas quality and sustainability

Credit: Roeslein Alternative Energy

The U.S. Department of Energy’s (DOE) Office of Energy Efficiency & Renewable Energy has  announced a new partnership between Roeslein Alternative Energy (RAE) and Argonne National Laboratory (ANL) for scaling up technology that ANL developed to synergistically use two waste biomass streams to generate two bioproducts.

The technology enhances the process of anaerobic digestion of wastewater sludge by incorporating biomass-derived, carbon-sequestering biochar within the digester, thus creating pipeline-quality renewable natural gas while using the remaining biosolids for a high-quality fertilizer. With funding from DOE’s Bioenergy Technologies Office (BETO) totaling $1.5 million over three years, researchers at ANL have been able to develop and de-risk this technology, which is now ready for scale-up.

Biochar, charcoal derived from plant material, is created in processes such as gasification and pyrolysis, which also produce energy in the form of syngas or liquid fuels. ANL has demonstrated success using biochar from gasification of both corn stover and woody sources.

Anaerobic digestion usually creates biogas that is mainly a combination of carbon dioxide (CO2) and methane. Extra steps are typically required to upgrade the biogas to renewable natural gas by removing the CO2 and other contaminants. Adding biochar directly to the anaerobic digester sequesters the CO2 and creates a biogas stream that is more than 90% methane and less than 5 parts per billion hydrogen sulfide, thus reducing the need for upgrading steps. The biochar also improves many of the operating conditions for anaerobic digestion, and furthermore, it is nutrient-rich, so the material left after the process is completed (called digestate) can serve as a high-quality fertilizer.

With the success of this research, ANL is preparing to scale up the technology with RAE, a company experienced at operating large-scale digester facilities to produce renewable natural gas ecologically and economically. RAE plans to perform field demonstrations during 2017 and drive further commercialization of the technology.

ANL’s technology could dramatically improve the economics of anaerobic digestion projects such as RAE’s. The reduction of upgrading steps alone could make biogas projects become more profitable. ANL’s technology further reduces capital and operating expenses by improving digester conditions and producing fertilizer, which would provide even greater economic benefit to farmers and land managers.

The project at ANL is part of BETO’s work to fund research, development, and demonstration of waste to energy technologies for more sustainable, cost-competitive biofuels and bioproducts from cellulosic biomass.

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