Anaerobic Digestion

Anaerobic digestion (AD) naturally creates sustainable energy using organic inputs that are often considered waste. First discovered centuries ago, anaerobic digestion is a series of processes where bacteria break down organic matter in an oxygen-free environment. AD is a natural technology that creates biogas, a gas mixture consisting mainly of methane. Biogas rises to the top of the air-tight digester where it is collected and cleaned of sulfur and other impurities. The biogas then consists of the same molecule as natural gas (87 percent methane). We call it Renewable Natural Gas (RNG) for internal combustion engines, heat, or power. We believe this proven set of ecologically friendly processes represents a pathway to large scale alternative fuel production, economic development, job creation, and the security provided by energy independence. Untapped Potential for Livestock Roeslein Alternative Energy believes there is great potential to provide significant amounts of RNG from livestock operations using AD.

“Anaerobic digestion (AD) of animal manures shows great promise in the United States and has environmental and economic advantages over land application of untreated manure.” Source: http://www.epa.gov/agstar/anaerobic/swine.html

Livestock waste is a significant source of methane, a greenhouse gas linked to global warming.Restored Native Prairie: A New Energy Crop to Produce RNG Roeslein Alternative Energy is leading the way toward establishing a new energy crop. Grasses harvested from highly erodible land restored to native prairie will be added to anaerobic digesters as a powerful additional source of RNG packed with environmental benefits. The practice is growing rapidly in Europe. Germany in 2012 had 7,600 AD systems using energy crops to generate biogas. There is a great diversity among energy crops according to information in “Biogas an All-Rounder” from the German Biogas Association. How Anaerobic Digestion Helps the Environment

  • AD captures methane (the primary element of biogas) which would have been emitted into the atmosphere because of the nature of most livestock waste handling systems.
  • The RNG created through AD is generally considered a carbon-neutral energy source.
    • RNG fuel releases atmospheric carbon that was recently fixed by the organic material used to produce it (like manure or native prairie grasses).
    • When replacing fossil fuel, which emits carbon stored over millions of years, RNG cuts greenhouse gas emissions.
    • The digestate produced during AD can be used as a natural fertilizer to replace agriculture fertilizer made from fossil fuels.

 Learn more about Anaerobic Digestion at the Center for Climate and Energy Solutions: http://www.c2es.org/technology/factsheet/anaerobic-digesters