Evaluating the Economic & Environmental Impacts of Biogas Management Technologies

Biogas produced from the anaerobic digestion of organic waste offers a valuable source of renewable energy. Considering the abundance of organic waste produced by various human activities, this could provide a significant source of renewable energy that is completely sustainable in the long-term. The biogas generating potential in California, for example, is estimated to be around 93 billion cubic feet of methane per year, or the equivalent of 800 million gallons of petroleum-based fuels when compressed for use as renewable natural gas or compressed natural gas to fuel vehicles.

Biogas producers often generate power on-site with gas turbines, micro-turbines, or reciprocating engines, which emit pollutants (nitrogen oxides) that contribute to ozone formation. In California, most of these biogas producers are located in areas where ozone criteria pollutants are strictly regulated, which can make getting the necessary permits a complicated process.

Taking advantage of innovative alternatives that are now available, such as upgrading the quality of the biogas to a standard suitable for injecting into a natural gas pipeline, incorporating it into fuel cells, and using biogas as a fuel to power vehicles, can have multiple environmental benefits, including reduced greenhouse gas emissions, improved air and water quality, reduced waste and odor generation, and a renewable alternative to dirty fossil fuels. However, both organic waste operators and regulators generally lack sufficient knowledge regarding the use of biogas management technologies for improving the environmental and economic performance of biogas-to-energy operations.

Having a clearer understanding of how these technologies can improve the economic and environmental performance of biogas operations can help local and state government departments, regulators, and biogas project developers to select the most cost-effective biogas management tool based on the geographic location and scope of the project.

In the following series of articles we will be discussing the environmental and economic performance of seven different technologies currently used as biogas management tools: 

1. Flaring
2. Combustion in a piston/reciprocating engine
3. Combustion in a combustion/gas turbine engine
4. Combustion in a micro-turbine engine
5. Conversion in a fuel cell
6. Upgrading for injecting into a natural gas pipeline
7. Compressed RNG for use as CNG vehicle fuel

The environmental and economic performance of each of these biogas-to-energy technologies is limited to the use of these biogas management technologies and is not a thorough lifecycle analysis. An assessment of upstream and downstream sources and sinks of greenhouse gases and pollutants is beyond the scope of this series of articles. Instead, the series is primarily a cost and emissions analysis of the various biogas management technologies, and as such, it will focus more specifically on the atmospheric emissions as well as the costs associated with each of the biogas management options listed above. We will also provide information on biogas management technologies that can be used to monitor biogas and air quality, as well as tools that can be used to help monitor and reduce atmospheric emissions in various scenarios.

Featured Image by Tommaso.sansone91, CC0, via Wikimedia Commons