The Future of Biogas as a Renewable Energy Source

By Benedette Cuffari, M.Sc.May 5 2020

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Image Credit: Dmitry Naumov/Shutterstock.com

In the United States, over 70 million tons of organic waste is produced each year. Unfortunately, the mismanagement of these wastes poses significant consequences to both public health and the environment in the form of surface and groundwater contamination.

Increasing the acquisition and utilization of biogas, which is a type of fuel that can be extracted from these organic wastes, could reduce these unwanted health effects while simultaneously offering consumers a new and exciting renewable energy source.

What is Biogas?

Biogas is a type of fuel that can be derived from various biodegradable materials, including livestock manure, food waste, industrial waste, sewage sludge, energy crops, the organic fraction of municipal solid waste, and even certain agricultural products such as straw.

This novel renewable energy source arises from a process known as anaerobic digestion, which relies on microorganisms to degrade the organic compounds present with these biodegradable materials into simple substances that make up biogas.

Biogas is being derived from biodegradable materials such as livestock manure. Image Credit: Rudmer Zwerver/Shutterstock.com

Chemically, biogas is comprised of 50-60% methane (CH₄), 40-50% carbon dioxide (CO₂), and several minor chemical products, such as ammonia (NH₃), hydrogen sulfide (H₂S) and water. Biogas can be upgraded to bio-methane through the removal of CO₂ and other impurities to create a final product that is comprised of approximately 97% CH₄ and less than 3% CO₂.

Biogas Cogeneration Plants

Both raw and upgraded biogas can be used for a variety of commercial energy applications, some of which include electricity and heat generation that is acquired by combined heat and power (CHP) units. Otherwise referred to as a biogas cogeneration plant, biogas CHP units can successfully convert this renewable fuel into electricity and heat with efficiency rates of 35% and 50%, respectively.

Some of the most suitable applications of biogas cogeneration plants can be found in hospitals, nursing homes, laundromats, hotels, academic institutions, prisons, and both residential and recreational facilities.

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Within any biogas cogeneration plant exists three primary components, including the biogas treatment system, the engine, and a control unit. Biogas CHP systems provide a greater level of energy efficiency to facilities with lower energy input requirements. Additional advantages of this technology include reduced emissions of air pollutants such as CO, nitrogen oxides (NO_x) and sulfur dioxide (SO₂), as well as improved reliability and grid support for customers.  

About the AB ECOMAX®

Gruppo AB Corporation is an Italian-based company that is one of the leading distributors of biogas systems in the world. To date, AB has installed a total power capacity exceeding 1,300 megawatts (MW) of biogas energy that has been provided by more than 1,000 systems that were designed and installed by AB. To this end, AB’s line of ECOMAX® modulated systems have been specifically designed to enhance the efficiency and eco-sustainability of biogas energy.

For any given application, a team of over 120 AB engineers works together to create a unique ECOMAX® module that is made up of integrated elements such as a heat exchanger, radiator, utility line, control room, and much more. To ensure that all elements of the ECOMAX® module meet the design specifications and ultimately reduce installation time, all systems are built in-house.

A single ECOMAX® module can be equipped with a power range of 250 kilowatts (KW) up to 4.4 MW. AB offers a total of five possible packaging lines, which include ECOMAX® Biogas, Greenhouse, Special Gas, Natural Gas, and Landfill Gas.

Biogas Fuel Cells

Another way in which both forms of biogas can be used as electricity sources is through the use of fuel cells. With its headquarters in Danbury, Connecticut, FuelCell Energy, Inc. (FCE) is an integrated fuel cell company that designs, produces, sells, and installs a variety of fuel cell technology across the United States. To date, FuelCell Energy offers three SureSource^TM fuel cell products that are all based on carbonate fuel cell technology.

The technology behind the FCE products begins with the injection of a hydrogen-rich fuel such as natural gas or biogas into any SureSource^TM fuel cell. This causes an electrochemical reaction to occur between the hydrogen and ambient oxygen molecules.

The reaction subsequently initiates an internal reforming process that generates a direct electric current (DC) that will subsequently be converted into alternating current (AC) power, whereas the heat and water vapor byproducts will be released by the cathode.

What is particularly unique about the SureSource^TM systems is that the released heat and water vapor, which would normally go to waste, can be used to warm incoming fuel or reused by the customer for facility heating.

Applications in the Transportation Sector

Some work has also shown that the conversion of this renewable fuel source into mechanical energy can be useful for the transportation sector when incorporated into internal combustion engines. Currently, several countries in Europe, including Germany, the Netherlands, the UK, and Sweden have upgraded their biogas for vehicle gas purposes.

However, the potential of this fuel source within the transportation sector has yet to be fully harnessed. Researchers estimate that switching from traditional gasoline to biogas fuels can reduce the transportation industry’s greenhouse gas emission by up to 80%.

Once purified to biomethane, this type of fuel can be used in the same manner that regular or natural gas is used in dual-fuel vehicles. While several countries around the world have improved their natural gas vehicle (NGV) infrastructure, which improves the ease at which biogas can be incorporated into their markets, biomethane production costs can be expensive when acquired from manure-based biogas as compared to when industrial wastes are used.

As of 2017, the total supply cost of biogas as a vehicle fuel ranges from 0.22 USD/m³ and 0.88 USD/^m3 methane for plants, which is comparable to natural gas prices that average at 0.13 USD/m³. Despite these challenges, extensive research is being done to move towards more efficient biomethane production systems.

Sources and Further Reading

• Korberg, A. D., Skov, I. R., & Vad Mathiesen, B. (2020). The role of biogas and biogas-derived fuels in a 100% renewable energy system in Denmark. Energy 199. doi:10.1016/j.energy.2020.117426.
• Hakawati, R., Smyth, B. M., McCullough, G., De Rosa, F., & Rooney, D. (2017). What is the most energy efficient route for biogas utilization: Heat, electricity or transport? Applied Energy 206; 1076-1087. doi:10.1016/j.apenergy.2017.08.068.
• “Electricity and heat production from biogas CHP: Discover technologies” – Biogas World
• “Ecomax®” – AB Cogeneration World
• Farooque, M., Leo, A., Rauseo, A., & Wang, J. (2015). Efficient and ultra-clean use of biogas in the fuel cell – the DFC experience. Energy, Sustainability and Society 5(11). doi:10.1186/s13705-015-0041-0.
• “Biogas for Road Vehicles Technology Brief” – International Renewable Energy Agency

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