According to the United States Environmental Protection Agency (EPA), there are four greenhouse gas compounds that are most often implicated in the global warming phenomenon — carbon dioxide (CO2), nitrous oxide (N2O), fluorinated gases and methane (CH4). Methane is emitted into the atmosphere during the extraction and processing of coal, natural gas and oil. Livestock flatulence is another source of observable methane release. Among these gases, methane is believed to contribute 10 percent to the overall presence of atmospheric greenhouse gases. Less noted is that methane is not strictly a by-product of energy production, it is also a growing source of power generation.

The Power of (and in) Methane

Organic materials can decompose in and out of the presence of oxygen. Whether dead trees, fallen leaves, animal carcasses, food waste, bird droppings or cut grass, these substances will all chemically disintegrate in one manner or another. When they do so absent oxygen, bacteria begin to break them down in phases so that methane is an end-product. This sequence of reactions is called anaerobic digestion. Occurring always in the natural world, anaerobic digestion can be perfected and accelerated by putting human ingenuity to work on it.

Sealed tanks that receive substrate, i.e. the organic matter, can effectuate anaerobic digestion, bringing it to its desired conclusion — renewable methane production — in less time than would be accomplished in nature. These systems are built to scale, from a household apparatus that supplies cooking fuel to a large biomethane plant that supplies power to water treatment facilities or public transit systems, for example. Biogas from cattle, swine or poultry manure is burned to create electricity that can serve whole farms and rural communities. Research is ongoing in order to discover new applications of biogas as an alternative fuel.

Biogas to Biomethane

The resulting biogas from anaerobic digestion contains more than just CH4. Accordingly, the biogas must be purified, cleansed of impurities and contaminant compounds. Among these adulterants are hydrogen sulfide, ammonia, siloxanes and volatile organic compounds. Some of these are dangerous to individual and public health as well as to the structural integrity of pipelines and tanks. Other non-CH4 components, like CO2 and water vapor, reduce the efficiency of biogas as an energy supply. In view of their ill effects, these excess compounds compromise methane renewable energy and must thus be removed to refine biogas to methane.

Biogas is purified through myriad techniques. Some call for the contaminants to be absorbed into liquid solutions. Other methane gas scrubber methods use solid surfaces of activated carbon and other elements to adsorb the undesirable biogas constituents. Other efforts involve manipulations of temperature and/or pressure. Refrigeration and condensation allow the various chemical components to separate from one another. Membrane technology works in a similar way, letting the contaminants to pass through the membrane while the methane is trapped. Processing of these sorts makes certain that whatever leaves the biomethane plant is safe and usable for the general public.

Biomethane to Electricity

One end use of this refined biogas is conversion to electricity. This can be achieved with fuel cells, which harness the chemical energy of biogas by receiving it into its negative electrode while air enters the cells positive electrode. The gas molecules are separated into protons and electrons; the latter flows to the positive electrode and this is where electricity is generated. Another medium for generation is the combustion engine: here, the burning of biogas powers a turbine which generates electricity. Like biogas methane production itself, this creative activity is accomplished on large and small scales. Biomethane is a renewable natural gas that — together with conventionally acquired natural gas — produce 26 percent of U.S. electricity.

Biomethane as Fuel

Biomethane (from biogas to methane) can also be utilized for heating fuel, cooking fuel and vehicular fuel. Indeed, according to the European Biogas Association, biomethane is completely compatible with internal combustion engines. Biomethane can be condensed into compressed natural gas or liquefied. Used by automobiles, utility vehicles and heavier trucks, biomethane is even on the drawing board for boats, ships and railroad locomotives. Should it be perfected for vessels across the transportation spectrum, biogas will sharply reduce fossil fuel emissions.

Purified biogas is a fitting substitute for natural gas in the heating of homes and commercial buildings. This may, however, require refitting of traditional burners and boilers. Since the right ratio of gas to air flow differs between biomethane and fossil fuel. The installation of gauges and meters that regulate this relationship is relatively simple and inexpensive. Boilers, on the other hand, need remodeling to accommodate the increased volume that biogas dictates. Worth noting is that community biomethane heating is an established reality in places like Suderbyn, Sweden. Each house, therefore, need not possess its own biogas plant

In Summary

Anaerobic digestion makes the ready and widespread use of biomethane available for diverse purposes like electricity production, home heating and transportation fuel. Proper cleansing, scrubbing and purification of biogas is essential so that biomethane operates safely and efficiently. Once adequately processed, this fuel can be put to use, sparing the environment the detrimental side-effects of fossil fuels. The increasing utilization of biogas in Europe and elsewhere demonstrates its success as an alternative fuel.