Biomethane is the energy of the future
Supported by clean fuel policies and incentives, biogas and biomethane production is gaining worldwide momentum as an alternative to fossil fuels. Considered as the energy of the future, biomethane is a renewable, clean and sustainable methane gas produced from biogas. Currently, biogas comes from biodigesters, landfill gas recovery systems and wastewater treatment plants, which convert industrial and agricultural organic wastes and municipal solid wastes and wastewater to a mixture of methane, carbon dioxide and small quantities of other gases. Therefore, the process of biogas purification to obtain biomethane varies, depending on the availability and variety of the feedstock.
Biogas upgrading to biomethane
Also known as renewable natural gas (RNG), biomethane is produced by removing carbon dioxide and other contaminants and increasing the concentration of methane in biogas. Due to the varying levels of carbon dioxide and other residues such as hydrogen sulfide, oxygen and nitrogen, the biogas purification process starts with pre-treatment to ensure the quality of methane concentration. This is particularly crucial to its usage as automotive fuels or in natural gas network. As a next step, water scrubbing and membrane separation technologies are deployed to upgrade biogas to biomethane. In comparison with water scrubbing, membrane separation is a containerized solution to biogas purification with low energy use and operating costs. Most importantly, membrane separation systems can be extended with a carbon dioxide recovery unit.
The future of biogas
Now, biogas is widely used to generate electricity and heat or as cooking fuel. Upgrading biogas to biomethane is a promising alternative to combined heat and power (CHP) generation. Biomethane can be injected to gas networks or used as a transport fuel, especially for regions where utilization of heat is limited. In addition, electricity-only biogas plants may be subjected to the decreasing electricity prices. Moreover, biomethane production has low environmental impact and can decarbonize gas supply. The by-product of biogas purification, carbon dioxide can be liquified and used for industrial and agricultural purposes such as food and beverage production and green houses.