• Natural gas is a gaseous combination of hydrocarbons.
• Biogas can come from landfills, livestock functions, wastewater treatment plants, and even crop residue and woody biomass.

Natural gas is odorless. It is a gaseous combination of hydrocarbons—mostly comprised of methane. Natural gas accounts for roughly 30 percent of all the energy consumed in the nation. Nearly 40 percent of the fuel goes to electric power generation. The rest is divided among residential and commercial purposes, like heating and cooking, and industrial actions.

Most natural gas in the United States is classified as a fossil fuel because it originates from sources developed over millions of years through intense heat and pressure applied on organic matter. However, renewable natural gas (RNG), also called biomethane, is a pipeline-quality vehicle fuel made from organic matter—like landfill and livestock waste—through anaerobic (existing without oxygen) digestion. RNG can be considered an advanced biofuel under the Renewable Fuel Standard.

Because RNG is chemically interchangeable to fossil-attained conventional natural gas, it can use the already present natural gas distribution system. It needs to be compressed or liquefied for vehicle use. Natural gas made by renewable techniques gives added benefits. RNG is basically biogas—the gaseous result of the breakdown of organic material—that has been refined to purity standards. Obtaining biogas from landfills and livestock functions lowers emissions by staving off atmospheric methane release. Also, making biogas through anaerobic digestion lowers unpleasant odors. It makes nutrient-rich liquid fertilizer.

Biogas can come from different areas including the following:

1. Landfills
   • Landfills are selected areas for getting rid of waste gathered from residential, industrial, and commercial structures. Landfills are the third-greatest source of human-associated methane emissions in the nation.
2. Livestock functions
   • Biogas recovery systems happening at livestock functions can be used to make renewable natural gas. Animal manure is gathered and sent to an anaerobic digester (microorganisms break down organic waste) to fortify and enhance methane generation. The product, biogas, can be prepared into RNG.
3. Wastewater treatment
   • Biogas can be made during the digestion of solids taken out during wastewater treatment activities. Energy made at U.S. wastewater treatment plants could possibility meet 12 percent of the U.S. electricity need.
4. Other biogas sources
   • Other sources of biogas include organic waste, such as food producers and wholesalers, supermarkets, restaurants, hospitals, and educational establishments.
   • Biogas can also be made from lignocellulosic matter, such as crop residues, woody biomass, and energy crops. This is underway in Europe, with restricted applications in the United States.