Natural gas reserves within the United States continue to rise. According to the Energy Information Administration, dry natural gas reserves increased by ten percent from 2010 to 2011, while wet natural gas reserves increased by 38% in 2011. Natural gas consumption also increased from 24.09 trillion cubic feet (TCF) to 24.48 TCF over the same period. As the natural gas supply, demand, and industry continue to grow methane losses across the supply chain will be inevitable. Since methane is a potent greenhouse gas, many studies are currently analyzing the loss of methane from the wells to the end user. As natural gas transmission systems grow there must be an increase in natural gas compressor and storage facilities.
Currently, there is not a detailed inventory describing the emissions associated with natural gas compressor system engines in terms of the emissions resulting from engine unit losses and leaks. Researchers from West Virginia University’s Center for Alternative Fuels, Engines, and Emissions (CAFEE) recently conducted methane leak and loss audits at five compressor stations with a special focus placed on the engine and compressor units. These audits focused on identifying and quantifying the leaks and losses associated with the engines and compressor units of a typically operating site. A micro dilution high volume sampling system was used in conjunction with a portable methane analyzer to quantify leaks and losses. Bag samples of exhaust gas and engine operating parameters were used to calculate the methane flow rate from the reciprocating engines and turbines used to operate compressors at these sites. Leaks are defined as unintended methane releases from components not designed to emit methane. Losses are defined as methane releases that are known to exist or exist by design.