Turning gas waste into power

Every year, some 400 million tonnes of CO2 emissions enter the atmosphere as a result of the flaring off of associated petroleum gas (APG). Formerly considered uneconomical, APG can actually be used as a source of energy for power generation while also reducing CO2 emissions, says Thomas Elsenbruch, Marketing Program Manager for GE Energy’s Jenbacher gas engines.

For many years, companies extracting mineral oil have barely made use of the associated gas obtained in the process, usually flaring it off. However, rising raw material prices coupled with increasingly stringent environmental regulations are putting growing importance on using the flare gas as an energy source. According to estimates by the World Bank, the total volume of associated gas flared off every year is equivalent to a monetary value of $30.6 billion U.S. at current rates. In fact, the quantity of APG flared off each year is large enough to supply the entire world with natural gas for 20 days!

Why is using APG so difficult?

Because APG is not highly pure methane gas, but a mixed gas of varying quality, there are several challenges when using it in gas engines. For instance, because the composition of the gas fluctuates and also varies greatly from one region to another, high fuel flexibility for the engine is required. The main criterion is to avoid knocking, which is an uncontrolled combustion caused by the often high content of higher hydrocarbons such as butane and pentane. LEANOX, GE Energy's internationally patented lean gas combustion control system, ensures the right air-gas mixture in the engine - even under difficult conditions - thus providing a constant combustion process.

Another critical topic in the utilization of APG is the proper removal of condensates from the gas. Condensates like water or heavier hydrocarbons can cause problems in the gas pressure control train as well as knocking in the engine.

Still another challenge is the ambient conditions under which engines need to be operated with APG. For instance, with extremely low temperatures during the winter, operations in the Western Siberian oil fields can be challenging. Still, five Jenbacher gas engines provide an independent and cost-efficient power supply at the Severnaya Neft crude oil pumping station close to the Arctic Circle. The Jenbacher engines provide more than 3.7 MW of electrical, covering the customer's power requirement, and about 2.2 MW of thermal output. The heat provided by the two cogeneration units is used for field operations and the workers' camp.

Power generation from APG

GE has many years of experience in the purification and utilization of a wide range of special gases - including APG. Today, there are more than 300 modified Jenbacher gas engines of the types J320, J420 and J620 delivered worldwide with an electrical output of more than 400 MW.

Specially modified Jenbacher gas engines offer an optimal means of utilizing APG economically, and at the same time have a positive impact on the environment.

Thomas Elsenbruch is the Marketing Program Manager at GE Energy's Jenbacher gas engines, Austria. He has 13 years of experience in the engine and power generation industry and holds a Diploma Engineer in Mechanical Engineering from the University of Landshut, Germany. Elsenbruch has worked at GE Energy's Jenbacher gas engine business as application engineer and Marketing manager in different fields of gas engine applications for more than eight years.