Methane is about 22 times more damaging to the climate than the CO2 produced when it is burned, methane-containing gases must be flared if they are not used beneficial in combined heat and power plants to generate heat and electricity. Internal combustion engines (gasoline engines and spark-ignition diesel engines) fail their service at methane concentrations below about 40% methane content due to no ignitability. As part of the FFG funded project “CHPs for weak and problem gases” we (under the patronage of Bioenergy 2020+) have recently shown, that CHPs with Frauscher alphagamma® Stirling engines still maintain stable operation and high efficiency at a methane content of 14%.
For example, lean gases are produced in landfills in the second phase of degassing or as a slip gas in biomethane production. As a result of admixing raw gas, lean gases can be disposed with much lower methane content. The result is particularly record-breaking if we consider the excellent emission values. With a residual oxygen content of 5.0%, only 29.9 mg/mn³ NOX and 149.2 mg/mn³ CO could be measured. The total electrical efficiency of 31% (for natural gas) only drops to 26%. “This is a result that we have achieved without any particular effort. We will get to a methane concentration of about 10% after some adjustments. The practical suitability under the given conditions are going to be investigated in field trials shortly.” Josef Frauscher, managing director of the Company.