Methane Slip Reduction

From aboard ship or transport vessel; out of lengthy pipelines and conduits; and where storage tanks sit, methane (CH4) can escape its confines and seep into the atmosphere. This is problematic from an ecological standpoint: although CH4 is much less abundant than carbon dioxide (CO2) and other greenhouse gases (GHGs) that contribute to the warming of the planet, methane packs an environmental punch that is proving to be damaging. So, even modest amounts of this gas have an adverse impact on climate change, making methane slip reduction imperative. In comparison with oil or coal, natural gas is more acceptable given its lesser effect on global temperature disruption. Nevertheless, it still supplies enough harm in methane as to earn a place among the most damaging GHGs emitted by industry, transport vehicles and farms. In fact, the United Nations environmental organ declares methane emissions 80 times more potent at warming than carbon dioxide.

How does methane slip happen?

The Intergovernmental Panel on Climate Change determined in 2021 that CH4 slip results from three factors. Scavenger leaking — this happens when a mix of air and methane flow directly into the exhaust because the exhaust valve is late in closing during gas injection. Hence, the CH4 is expelled prior to combustion. Incomplete combustion — sometimes, a perfect storm of low pressure and low temperature lead to the combustion flame being snuffed out. The remaining methane is subject to slip because the extinguishing occurs at the coldest section of the fuel chamber. Combustion chamber crevices — stagnant gas can form in crevices in the combustion chamber. The volume of this methane gets trapped and untouched by the flame. These crevices are responsible for up to half of the instances of methane slip.

Effects of escaped methane on the environment

While CO2 is often the most derided villain with regard to heat trapping, molecule for molecule, methane is more effective at ensnaring heat within the atmosphere. Yes, carbon dioxide lives much longer and is much more abundant but CH4 remains more climatically disruptive nonetheless. This makes methane slip reduction all the more necessary. The U.S. National Aeronautics and Space Administration (NASA) is capable of tracking methane presence by means of various technologies including Airborne Visible InfraRed Imaging Spectrometer – Next Generation (AVIRIS-NG), Earth Surface Mineral Dust Source Investigation (EMIT) attached to the International Space Station, and Arctic Boreal and Vulnerability Experiment (ABoVE) which tracks methane releases with a primarily natural genesis.

What measures aid in methane slip reduction?

One such project is developing a new combustion model that increases "lean burn," that is a higher air to fuel ratio in natural gas engines. As engines stand now, intake air and fuel are pre-mixed to attain an effective combustion. At the same time, however, this pre-mix is a factor in CH4 slip. The new model would isolate the natural gas in a separate chamber until the point of combustion. The desired result: a 90 percent methane slip reduction. Another idea looks to improve methane flaring. Utilizing chemical plasma, a proposed system will target ignition and flame security. The plasma receives power from a solar battery, keeping energy costs low. The expected outcome is an elimination of up to 72 percent of CH4 emissions from flares.