Reducing CO2 emissions in heavy-duty spark ignited engines for electric power using alternative fuels

Carbon dioxide (CO2) emissions can be reduced through newer powertrain concepts with electrification, efficiency optimization, and through alternative fuels. The focus of this work is on alternative fuels and optimizing engine efficiency for selected fuels on a large bore engine (> 170 mm). We surveyed alternative fuels with a lower carbon to hydrogen ratio than diesel fuel, or fuels without carbon. Examples of such fuels are: natural gas (including liquified natural gas (LNG) and its variability), methanol, ethanol, liquefied petroleum gas, ammonia, and hydrogen. The knock limited loads and possible efficiency targets were estimated using a closed cycle simulation with chemical kinetics. The achievable power densities and emitted CO2 levels are presented. In addition to simulation, single cylinder test results are presented for natural gas fuels. The total cost of ownership (TCO) analysis focused on a high fuel use application, in this case, stationary electric power generation. Natural gas is a good alternative fuel for heavy duty applications based on cost and availability.