Internal combustion engines operate in a manner similar to the engine in your automobile. Electricity generators burn some form of fuel, like natural gas, landfill gas, petroleum liquids or diesel in the engine. But, instead of turning a drive shaft that is connected to the wheels on your car, the shaft coming from the engine is connected to an electric generator. The generator operates in the same manner as the steam turbine described in a previous section, with copper coils located adjacent to a strong magnetic field as the means to generate electricity.
EIA numbers indicate that there are over 250 separate internal combustion engines operating in Michigan, but they tend to be very small, averaging 2.1 MW capacity. As with combustion turbines, they tend to be used in a peaking capacity, providing electricity to “top up” electric production during periods of increased demand, or to provide energy when other sources are not available.
A key benefit of this technology is that it is relatively inexpensive to build, is very well understood and widely available, even for small or localized applications. This technology also fits well with the widely variable nature of generation from renewable technologies. Internal combustion engines are able to “ramp up” to full production in as little as five minutes, when the wind speeds drop below (or go above) the generation threshold for wind turbines, or when there is little sunlight to power solar generation.
Challenges associated with using internal combustion engines include the emissions commonly associated with the combustion of fossil fuels, like nitrogen oxides, sulfur dioxide and particulate matter. Additionally, the fast-ramping and typically smaller generation capacities of these engines makes them less well suited to baseload operations than combined-cycle turbines, coal-fueled, nuclear options, or large hydroelectric options.