Natural gas emerged as the leading fuel for baseload power generation in the USA in the 2010s, following the large-scale commercialization of horizontal drilling and hydraulic fracturing in the Barnett Shale by Mitchell Energy in the late 1990s. Natural gas overtook coal as the main fuel for power generation in the US around 2016.1
Simple cycle
Simple cycle generators run an engine of some sort (reciprocating, like a car, or a turbine, like a jet plane) that’s fueled by a hydrocarbon (like natural gas) to spin an alternator to generate electricity.
Combined cycle
Combined cycle power plants run two different turbines to capture more electricity from the combustion of a hydrocarbon, typically natural gas:
- Gas turbine: Natural gas is burned, and the combustion products (gases) are used to spin a turbine to generate electricity. This is the same as the simple cycle.
- Steam turbine: The hot gases that exhaust from the gas turbine are then used to boil water and generate steam. That steam passes through a second turbine, generating more electricity.
These power plants typically have higher efficiencies (60% or higher) than simple-cycle generators such as are commonly used with coal. They still emit CO2, but generate more power per unit of greenhouse gas produced.