In this process, a fuel — coal, natural gas, oil, biomass, etc. — is fed into a boiler and combusted, or burned, to produce heat. Fission of radioactive isotopes — uranium, plutonium or thorium — can also be used to produce heat. This energy heats water in pipes that line the boiler or reactor. As heated water expands in this closed loop system, it becomes pressurized steam that moves through the pipes to a turbine. The force of the steam moving over the blades of the turbine causes it to spin, much like a waterwheel is turned by the force of water flowing past it.[*] The shaft connected to the turbine spins an electrical generator that has magnets surrounding a spinning copper coil, or coil surrounding spinning magnets. The electrons in the copper are excited by the changing magnetic field, created by the motion around the magnets, and this produces electricity.
After going past the turbine, the steam is cooled and condensed in a condenser and is recycled back through the system to be reheated into steam again. In some cases, the so-called “waste heat” from the condensation process can also be captured and used to heat adjacent buildings — a process called “district heating,” or “combined heat and power.”
Steam turbines are a widely used and well-tested method of producing electricity and have been the primary means used to produce electricity around the world since the late 1800s. The U.S. Department of Energy refers to them as a “mature technology” and notes that they are used to produce the majority of electricity in the United States.
The benefits of this technology are that it is extremely well understood and has been used extensively for centuries. It also uses steam as the primary force for moving the turbine to generate electricity. Water is typically inexpensive to access, widely available and very safe for people and the environment.
The challenges associated with this technology tend to be more related to the specific fuels chosen to drive the generator. Those challenges are discussed in specific fuel sections later on.
[*] The process used in this setting is typically the Rankine cycle. For more information, see: Bethel Afework et al., “Rankine Cycle” (University of Calgary, July 21, 2018), https://perma.cc/ QZX6-ZJX9.