The type of primary fuel or primary energy flow that provides a power plant its primary energy varies. The most common fuels are coal, natural gas, and uranium (nuclear power). A substantially used primary energy flow for electricity generation is hydroelectricity (water). Other flows that are used to generate electricity include wind, solar, geothermal and tidal.

Different countries get their electricity from different types of power plants. For example, in Canada, most electricity generation comes from hydroelectric power plants which accounts for about 60% of the total electricity generated in Canada. But the most usual power plants are thermal ones all around the world.

Most thermal power plants use fuel to heat up water from a reservoir, which generates steam(usually at a high pressure). The highly pressurized steam then travels through pipes to rotate the fan-like blades of a turbine (see Rankine cycle for more info). As the turbine begins to spin, it causes giant wire coils inside the generator to turn. This creates relative (continuous) motion between a coil of wire and a magnet, which pushes electrons and starts the flow of electricity.

• Fossil fuel power plants burn their fuel in order to create the thermal energy to run their external heat engines. A simple cycle gas plant does not use steam like the others: it works similar to a jet engine where natural gas is ignited and burned and the heat creates pressure that turns the turbine. Combined cycle gas plants use both the heat and steam as well. Types of fossil fuel plants include coal-fired power plants and natural gas power plants—accounting for the largest producers of electricity around the world 
• Nuclear power plants use fission processes to generate electricity. In these plants, uranium nuclei are split which creates the thermal energy needed to create steam. It then works just like fossil fuel power plants where the steam spins a turbine, generating electricity. The power plants require the use of nuclear reactors to carry out these fission processes. Some types of reactors include pressurized water reactors, CANDU reactors, RBMK reactors, and boiling water reactors.
• Solar thermal power plants use heat from the sun’s rays to create the steam that is needed to rotate the turbine.

Renewable energy power plants get their energy directly from their respective flows in order to generate electricity. These primary energy sources replenish themselves eventually, but are limited in the amount of energy that is available at any given time or place. Therefore they are often intermittent and non-dispatchable.

• Hydroelectric facilities use energy from falling water in rivers and reservoirs to spin a generator and create electricity. This energy source tends to be more reliable (dispatchable) than other renewable resources, especially when the facility runs off of a reservoir.
• Wind turbines get their energy from wind, which upon contact slows down and transfers kinetic energy to the turbine. Air drag causes the turbine to spin, and the maximum efficiency of turbines is given by the Betz limit.
• Solar panels use photovoltaic cells in order to create electricity. The incoming photons from the Sun hit atoms inside the panel’s semiconductors which causes electrons to flow. Solar energy is intermittent but combined with energy storage technology their power can be much more reliable.