How is electricity produced? We study the principles, advantages, and disadvantages of each method of power generation.
Basic Knowledge
Main methods of power generation:
① Thermal power generation: Fossil fuels (coal・oil・natural gas) are burned → steam → turbine → generator. Problems include CO₂ emissions and fuel depletion
② Hydroelectric power generation: Gravitational potential energy of water → kinetic energy → turbine → generator. No CO₂ emissions, but environmental modification is a problem
③ Nuclear power generation: Thermal energy from nuclear fission → steam → turbine → generator. Low CO₂ emissions, but problems include nuclear waste and safety
④ Solar power generation: Light → electricity through the photoelectric effect. Renewable, but weather-dependent
⑤ Wind power generation: Kinetic energy of wind → turbine → generator. Renewable, but problems include suitable locations and noise
⑥ Fuel cells: Chemical reaction between hydrogen and oxygen → electricity. No CO₂ emissions (depends on the method used to produce hydrogen)
Thermal power generation（a turbine is driven by heat from burning fuel. CO₂ emissions are an issue）
Nuclear power generation（a turbine is driven by heat from nuclear fission. Radioactive waste is an issue）
Solar power generation（sunlight is directly converted into electricity by the photoelectric effect）
Renewable energy（energy sources such as solar, wind, hydroelectric, and geothermal energy that do not become depleted）
Fuel cell（a cell using the oxidation reaction of hydrogen. The only emission is water）
Pumped-storage hydroelectricity（surplus electricity pumps water to a high place, and the water is released to generate electricity when demand is high）
Further Exploration (Background and Significance)
Many power-generation methods (thermal, hydroelectric, nuclear, geothermal, and tidal power) are essentially the same in that they turn a turbine to operate a generator. They use electromagnetic induction (Faraday's law) to convert mechanical energy→electrical energy. Solar power generation alone directly converts energy through the photoelectric effect, so its structure is fundamentally different.
Japan's energy self-sufficiency rate is about 13% (2022, IEA), which is extremely low, making energy security an issue. After the 2011 Great East Japan Earthquake, nuclear power plants were shut down, increasing dependence on thermal power. Expanding renewable energy is urgent.
Smart grid: A system that combines unstable renewable energy, such as solar and wind power, with storage batteries and demand control to supply electricity stably. AI-based supply-and-demand forecasting is also used.
- Many power-generation methods: turbine → electromagnetic induction
- Solar power only: direct conversion through the photoelectric effect
- Renewable sources: solar・wind・hydroelectric・geothermal
- Thermal power: CO₂ emissions・depletion of fossil fuels
- Nuclear power: low CO₂ emissions・radioactive waste
- Fuel cell: H₂ + O₂ → H₂O + electricity
- Pumped-storage hydroelectricity functions as “storage” for electricity
Notes (Common Confusions)
① Nuclear power does not directly emit CO₂, but energy is required for construction, decommissioning, and fuel refining. ② The principle of solar power generation is the photoelectric effect; it does not use heat. ③ Although a fuel cell is called a “cell,” it is not rechargeable; hydrogen must be continuously supplied. ④ Renewable energy does not mean “infinite”; it means energy supplied at a rate that does not lead to depletion.
Practice
- State the conversion principle of solar power generation.
- What mechanism is common to hydroelectric and thermal power generation in the final stage of power generation?
- State the emission product of a fuel cell.