16.1. Traditional energy sources
16.1.1. Thermal power (oil, natural gas, coal)
16.1.2. Nuclear power
16.2. Renewable energy sources
16.2.1. Solar power
16.2.2. Wind power
16.2.3. Hydropower (see 2.1.2. Hydropower)
16.2.4. Geothermal power
16.2.5. Biopower
16.2.6.1. Pumped-storage hydroelectric power stations
16.2.6.2. Compressed air energy storage
16.2.6.3. Flywheel energy storage
16.2.6.4. Electrochemical energy storage systems
16.2.6.5. Electric energy storage technologies
16.3. Energy efficiency and conservation
16.3.1. Energy efficient methods and technologies
16.4. Energy policy and regulation
16.5 Energy security (see 14.4.3. Energy security)