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
16.3. 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)