Distinguishing Energy Sources and Energy Forms
An energy source identifies where the energy comes from before conversion. An energy form identifies how energy is stored or transferred.
Trace the energy from its source through a conversion device to the useful energy it supplies.
Primary energy sources occur in nature. Energy carriers such as electricity and hydrogen are produced using those sources. Electricity can be generated from coal, flowing water, sunlight, wind, geothermal heat, or biogas.
Renewable Sources Still Depend on Time and Place
A renewable energy source is replenished by natural processes on a human time scale. It is not necessarily available at every moment. Solar output depends on the time of day and weather, wind output on wind speed, and hydropower output on season and water flow rate.
Renewable sources are naturally replenished, but their available output still depends on local resource conditions. These sources include biomass, hydropower, geothermal, wind, and solar energy.
Compare Sources through Energy Conversion Paths
Compare an energy source by tracing its initial energy form, conversion device, and practical limitation. The table summarizes each pattern briefly.
| Energy source | Short conversion pattern |
|---|---|
| Coal, petroleum, natural gas | Burning fossil fuel converts its chemical energy into heat that can drive a turbine. |
| Biomass | Chemical energy stored in organic material becomes heat through combustion, or the material is processed into another fuel before use. |
| Biogas | Microorganisms produce methane-rich gas from organic material without oxygen. Burning the gas releases its chemical energy as heat. That heat can drive machinery or generate electricity. |
| Water | Gravitational potential energy and kinetic energy of flowing water spin a turbine. |
| Wind | Kinetic energy from moving air spins turbine blades. |
| Sunlight | Radiant energy from the Sun becomes electricity in solar cells or heat in solar heating systems. |
| Ocean waves and tides | Technologies such as buoys, oscillating water columns, and marine turbines convert the mechanical energy of moving seawater into electricity. |
| Geothermal heat | Hot fluid or steam carries thermal energy from inside Earth and drives a turbine. |
Fossil fuels depend on finite reserves. Biomass and biogas require a reliable feedstock and maintained equipment. Hydropower output depends on flow rate and height difference, wind power on wind speed, and solar power on incoming sunlight. Ocean energy requires suitable coastal conditions, while geothermal energy requires suitable geology.
Coal, petroleum, and natural gas formed from ancient living remains over very long periods.
Distinguishing Similar Energy Terms
Biogas comes from biomass broken down by microorganisms without oxygen. This process is called anaerobic digestion. Biogas consists mainly of methane, , and carbon dioxide, .
Solar energy can be converted in different ways. Photovoltaic panels convert light directly into electricity, while solar thermal systems collect heat from sunlight.
Marine energy includes waves, tides, ocean currents, and temperature differences in seawater. Some technologies use the kinetic energy of waves, currents, and tides. Ocean thermal energy conversion instead uses the temperature difference between warm surface water and colder deep water.
Geothermal energy is heat from inside Earth. Geothermal resources can supply electricity, heating, cooling, and direct heat.
Compare Energy Sources in Indonesia
Indonesia's Ministry of Energy and Mineral Resources uses the term New and Renewable Energy, or EBT in Indonesian policy language, for sources such as solar, wind, hydropower, bioenergy, geothermal, and ocean energy.
For a steam, wind, solar, hydroelectric, or geothermal power plant, compare the complete conversion path:
Identify the source and its initial energy form, then the conversion device that produces electrical energy.
Once the conversion path is clear, compare the source's physical conditions, cost, emissions, land or water needs, and maintenance requirements.