Every power station and panel taps a store somewhere: ancient sunlight locked in coal, the wind and waves the Sun stirs up, the heat deep in the Earth, the pull of the Moon on the tides, or the nucleus of an atom. Each choice trades reliability against its cost to the planet.
Energy resources are either non-renewable (fossil fuels and nuclear fuel, which run out) or renewable (replenished as fast as they are used). Most of our energy can be traced back to the Sun. The exceptions are nuclear, geothermal and tidal.
Build the electricity grid for a small city, then run a full day. Choose how much of each resource to install, from reliable coal, gas and nuclear to the Sun and Moon driven renewables, and watch whether your supply keeps the lights on from dawn to dusk and through the night. The catch is the trade-off: the cleanest mixes are often the least reliable, so aim for a grid that stays lit with the lowest emissions.
| Non-renewable | Renewable |
|---|---|
| coal, oil, natural gas (fossil fuels) | solar, wind, hydroelectric |
| nuclear fuel (uranium) | geothermal, tidal, wave, biofuel |
| finite: will eventually run out | replenished as fast as used |
| reliable, high energy output on demand | often intermittent, depends on conditions |
Fossil fuels store energy from ancient sunlight captured by plants; wind, waves and the water cycle that feeds hydroelectric power are all driven by the Sun heating the Earth; biofuels come from recently grown plants. The genuine exceptions are nuclear (energy from the nucleus), geothermal (heat from the Earth's interior) and tidal (the gravitational pull of the Moon and Sun).