Energy resources: renewable and non-renewable
Physics · GCSE · The School
Renewable means it replenishes faster than it is used
A renewable resource is replaced by nature as fast as it is used. Wind, solar, hydroelectric, tidal, geothermal and biofuel are all renewable. None of them will run out on any timescale that matters. A non-renewable resource is finite. Coal, oil, gas and nuclear fuel are non-renewable. Every tonne burned is a tonne the planet will not replace.
Non-renewables are reliable, but not clean
Fossil-fuel and nuclear stations generate on demand. Output stays steady in any weather. That is why they have carried most of the world’s electricity for over a century. Burning fossil fuels releases carbon dioxide, which drives climate change. Nuclear fuel produces no CO₂ while running, but it leaves radioactive waste. That waste must be stored safely for thousands of years.
Renewables are clean, but not always available
Wind and solar produce no CO₂ while generating power. But a turbine only works when the wind blows. A solar panel only works in daylight. Neither can simply be turned up to meet demand. Hydroelectric and tidal power are steadier, since river flow and tides follow known patterns. Good sites for them are limited by geography, though.
Comparing two stations: a worked example
A gas station and a wind farm are both rated at 500 MW. The gas station can run near 500 MW almost all year. The wind farm cannot: it depends on the wind actually blowing. Averaged over a year, it typically reaches only about 30% of its rated output. That is roughly 150 MW, not 500 MW.
Why the UK mix has shifted
Coal supplied most UK power a few decades ago. Today it supplies almost none. Gas and a growing share of wind replaced it. Three things drove the change. Climate targets require cutting carbon dioxide. Wind and solar have become much cheaper. And people worry about air pollution and where energy comes from.
No single resource solves everything
An exam answer that says "just use renewables" misses something important. A real power grid needs both steady output and low emissions at once. So does an answer that says "just use nuclear" and ignores its waste. A sensible mix uses steady sources alongside clean ones. It also needs a way to store or import power for when renewable output is low.