KCSE 2025 Physics P1 Q13 — Sources of Non-Renewable Energy (coal)
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The Question
“State one source of non-renewable energy.”
Recall what non-renewable means
A non-renewable energy source is one that gets used up when we use it and is not replaced within a human lifetime. Once the reserves are exhausted they are effectively gone, unlike renewable sources such as the sun, wind or moving water which are constantly replenished.
Give a valid example
Coal is a clear example. It is a fossil fuel formed over millions of years from the remains of ancient plants, so it forms far more slowly than we burn it. Oil (petroleum) or natural gas would also be accepted, as they are fossil fuels for the same reason.
Final Result
Coal is a source of non-renewable energy. Oil (petroleum) or natural gas are equally acceptable answers, since all three are fossil fuels.
Why this method works
Fossil fuels count as non-renewable because they form over geological timescales of millions of years, while we extract and burn them within decades. That means the rate of use vastly outstrips the rate of formation, so the reserves shrink and cannot recover on any useful timescale — the defining feature of a non-renewable resource. This is the opposite of renewable sources like solar, wind, hydro, tidal and geothermal energy, which draw on flows that are naturally topped up as fast as (or faster than) we use them.
Ask whether the source runs out with use: coal, oil and gas do, so they are non-renewable; sunlight and wind do not, so they are renewable.