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Major electricity sources and sustainability

Short answer

Major sources are coal (~35%), gas (~22%), hydro (~15%), nuclear (~9%), wind, and solar. Present supply is unsustainable because fossil fuels are finite, emit CO₂ causing climate change, cause air pollution, have low efficiency (30-40%), and create energy security risks. Transition to renewables is needed.

What are the major sources of electricity worldwide? Give reasons why the existing electricity supply scenario is not sustainable.

Major sources of electricity worldwide (approximate shares, early 2020s)

SourceShare of world generation
Coal≈ 35 %
Natural gas≈ 22–23 %
Hydropower≈ 15 %
Nuclear≈ 9 %
Wind≈ 7–8 %
Solar≈ 5–6 %
Oil, biomass, geothermal, others≈ 4–5 %

So about 60 % of world electricity still comes from fossil fuels.

Why the present supply scenario is not sustainable

  1. Depletion of fuels: Coal, oil and gas are finite; at current use, known reserves will last only decades (oil and gas) to about a century or two (coal).
  2. Climate change: Burning fossil fuels emits large amounts of CO₂; the power sector is the largest single source of greenhouse gases, causing global warming.
  3. Air pollution and health: SO₂, NOx, particulates and mercury from coal plants cause acid rain, smog and respiratory disease.
  4. Low efficiency: Thermal plants convert only 30–40 % of fuel energy into electricity; the rest is wasted as heat.
  5. Energy security and prices: Many countries depend on imported fuel; prices fluctuate with geopolitics (e.g. oil and gas price shocks).
  6. Nuclear issues: Radioactive waste disposal, accident risk (Chernobyl, Fukushima) and high cost.
  7. Unequal access: Many people (especially in rural areas) still lack reliable electricity.
  8. Water and land use: Thermal plants need large quantities of cooling water; mining damages land.

A sustainable path needs more renewables (hydro, solar, wind), better efficiency, storage and smart grids. Nepal, with large hydro potential, can contribute by exporting clean hydropower.

✓ Answer checked by Claude Opus 5.5 (high effort)

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