State that radiation from the Sun is the main source of energy for all our energy resources except geothermal, nuclear and tidal.
Solar constant (top of atmosphere): \(S = 1361\ \text{W m}^{-2}\)
| Resource | Primary Energy Source | Typical Use | Advantages (renewability, emissions, etc.) | Disadvantages (availability, efficiency, environmental impact) |
|---|---|---|---|---|
| Solar photovoltaic (PV) | Solar radiation – direct | Electricity generation (rooftop, utility‑scale) | Zero‑emission operation; abundant; modular | Intermittent (day/night, clouds); conversion efficiency 15–22 % |
| Solar‑thermal (collectors, CSP) | Solar radiation – direct | Domestic hot water, space heating, steam‑turbine power | Low‑emission; can incorporate thermal storage | Efficiency 40–70 % (depends on temperature); performance falls in hot ambient conditions; needs storage for night use |
| Wind power | Solar‑driven atmospheric temperature gradients (indirect) | Electricity generation (on‑shore & off‑shore turbines) | Renewable; no fuel cost; relatively high capacity factor in windy sites | Variable wind speed; site‑specific; visual & noise concerns; efficiency of rotor ~30–45 % |
| Hydroelectric power | Solar‑driven water cycle (evaporation → precipitation) (indirect) | Electricity generation (large dams, run‑of‑river) | Renewable; can provide base‑load and storage (pumped‑storage) | Depends on rainfall & river flow; ecological impacts on rivers; efficiency 80–90 % for turbines |
| Biomass / bio‑fuels | Solar radiation via photosynthesis (indirect) | Heat, electricity, transport fuels (e.g., biodiesel, ethanol) | Carbon‑neutral if sustainably managed; can use waste streams | Land‑use competition with food; seasonal availability; conversion efficiency 20–35 % |
| Fossil fuels (coal, oil, natural gas) | Ancient solar‑derived biomass (indirect) | Heat, electricity, transport (most of today’s energy mix) | High energy density; existing infrastructure | Finite reserves; high CO₂ & other pollutant emissions; efficiency of combustion plants 30–45 % |
| Resource | Primary Energy Source | Typical Use | Advantages | Disadvantages |
|---|---|---|---|---|
| Geothermal | Earth’s internal heat (radioactive decay of U, Th, K) | Electricity generation (high‑temperature plants) and direct heating | Low emissions; reliable base‑load; long‑term resource | Geographically limited; high upfront drilling cost; gradient ≈ 30 °C km⁻¹ |
| Nuclear (fission) | Binding energy of atomic nuclei | Large‑scale electricity generation | Very low CO₂ during operation; high energy density | Radioactive waste; high capital cost; public acceptance & safety concerns |
| Tidal | Gravitational pull of the Moon (and Sun) – dominant driver is the Moon (≈ 54 % of tidal force) | Electricity generation at high‑tidal‑range sites | Predictable, renewable output; long‑life turbines | Limited to suitable coastlines; ecological impact on marine habitats; relatively high capital cost |
The flow‑chart shows how solar radiation drives all the listed energy resources. Geothermal, nuclear and tidal are omitted because they do not depend on the Sun.