Energy resources

Gas power stations can start quickly and provide electricity when required.

Solar is renewable but intermittent. Nuclear is reliable and low-carbon while operating, but produces radioactive waste.

A mixture balances reliability, cost and environmental impact because no single resource is ideal in every situation.

Any two of: wind, solar, hydroelectric, tidal, geothermal, biofuel (1 each, max 2)

Solar output depends on the weather and time of day (1); it produces little or no electricity at night or when cloudy, so the supply cannot be guaranteed (1)

Advantage: nuclear releases no carbon dioxide while generating, unlike burning coal (1); Disadvantage: nuclear produces radioactive waste that stays dangerous for a very long time (or risk of accident) (1)

Burning fossil fuels releases carbon dioxide (1), which adds to the greenhouse effect and causes global warming/climate change (1)

Tidal is very reliable and predictable as tides occur daily (1) but a barrage is expensive to build and can damage estuary habitats (1); wind turbines are cheaper per unit and clean (1) but unreliable because they only generate when it is windy, so the town may also need a backup supply for calm periods (1)

A carbon neutral resource releases no net carbon dioxide over its full cycle (1); when biofuel crops grow they absorb carbon dioxide by photosynthesis (1); when the fuel is burned that carbon dioxide is released again, so the net emission is approximately zero (1); however, farming and processing the crops may require fossil fuels, so biofuels are only approximately carbon neutral rather than completely neutral (1)

Hydroelectric stations store water in a reservoir and can generate electricity on demand simply by releasing the water, making them very reliable (1); however, building a dam floods large areas of land, destroying habitats for animals and plants (1); the altered water flow can also disrupt fish migration and the ecology of the river downstream (1)

Wind power produces no carbon dioxide during operation, so switching to it would reduce greenhouse gas emissions and help slow climate change (1); however, wind is intermittent and unpredictable, so generation falls when the wind is too slow or too fast, making a 100% wind supply unreliable (1); to guarantee supply, either significant energy storage (such as large batteries or pumped hydro) or backup generation would be needed, adding cost and complexity (1); changing all existing infrastructure and the grid to rely solely on wind would take decades and enormous investment, so a complete switch in the near term is not currently feasible (1); a more realistic approach would be a diverse mix of renewables alongside storage and demand management (1) — award max 4

Both nuclear and gas power stations can generate electricity reliably on demand (1); gas combustion releases carbon dioxide and contributes to global warming, whereas nuclear produces no carbon dioxide during operation (1); nuclear creates radioactive waste that remains hazardous for thousands of years and is difficult and costly to store safely, whereas gas produces mainly CO2 and water (1); nuclear carries the risk of a serious accident such as a meltdown, while gas-fired stations pose a risk of explosion and contribute to air pollution (1)

Offshore wind is renewable and produces no carbon emissions during operation, helping to meet climate targets, but its output is intermittent, so it cannot guarantee supply during calm periods; it also has high installation and maintenance costs (1). Nuclear power provides a large, reliable, low-carbon baseload supply for decades, making it valuable for meeting constant demand, but power stations take many years and billions of pounds to build, produce radioactive waste requiring long-term storage, and carry the small but serious risk of accidents (1). Natural gas stations can respond rapidly to spikes in demand and use existing infrastructure, but combustion releases carbon dioxide, contributing to climate change, and reserves are finite so the resource will eventually run out (1). A mixed strategy uses wind to supply much of the electricity when available, reducing fuel costs and emissions; nuclear provides the reliable baseload that wind cannot guarantee; and gas acts as a flexible backup for peaks in demand or during periods of low wind, reducing the risk of power cuts (1). This diversity means the failure or unavailability of any single source has less impact on the overall supply, improving energy security; it also spreads investment risk and allows the energy mix to evolve as technology improves and costs fall (1). Overall, a mixed strategy better balances reliability, cost and environmental impact than relying on one source alone (1) — award max 6