How can we meet rising energy demand while reducing environmental harm?
Energy: the demand for energy, the comparison of fossil fuels, nuclear power and renewable energy sources, and the move towards a sustainable, low-carbon energy supply.
An SQA Higher Environmental Science answer on energy, covering the demand for energy, the advantages and disadvantages of fossil fuels, nuclear power and renewable sources, and the transition towards a sustainable, low-carbon energy supply.
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What this dot point is asking
The SQA wants you to explain the demand for energy, compare fossil fuels, nuclear power and renewable energy sources by their sustainability and environmental impact, and explain the move towards a sustainable, low-carbon energy supply. This is a central sustainability topic and connects directly to climate change.
Demand for energy
Energy demand is rising with population growth, industrialisation and rising living standards. Most of the world's energy still comes from fossil fuels, but their environmental costs and finite supply are driving a transition. Reducing demand through energy efficiency and conservation is part of the answer, alongside changing how energy is generated.
Fossil fuels
Fossil fuels are energy-dense, reliable and supported by existing infrastructure, which is why they still dominate. But they will eventually run out, and their combustion is the largest source of greenhouse-gas emissions, making them the least sustainable option.
Nuclear power
Nuclear power generates electricity from the energy released by nuclear fission of uranium.
- Advantages: very low carbon dioxide emissions in operation; a large, reliable baseload output; and a high energy density (a small mass of fuel yields a lot of energy).
- Disadvantages: it produces radioactive waste that stays hazardous for a very long time and must be stored safely; there is a risk of accidents; and plants are expensive and slow to build.
Nuclear is therefore low-carbon but raises distinct waste and safety questions.
Renewable energy sources
- Advantages: effectively unlimited, and low or zero carbon in operation, so they are far more sustainable and help cut emissions.
- Disadvantages: many are intermittent (wind and solar depend on the weather and time of day), so they need storage or backup; they can require large areas or specific sites (a windy coast, a river to dam); and manufacture and habitat change carry some impact. Hydroelectric dams can flood land and disrupt rivers; biomass is only low-carbon if grown sustainably.
The move to a sustainable, low-carbon supply
A sustainable energy future combines two strategies: reducing demand through efficiency and conservation, and shifting generation from fossil fuels to low-carbon sources (renewables and, where chosen, nuclear). Improving energy storage and grid management helps cope with the intermittency of renewables. This transition directly reduces the carbon emissions that cause climate change.
Examples in context
Example 1. Scotland's renewable electricity. Scotland generates a very large share of its electricity from wind and hydro, cutting emissions sharply compared with coal and gas. It shows a real shift towards a low-carbon supply, while the need for storage and grid balancing illustrates the intermittency challenge of renewables.
Example 2. Nuclear waste storage. Spent nuclear fuel remains radioactive for thousands of years, so countries are developing deep geological repositories to isolate it safely. It highlights the central trade-off of nuclear power: low operational carbon against a long-lived waste-management burden.
Try this
Q1. State why fossil fuels are considered unsustainable. [2 marks]
- Cue. They are finite (will run out) and burning them releases carbon dioxide that drives climate change.
Q2. Give one advantage and one disadvantage of wind power. [2 marks]
- Cue. Advantage: renewable and low-carbon. Disadvantage: intermittent (depends on the weather), so it needs storage or backup.
Exam-style practice questions
Practice questions written in the style of SQA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
SQA Higher specimen4 marksCompare fossil fuels and renewable energy sources in terms of their sustainability and environmental impact.Show worked answer →
A 4-mark compare answer needs points on both sides.
Fossil fuels (coal, oil, gas) are finite and non-renewable, so they will eventually run out, and burning them releases carbon dioxide that enhances the greenhouse effect, plus pollutants causing acid rain and poor air quality.
Renewable sources (wind, solar, hydro, wave, tidal, geothermal, biomass) are effectively unlimited on a human timescale and produce little or no carbon dioxide in operation, so they are far more sustainable and lower-carbon.
However, renewables have their own impacts: many are intermittent (wind and solar depend on weather), they need large areas or specific sites, and manufacture and habitat change carry some impact.
Markers reward fossil fuels being finite and high-carbon, renewables being effectively unlimited and low-carbon, and a valid limitation of renewables such as intermittency.
SQA Higher specimen3 marksState two advantages and one disadvantage of nuclear power as part of a low-carbon energy supply.Show worked answer →
This is a 3-mark answer about nuclear power.
Advantages: (1) nuclear power produces very low carbon dioxide emissions during operation, so it does not add much to the greenhouse effect; (2) it provides a large, reliable, continuous (baseload) output from a small amount of fuel, unlike intermittent renewables.
Disadvantage: it produces radioactive waste that remains hazardous for a very long time and must be stored safely; alternatively, the risk of accidents or the high cost and long build time of plants.
Markers reward two genuine advantages (low carbon, reliable baseload, high energy density) and one valid disadvantage (radioactive waste, accident risk, cost).
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Sources & how we know this
- Higher Environmental Science Course Specification (C826 76) — SQA (2021)
- Higher Environmental Science course overview and resources — Qualifications Scotland (2026)