How does geology supply energy, and how can resources be used sustainably?
The formation of coal and its rank, the geological basis of energy resources (fossil fuels, geothermal, nuclear fuels) and bulk materials, the distinction between renewable and non-renewable resources, and the environmental impacts and sustainable management of extraction, including carbon capture and storage.
A focused WJEC and Eduqas A-Level Geology G4 answer on the formation and rank of coal, the geological basis of energy resources (fossil fuels, geothermal and nuclear fuels) and bulk construction materials, the difference between renewable and non-renewable resources, and the environmental impacts and sustainable management of extraction, including carbon capture and storage.
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What this dot point is asking
This dot point widens G4 from individual resources to the whole picture of energy and sustainability. WJEC wants the formation and rank of coal, the geological basis of the range of energy and bulk resources, the renewable versus non-renewable distinction, and an informed discussion of environmental impact and sustainable management, including carbon capture and storage. It ties resources back to palaeoclimate and to society.
The answer
Coal: formation and rank
Coal is a biogenic fossil fuel formed from land plants:
The range of geological energy resources
- Fossil fuels (coal, oil, gas): non-renewable, formed over millions of years.
- Geothermal energy: heat from radioactive decay and the Earth's interior, tapped where hot rock or hot water is near the surface (renewable if managed).
- Nuclear fuels: uranium ore, a non-renewable mineral resource concentrated by geological processes.
The Earth also supplies bulk materials: aggregate, building stone, limestone for cement, clay for bricks and sand for glass, all geologically sourced.
Renewable versus non-renewable
Environmental impact and sustainability
Extraction affects land (scarring, dust, spoil heaps, subsidence), water (lowered water tables, acid and toxic mine drainage) and air (carbon dioxide from burning fossil fuels). Impacts are reduced by site restoration, treatment of mine drainage, recycling, and carbon capture and storage (CCS), which injects carbon dioxide into deep porous reservoirs sealed by an impermeable cap rock, using the same trapping principle as a petroleum trap.
Examples in context
The South Wales Coalfield produced high-rank anthracite where the coals were most deeply buried and mildly metamorphosed, a direct illustration of rank increasing with burial. Geothermal schemes such as the United Downs project in Cornwall tap heat in hot granite. Depleted North Sea gas fields are being assessed for carbon capture and storage, reusing proven traps to store carbon dioxide deep underground.
Try this
Q1. State the rank sequence of coal from lowest to highest. [2 marks]
- Cue. Peat, lignite (brown coal), bituminous coal, anthracite.
Q2. Distinguish a renewable from a non-renewable resource, with one example of each. [2 marks]
- Cue. Renewable is replenished on a human timescale (geothermal); non-renewable forms far slower than it is used (coal, oil, uranium).
Q3. Explain how carbon capture and storage uses geological principles to reduce emissions. [2 marks]
- Cue. Carbon dioxide is injected into a deep porous reservoir sealed by an impermeable cap rock, the same trapping principle as a hydrocarbon trap, keeping it out of the atmosphere.
Exam-style practice questions
Practice questions written in the style of WJEC exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
WJEC Eduqas 20206 marksDescribe how coal forms and how increasing burial changes its rank.Show worked answer →
Describe the accumulation, then the progressive change with burial, because rank tracks burial.
Coal forms from plant material that accumulates in a waterlogged, oxygen-poor swamp, where lack of oxygen prevents full decay and the plant matter builds up as peat. The swamp must subside so that thick peat can accumulate and be buried.
As burial increases, heat and pressure drive off water and volatiles and progressively concentrate the carbon, raising the rank of the coal. The sequence is peat, then lignite (brown coal, low rank), then bituminous coal, then anthracite (high rank).
So higher rank means deeper burial, higher carbon content, fewer volatiles and a higher calorific value. Anthracite, the highest rank, has experienced the greatest burial (and sometimes mild metamorphism).
Markers reward accumulation of plant matter in an anoxic swamp forming peat, subsidence and burial, and the rank sequence peat to lignite to bituminous to anthracite with rising carbon content.
WJEC Eduqas 20215 marksDiscuss the environmental impacts of extracting geological resources and one way these impacts can be reduced.Show worked answer →
Set out the impacts, then a named mitigation, because the question asks for both.
Extraction has many impacts: opencast and quarrying scar the landscape and produce dust and noise; spoil heaps and tailings can be unstable and release acid or toxic drainage; mining can lower the water table and cause subsidence; and burning fossil fuels releases carbon dioxide, contributing to climate change.
These impacts can be reduced in several ways. Restoration of worked sites (backfilling, landscaping and replanting) returns land to use. Treating mine drainage prevents pollution. For climate, carbon capture and storage (CCS) traps carbon dioxide from power stations and injects it into deep porous reservoirs sealed by impermeable cap rock (the same trapping principle as a hydrocarbon trap), keeping it out of the atmosphere.
So extraction damages land, water and air, but restoration, drainage treatment and carbon capture and storage can reduce the impacts, supporting more sustainable resource use.
Markers reward named impacts on land, water and air, and a named mitigation such as site restoration or carbon capture and storage, correctly explained.
Related dot points
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Sources & how we know this
- WJEC Eduqas A-level Geology specification — WJEC Eduqas (2017)