Energy resources and the energy transition: HSC Earth and Environmental Science Module 8
“Evaluate the formation, use and environmental impact of renewable and non-renewable energy resources, including but not limited to fossil fuels, solar, wind and hydro, and the transition to lower-emission energy in the Australian context”
Non-renewable fossil fuels are buried stored solar energy: coal from swamp plants (Hunter and Bowen Basins) and oil and gas from marine plankton; burning them releases carbon dioxide. Renewables draw on continuous flows: solar (excellent inland resource), wind (South Australia, Victoria) and hydro (Snowy Scheme, Snowy 2.0 storage), with low operating emissions but variability and their own land and material impacts. Australia is a major coal and gas exporter transitioning to renewables backed by storage, which is necessary and achievable if storage and grid capacity keep pace.
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What this dot point is asking
NESA wants you to compare renewable and non-renewable energy resources: how they form, how they are used, their environmental impacts, and how Australia is shifting toward lower-emission sources. The command word evaluate means weighing the trade-offs and reaching a judgement, supported by named Australian examples.
The answer
Energy resources are classified by whether they are replenished on a human timescale. Non-renewable resources (fossil fuels and uranium) exist in fixed amounts and are consumed faster than they form. Renewable resources (solar, wind, hydro and others) are continuously replenished. Australia is richly endowed with both, which shapes its economy and its emissions.
How fossil fuels form
Fossil fuels are stored solar energy: ancient organisms captured sunlight by photosynthesis, and their carbon was buried and altered over millions of years. Coal forms from plant matter accumulated in swamps, compressed and heated through burial; Australia's vast black coal of the Hunter and Bowen Basins formed this way. Oil and natural gas form from marine plankton buried in sediments and cooked into hydrocarbons, then trapped beneath impermeable rock. Because they take millions of years to form, fossil fuels are non-renewable, and burning them releases the stored carbon as carbon dioxide, the main driver of the enhanced greenhouse effect from Module 7.
Australia is one of the world's largest exporters of coal and liquefied natural gas. The fossil carbon it sells is burned overseas, so those emissions are counted in other countries, even though the resource and the extraction impacts are Australian. This is why Australia's role in global emissions is larger than its domestic figures alone suggest.
Renewable energy resources
Renewable sources draw on continuous natural flows. Solar power converts sunlight directly to electricity; inland Australia has one of the world's best solar resources, and large solar farms and rooftop solar are expanding rapidly. Wind power converts moving air, with major wind farms across South Australia and Victoria. Hydroelectricity converts the energy of falling water; the Snowy Mountains Scheme has generated low-emission power and stored water for decades, and the Snowy 2.0 pumped-hydro project adds large-scale energy storage. These sources produce little or no greenhouse gas while operating, though they have their own impacts: land and habitat use, visual and noise effects, dam flooding of valleys, and the mining required for panels, turbines and batteries.
Comparing impacts
Fossil fuels are energy-dense, reliable and easy to store and transport, which made them the backbone of industrial energy, but they release carbon dioxide and other pollutants and are finite. Renewables are clean while operating and inexhaustible, but most are variable (the sun sets, the wind drops), so they require storage (batteries, pumped hydro) and a strengthened grid to deliver reliable supply. Evaluating them means weighing reliability and cost against emissions and finiteness.
Australia's energy transition
Australia is shifting from a coal-dominated electricity system toward renewables backed by storage. Coal-fired power stations are closing as solar and wind, supported by batteries and pumped hydro such as Snowy 2.0, take a growing share. The transition reduces emissions and exploits a world-class renewable resource, but it raises challenges of reliability, grid investment, and supporting workers and regions that depend on coal. A balanced judgement is that the transition is both necessary for emissions reduction and technically achievable, provided storage and grid capacity keep pace.
- Calling nuclear or uranium renewable
- Uranium is a finite, non-renewable resource, even though it emits little carbon dioxide when used.
- Saying renewables have no impact
- They have lower operating emissions but real impacts: land use, habitat, dams flooding valleys, and mining for materials. Acknowledge these when evaluating.
- Ignoring exported emissions
- Australia's exported coal and gas are burned overseas, so its global emissions role exceeds its domestic figures.
Try this
Q1. Explain why fossil fuels are classified as non-renewable and describe how coal forms. [3 marks]
- Cue. They take millions of years to form and are used far faster than they form; coal forms from plant matter buried, compressed and heated in ancient swamps.
Q2. Evaluate the replacement of coal-fired electricity with solar and wind backed by storage in Australia. [4 marks]
- Cue. Renewables cut emissions and use a world-class resource but are variable, so storage and grid investment are needed; supported judgement that the transition is necessary and achievable with adequate storage.
Exam-style questions
Questions in the style of NESA exam questions on this dot point, each with a worked answer. They are written by ExamExplained unless tagged "Past paper"; the year shows the paper a question is modelled on.
2021 HSC-style1 markThe most effective strategy for NSW to help reduce rising global temperatures would be to A. replace hydro power with solar. B. buy electricity from another state. C. replace coal-fired power stations with gas. D. replace coal-fired power stations with wind power.Show worked answer →
The correct answer is D: replace coal-fired power stations with wind power.
Rising global temperatures are driven by carbon dioxide emissions, so the most effective action is to cut emissions at the source. Coal-fired power stations are a major emitter; replacing them with wind, a renewable source that produces effectively no greenhouse gas while generating electricity, removes those emissions and supports the transition to lower-emission energy.
A swaps one low-emission source for another, so it does not cut emissions; B just shifts the emissions to another state rather than reducing them; C still burns a fossil fuel (gas), which only partly reduces emissions rather than removing them.
2024 HSC-style4 marksAssess the present and likely future use of a named resource.Show worked answer →
Assess means make a supported judgement; for 4 marks, name a resource, state its present use, predict its future use, and judge how that use will change.
- Named resource: copper
- Present use: copper is an essential metal used worldwide in electrical wiring, motors and electronics because of its high electrical conductivity.
- Future use
- Demand for copper is likely to grow substantially, because the transition to lower-emission energy relies heavily on copper, for example in wind turbines, solar farms, batteries, electric vehicles and the expanded electricity grids needed to connect them.
- Judgement
- Copper will become even more important in the future than it is today; because it is a finite (non-renewable) resource, this rising demand makes efficient extraction and recycling essential to keep its use sustainable. (Any well-justified named resource, renewable or non-renewable, is acceptable.)