Mitigation Strategies, Renewable Energy
In 2021, the Australian Energy Market Operator reported that rooftop solar met 100% of South Australia's daytime electricity demand on 117 separate days, a world first for a major grid.
Printable Worksheets
Print or save as PDF, or build a custom worksheet from any module's questions.
● Know
- Mitigation means reducing greenhouse gas emissions; adaptation means adjusting to locked-in changes
- Key renewable technologies: solar PV, wind, hydro, geothermal; nuclear is low-carbon but not renewable
- The main grid challenge is intermittency; solutions include pumped hydro and batteries
● Understand
- Why LCOE (levelised cost of energy) has made solar and wind the cheapest new electricity sources
- The difference between embodied emissions (manufacturing) and operational emissions (running)
- Why nuclear has zero operational emissions but significant barriers in time, cost and waste
● Can do
- Match each renewable technology to its main limitation
- Identify which energy source in a list is not technically renewable
- Evaluate why intermittency is a grid challenge and describe two storage solutions
In 2023, the South Australian town of Port Augusta, once home to a coal-fired power station that closed in 2016, powered up one of Australia's largest solar thermal plants, a 150 MW facility that stores heat in molten salt to generate electricity after dark. That project illustrates the two fundamentally different ways a society can respond to climate change, and they are not either-or: climate responses fall into two broad categories:
Mitigation means reducing the causes of climate change, primarily cutting greenhouse gas emissions or enhancing natural carbon sinks (forests, wetlands). Mitigation addresses the root cause and reduces the total magnitude of future change. Examples include transitioning from fossil fuels to renewable energy, electrifying transport, reducing deforestation, and changing agricultural practices.
Adaptation means adjusting to climate changes that are already locked in or will inevitably occur. Adaptation does not prevent climate change, it reduces harm from changes that are already committed. Examples include building sea walls, developing drought-resistant crops, and redesigning cities for extreme heat.
Both are necessary. Some degree of warming is already locked in, adaptation handles that. But unlimited adaptation without mitigation leads to scenarios where change outpaces any adaptive capacity. Scientists often use the phrase: "the more we mitigate, the less we need to adapt."
Imagine a bathtub overflowing. Mitigation is turning off the tap. Adaptation is mopping up the water. You absolutely need to mop while the tap is running (some water has already spilled), but if you only mop and never turn off the tap, you will eventually be overwhelmed. Both actions are required, but turning off the tap (mitigation) is the fundamental fix.
Australia's dual challenge: Australia is simultaneously a major coal and gas exporter (facing economic disruption from mitigation globally) and one of the most climate-vulnerable developed nations (requiring adaptation). Australian policy must navigate this tension. State governments have largely moved ahead of the federal government on renewable energy targets, with South Australia, Victoria and Queensland each committing to 100% or near-100% renewable electricity within the next two decades.
"We can adapt our way out of climate change, we don't need to reduce emissions." Adaptation has limits. Some systems (coral reefs, glaciers, low-lying island nations) cannot adapt fast enough or at all. There are also limits of economic feasibility: protecting every vulnerable coastline with sea walls is not possible. Beyond ~2°C of warming, IPCC scientists project that adaptation costs rise steeply and some risks become "unavoidable" regardless of adaptive capacity.
Solar photovoltaic (PV): Converts sunlight directly into electricity using semiconductor cells. Australia is the world leader in rooftop solar installations per capita, over 3.5 million homes have rooftop panels. The LCOE of utility-scale solar has fallen by over 90% since 2010, making it now cheaper than new coal or gas plants. Main limitation: intermittency (no output at night or on heavily overcast days).
Wind power: Converts kinetic energy of wind into electricity via turbines. Australia has exceptional offshore wind potential along its southern and eastern coasts. Main limitation: intermittency (varies with wind conditions) and visual/noise concerns for onshore turbines near communities.
Hydroelectricity: Uses flowing or falling water to drive turbines. Reliable and dispatchable (can be turned on/off quickly). Main limitation: geographical constraint (needs suitable rivers/terrain), environmental impacts on river ecosystems, and vulnerability to drought (significant issue in water-stressed Australia). Snowy 2.0 (under construction) will add ~2,000 MW of pumped hydro storage capacity to Australia's grid.
Geothermal: Uses heat from the Earth's interior. Excellent potential in the Cooper Basin in central Australia (hot dry rock technology), where high-temperature rocks exist at accessible depths. Main limitation: high drilling costs and the technology for extracting heat from dry rock is not yet commercially proven at scale in Australia.
South Australia (SA) regularly generates more than 100% of its electricity needs from wind and solar, exporting surplus to other states. SA has achieved this through a combination of wind farms, rooftop solar, the Hornsdale Power Reserve (the world's largest grid-scale lithium-ion battery when built in 2017), and interconnectors to Victoria. SA's renewable transition has lowered wholesale electricity prices during high-generation periods and demonstrated that a major grid can run predominantly on intermittent renewables.
CSIRO GenCost report (published annually) compares the cost of different electricity sources for Australia. As of 2024, utility-scale solar and onshore wind have the lowest LCOE of any new electricity source, including cheaper than building new gas or coal plants. Battery storage costs have also been falling rapidly (~15% per year). These economic shifts, not just environmental policy, are driving the renewable transition in Australia and globally.
"Renewables are too expensive." This was true 20 years ago but is no longer accurate. Solar PV LCOE has fallen by 90% since 2010 and wind by 70%. New utility-scale solar is now cheaper per MWh than new coal in most countries, including Australia. The remaining cost question is about system integration (storage, transmission) rather than the generation cost of solar or wind panels themselves.
Nuclear fission produces electricity with near-zero operational greenhouse gas emissions, making it relevant to climate mitigation. A single uranium fuel pellet contains the energy equivalent of 1 tonne of coal. Globally, nuclear provides about 10% of electricity and has historically prevented significant CO₂ emissions.
However, nuclear is not considered a renewable energy source. Uranium is a finite mineral resource mined from the ground (like coal or oil). "Renewable" means the energy source is naturally replenished on a human timescale, sunlight, wind and flowing water qualify; uranium does not.
Arguments for nuclear: Reliable, dispatchable power (operates 24/7 regardless of weather); high energy density; low lifecycle emissions comparable to wind and solar; can support grid stability.
Arguments against nuclear: Very high capital cost and long construction time (10–20 years for new plants); nuclear waste remains radioactive for thousands of years and requires safe long-term storage; significant water use for cooling; public safety concerns (Chernobyl 1986, Fukushima 2011); Australia has no experience operating commercial nuclear power and a moratorium on it at the federal level (under review as of 2025).
Given the urgency of reducing emissions in the 2020s and 2030s, the 10–20-year construction timeline for new nuclear plants is a significant problem. A new nuclear plant announced today in Australia would not generate electricity before 2040–2045. By contrast, a utility-scale solar farm can be installed and operating within 12–18 months. This timing argument (not just cost) is why many climate scientists argue nuclear should not be the primary climate strategy for near-term emissions reduction, even if it may play a role in longer-term deep decarbonisation.
Australia's nuclear debate: Australia has the world's largest uranium reserves (about 28% of global reserves) and exports uranium for use in other countries' power plants, but has never had a commercial nuclear power plant. The AUKUS submarine agreement has introduced nuclear-powered (not nuclear-armed) submarines, reigniting the broader nuclear debate. A 2024 federal parliamentary inquiry examined the feasibility of nuclear power for Australia, with proponents citing grid reliability and opponents citing cost, time and waste management challenges specific to Australia's geography and regulatory environment.
"Nuclear energy is renewable." This is a common misconception. Nuclear uses uranium, a finite mined resource, as fuel. The definition of "renewable" requires the energy source to be naturally and continuously replenished on human timescales. Sunlight, wind and water flows meet this definition; uranium does not. Nuclear is correctly described as "low-carbon" or "low-emission" but not "renewable."
The intermittency challenge: A grid must always balance supply with demand, moment to moment. Solar and wind output varies with weather and time of day. When solar generation exceeds demand (e.g. sunny midday), prices crash and excess power must be stored or exported. When generation is low (night, overcast), other sources must cover demand. This is the core engineering challenge of a high-renewables grid.
Storage solutions:
Pumped hydro: By far the largest form of grid-scale storage globally (over 90% of grid storage capacity). Snowy 2.0 in NSW will add approximately 2,000 MW / 350,000 MWh of storage. High capital cost but long lifetime (50+ years) and proven technology.
Batteries (lithium-ion): The Hornsdale Power Reserve in South Australia (originally 100 MW/129 MWh, later expanded) was the world's largest battery on installation in 2017. Batteries respond to grid imbalances in milliseconds, improving grid stability. Costs are falling rapidly (~15% per year).
Electrification of transport and industry reduces emissions in sectors beyond electricity generation. Electric vehicles effectively become mobile battery storage. Industrial processes (steel, aluminium, cement) currently use fossil fuels for high-temperature heat and as chemical feedstocks, electrification here is harder but essential for deep decarbonisation.
Nature-based solutions: Forests absorb CO₂ through photosynthesis. Blue carbon ecosystems (seagrasses, mangroves, tidal marshes) store carbon at exceptionally high rates, up to 10× more per hectare than tropical forests, and are particularly relevant for coastal Australia. Protecting and restoring these ecosystems is a cost-effective mitigation strategy.
CCS is often proposed as a way to continue using fossil fuels while capturing the resulting CO₂. However, CCS faces significant barriers: high energy cost (capturing CO₂ from flue gas consumes 15–30% of a plant's output), very high capital cost, limited geological storage availability, long-term leakage risk, and the fact that it can only be applied at large point sources (power plants, industrial facilities), not to the billions of vehicles and small appliances that collectively produce much of global emissions. CCS is most viable for industrial processes (e.g. cement and steel production) where there is no easy substitute for combustion chemistry.
Blue carbon in Australia: Australia holds approximately 5–11% of the world's blue carbon stocks in its mangroves, seagrass meadows and saltmarshes, making it one of the top blue carbon nations globally. The CSIRO and Australian universities are mapping and studying these ecosystems to quantify their carbon storage potential and develop them as verified carbon offsets. Protecting existing blue carbon ecosystems is far cheaper than restoring them once degraded, and coastal developments (ports, aquaculture) can destroy decades of carbon storage overnight.
"We can solve climate change by just planting trees." While forests are important carbon stores, the area required to offset current annual CO₂ emissions through tree planting alone would be several times the land area of Australia. Forests also face risks (fires, drought, disease) that can release stored carbon. Nature-based solutions are valuable but complementary to, not a replacement for, reducing emissions at source. The most important intervention remains not emitting the CO₂ in the first place.
Wrong: "Solar panels take more energy to manufacture than they ever produce." This was approximately true for early panels in the 1970s, but modern panels typically repay their embodied energy within 1–4 years and then produce clean electricity for 25–30 years. The energy payback ratio for modern solar PV is 10:1 to 30:1.
Right: Modern solar panels have an energy payback period of 1–4 years and a lifetime of 25–30 years. Over their lifetime, they produce 10–30 times the energy that went into making them. Embodied emissions exist but are minor compared to the avoided emissions from displacing fossil fuel electricity.
Wrong: "Renewables can never power a whole grid, you always need coal or gas as backup." South Australia routinely runs on 100%+ renewables for extended periods. Germany, Denmark and Portugal have exceeded 100% renewable electricity for hours and days. Grid management with storage and interconnectors can achieve very high renewable fractions.
Right: High-renewable grids are already operating at scale. The challenge is grid management (storage, transmission, demand response), not a fundamental physics barrier. As storage costs fall and grid intelligence improves, the intermittency problem is increasingly solvable.
Wrong: "Nuclear power is a type of renewable energy." Nuclear uses uranium, a finite mined resource. It does not draw on a continuously replenished natural flow of energy. It is correctly classified as low-carbon (or low-emission), not renewable.
Right: The correct classification of nuclear is "low-carbon" or "low-emission." Renewable specifically means the energy source is naturally replenished on human timescales: sun, wind, flowing water, and geothermal heat from Earth's interior all qualify. Uranium ore is a finite mineral resource that does not replenish.
Australia's Renewable Energy Opportunity
World-class resources: Australia has some of the highest solar irradiance on Earth, strong wind resources along both coasts, and significant pumped hydro potential in the Snowy Mountains and other ranges. The Australian Energy Market Operator (AEMO) projects that Australia could run on 83% renewables by 2030 under current and committed policies.
Green hydrogen: Australia is developing green hydrogen, hydrogen produced by electrolysing water using renewable electricity, as a potential export commodity and industrial fuel. Projects in Western Australia and Queensland are targeting hydrogen exports to Japan, South Korea and Germany as a replacement for LNG exports.
Indigenous land and renewable energy: Many large-scale solar and wind projects in Australia are being developed on or near Indigenous land. Some projects involve revenue-sharing agreements with Traditional Owners, offering economic opportunities alongside environmental benefits. Indigenous community energy projects also bring energy independence and lower power costs to remote communities that currently rely on expensive diesel generators.
Renewable Energy Comparison
Energy Storage Design Challenge
Consider this question: If Australia built the world's largest solar farm covering 1% of the Outback (~76,000 km²), could it theoretically generate enough electricity to power the entire world? And if so, what would be the main practical obstacle?
How close was your prediction?
The hook at the start of this lesson pointed out something most people miss: Australia has world-class solar resources, we're not short of sunshine. The real challenge isn't building solar panels; it's that the sun doesn't shine at night or on cloudy days. The barrier to a renewable grid is storage and grid management, not the energy source itself.
Now that you've worked through the technology and systems involved, look back at your original thinking. Did you realise storage was the main bottleneck? How has your answer to "what's stopping 100% renewables?" changed?
Earlier you defined mitigation and listed renewable energy sources.
Now that you've worked through the lesson, write a fuller answer: What is the single biggest engineering barrier to a 100% renewable grid, and what are the two most promising solutions Australia is investing in?
Q1. Explain what "intermittency" means in the context of renewable energy. Describe TWO storage technologies that can address this problem and compare their advantages and disadvantages.
Q2. Explain why nuclear energy is described as "low-carbon" but is NOT classified as "renewable." In your answer, define what "renewable" means in the context of energy sources.
Q3. Evaluate whether carbon capture and storage (CCS) can be a major solution to climate change. In your answer, identify TWO limitations of CCS and explain why scientists argue that reducing emissions at source is more effective.
Revisit Your Thinking
Go back to your Think First answer about renewable energy sources.
- Did you correctly distinguish renewable from non-renewable low-carbon sources?
- What was the most surprising limitation or advantage you learned about?
Model answers (click to reveal)
Answers
▾MCQ 1
A Mitigation addresses the cause (reducing emissions); adaptation addresses the consequences (adjusting to changes that are occurring or locked in). Both are needed.
MCQ 2
C Nuclear fission uses uranium, a finite mined resource. It is low-carbon but not renewable. Solar, wind, hydro and geothermal all draw on continuously replenished natural energy flows.
MCQ 3
B Snowy 2.0 is a pumped hydro storage project, not a new generation source. It stores excess renewable energy when supply exceeds demand, then generates electricity when needed.
MCQ 4
D Blue carbon ecosystems (seagrass, mangroves, saltmarshes) store carbon at rates up to 10× higher per hectare than terrestrial forests, making them highly effective nature-based mitigation tools.
MCQ 5
B Surplus solar should be stored (pumped hydro, batteries) for use when solar generation is insufficient. Curtailment (shutting down panels) wastes clean energy and reduces the economic case for solar investment.
Short Answer 1
Model answer: Intermittency means that renewable sources like solar and wind do not generate electricity continuously, solar produces nothing at night, and wind output varies with weather conditions. This makes it challenging to match electricity supply to demand at all times. Two storage solutions: (1) Pumped hydro, stores energy by pumping water to an elevated reservoir when electricity is surplus, then releases it through turbines when needed. Advantages: large capacity, long lifetime (50+ years), proven technology; Snowy 2.0 will add ~350,000 MWh. Disadvantages: high capital cost, requires suitable terrain, geographical constraint. (2) Battery storage (lithium-ion), the Hornsdale Power Reserve in SA demonstrated rapid-response grid stabilisation. Advantages: responds in milliseconds, scalable, modular, falling costs (~15%/year). Disadvantages: shorter lifespan than pumped hydro, higher cost per MWh at grid scale.
Short Answer 2
Model answer: A renewable energy source is one whose primary energy input is naturally and continuously replenished on human timescales, examples include sunlight, wind and flowing water. Nuclear fission is low-carbon because it produces electricity with near-zero operational greenhouse gas emissions, no CO₂ is released in the fission reaction itself. However, it is not renewable because it uses uranium as fuel, a finite mineral resource mined from the ground that is not replenished by natural processes on human timescales. The correct classification for nuclear is "low-emission" or "low-carbon," not "renewable." Nuclear also has significant embodied emissions in construction and waste management.
Short Answer 3
Model answer: Carbon capture and storage (CCS) is a technology that captures CO₂ at point sources (e.g. power plant chimneys) and stores it in underground geological formations. Limitation 1: CCS is only applicable to large, stationary emission sources. It cannot capture CO₂ from dispersed sources like cars, planes or household appliances, which together contribute a large fraction of total emissions. Limitation 2: CCS is expensive and energy-intensive, capturing CO₂ from flue gas consumes 15–30% of a plant's electricity output, making it less efficient. The long-term integrity of underground storage sites is also uncertain. Reducing emissions at source is more effective because it avoids the CO₂ being produced in the first place, is more cost-effective across the full economy, and applies to both stationary and mobile emission sources. The principle of not creating pollution in the first place is always more efficient than capturing and managing it after creation.