Energy questions can tempt candidates to make technical claims they cannot support: one source is completely clean, another will run out soon, or a policy will solve climate change. IELTS does not require specialist knowledge for Writing Task 2. A stronger answer uses language that separates a limit from a shortage, reduced reserves from exhaustion, a cutback from cancellation, and a workable option from a guaranteed success.
| Expression | Energy decision | Essential boundary |
|---|---|---|
| finite | state that a supply or capacity has a limit | Does not mean small, scarce, or nearly exhausted |
| deplete | show a stock or reserve being reduced through use | Does not mean nothing remains |
| curtail | cut back the extent or duration of an activity | Does not necessarily stop it entirely |
| viable | judge whether an option can work under stated conditions | Does not mean ideal, certain, or universally suitable |
| mitigate | reduce harm, risk, or severity | Does not remove every cause or consequence |
IELTS Speaking Part 3 asks test takers to explain opinions and analyse, discuss, and speculate about issues. Writing Task 2 asks for a clear, relevant, well-organised argument supported by evidence or examples. The examples below are hypothetical language models, not technical findings or policy recommendations.
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1. Finite: a limit is not the same as an immediate shortage
Finite means having a limit, bound, or end; it cannot be treated as endless.
"The region has a finite amount of land suitable for large energy projects."
Natural patterns include finite resources, a finite supply, finite capacity, and finite time. The word is neutral about size. A finite reserve can be enormous, and a small flow can renew continually.
Do not infer scarcity or urgency from the adjective alone:
"Fossil-fuel reserves are finite" states that there is a limit. "The remaining reserve will be exhausted within ten years" makes a much more specific claim requiring evidence.
Likewise, a grid has finite capacity, but that does not tell us whether present demand is close to the limit. Use finite to establish why choices and trade-offs exist, then add only facts supported by the prompt or your clearly hypothetical example.
2. Deplete: describe a stock being drawn down
Deplete + stock, supply, reserve, or resource means reduce it by drawing on, consuming, or removing it.
"Continuous extraction can deplete a reserve faster than it is replenished."
The verb is transitive: deplete reserves, deplete a resource, or deplete the soil of nutrients. The noun is depletion; the adjective is depleted.
The verb does not mean complete exhaustion. Degree must be added: slightly depleted, severely depleted, or almost completely depleted. It also does not tell us whether the reduction was rapid, deliberate, permanent, or harmful.
Choose an object that behaves like a stock. A mine can be depleted of an extractable resource. An appliance consumes electricity, but it would be odd to say it depletes the electricity system unless it measurably draws down a stored reserve. This distinction makes an energy argument more exact.
3. Curtail: cut back without claiming cancellation
Curtail + activity, service, production, use, or right means reduce or limit its extent, scope, or duration.
"A temporary shortage may force factories to curtail energy-intensive production."
Natural combinations include curtail consumption, curtail production, curtail a programme, and curtail operating hours. The verb is transitive. The noun is curtailment.
Curtailment is not necessarily total or permanent. If operations continue at half their previous level, they have been curtailed. If they stop completely, suspend, halt, or cancel may fit the facts better.
The word also does not say the cutback was deliberate or desirable. Low water levels could curtail generation; a policy could deliberately curtail consumption. State the agent or cause:
"Higher efficiency standards are intended to curtail unnecessary consumption, but their actual effect would need to be measured."
The sentence distinguishes policy purpose from demonstrated outcome.
Understanding is only the first step.
Lyra Practice helps you retrieve and use high-value workplace expressions in realistic situations until they feel natural.
Start a practice session →4. Viable: workable under which conditions?
Viable means capable of working successfully or continuing to work under the stated conditions.
"Small-scale generation may be viable for remote communities where extending the main network is unusually costly."
Useful patterns include a viable option, economically viable, commercially viable, and remain viable under + condition. Viable overlaps genuinely with feasible in many contexts, so do not force a universal difference between them.
The word does not mean perfect, cheap, low-impact, or guaranteed. A technically viable project may face financial constraints; an economically viable option may still have environmental costs. Always state the conditions or criterion:
"The proposal is viable only if storage and maintenance can be provided within the available budget."
This conditional frame is especially useful in Task 2 because it prevents a broad technology claim from floating free of context.
5. Mitigate: reduce a specified harm
Mitigate + negative object means make harm, risk, severity, or consequences less serious.
"Better insulation can mitigate some of the pressure created by peak energy demand."
Common objects include mitigate risk, mitigate environmental harm, mitigate the impact, and mitigate pressure. The verb overlaps with reduce and alleviate on the shared idea of making something less severe.
Mitigation is not elimination. A measure can reduce one impact while leaving another untouched. It is also not proof of effectiveness merely because it is proposed:
"The plan is designed to mitigate disruption during the transition, although its performance has not yet been measured."
Keep the target visible. Renewable energy mitigates everything is both vague and technically unsupported. Diversifying supply may mitigate the risk associated with relying on a single source is a bounded hypothetical claim.
Build an energy argument as a sequence
A useful sequence for Speaking Part 3 or Writing Task 2 is:
- Resource condition: identify what is finite or being depleted.
- Demand or activity: state what consumes the resource or creates pressure.
- Response: explain what could be curtailed, changed, or replaced.
- Feasibility: define what would make the alternative viable.
- Residual effect: state which harm could be mitigated and what remains.
This structure prevents several common leaps. The fact that a resource is finite does not show when it will become scarce. A viable alternative does not guarantee a smooth transition. Mitigating one impact does not prove a source has no other costs.
A worked Speaking Part 3 answer
Question: Why should countries use different sources of energy?
"One reason is that every system has finite capacity, and some fuel reserves can be depleted through continued extraction. Depending entirely on one source may also create supply risk when equipment fails or demand peaks. A more diverse mix could mitigate that risk, although adding sources does not automatically make the whole system reliable. Each option has to be viable under local conditions, including cost, infrastructure, and maintenance. During a shortage, authorities may still need to curtail some consumption, so diversification should not be presented as a guarantee against disruption."
The answer makes no claim that one technology is universally best. It defines the limits of every expression.
A worked Writing Task 2 paragraph
Prompt: Governments should invest more in alternative sources of energy. To what extent do you agree?
"Investment in alternatives is reasonable because many conventional fuel reserves are finite and continued extraction can deplete them. However, a replacement is useful only if it is viable under the relevant geographic, technical, and financial conditions. Public funding could support trials and infrastructure that help mitigate transition risks, but it should not assume that every project will succeed. Demand-side measures may also curtail unnecessary consumption while new capacity is developed. I therefore support broader investment combined with transparent evaluation rather than an unconditional commitment to one source."
The paragraph demonstrates energy vocabulary without asserting unsupported technical findings.
Common energy-vocabulary mistakes
- Finite equals scarce: a finite supply has a boundary, but it may still be large.
- Depleted equals empty: state the degree if it matters.
- Curtail equals cancel: an activity can continue at a reduced extent.
- Viable equals ideal: identify the conditions under which the option can work.
- Mitigate equals eliminate: name the remaining pressure or harm.
- Clean as an absolute: an energy source may reduce one impact while creating another.
- Reliability without a system: distinguish a source's output from the reliability of the wider network.
- Examples presented as findings: make hypothetical scenarios explicit and avoid fabricated figures.
Quick check
1. A reserve has a limit but may be very large. It is:
A. finite B. necessarily scarce today C. necessarily depleted
2. Extraction reduces a stock, but some remains. It has:
A. depleted the stock to some degree B. proved the stock is infinite C. curtailed the stock from
3. Production falls for two months but continues. It is:
A. curtailed B. necessarily cancelled forever C. mitigated to zero
4. Which evaluation states the condition?
A. "The option may be viable if maintenance can be funded locally." B. "Viable means perfect everywhere." C. "The option mitigates because it is new."
Answers: 1-A, 2-A, 3-A, 4-A. Finite states a boundary. Deplete describes reduction of a stock. Curtail describes a cutback. Viable requires workable conditions.
Controlled practice
Choose a hypothetical energy proposal: home insulation, public transport electrification, local solar generation, or reduced industrial demand at peak times. Write five sentences that:
- identify one finite resource or capacity without claiming immediate scarcity;
- explain which stock could be depleted through use;
- state what activity might be curtailed, and by how much or for how long;
- define the conditions that make the proposal viable; and
- name one harm it may mitigate without claiming total removal.
Remove any technical or policy statement that your example does not actually support.
If you want to practise retrieving precise vocabulary for energy arguments, try Lyra Practice.
Sources
- IELTS Academic Speaking test format — IELTS
- IELTS Academic Writing test format — IELTS
- IELTS Writing band descriptors — IELTS
Related
- IELTS Vocabulary Practice
- Exam English Vocabulary Practice
- IELTS Environment Vocabulary
- IELTS Technology Vocabulary
- IELTS Cause-and-Effect Vocabulary
- IELTS Advantages and Disadvantages Vocabulary
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