Household energy use by source, 1990 to 2020
An IELTS Academic Writing Task 1 line graph answer with a band 9 model, showing how to write the overview, group the data and select the significant figures rather than listing every number.
Write your answer
Do this before you scroll. The model answer below will make sense as a comparison and not much use as a template.
Task 1 Academic · 20 minutes · at least 150 words
The graph below shows the percentage of household energy in one country supplied by four sources between 1990 and 2020. Summarise the information by selecting and reporting the main features, and make comparisons where relevant.
Coal: 52% in 1990, 41% in 2000, 26% in 2010, 12% in 2020. Natural gas: 24% in 1990, rising to 33% in 2000, peaking at 38% in 2010, then 35% in 2020. Renewables: 4% in 1990, 7% in 2000, 16% in 2010, 38% in 2020. Nuclear: 20% in 1990, 19% in 2000, 20% in 2010, 15% in 2020.
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How to plan this one
- 1Write the overview before the body. It is the single most heavily weighted thing in Task 1, and candidates who leave it to the end run out of time and omit it.
- 2The overview states the big movements with no figures in it. Numbers belong in the body paragraphs.
- 3Group the data by behaviour, not by source. Here two things rise, one falls and one is flat, which gives you two natural body paragraphs.
- 4Never explain why. Task 1 asks what the data shows. A sentence beginning "This is because" is outside the task and earns nothing.
- 5Select. Reporting all sixteen figures is a list, not a summary, and it costs you Task Achievement.
Model answer
Written at the top of the band. Read it for the moves it makes, not the opinions it holds: a memorised essay on this topic will not fit the prompt you actually get.
The line graph compares the proportion of household energy supplied by coal, natural gas, renewables and nuclear power in one country over a thirty year period from 1990 to 2020.
Overall, the country moved decisively away from coal towards renewable sources, which exchanged positions over the period. Natural gas grew and then levelled off to remain a substantial contributor throughout, while nuclear power was the only source to stay broadly stable.
Coal and renewables followed opposite paths. Coal supplied just over half of household energy in 1990, at 52 per cent, and then declined steadily across every decade to reach only 12 per cent by 2020. Renewables moved in the reverse direction from a negligible base of 4 per cent, rising slowly at first to 16 per cent in 2010 before climbing steeply over the final decade to 38 per cent. By 2020 renewables had become the largest single source, a position coal had held thirty years earlier.
The remaining two sources were more stable. Natural gas rose from 24 to 38 per cent between 1990 and 2010, at which point it overtook coal, but it then fell back slightly to 35 per cent. Nuclear power varied only marginally, remaining at or near 20 per cent until 2010 before edging down to 15 per cent in the final decade, making it the smallest contributor by the end of the period.
Why it scores, criterion by criterion
Task Achievement
The overview is a separate paragraph with no figures in it, stating the two movements that matter. The body then selects: sixteen data points exist but only the turning points, the extremes and the crossover are reported. The answer never speculates about causes, which is outside the task.
Coherence and Cohesion
Data is grouped by behaviour rather than taken source by source, so the two body paragraphs each have a reason to exist: the pair that swapped places, and the pair that did not. "Coal and renewables followed opposite paths" tells the reader the organising idea before the figures arrive.
Lexical Resource
Movement is expressed with varied and accurate pairings of verb and adverb: "declined steadily", "rising slowly", "climbing steeply", "edging down", "fell back slightly", "varied only marginally". Note that the degree of change is matched to the actual figures rather than applied at random.
Grammatical Range and Accuracy
Comparative structures carry the answer, and the past simple is used consistently for a completed period. The relative clause "at which point it overtook coal" folds a comparison into a trend sentence, and "a position coal had held thirty years earlier" uses the past perfect correctly to reach further back.
Language worth stealing
Each of these carries a trap as well as a use, so the note matters as much as the phrase.
- Overall, ...
- Start the overview with it. Examiners look for the overview, and this word makes it impossible to miss.
- from a negligible base
- For a figure that starts near zero. More precise than "from a small number", and it sets up a large percentage rise honestly.
- at which point it overtook ...
- Puts a crossover inside a trend sentence instead of giving it a sentence of its own. Crossovers are exactly what "make comparisons where relevant" means.
- edging down / fell back slightly
- For small movements. Using "plummeted" for a three point fall is a lexical error, not an impressive word.
Last updated 13 September 2026.