Academic Writing Task 1 · process diagram

The process of generating electricity using a geothermal power plant

The diagram below shows how geothermal energy is used to produce electricity.

Summarise the information by selecting and reporting the main features, and make comparisons where relevant. Write at least 150 words.

Geothermal power plant operation

1.Cold water is stored at the surface
2.Cold water is pumped down a 4.5 km injection well
3.Water travels through the geothermal zone of hot rocks
4.Hot water is pumped up through the production well
5.Hot water is converted to steam in the condenser
6.Steam powers a turbine connected to a generator to produce electricity

Chart redrawn by BandLadder from the data in the original IELTS practice task. Many IELTS practice tasks come from the Cambridge IELTS series (Cambridge University Press & Assessment); all rights in the original tasks remain with their owners.

Band 8 sample answer

The provided diagram illustrates the mechanical process by which a geothermal power plant converts underground heat into electrical energy. Overall, the system operates as a continuous cycle, utilising a deep injection well to transport cold water to a geothermal zone, where it is heated before being returned to the surface to drive a turbine.

Initially, cold water is held at the surface before being pumped down an injection well that reaches a depth of 4.5 kilometres. Once underground, the water circulates through a geothermal zone consisting of hot rocks, which significantly increases its temperature. This heated water is subsequently forced upwards through a production well.

Upon reaching the surface, the hot water enters a condenser, where it is transformed into steam. This steam is then directed into a turbine, causing it to rotate. The turbine is mechanically linked to a generator, which converts this kinetic energy into electricity. Finally, the generated power is transmitted via an electricity pylon for distribution. The entire process relies on the natural thermal energy of the earth to maintain the cycle of steam production and power generation.

182 words. Every figure in the answer comes from the chart above.

How to write about process diagrams

Say how many stages there are and where the process starts and ends.
Use the passive and sequencers: first, after this, once, finally.
Keep every stage; a missing step costs task achievement.

illustrates: shows or makes clear by using a diagram
continuous cycle: a series of events that repeat indefinitely
subsequently: happening after something else in a sequence
transformed: changed completely in form or appearance
mechanically linked: connected physically to transfer motion or power
relies on: depends on something to function or succeed

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Frequently asked questions

What should the overview say?

The process involves a closed-loop system where cold water is heated by underground rocks to produce steam, which then drives a turbine to generate electricity.

How long should an IELTS Task 1 answer be?

At least 150 words; 170 to 200 is the safe range. Spend about 20 minutes on it and leave 40 for Task 2, which carries twice the marks.

How do I describe process diagrams?

Say how many stages there are and where the process starts and ends. Use the passive and sequencers: first, after this, once, finally. Keep every stage; a missing step costs task achievement.