Electricity Generation in a Hydroelectric Power Station

6 Sample Responses · Bands 6.0–7.5

The diagram below shows how electricity is generated in a hydroelectric power station. Summarise the information by selecting and reporting the main features, and make comparisons where relevant.

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Sample responses and feedback

Response 01

Must fixSuggested

The diagram describes how electricity is produced in a hydroelectric power station.

A high-level reservoir situated just beneath the flowing river is used for reserving the water from the flowing river. A dam is right after the reservoir, which has a tunnel beneath it responsible for the passage of the reserved water . This tunnel opens in the daytime and closes at night, and it allows water to be transferred to the power station for the generation of electricity.

The flow of water towards the powerhouse has two main features whereby the water moves forward at daytime to generate electricity whiles it moves backwards at night for the pumping of water.

In the first stage of the manufacturing process, two reversible turbines are situated within the power station, which operates the generator at daytime and pumps water from the low-level reservoir back into the high-level reservoir. The generator has the power lines which supplies the final manufactured electricity to the national grid.

Overall, the process consists of seven (7) stages starting from the high-level reservoir to the supply of electricity to the national grids.

Score details

Response 01
Estimated band6.0/ 9

Overall assessment

The response covers the main components and contrasts daytime generation with nighttime return flow, with a broadly understandable organisation. However, the water route is incomplete because the daytime flow into the low-level reservoir is not stated. The intake needs more precise naming, the concluding overview omits the return cycle, and some awkward vocabulary and unclear reference weaken the description.

TA

Task Achievement

The response identifies the main components and contrasts daytime generation with nighttime return flow. However, it calls the intake a tunnel, gives an unnecessary turbine count, and does not explicitly describe water entering the low-level reservoir by day. The concluding overview omits the return cycle.

6.0
CC

Coherence and Cohesion

The response is organised into logical paragraphs with a progression from reservoir to power station to grid, though referencing and some links, such as the abrupt presentation of the two flow directions, remain mechanical at points.

6.0
LR

Lexical Resource

There is adequate topical vocabulary covering dams, turbines, reservoirs, and generation, but imprecise usage including 'reserving', 'whiles', 'manufactured electricity', and 'national grids' reduces accuracy and flexibility.

6.0
GRA

Grammatical Range and Accuracy

Complex structures and relative clauses convey most relationships, but reference is sometimes unclear. In particular, the clause after power station obscures the turbines as the operating component, and power lines which supplies contains a subject-verb agreement error.

6.0

What to work on next

Trace the complete water route in each operating mode, including the daytime outlet into the low-level reservoir. Name the intake and the turbines precisely, and use the conclusion to summarise daytime generation and nighttime pumping.

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