Year 9 Science · Unit 3 · Lesson 14
Challenge Worksheet
Learning Goals
1. What is inertia in the grid? Explain why a coal-fired power station provides it but a solar farm does not.
2. What is demand response? Describe one example of it from the lesson.
Find the mistakes: four statements about transmission
(a) “A 660 MW power station sends power at 330 kV, so I = V ÷ P = 330,000 ÷ 660,000,000 = 0.0005 A.”
(b) “If the current in a line is halved, the heat lost in the line is halved too.”
(c) “A step-up transformer increases the power that a power station sends out.”
(d) “A 500 kV line carries about 45 times less current than an 11 kV line carrying the same power, so it loses about 45 times less energy.”
3. Each statement has one error. Say what is wrong, and give the correct statement or answer.
| Part | What is wrong | Correct statement or answer |
|---|---|---|
| (a) | ||
| (b) | ||
| (c) | ||
| (d) |
Data: a hot evening in one state
At 6:30 pm on a hot evening, demand on one state’s grid reaches 11,500 MW and stays near that level for 3 hours. The state’s grid battery can supply 600 MW and stores 1,200 MWh.
| Source | Supply available (MW) |
|---|---|
| Coal (baseload) | 6,000 |
| Wind | 1,800 |
| Solar | 200 |
| Gas peaking plants (at their maximum) | 2,500 |
Source: sample values for this worksheet.
4. Calculate (a) the total supply in Table 1, and the shortfall (b) without and (c) with the battery supplying its full 600 MW.
(a) Total supply MW
(b) Shortfall without the battery MW
(c) Shortfall with the battery MW
5. For how many hours can the battery supply 600 MW? The peak lasts 3 hours: what must the operator do to cover all of it, and what happens if every option runs out?
Battery lasts hours
6. The operator could instead import electricity from a neighbouring state through an interconnector. Explain one risk of relying on imports during a heatwave, one reason imports still help, and one other action from the lesson that the operator could take.
Someone claims…
“The National Electricity Market is outdated 20th-century technology that simply cannot handle Australia’s renewable energy transition. It was designed for large central coal plants and will need to be completely rebuilt from scratch before we can have a clean energy future.”
7. Evaluate this claim. Say which parts are supported by the lesson and which are overstated, using at least two specific ways the grid is already adapting.