Demand Side Management Questions and Answers

Answer: C

Correct answer: takes the measure because of the programme without claiming the incentive

A free driver is the opposite case: the programme changed their behaviour but the saving is not recorded against it, usually because they were persuaded by neighbours or by the publicity rather than by applying. Free drivers therefore understate the programme’s effect just as free riders overstate it.

Answer: D

A household given efficient lighting may leave more lights on, and one given efficient heating may heat to a higher temperature, so the realised saving falls short of the engineering estimate. It is a genuine welfare gain and an accounting nuisance.

Answer: A

Correct answer: the surge of demand when a controlled load is restored

When thousands of water heaters or air conditioners are switched back on together, they all draw current at once and the diversity that normally exists between them is gone. The restored peak can exceed the original one, so restoration is staggered in groups rather than done in a single step.

Answer: B

Correct answer: 0.60

\[ \frac{480}{800} = 0.60. \] Sixty per cent is typical of a mixed distribution system. A higher figure means the network and the generation are being used more of the time, which is the object of nearly every measure discussed here.

Answer: C

Correct answer: 0.67

The peak falls to 720 MW while the average is unchanged: \[ \frac{480}{720} = 0.667. \] Clipping ten per cent from the peak has raised the load factor by seven points, and it has done so by reducing the denominator - which is why peak reduction is worth more per megawatt hour than a general reduction in consumption.

Answer: D

Correct answer: 1.25

\[ \frac{10 \times 50}{400} = \frac{500}{400} = 1.25. \] The group’s maximum is a fifth less than the sum of its members’ maxima, because they do not all peak together. The factor exceeds one by definition, so an answer below one would indicate the ratio taken the wrong way up.

Answer: A

Correct answer: 0.80

\[ \frac{1}{1.25} = 0.80, \] equivalently \( 400/500 \). Eighty per cent of the connected maximum actually coincides. The two factors are reciprocals, so one exceeds unity and the other falls below it - which is the quickest check on whether the right one has been quoted.

Answer: B

Correct answer: 4000 million

\[ 100 \times 40 = 4{,}000\ \mathrm{million}. \] The figure is a deferral rather than a saving outright, since the plant may still be needed later, but deferring capital for several years is worth a substantial fraction of its cost - and it is the avoided capacity, not the avoided energy, that usually justifies a demand side programme.

Answer: C

Correct answer: 40 MW

\[ 50 \times (1 - 0.20) = 40\ \mathrm{MW}. \] The gross figure counts everything the participants did; the net counts only what the programme caused. Since the programme is judged on cost per megawatt actually saved, the free rider adjustment can change a favourable evaluation into an unfavourable one.

Answer: D

Shifting moves consumption in time and removes none of it, which is why it helps the utility's capacity position without hurting its revenue. In practice the off-peak losses are lower, so the generation required falls slightly.