Question Video: Understanding the Balance between Electricity Supply and Demand | Nagwa Question Video: Understanding the Balance between Electricity Supply and Demand | Nagwa

# Question Video: Understanding the Balance between Electricity Supply and Demand Physics

A nuclear power station in the UK develops a fault and needs to be shut down quickly so that it can be repaired. Which of the following types of power station could be quickly turned on to compensate for the supply lost by the nuclear power station shutting down? [A] A solar farm [B] A wind farm [C] A gas-fired power station [D] Another nuclear power station [E] A tidal barrage

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### Video Transcript

A nuclear power station in the UK develops a fault and needs to be shut down quickly so that it can be repaired. Which of the following types of power station could be quickly turned on to compensate for the supply lost by the nuclear power station shutting down? A) A solar farm. B) A wind farm. C) A gas-fired power station. D) Another nuclear power station. E) A tidal barrage.

Okay, so in this question, we’ve been told that a nuclear power station is malfunctioning and it needs to be shut down quickly so that it can be repaired. Now whilst this nuclear power station is being repaired, we need to start up another power station so that it can compensate for the supply lost by the nuclear power station. And crucially, this new power station needs to be able to switch on quickly. This is so that we don’t waste too much time in between the nuclear power station closing down and the second power station starting up. If this second power station doesn’t start up quickly enough, then there will be a period of time where not enough power is being produced. And homes or businesses for example may have to go without electricity for a while.

So we need to find a type of power station that starts up quickly out of these five options given to a us here. So let’s look at option A, a solar farm. Now a solar farm consists of lots of different solar panels. And they absorb light coming from the sun and convert this into electrical power. So a solar farm will have no problem starting up relatively quickly assuming that it’s sunny outside. However, what if it isn’t sunny outside when the nuclear power station shuts down? What if it’s cloudy or if it’s the evening time? Well in that case, there is no guarantee that the solar farm will produce enough energy to compensate for the supply lost by the nuclear power station shutting down. Therefore, option A is not the answer to our question.

Option B then, a wind farm. Now, a wind farm contains lots of wind turbines which rely on the wind blowing past them and turning their rotors. When these rotors do turn, the kinetic energy of the rotor blades is then converted into electrical power. However, a wind farm suffers from the same problem that a solar farm does. The conditions have to be right in order to be able to produce as much energy as necessary. For example, what if it’s not windy when the nuclear power station shuts down? In that case, the wind farm also won’t be able to produce enough power to compensate for the supply lost. And hence a wind farm is not the answer to our question.

Let’s look at option C then, a gas-fired power station. Now in a gas-fired power station, natural gas is combusted. And the energy from that chemical reaction where the natural gas is combusted is used to heat up water which then turns into steam. In other words, the energy from the chemical reaction is transferred to the water, thus turning into steam. And then the steam actually turns a turbine. That turbine is connected to an electrical generator, and, therefore, turning the turbine generate electricity. Now, the interesting thing about a gas-fired power station is that gas is actually very easy to transport. It can be easily sent down a pipe to the combustion chamber.

Therefore, gas can be quickly sent from where is being stored to the combustion chamber. And the gas-fired power station can be started up quickly. As well as this, it’s a very reliable source of energy in that it will produce as much as we need, assuming we have enough gas at hand. In other words, it’s not dependent on the weather conditions that day, whereas we’ve seen already solar farms and wind farms are dependent on that. So a gas-fired power station can be started up quickly and produce as much energy as we need reliably as well. So it looks like a gas-fired power station might be the answer to our question. Let’s quickly go to the other options just to make sure.

Option D is another nuclear power station. Now before shutting down a nuclear power station and we start up another nuclear power station in its place, then there’s no doubt that if the second nuclear power station is of a similar size to the first one that it could produce enough energy reliably as we need it. However, the problem with a nuclear power station is that it takes a very very long time to start up. Usually, the startup time is on the scale of a few days. And so as soon as we find out that the first nuclear power station is shutting down, we wouldn’t be able to start up the second nuclear power station quickly enough. Hence, a second nuclear power station is not the answer to our question.

So the final option that we’ve been given is a tidal barrage. Now, a tidal barrage is almost a dam-like structure that’s built across either a river or a bay and relies on a mass movement of water through it, for example, when the tide is coming in or going out. Now the kinetic energy of all of this water moving through the tidal barrage then gets converted into electrical energy. But the problem is that the tide may not be coming in or going out when we find out the nuclear power station that’s broken down has done so.

And so a tidal barrage suffers from the same problem as a solar farm and a wind farm. We’re too dependent on the conditions to be right in order for a tidal barrage to produce as much power as necessary. Hence, we can say that E is not the answer that we’re looking for. And at this point, we’ve arrived at our conclusion. The type of power station out of the five given to us that could be quickly turned on to compensate for the supply lost by the nuclear power station shutting down is a gas-fired power station.

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