[Tea-making montage]
Here in Britain, we love a cup of tea, and I’m no exception.
In fact, in the UK, we love it so much we drink
one hundred and sixty five million cups of tea every day!
But whether we’re switching on lights, flicking on the kettle, or turning on the TV,
we don’t really think about how the electricity we’re using gets to our homes.
[90s montage]
At 11am on Wednesday the 11th August 1999, millions of people across the UK stopped what
they were doing and went outside to stare up at the sky
to watch a total solar eclipse passed overhead.
This meant a huge drop in the amount of electricity that we were using.
And half an hour later, when people went back inside to their homes
and offices and factories, the amount of electricity needed shot up again.
By three thousand megawatts in fact. The largest increase we’ve ever seen in
the UK. That’s the equivalent of an extra five million
cups of tea. Today, we’re headed to the place responsible
for balancing the supply and demand of electricity that we use.
The National Grid Control Centre.
[Tom] First off, what is the National Grid? [Duncan] The national grid is sort-of like the motorway
network for electricity in the country. So, behind us on the wall you can see a big
wiring diagram and that shows the whole of the electricity
motorway network running right from Scotland in the north down
to London and the south coast in the south.
And that carries nearly all of the electricity you use everyday
to boil your kettle, to light and heat your home.
So from here we are constantly balancing the supply of electricity from generators
and matching that against the demand we see across the country.
And that demand varies minutes by minute, day by day,
in ways that we can forecast, but in ways that do change
based on the weather and the time of year and what people are doing.
[Tom] So, how do you balance supply and demand? [Duncan] The British grid system runs at a frequency
of 50 hertz That means the electricity is always pulsing
backwards and forwards 50 times a second. And that’s what puts power into your lights
into you cooker, into everything else, that 50 hertz power
Now, what actually happens is that if we have a little bit more generation than demand
a little bit more supply than demand then it speeds up a bit.
A bit like you’re going down a hill too quickly.
And it goes to 50.1 hertz, a little bit more. If we’ve not got quite enough generation,
then the speed slows down. A bit like when you’re peddling uphill on
your bike and it’s really hard work. And we see it just dip down to 49.9 hertz.
It’s a tiny little system frequency variation, you wouldn’t see it at home,
but to us it’s all important. And if we get it wrong then the system frequency
will drop a little bit, then we’ll just have to push a little bit
more power in to make sure we get it right. And it’s a bit like flying a plane in to land,
You just need to trim it a little bit each way
just to keep yourself on track. And that’s exactly what we’re doing here.
[Tom] And in order to keep flying that plane, the grid draws upon a variety of different
energy sources. This model uses the same method we’ve used
for over a century to generate electricity. Water is heated and turns into steam; that
steam turns a turbine, which turns a generator, to produce the electricity.
[whistle]
Coal, gas, biomass, and nuclear power plants all use this method,
but with different sources to heat the water.
Wind turbines, hydroelectric dams and tidal barrages also turn a turbine to generate electricity,
but without heating water.
And finally we have solar panels, which use the photovoltaic effect.
These methods each have their own advantages and disadvantages.
But what percentage of these power sources do we use day to day?
[Duncan] On a typical day, about half the power we get these days is from burning gas.
From gas-fired power stations Maybe 10 or 15% from nuclear.
Most of the rest is coming from renewables or trading with our neighbouring countries
through cables under the sea, through interconnectors. And then just a little bit from coal.
[Tom] We had a few days recently where we didn’t use any coal power, is that right?
[Duncan] That’s right, for us it’s amazingly exciting and one of those major milestones.
This summer just gone we had for the first time in 130 years
we ran the electricity grid without burning any coal.
And I think if you look today, there’s actually more solar running than there is coal on the
grid, even right now. As that coal closes, it’s quite a small
gap to fill. So we would expect even more renewable to
come on. Of course we might see additional nuclear
and we expect to see additional nuclear coming on over the coming
years And some of those coal stations have converted
from burning coal to burning what we call ‘biomass’.
And so those power stations will carry on with a new life.
[Tom] Describe for me the flow of electricity from its source to my kettle
[Duncan] Oh yeah, OK, great question. Great question,
because it’s not here is it? So what happens is that your power will be
generated either at a big power station like at Hinkley Point nuclear power station or one
of the other big power stations around the country.
One of those on it's own can feed a whole city, supply a whole city with power.
Or it might be generated at a wind farm, either at a farm down the road, or out in
the sea somewhere of the coast of Britain. Or it could be at some solar panels.
That power feeds into the grid, into the big motorway network here
And then it moves around the grid like water to where it’s needed.
And then it’ll flow from the motorway network, from the transmission grid here,
it flows down into the local distribution grid in a town or city near you.
And it flows down to a big grey box at the end of your street.
And from that grey box it flows out on a single wire which feeds every single house individually
on the street, under the road up into the middle of the house
probably to a fuse box. And then from that fuse box it goes out into
a little ring, which is in the wall all the way around the
house, all the way around to the kettle socket probably
halfway up the wall in your kitchen. And then out of that into the kettle.
And obviously it only goes into the kettle when it’s turned on.
[Bleep] So, we know how National Grid manages electricity,
but what happens when a large group of people cause a simultaneous surge in electricity
demand after watching an eclipse or making a cup
of tea after their favourite TV show?
[Duncan] We see a huge surge for power just at the end of those TV programmes, just as
the adverts come on. We know that's happening, we’ve got a TV in
here we will watch as well, and we look at how interesting and exciting
the TV programme is going to be. And if we know that loads of people are going
to sit down and watch it we’ll get extra power ready so that at the
end of the programme we can push it all in and just match off against demand.
If we didn’t do it, the system frequency would fall.
[Tom] So, you’ve got the energy on standby. Is that stored somewhere?
Or are you switching somewhere on? How do you communicate with power stations to say
what you need? [Duncan] What we’ll do, is we’ll warn
people that we might want to use them, and some of the power stations we can get
them ready so that they’re ready to go in seconds.
And big example of that is the pump storage stations.
So pump storage power is where you have a big lake at the top of a mountain and a big
lake at the bottom. Almost like a bath, you can empty the top
lake down a tube, through an electricity generator, and then
into the bottom lake. And we have several really large pump storage
stations around the country. And then just as a TV programme finishes,
you pull the plug of the top lake, all the water comes rushing down the hill,
hits the turbine, we get huge bursts of electrical power in
10, 15, 20 seconds. Then that surges into the grid and helps meet
that big pickup in demand. And the great thing that we have is that electricity
pretty much travels as fast as you can imagine, almost at the speed of light. So it can go
from one power station, it spreads all around the country
in an instant. As fast as you can think.
[Tom] The electricity available at our fingertips is instantaneous and seemingly infinite.
But perhaps the next time you make a cup of tea, have a think about the dynamic
but unseen system of technology and people behind that power;
and the thousands of others simultaneously making their own hot cup of tea.
Thank you to everyone who helped to make this video possible.
If you liked it please share, subscribe and check out our previous videos. Thanks for watching!
[beep] This feels like the lamest episode
of Topgear [beep] We wanna try out this little Citroen.
So we’re gonna take it to the National Grid.