How does the National Grid work?

28 February 2020 | OVO Energy

The National Grid gives us the power we need to complete Netflix marathons, boil up the perfect cuppa, and work from home (bliss)  – but who knows how it works? This blog explains the basics.

I get it – the National Grid isn’t something most people spend time talking about. And in the past, it hasn’t really mattered if people understand how it works or not. As long as there’s enough energy to go around, why worry? But as we start to work towards a future that’s solely powered by renewables, it’s more and more important for each of us to understand how this key system works – and how changing our relationship with it will help us reach net zero carbon by 2030. More on that later.

How does energy actually get to houses?
So this comes down to the National Grid and the way it delivers electricity to homes. Think of it a bit like our system of motorways and roads. There are big motorways (power lines) carrying energy around from large hubs like power stations and wind farms, which split off into smaller and smaller roads that take electricity to houses. All the energy produced, whether it’s from renewable sources or dirtier sources, is put on the same motorway, jumbled up together – and sent out to our houses.  

If I pay for 100% renewable electricity or green gas, how do you make sure that’s what I get?

Since all the energy gets pooled into the same network, you can’t guarantee that each individual zap of electricity powering your home started out at a renewable source. So, what we – and most other energy companies – do when you sign up for renewable energy, is guarantee that enough green energy is being put into the grid to match the amount of energy you use at home. 

We do this through a system of certificates called Renewable Energy Guarantees of Origin or REGOs. These are certificates that get generated for every unit of green electricity that goes into the grid. By buying these certificates we can make sure that as much green energy has been put into the grid as you’ve used. 

This doesn’t mean that at any one time there’s a set percentage of renewables on the grid. Just that overall, in a year, there’s been equal amounts put in and used. 

It’s the same process for gas - it all gets pooled, biogas and natural gas alike - and sent to houses. To guarantee that there’s as much green gas in the system as you’re paying for we use a similar system to REGOs called Renewable Gas Guarantees of Origin (RGGOs). These get given to certify each kWh of green gas that’s put into the grid.


How do we make sure there’s enough power for everyone?

For gas this is nice and easy. Gas can be stored ready for use when people need it. So it gets put into the system continually, at roughly the rate it’s being used. 

Electricity is where it gets interesting. The first thing to keep in mind is that traditionally electricity couldn’t be stored in large quantities. This is starting to change as the technology advances and becomes affordable, like Centrica’s giant battery in Cumbria, but by and large it’s still true that we don’t store our energy in large volumes. It can be stored in batteries big enough to power our cars, or individual homes, for example. 

Read all about battery technology, and why the future of renewable energy depends on it, here.

One of the key jobs of the National Grid is to make sure there’s enough power being produced for everyone that wants it at any one time. They do this by splitting the day into 30-minute time periods.

Each energy company has a team of traders who buys energy for these periods of time – they can buy energy up to an hour before each half-hour period. For each half an hour, the National Grid also does some very complicated forecasting to work out exactly how much power the UK is going to need for that period (even down to the second!). They then make sure enough power is being produced around the country, or imported from Europe, to match the amount we need each moment of the day. If they get it slightly wrong, they can react in near real-time to make adjustments. Clever stuff. 

If demand is higher than the predicted supply – or the predicted supply is higher than the actual demand – this can cause real problems. So it’s important to get it right!

Why is this so important?

Well, turning on or off more traditional forms of energy (nuclear, coal or gas power stations) can be done on demand. But you can’t do this with wind or solar power. You can’t turn the sun on (we wish!), or ask it to be windier at the drop of a hat. 

So if there’s a big demand for energy, and not enough renewable power coming available at that time, the grid has to depend on other forms of energy to keep the lights on. 

We can all help solve that problem by making sure to waste as little energy as possible. Think turning off appliances at the wall when they're not in use, or switching to LED lights. More on that soon...

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