Mike Hemsley, Committee on Climate Change: An understanding of renewable sources of electricity

Mike Hemsley: Hello. I'm Mike Hemsley from the UK's committee on climate change. It is great to be with you today to tell you about one of my favourite topics. You've heard from some of my colleagues already, but today I'm gonna be talking about the UK's electricity system and renewable electricity. I've been at the CCC for six years now, focusing on how to reduce emissions from the UK's electricity system in the lowest cost way.

So, moving on to slide two for an overview of what we'll cover today. So first of all, what do I mean by renewable electricity? So I mean electricity which isn't from fossil fuels such as coal and gas, and electricity that isn't from nuclear power. And these will be covered in a different session.

So what we're gonna cover today are different types of renewable electricity. So variable renewables, that's wind and solar, mostly, that's where their output changes because of the weather, but also other types of renewables as well. We're gonna look at the technology costs and the potential scale of some of these technologies for the UK, and how system design might need to change in a low carbon world as well.

So moving on to slide three for an overview of low carbon electricity options. So the key thing about electricity is that we need to produce almost exactly the same amount of electricity that we use at all times. So if I switch on the light in my home somewhere, that's noted, and something turns on or increases output so that my light could be as bright as I wanted it to be.

Now this table notes what types of low carbon electricity we could have in the UK, the role they play in the UK's electricity system, and their current share of the system. Not all of these technologies are renewable technologies. All the technologies that aren't renewables will be covered in a later session by Jim Watson. Although Bio Energy is a renewable source of electricity, this will be covered in a later presentation by Patricia Thornberry.

So, looking at the table now and in the second column, we have technologies that are available some of the time. That's the title of the column. So these technologies produce electricity when the wind is blowing, when the sun is shining, or when the tides are coming in and out. But that varies according to the weather, which is why I called them variable renewables. So they're good when they're there, but you can't rely on them for constant supply. These technologies were 1/4 or 26% of electricity generation last year. This is mostly from wind as well as some solar and hydro, and there is potential for wave and tidal power to play a role in the future.

So next up in the third column are technologies that run all of the time. Generally this is a good thing. Constant supply means it's often cheaper for operators to produce their power. But this means that they can't flexibly reduce or increase their output according to what the system might need, which means they're slightly less useful to the system than technology that can change their output. These technologies produced around 1/3 or 31% of the UK's electricity last year. This is mostly from nuclear power, but also from large scale bio energy and other technologies could play a role here, so you could use natural gas in combination with carbon capture and storage, which is called CCS on this side. Um, or other technologies such as geothermal energy, which I'll cover slightly later.

So now, looking at the last column on the right hand side, we have what I call flexible gas generation, and this is really useful because it's available when you need it. It can increase or decrease output in a matter of seconds, which is really helpful for the system. Currently doing this on the system is high carbon gas and coal, and it's quite a big proportion of the system, just under half, or 43%. But to be low carbon, you'd have to capture the emissions from burning the gas in a process called carbon capture and storage and then bury the emissions underground, or use a gas without any carbon in it in the first place such as hydrogen, and we don't currently have any power stations that do that in the UK.

So moving away now onto slide 4, focusing on the variable renewables that are available some of the time. So these are the cheapest source of electricity in the UK because although there's a cost to build the wind turbines or the solar panels, or the turbines that you put in rivers or in the sea, once you've built them the fuel is free because its sun, it's wind, or it's water and they're all naturally available in the UK.

So let's go through each one in order, including what their current status is, how much of a role they could play in the future, and their costs. Starting with onshore wind. This is grown from nothing to around 10% of electricity in the last 10 years, particularly up until around 2017 when the government stopped offering contracts to it because they were concerned about public acceptability. There's currently around 8500 turbines installed in the UK and this potential for probably around 10 times that much overall, though people may not want to cover that much land in wind turbines, and that's the decision that needs to be made. The cost is about the same or cheaper than higher carbon electricity, and the cost of this technology continued to fall.

Now, looking at offshore wind. This is the same kind of wind turbines but placed in the sea rather than on the UK's land. This has grown again from nothing to around 10% of the UK is electricity in the last 10 years, and it's now the fastest growing source of electricity thanks to government support. There's currently around 2000 turbines in the UK's waters, although these turbines are often bigger than the turbines that you see on land. And in terms of overall scale, we don't really see a limit here. In fact, we think that if offshore wind was to provide all of the electricity that the UK currently needs, then this would only take up 1% of the UK's seabed. So there's vast potential there. The cost is similar to onshore wind, so it's now the same or cheaper than higher carbon electricity. And again, the cost of this technology continued to fall. What I mean by higher carbon electricity is electricity from coal or gas in the UK.

Moving on to solar power. This has grown from 0% to around 4% of the UK's electricity on a similar time scale to onshore wind. And even though we might not be the sunniest country, there are currently around 800,000 households and businesses in the UK with solar panels on their roofs. The potential for solar power is high, probably as high as onshore wind, but there is a limit to how useful its output is as it mostly produces electricity during the day in summer, whereas actually the UK needs most electricity on dark winter evenings. If you put these panels in a field, then the cost is about the same as wind power, but actually if you put them on people's roofs it is a bit more expensive.

So just to clarify the difference between hydro power, tidal power and wave power. By hydro power, I mean capturing the energy from the UK's rivers. By tidal power, I mean capturing the energy from tidal flows, so when the tide comes in and out across the UK's coasts. And by wave power, I mean capturing the energy from the crashing of the waves in the seas around the UK. Hydro power provides around 2% of the UK's electricity and it has done for more than 30 years via small turbines dotted around rivers around the UK. Actually, what this means is a lot of the best sites have now been taken, and there's limited potential for future growth. And the cost look to be higher than both wind and solar. Tidal and wave power are both promising technologies, but unfortunately not enough progress is currently being made on them for us to believe that they can be deployed at a significant scale by 2050. Big new dams are expensive and controversial, as are tidal lagoons which is a newer form of dam. There are other ways of getting energy out of the tide or waves, but they're not as advanced and they're currently around 5 to 6 times the cost of wind or solar power, so really quite expensive.

So in conclusion, variable renewables are cheap. There's still vast potential for onshore wind and solar power in the UK, and the potential for offshore wind is tremendous. So moving on to slide five. There are other renewable options where output is more predictable. First of all, there's geothermal energy. So to get this energy, you need to drill pipes deep into the earth's crust to extract heat and then turn this heat into electricity. This is popular in other countries, particularly countries with high temperatures relatively close to the surface of the earth such as Iceland where there's a lot of volcanoes. But there's not that much potential for it in the UK although there are some projects in Cornwall.

Another technology that can play a similar role in the system is bio energy, including waste to energy. And this is a renewable source of electricity, but this is going to be covered in a later presentation.

So moving on to slide six now to talk about how the design of the UK's electricity system needs to change in a low carbon world. So, as I mentioned already, the electricity system is designed to produce the same amount of electricity as we're using at all times. So even though demand for electricity does change, such as when you or I turn on our kettles, this can largely be predicted and the supply of electricity can be matched to it. This becomes more difficult with variable renewable energy as there may be times where it's not windy or not sunny, or actually the opposite where there's too much energy for the system to cope with it.

Now moving on to slide seven to look at some of the options to deal with this. We talk about adding system flexibility in order to help manage valuables on the system, and there's four options there. So one is battery storage which can store electricity to use at a later time. This can be done on the wider electricity system itself, or in businesses or people's homes. We can change when we use electricity, so move electricity consumption to a more useful time for the system. So, for example, in the future you might have an electric vehicle and you could schedule your electric vehicle to charge when it's windy or sunny. We could build electricity cables to other countries to allow countries to share resources and solutions, and we can use gas power plants to respond to changes in output from renewables, and act as a backup source of electricity generation. The good news is that all of this is well underway both in the UK and around the world, and though there is some cost to this, it is expected to be small in the grand scheme of things.

So now moving on to slide eight to wrap up, this is just a recap of what we've covered today. So we've looked at different technology types, variable renewables such as wind and solar, but other types of renewables as well. We've looked at the costs and potential scale of these technologies, and we've looked at how system design might need to change in a low carbon world.

And then, lastly, moving on to slide nine. Here's a summary of what I'm hoping you'll take away from this session. Firstly, variable renewables are the cheapest source of electricity in the UK, wind and solar are currently the best options to produce renewable electricity at scale, and system design needs to change in this low carbon world. But this is already well underway in the UK and around the world. Thank you very much.