An Overview of Electricity in the UK

I've been diving into the various sources of CO2 by industry and by country, whilst trying to wrap my head around climate change, and the causes of it. I'll save the details of the breakdown of CO2 for another post, but the biggest sectors by far were energy generation and transport. Transport will also need to be tackled elsewhere, as it's a vast and complex sector, but I wanted to dive into energy.

I live in the UK, so wanted to get a handle on how energy works here - what generates our power, how is it distributed, all that good stuff. I initially approached this from the angle of trying to find out how green my utility suppliers were, then got sucked into the complexities of how utilities work in this country, which is another whole story. I'll cover a little of everything here, to give an overview of how things work.

N.B. I'm diving into how electricity is generated, rather than energy more generally, which could cover things such as gas, oil, and other forms of fuel not consumed solely for the purposes of generating electricity.

A history lesson

A high voltage cable sign dating from the days of the BEA Image Source

The UK has a national power grid covering most of England, Scotland and Wales, as well as some of the outlying islands. There are also some interlinks to France, the Netherlands, and Ireland, for importing/exporting power. The early history of the power grid is a little involved, and I'll leave it out here (Wikipedia has a lot more information if you're interested). However, the grid as we know it today started coming together in the late 1930s, and was run by the Central Electricity Board (CEB). In 1947, the Electricity Act nationalised all of the electricity supply companies, and combined them with electricity departments of local authorities and the CEB to form the British Electricity Authority (BEA). This comprised of a central authority, and 14 regional boards, each in charge of an area of the UK. The idea was that by unifying suppliers and the grid into a single unit, it'd be more efficient to supply electricity in a coordinated and economical fashion (prior to this nationalisation, electricity generation and supply comprised some 505 separate organisations).

This lasted a whole 7 years, before being succeeded by the Central Electricity Authority, which then was replaced 3 years later by the Central Electricity Generating Board (CEGB). Fortunately, this time, the layout stuck, and the CEGB was responsible for electricity generation in England and Wales (Scotland had a couple of equivalent Electricity Boards) for close to 40 years, before being privatised in the 1990s. There was also the Electricity Council that oversaw more of the policy side of things during the same era.


In the 1990s, it was decided that the CEGB needed to be broken up and privatised, splitting its responsibilities into four separate companies, and forming an electricity market in the UK - allowing electricity to be bought and sold as a commodity. This break up resulted in four brand new companies. Three of these would be responsible for the generation of electricity - PowerGen, National Power and Nuclear Electric - whilst the remaining company would take over the grid itself (the transmission infrastructure) - National Grid Company.

This didn't all happen at once. Initially the nuclear power plants were going to be assigned to National Power, but that decision was rethought, and Nuclear Electric was formed to hold the nuclear stations. These were then held in public hands for a further five years, before being privisated finally in 1995.

So that deals with generation and transmission. But what about supplying power to homes and businesses? Prior to privatisation, that was handled by twelve regional boards (the successors of those mentioned earlier, after the Scottish boards had gone their own way). Upon privatisation, each of those boards was turned into a private company, and they were also allocated shares of the newly formed National Grid Company. Thus, there were now twelve regional companies, each supplying consumers as well as owning a part share of the grid infrastructure, and three generation companies.

The generation companies were originally split 60/40 between private investors and the UK government, but in 1995 the government sold off its 40% stake, and then the markets went to town, merging and splitting companies left, right and centre. Powergen has been bought out by E.ON and National Power split into nPower, and Engie Energy International. Nuclear Electric, which as the name suggests, held the English and Welsh nuclear power generation amongst other assets, merged with an equivalent Scottish company, then most of it ended up as EDF Energy.


That covers supply fairly well. Transmission, as mentioned earlier, was privatised as the National Grid Company, now National Grid plc. They now own and operate the grid in England and Wales, as well as operating the Scottish grid (though that's owned by Scottish Power and SSE plc). They also part-own the interconnects to France and the Netherlands, as well as the gas transmission network (National Transmission System). They've also expanded into the US, and operate a lot of the electricity transmission infrastructure across New York, Massachusetts and Rhode Island.

Consumer supply

In the years since privatisation, the supply side has proliferated massively. There have been many mergers and splits since the original 12 boards were privatised, and particularly in recent years, a host of new companies have sprung up to cater to new niches. There are now six major firms dominating supply of gas and electricity (known, rather unoriginally, as the Big Six). Some of these supply companies purely deal with consumer supply - they buy gas or electricity from the energy markets, and sell on to consumers, differentiating through customer service, pricing and other factors. Others, such as EDF Energy, are also involved in the generation side, both generating power to sell to the grid, and supplying that grid power to consumers.

This means that trying to figure out if a given consumer utility provider is 'green' is actually rather hard, as all the suppliers are buying electricity from the grid, and whilst some also produce, what they produce they may not actually be selling to consumers. So far, I've not found an easy way to tell who buys what power, or how the electricity market works. Some providers, such as Ecotricity, market themselves as green providers, selling energy either generated from their own green sources (wind, solar, etc), or purchased from the energy market (it is possible to buy electricity by source, such as nuclear).

UK Power Generation

So, what about the power itself? What sources are there, and how much is generated and used? For this, I've made heavy use of some lovely interactive tools by the US Energy Information Administration (EIA), which has statistics on energy production for the UK, as well as many other countries around the world. You can select/deselect different data series, represent the data in different ways, compare countries, and it even has neat downloadable charts (the source of the images in this post).

Overall UK electricity production/consumption between 1980 and 2016 Image Source

As you can see above, UK energy generation and consumption has risen steadily since the records begin in the 1980s, peaking at around 370 billion kWh in 2005. Since then, there's been a gradual but continuous decline, to our current levels of around 310 billion kWh. We also import around 20 billion kWh per year, exporting around 2 billion kWh. However, this overall consumption figure, whilst nice, doesn't really give much of an idea of the make-up of that energy generation. For that, we need to dive into sources of power - what kind of power generation is going on?

Electricity capacity by type from 1980 to 2016 Image Source

If we dive into sources, we can see that overall installed capacity has gradually risen since the 1990s. Indeed you'd expect this, having seen the consumption figures from the previous graph. If consumption rises without increases in production, you'll end up with a deficit, which will result in power shortages, or having to buy in power from other countries. Indeed, in the early 2000s, there was concern that there would be an 'energy gap' in the UK, as there were still a number of older coal-fired power stations, that were not able to meet EU clean air requirements, and thus would need shutting down. In addition, Britain still relied on several Magnox nuclear power stations, an early design that was at the end of its life, and due to be closed imminently. Fortunately, most of the energy gap disappeared with reducing demand - a combination of the economic recession that started around 2007, and changes in lifestyle, where people started switching to LEDs and other more power-efficient lighting, along with improvements in home appliance efficiency.

In terms of the sources of our electricity, one of the most marked trends is the sharp drop in fossil fuel usage since around 2010. Coal has been gradually phased out due to emissions regulations, but around 2010, a combination of high gas prices and the economic recession meant that a number of the older, less efficient gas power plants were mothballed. In more recent years, the growth of renewables has soared, meaning that whilst still held in reserve, the more stable but more polluting coal- and gas-fired power stations have needed to be running less and less. Indeed, in 2017, the UK went for the first 24 hour period without burning any coal whatsoever. It's unlikely that fossil fuels will go away entirely for some time yet, as whilst renewables are growing rapidly, fossil fuels provide a reliable backup that can stabilise a lot of the fluctuations from sources such as wind and solar.

Nuclear production has remained more or less constant, with a slight decline over the past two decades or so. The decline is mostly due to old designs such as the first-generation Magnox reactors being shut down at the end of their life. Nuclear provides an excellent baseline capacity for the grid, but all but one of the stations we have now are AGR designs, and were first connected the grid in the 70s and 80s. Most of these reactors are scheduled for closure in the next decade, even with several extensions. We have a single PWR station - Sizewell B - but even that is 24 years old. It is currently projected, with various life extensions proposed by EDF (the current operators) to operate until the 2050s, but with new reactors in doubt, nuclear power in the UK has a questionable long term future - a pity when it comes to reducing CO2 emissions and reliance on fossil fuels. I'll dive into nuclear power more in a future post, as it's a fascinating topic.

Dinorwig Power Station - the largest pumped storage facility in the UK Image Source

Hydroelectric power generation has also been very constant in the UK in the past thirty years, with basically no major changes in the amount of installed capacity. A lot of this is due to the nature of hydroelectric power - it's very location-dependent, and most of the sites that can be used for it in the UK have already been exploited, or are unlikely to be used due to lying in national parks or similar areas. However, we do have some very interesting hydroelectric stations, including Dinorwig and Ffestiniog, both in Snowdonia, which are both pumped storage stations. This essentially means that they use cheap power (for example, power generated overnight, in times of low demand) to pump water up a hill to a high elevation. This water can then be used as a battery, and when there's high demand, the water is dropped down to low elevations, powering huge water turbines which generate power. Dinorwig, in particular, is one of the largest pumped storage stations in Europe, and can produce power on demand in a mere 18 seconds - a very useful ability to deal with sudden surges in demand which can't be catered for by slower-responding coal- or gas-fired power stations. It is also possible to visit - I'd highly recommend it if you're into engineering and are in the area!

One fun discovery during this investigation was this dashboard, which gives near real time numbers on overall demand, as well as by type, with daily, weekly and monthly numbers, all wrapped up in a slightly ridiculous but awesome car dashboard-styled site. They've even recently expanded to show numbers for France as well! I love interesting presentations of open data.


Renewable energy capacity in the UK from 1980 to 2016, by type Image Source

As mentioned above, growth in renewables has been excellent since 2010, but has been growing since 2000 or so. There's a number of reasons for this. One of the biggest has been extensive subsidies for renewables, both in the UK and across Europe (and the in US as well), which have helped make solar and wind power viable despite their high price. This in turn has encouraged growth in these industries, which has driven the price down massively, causing more demand, to the point where even without subsidies, solar and wind can now compete with fossil fuel power in some circumstances. This is an excellent example of using government policy to drive adoption of a new technology. It's just a shame that the UK still subsidises fossil fuels so heavily - indeed, as of January 2019, they subsidise them more than renewables, and more than any other country in the EU, to the tune of €12bn/year.

The UK's strong position in wind is also visible in this graph. Solar has taken a while to be competitive in the UK, partly due to high price, but also we're not a particularly sunny country. We do, however, have a good deal of wind, especially offshore, and the trend in wind power reflects this. As of October 2018, the UK has the largest installed offshore wind power capacity of any country in the world, at 8.2GW. Many of the UK's wind turbines are still manufactured abroad, which is a bit of a missed opportunity - given that the UK has, by some estimations, a third of Europe's total wind resource, there's a major opportunity for the UK to take the lead in wind turbine technology and manufacture.

Energy consumption by fuel type

Electricity generation by source, in 2015 and 2016 Image Source

Lastly, I thought I'd show some official UK government statistics from 2016 (the latest I could find) which reflect the trends shown above. Coal as a percentage has dropped massively, with most of the deficit taken up by gas power. This coincides with the closure of the last deep coal mines in the UK, and a massive drop in coal production and imports from 2014.

What next?

This post was rather impromptu, as I was investigating the UK electricity system and how things worked. However, there's a number of follow-up areas I'd like to dive into. I'd like to know more about how the electricity market works - what can you buy, how do you buy, and who buys what? I also want to dive more into the different kinds of electricity generation, and how green (or not) the various types are, again with a view to figuring out how green different suppliers are. The topic of renewable subsidies/credits in the UK is also a mystery, so that's another whole rabbithole I'd like to dive into at some point soon. There're also a lot more topics related to power, renewables and other related topics I'd like to research more and write about, so expect to see more on those before too long!

I've tried to dig around for accurate figures where I can for this, but there's a chance I've missed things, or got things wrong. If you have any comments, questions or corrections, please do get in touch, and I'll get back to you as soon as I can!