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The role of gas in generating electricity

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This is the second in a series of briefings from Energy UK and the Carbon Capture and Storage Association (CCSA), exploring the role of gas in the transition to a Net Zero economy.

This briefing specifically focusses on the role of gas in generating electricity. The first briefing in the series looked at the broad role of gas across the whole economy. Visit the Fuelling the Future webpage to read further briefings.

It is clear that we need to decarbonise our electricity supply and to do so we need to replace unabated gas (where the emissions aren’t captured and stored) with low-carbon alternatives over the coming decades. This will mostly happen by ramping up renewables, especially wind and solar.

Gas currently plays an important role in electricity generation and is the largest single source of electricity generation. It’s currently used for flexibility and resilience, so it is important to manage the inevitable reduction of gas for generation carefully.

To meet energy demand in the UK, the Government has proposed that the UK will need a limited amount of unabated gas into the 2030s, and possibly beyond, due to delays in developing low-carbon infrastructure, such as carbon capture, utilisation and storage (CCUS). Therefore, we need to consider a wider range of technologies to replace unabated gas to replicate its roles, which includes using flexible demand, electricity storage and interconnectors with Europe. It is paramount for the UK to ensure that these technologies are deployed as quickly and effectively as possible.

Gas with carbon capture and storage (CCS) and hydrogen-to-power (H2P) are also likely to play a unique role because of the importance of having low-carbon and dispatchable sources of electricity that use a fuel. CCS and H2P offer a way of delivering the benefits that gas currently provides to the electricity system, but with reduced emissions (termed “abated” gas). This is in addition to storage technologies like batteries.

The Government needs to provide clarity on the targets for decarbonising the electricity system, as well as going further and faster in creating new markets and continuing to develop business models for alternatives to unabated gas.

Although renewable energy is increasingly becoming a significant portion of our electricity mix, gas usually generates around a third of the total electricity for the UK, more than any other single source. Broadly, there are two different roles played by gas:

Although useful to maintain a stable electricity supply, burning gas creates carbon emissions. To avoid those emissions and take advantage of alternative technologies (especially renewables and storage) that are getting cheaper and more efficient over time, the role of gas will change. By 2030, if not before, most electricity will be generated by renewables.

Since 2000, the amount of electricity from gas has remained relatively stable, varying between just over a third and just under a half of total generation. However, the role that gas plays in providing electricity changed significantly during that period and it will continue to change dramatically in the coming years.

The renewable energy revolution

In the early 2000s, gas and coal provided most of our electricity, with gas plants running almost constantly and occasionally ramping up to meet peaks in demand. As seen in Figure 1, there has been a shift in the past 15 years in which coal generation has been removed almost entirely from the grid, balanced by a colossal increase in renewables.  

Figure 1: Electricity generation by source (2000-2023)

Figure 1: This chart shows the electricity generation by source for Great Britain from the year 2000 to the year 2023. It is broken down by different colours representing the generation source including gas, nuclear, coal, renewable and other forms of electricity. The chart shows the use of coal generated around one third of electricity in the year 2000 and by the year 2023 this had reduced to a few per cent. The chart also shows the use of gas remaining relatively stable at around one third of electricity generation and also that renewable energy has become the largest electricity source for Great Britain from 2023.

Source: DESNZ energy trends

The displacement of coal with renewables has allowed the UK’s electricity sector to reduce its emissions by two-thirds in just over a decade.[1] It has also meant gas has taken on a different function.  

[1] DESNZ (2024): Provisional UK greenhouse gas emissions national statistics 2023

Currently, there are significant periods when wind and solar (alongside nuclear, biomass and stored and imported electricity) can provide almost all of the electricity we need, resulting in some gas power plants to be idle for part of the time. Recent record low-carbon intensities of electricity generation exemplify this, as shown in Figure 2. For example, at 1pm on 15th April 2024, only 2.5% of electricity came from fossil fuels. By comparison, in 2010 the lowest share was 57% and in 2018 it had never dipped below 10% [2] , [3]

Figure 2: Share of renewable versus fossil fuel generated course of electricity 2010 – 2024

Figure 2: This chart shows the share of fossil fuel vs renewable electricity generation for Great Britain’s energy mix. The chart shows that in 2010, only around 10% of Great Britain’s energy was generated by renewable energy, this increased to 74% in 2024.

Source: ESO (2024): Historic generation mix and carbon intensity

[2] ESO (2024): Historic generation mix and carbon intensity

[3] DESNZ (2023): Digest of UK Energy Statistics 2023

Conditions change though and when there isn’t enough electricity generated by the wind and sun, gas plants come online to make up the difference. This means the amount of electricity that is generated from gas is increasingly variable, but necessary to ensure that demand is met at all times.

A vital stepping stone to the UK reaching Net Zero carbon emissions by 2050 is the official Government target for our electricity generation to be decarbonised by 2035.[4] This will be achieved by replacing unabated gas with other sources of electricity, mostly by building more renewable and nuclear capacity.  

[4] HM Government (2022): British energy security strategy

The UK has ambitious targets of 50GW of offshore wind by 2030, 70GW of solar by 2035 and 24GW of nuclear by 2050.[5] This will enable the amount of electricity generated to increase by up to three times between now and 2050, which we will need to meet the increased demand for electricity from heat pumps and electric vehicles (EVs), for example.[6

[5] HM Government (2022): British energy security strategy

[6] Energy UK analysis of ESO (2023): Future Energy Scenarios 2023

Even with a faster rollout of renewables, it has been proposed by the Government that unabated gas will continue to play a role in back-up capacity to plug the near-term supply gap arising from delays in low-carbon infrastructure and generation.

As Figure 3 shows, the capacity of unabated gas power stations will be around the current level for the next decade before gradually falling away. The amount of electricity generated from gas (and therefore carbon emissions), however, will decline rapidly in the coming years as it is displaced by renewables. 

Figure 3: Unabated gas capacity and generation in a range of Net Zero scenarios

Figure 3: This chart shows the decreasing amount of electricity which will be generated by unabated gas by 2050. The chart shows that although capacity of gas power stations will remain fairly high into the mid-2030s, the amount of electricity generated by gas will drop dramatically leading up to 2030 and beyond.

Source: Electricity System Operator (2023), Future Energy Scenarios

The amount of electricity generated from gas (and therefore carbon emissions), however, will decline rapidly in the coming years as it is displaced by renewables.  

The rest of this briefing explains why in the medium term it is not possible to keep the lights on through the next phase of the energy transition in the UK without relying on unabated gas for at least some of the time. At the same time, the UK must make sure the technologies that will take over from unabated gas are deployed as quickly and effectively as possible.  

Ensuring that electricity is available at the flick of a switch is a unique challenge. Unlike any other product we consume, the supply of electricity must match the demand for electricity in real time, 24 hours a day. That becomes harder with more renewable generation on the grid, although advances in technology and markets make it possible to run a more flexible, renewables-led energy system.   

Figures 4 and 5 show how gas currently steps in to make electricity when renewables are not providing enough. Despite fluctuations depending on the weather, weekends and holidays, daily demand is relatively stable as is the electricity provided by nuclear and biomass power stations. Wind, however, while being largely predictable does change frequently with gas generation making up the shortfall, and little gas generation when there is a lot of wind. The latter will occur more frequently as more wind capacity comes online.

Figure 4: Daily electricity generation in Q4 2023 

Figure 4: This chart shows the detailed generation mix from October to December in 2023. The chart has two lines highlighting the electricity generation mix on 2nd December and 9th December. The chart highlights the flexible role of gas making up a shortfall of wind on 2nd December, compared to a significant amount of wind being produced a week later on the 9th December when there was not much need for gas.

Source: Energy UK analysis of Elexon Balancing Mechanism Reporting Service

Note: Great Britain excludes embedded generation (e.g. solar)

This can be seen in Figure 5 which compares two half-hour periods a week apart in winter 2023. On a still morning on Saturday 2nd December 2023, 70% of electricity was provided by gas, whereas on a blustery morning a week later on the 9th almost half of electricity came from wind, with gas providing only 7%.

Figure 5: GB electricity demand by generation source on a high-gas and low-gas day

Figure 5: This chart is a bar chart showing further detailed breakdown on the information in Figure 4, which compares the electricity mix for two 30-minute periods on 2nd and 9th December 2023. There are two bars on the chart showing the electricity generation on 2nd December comprised 70% gas and 26% wind, compared to the 9th December where only 7% of gas was needed, with 46% of wind providing the bulk of electricity for that 30-minute period.

Source: Energy UK analysis of Elexon Balancing mechanism reporting service

Note: Great Britain excludes embedded generation (e.g. solar)

Gas, for now, also plays a role in how the grid is fine-tuned in real-time. To ensure a steady supply of electricity, the National Grid has to balance supply and demand throughout the day. To do this the control room asks power stations (as well as batteries, large users of electricity and cables to Europe) to make or use more or less electricity on a second-by-second and minute-by-minute basis in a market called the Balancing Mechanism.[7]  

[7] See the Energy System Operator’s guide to the Balancing Mechanism here

This ensures that if millions of people put the kettle on at the same time or a power station has a problem and needs to quickly shut down, there is still a constant flow of electricity. The flexibility of gas means that it is currently used for a significant proportion of the actions taken by the control room.

Figure 6 shows gas and other fuels used to provide additional power in recent years, with gas consistently representing the majority of “buy” actions where the control room needs additional electricity at short notice. This will begin to change, however, with the rollout of further ways to store low-carbon electricity for extended periods.

Figure 6: Fuels used to provide additional power at short notice in the Balancing Mechanism

Figure 6: This bar chart shows has four bars showing the total number of buy actions for various fuels each year from 2020 until 2023. Each bar is made of two colours, one showing how many buy actions there are for gas and the other showing non-gas buy actions. Each bar for 2020 until 2024 is heavily dominated by buy actions for gas.

Source: Energy UK analysis of Elexon Balancing Mechanism Reporting Service

Note: excludes embedded generation (e.g. solar)

There is no single solution that will allow us to entirely remove unabated gas from the electricity grid. Instead, a combination of technologies will need to be used, alongside innovations in the market for electricity. It will take time to deliver this, but bold decisions and ambition from Government can see us move away from unabated gas more quickly.

Flexibility 

Market mechanisms can help electricity usage patterns better match the electricity being generated from renewables:

More grid infrastructure 

Being able to move more electricity within Great Britain and internationally will allow us to maximise the use of renewables:

Energy storage 

We will need to be able to store excess electricity for use at later times, both over a couple of hours (like saving spare, midday solar power for the evening) and between seasons (like storing electricity in preparation for a cold winter). A range of technologies can do this, such as:

There are many more storage technologies early in their development which might play an important role but require more support to research and scale. These include novel batteries, compressed air and gravity systems. 

Burning a gas (whether that is natural gas or hydrogen) to spin a turbine will remain a key tool in making electricity. This is because natural gas is a traded commodity that can be stored until needed, independently from the electricity grid, making it indispensable for extreme situations like a very cold winter or an extended period with below-average winds. Whilst the industry is still in its early stages of development, the same will likely be true of hydrogen. Therefore, we need to find ways of burning natural gas and hydrogen without emitting carbon. This can be done in two ways.

Hydrogen  

Most hydrogen is currently made from natural gas in a process that emits carbon. In the future, however, more hydrogen will be made either from fossil fuels and capturing and storing the emissions from its manufacture (blue hydrogen) or through electrolysis (green hydrogen), which needs only water and clean electricity. To enable these to be price competitive with natural gas, there will need to be subsidies to drive decarbonised solutions.

Pure hydrogen, as well as hydrogen blended with natural gas can be burned in gas generating plants which are similar to the standard gas-powered plants that we have today. Some significant modifications to the plant will be needed for higher hydrogen blends, whilst plants running on pure hydrogen are under development.

Power CCS

Fitting natural gas generation with CCS, where the carbon from the power station’s exhaust is captured and stored safely underground, is a key pathway for conventional plants to continue using gas without adding more carbon to the atmosphere.

It is hard to tell exactly what our energy system will look like in future, but some estimates include:

It will take a concerted effort and decades of development to move from where we are today to an electricity system that uses no or very little unabated gas. The following actions from Government will be crucial to delivering our ambitions: