Above: Aerial view of Sizewell C (Photo credit: EDF)


INVESTING IN A NUCLEAR POWER plant, bulk power generation comes as standard. But in today’s power industry more is expected. The system operator needs flexibility to help manage power on the network as demand and supply changes minute by minute, or storage for longer periods when other generators cannot supply. Investors want to increase their return, and that includes making use of the heat – typically around 60% of the energy produced – that is currently dissipated. The world needs to minimise carbon emissions. And, increasingly, local stakeholders want to see an investment in place-based ‘whole system’ approaches to energy, where local resources – whether that is land, wind, skills or industry – are used to meet specific local needs as well as exporting to users elsewhere, aiming both to maximise efficiency and win local support.

Meeting all these needs presents a more complex challenge to power generators than simply maximising power production, not just in design and construction but in day to day operations, and it is perhaps more of a leap for nuclear generators, for whom bulk electricity and an ‘always on’ approach has been an important part of the offering in the past. However it is at the heart of a new approach as part of proposals for the planned Sizewell C EPR on the UK’s east coast.

The new approach comes from using the heat from a nuclear plant that is not used — representing about 60% of the total energy, says Julia Pyke, director of financing at Sizewell C company. This enormous heat loss has not been tapped before, because it left the plant at a temperature only really suitable for district heating, which generally has had low take-up in the UK and is particularly difficult to link up with relatively remote nuclear sites.

The difference at Sizewell C comes down to including an extra valve or valves that will allow high temperature steam to be tapped from the turbine.

When the steam is used it involves a reduction in the electricity generated. But that means greater system flexibility, and in a system led by renewables, where there is an excess of power in some periods, that is a positive benefit. There will be periods of oversupply (and prices crash), and allowing the plant to reduce its power exports in favour of other products will enable it to maximise value from heat or power. And the addition of hydrogen to the energy system also introduces flexibility over longer timescales.

Pyke says the Sizewell C design team is currently looking at the exact placement of the valve in the steam train.

The valve has to be positioned where it does not affect the nuclear safety case and where the temperature and pressure is suitable for the applications being considered. Hottest may not be the best.

Local transport needs

If there was no market for low-grade heat around the Sizewell C sites, will there be one for high-grade heat? One answer is the production of hydrogen – and it illustrates the importance of a ‘place-based, whole system’ approach.

The possibility of using hydrogen for hard-to-decarbonise sectors, like replacing natural gas for home heating or fuelling heavy transport, is creating a buzz in the energy sector and potentially a big new industry. Hydrogen may be extracted via steam reforming of natural gas or electrolysis of steam and it is the latter that has attracted attention at Sizewell. Using steam instead of electricity to reach the necessary temperatures can improve the performance of solid oxide electrolysers by up to 10%, so the combination of excess power from Sizewell at times of high renewable production, alongside process heat, could allow bulk hydrogen production at low prices.

Who are the customers for that hydrogen?

This area of the UK’s east coast is home to major ports that see thousands of heavy goods vehicles (HGVs) pass through the region. Currently diesel-fuelled, those vehicles are expected to use carbon-free hydrogen fuel in the medium term. They offer a potential local market for hydrogen produced using Sizewell’s heat offtake (as does the local gas grid).

Building a market for hydrogen transport fuel has been a ‘chicken and egg’ situation in which new fueling stations and new customers each wait on the other. But Pyke suggests that as well as offering fuel to these industries long-term, the construction phase at Sizewell — and vehicles required onsite — could kick start the market.

To do that, EDF is planning to test the market by installing up to a 2MW electrolyser by the Sizewell site in 2022, which can use electricity from Sizewell B to produce hydrogen to fuel site construction traffic.

The 2MW unit, the size of a shipping container, could produce hydrogen at a rate of 800kg H2/day — enough to power site vehicles equivalent to 16 buses.

For EDF this is part of decarbonising the construction phase of Sizewell C (see more below); for others it is the start of investment in ‘hydrogen for transport’ that could form the nucleus of a local industry. The Sizewell C company published a call for expressions of interest in November that invited companies to get in touch. They will have opportunities to install and run the hydrogen production, manage a hydrogen vehicle fleet or both — “they may bid into both sides,” says Pyke.

Long term, the Sizewell C company, which is looking for new investors alongside the UK government, EDF and China’s CGN, will have to decide whether it is in the business of providing hydrogen fuel, or simply heat and electricity for the process. That strategy should emerge over the next decade, as Sizewell C’s need for hydrogen-fuelled vehicles rises and falls and other customers arise. Locating the first electrolyser close to Sizewell C will allow for efficient use of the hydrogen. As it moves to commercial scale, a large scale provider is likely to look for an optimal site balancing access to Sizewell’s heat and power with proximity to its hydrogen customers.

Carbon negative?

The ability to tap high-grade heat from Sizewell C opens up other opportunities. One that could change the plant from low-carbon to carbon negative across its lifetime is the potential to install ‘direct air capture’, which absorbs carbon dioxide from the air.

‘Carbon negative’ technologies are attractive in the UK, whose Net Zero target will require offset for some emissions. Currently the only technology on offer is biomass-fuelled power generation with carbon capture and storage, in an initiative led by the Drax site, but biomass remains contentious in the UK and considerable land area is required.

Using direct air capture at Sizewell would initially offset the plant’s site emissions — Pyke says DAC of 121,000t of CO2 per year would be required, which would currently require 24GWh/yr of electricity and 240GWh/yr of heat at 100°C — very small in proportion to the thermal power that will be produced by SZC and likely to become more efficient as DAC moves into commercial production.

The resulting carbon dioxide would require long term storage, but the UK government is already investigating storage of carbon dioxide using exhausted offshore oil and gas facilities, of which — in another example of a place-based whole-system approach — there are several off the coast on which Sizewell C sits.

The UK government has promised investment in carbon capture and storage technologies, and on 9 November the Department for Business, Energy and Industrial Strategy launched the Greenhouse Gas Removals Competition to develop a DAC demonstrator project. In response, the Sizewell C company published a second call for expressions of interest in late November, seeking partner companies to develop and trial that technology.

Thinking heat

Once a large power plant like Sizewell has the option of supplying process heat — and a business model that can balance its value against electricity – many options open up.

Pyke suggests that companies may want to use the plant’s no-carbon heat, hydrogen and carbon dioxide to produce synthetic fuels. That may be clean shipping fuels, where Sizewell C would be “well placed to work with the UK ports industry to make clean shipping fuels and help the UK lead the market in sustainable short sea shipping”. Aviation – another hard to decarbonise sector – is another potential offering, one that has been dubbed ‘Jet Zero’.

In this initiative, syngas or other synthetic fuels (made using CO from air-captured CO2, and H2 from steam) are produced at the same time using low-carbon heat and electricity from SZC. So-called ‘co-electrolysis’ is more efficient than single processes and the technology already exists but is not yet available at a larger commercial scale.

Pyke says Sizewell C will start talking to local industry about process heat. Those could include the port operators who supply energy to industry on port land, in addition to the hydrogen fuelled vehicles that will be passing through. And finally, the company is looking again at selling low temperature heat, to businesses such as greenhouse growers, either close to the power plant, or as a byproduct where high-grade heat has been transported to fuel industrial processes closer to other homes and businesses.

Business models

Sizewell C will not be in operation for a decade or more and the first step is winning permission to build the power plant. That is a slow process in the UK, but while consenting makes progress, “things are moving fast” on these potential new activities, say Pyke and her colleague Shekhar Sumit, head of future markets.

The potential is huge. Across the UK economy, hydrogen could unlock £18 billion in GVA by 2035 and support 75,000 additional jobs, according to various industry estimates, while a domestic industry for production of sustainable fuels could generate a GVA of up to £742 million annually, and support up to 5200 UK jobs. A further 13,600 jobs could be generated from a global export market for sustainable aviation fuels. Offering a heat and power combination — and links with other local industries — will enable Sizewell C to take a part of that market.

It remains to be seen which of the projects highlighted by Pyke and Sumit move from pilot to commercial operation or even become the kernel of a new industry. Most important is the thought that is going in to the new business models. They move the nuclear plant on from being the source of a single product — electricity — that is delivered at bulk from behind high walls, whether it is needed or not. Instead, the model is of a major source of energy products that can meet local and national needs as they change from day to day — and one that can offer local and national customers some tailored low-carbon solutions to their energy needs — including power. And it gives the Sizewell C company a range of futures delivering power, heat, hydrogen or fuel depending on where the company’s evolving ownership sees the best return.

Author information: Janet Wood, Expert author on energy issues