As the government strives to expand capacity to meet future electricity demand, nuclear power and tidal energy are at the opposite ends of the spectrum in terms of support. New sources of electricity generation must be built and brought online in the next decade if the government is to achieve its aim of decarbonizing the UK’s power system by 2035. To reach the goals set out in the government’s Net Zero Strategy, published in October 2021, the UK will need to more than double its current 108GW of total installed capacity to meet the projected demand of between 218GW and 262GW in 2035. Analysis by consultant Atkins in June 2022 showed that 49GW of electricity generation assets will go offline by 2035 – a mixture of nuclear power plants, fossil fuel plants and older renewables. As a result around 14GW of new build capacity must be added each year if demand in 2035 is to be met. But since 2010, the average capacity added annually has only been slightly more than 4GW.

Target Energy Mix

Alongside offshore wind power, the government has committed to nuclear power as the main source of energy to make up this shortfall. It has not yet released a target energy mix for 2035, but it is expected that solar will account for a chunk. In contrast no commitments to tidal energy development have been made, so this source’s contribution is expected to be minimal. Nuclear power stations in the UK currently have a combined capacity of 6.5GW, accounting for 15% of the energy mix. The government’s aim is for that to reach 24GW by 2050. That is more difficult to achieve than it appears, as four of the UK’s five operating nuclear plants accounting for 4.84GW of capacity will be decommissioned within a decade. The new nuclear plants in development, Hinkley Point C and Sizewell C, will provide a combined capacity of over 6.4GW. They will more than cover the capacity that is due to be decommissioned but to go beyond that more investment and forward planning is needed. Building nuclear power plants is costly in terms of time and money. The 3.2GW capacity Hinkley Point C power station has encountered continuous cost increases and construction delays. It is now expected to cost £32.7bn compared to the £16bn forecast in 2012 and is expected to come online in 2028 – 11 years after construction started and three years later than the planned 2025 completion date. Atkins nuclear new build market director Tom Lambkin believes these complications will decrease with repetition. “The whole philosophy from Hinkley Point C to Sizewell C is no change, it’s pure replication. It’s a repetition of a design that’s already been built within the UK regulatory environment,” he says. “That’s where the opportunities for efficiencies start to come; if we build a third site, those efficiencies will be magnified even further.” Plans for 3.26GW capacity Sizewell C are progressing and in November 2022 the government committed £700M to it. It has also been confirmed that Sizewell C will be funded through the regulated asset base model, where the government takes on the construction risk and consumers pay back the costs through increased energy bills. Although this is the first time this funding model has been used for a nuclear plant, it has been written into law that future nuclear projects will be funded in this way. There are no concrete plans to build any more large scale nuclear plants at present. Instead, plans for small modular reactors (SMRs) are advancing. Rolls-Royce’s design for a 470MW SMR has passed the first assessment hurdle and the company hopes the first one would be online by 2030.

SMRs Could Be Crucial To Efforts To Decarbonize The Energy System.

with their small size being their main advantage. “It’s a smaller capital cost to build the first and then revenue generation from that can be reinvested in subsequent stations,” Lambkin says. “Their small scale also unlocks potential sites that aren’t suitable for large scale nuclear projects.” Lambkin emphasizes that SMR and conventional nuclear plants are going to be crucial when it comes to meeting the decarbonization targets. The government established Great British Nuclear in the spring Budget in March. It has the objective of facilitating delivery of the government’s programmed of new nuclear projects. Its first task is to identify the best SMR technology. Tidal Renewable energy is going to have to play a massive part in decarbonizing the power industry. There are nearly 3,000 renewable projects at different stages of planning and construction in the government’s Renewable Energy Planning Database. Even if all of these are completed, they will not cover the capacity shortfall anticipated in 2035. Aside from offshore windfarms, the only renewables project in planning with over 1GW of installed capacity is the Corie Galas pumped storage hydroelectricity scheme. Another form of renewable energy that could provide high generating capacity is tidal range power produced by tidal lagoons or tidal barrages. Tidal range power is generated by building a barrage across a river or estuary, or a lagoon in a bay, then using the tides to create a water level difference on each side. This stores up potential energy, which is then used as the water is released through the barrage wall, spinning turbines to generate power. Tidal range power is different from tidal stream power, the more common type of tidal energy scheme. This features turbines on the seabed that generate energy as water moves through them. Four tidal stream power schemes are operational in the UK, with a meagre combined capacity of 10MW. Another seven are at various stages of planning and construction, but combined these will only provide 667MW of capacity. Of the two, tidal range power has the potential to make a significant contribution to the energy mix in the UK according to Cardiff University emeritus professor of water and environmental engineering Roger Falconer. He notes that the west coast of the UK has some of the highest tidal ranges in the world, making it ideal for lagoon or barrage schemes. There are currently eight projects on the west coast that are proposed or in the very early stages of development and they could provide more than 20GW of capacity. The annual output of a tidal range power scheme is about a quarter of that of a nuclear plant of comparable capacity due to tidal output not being constant in the way nuclear generation is. But tidal range schemes have a design life of 120 years – double that of nuclear power stations. Tidal energy also has the advantage of being entirely predictable, unlike wind and solar energy. But the government has shown no inclination to support tidal range power schemes. “From what we’re seeing, that’s not a technology that’s been mentioned in any of the government scenarios,” Lambkin admits. Falconer says this technology has been proved at scale overseas, most notably with France’s 240MW capacity tidal barrage on the River Ranke and South Korea’s 254MW capacity Schwa Lake Tidal Power Station.

Most of The Proposed UK Schemes Would Have Larger Capacities Than Those.

The biggest, the Severn Barrage, is projected to have a generating capacity of at least 8GW. However, such schemes require a large investment commitment up front, which causes hesitance. Falconer is positive that the money can be found with the right messaging. “If the government were to say it thinks the UK has enormous potential with tidal energy and it wanted to help it get off the ground, then I think we would raise the private investment to take things forward,” he says. “I think we could see tidal range play a major part in producing green, indigenous energy.” No tidal range power scheme has been built in the UK so the construction timeframe is uncertain, but Falconer believes it would take around 10 years to secure consents and carry out construction work. One tidal range scheme, the 320MW Swansea Bay tidal lagoon, has won planning consent in the UK. But the development consent order lapsed in 2020 after five years without work starting on site. Falconer believes it is important to make a start on developing tidal range power schemes in the UK as soon as possible. Similar to the offshore wind industry, initiating the construction of tidal schemes will begin the formation of a supply chain that will grow and strengthen, Falconer explains. This will make construction of subsequent tidal range power schemes cheaper and more efficient.

Battery storage

Although tides are predictable, the tide times vary so sometimes the highest energy production on a tidal range scheme will be in the middle of the night. Like all renewable energy sources, tidal power’s value will be more significant if it can be stored for dispatch at peak hours. Ways of developing high capacity energy storage are also needed so that the troughs in energy capacity can be evened out. Energy & Climate Intelligence Unit head of analysis Simon Cram McGeehan says that good progress with high capacity battery storage technology is being made although it is not used widely enough. Until large scale battery storage is widespread, the government might not be ready to commit to large-scale tidal range schemes. However, Cram McGeehan says that recent developments in other energy sectors suggest there is a glimmer of hope that this view will shift. “The government is taking a huge public sector stake in Sizewell C, having previously hoped that nuclear power plants would be built by the market alone,” he says. “So I think its appetite for putting up money for big energy projects has changed.”