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.
Nuclear Engineering International 20th Jan 2021 read more »