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Wind versus nuclear

A bit of a revelation emerged recently when EDF’s submission to the UK governments renewable energy strategy consultation was made public. EDF, the French company that is planning to build a new fleet of nuclear plants in the UK now that it owns British Energy, said:

‘As the intermittent renewable capacity approaches the Government’s 32% proposed target, if wind is not to be constrained (in order to meet the renewable target), it would be necessary to attempt to constrain nuclear more than is practicable’.

EDF presumably want to build some European Pressurised -water Reactors (EPR’s) but noted that, although ‘EPR nuclear plant design can provide levels of flexibility that are comparable to other large thermal plant…there are constraints on this flexibility (as there are for other thermal plant). For example, the EPR can ramp up at 5% of its maximum output per minute, but this is from 25% to 100% capacity and is limited to a maximum of 2 cycles per day and 100 cycles a year. Higher levels of cycling are possible but this is limited to 60% to 100% of capacity’.

At present, when demand is low, e.g. at night in summer, fossil fuel plants are throttled back, and they are also run up to full power to meet peak demand. So, given demand changes, they may have to cycle up and down several times a day. With wind plants on the grid they may have to do this a few more times a year, when wind input is low, but that’s hardly a major issue. However, if we have a lot of wind and other variable renewables on the grid, and also a lot of nuclear, then balancing the system gets harder. As EDF admit, the nuclear plants can’t cycle up and down well - and there will be less fossil plant to do this. So, in the absence of major electricity storage or export facilities, when demand for energy is low but there is plenty of wind, what happens? Do we just curtail wind generation then? Or should we limit how much nuclear capacity we install?

Perhaps unsurprisingly, EDF say we will have to limit how much variable electricity generating capacity we build, although they are happier with heat supplying renewables - since they don’t enter into the electricity balancing equation: ‘A lower volume of intermittent renewable electricity generation and higher volume of renewable heat generation by 2020 would create a better investment climate for all low carbon technologies, including nuclear and CCS’.

Source: ‘UK Renewable Energy Strategy: Analysis of Consultation Responses’ Prepared for: Dept of Energy and Climate Change www.berr.gov.uk/files/file50119.pdf

Posted by Dave Elliott on May 2, 2009 6:39 PM | Permalink