Estimates of the back-up costs of renewables, including wind power, were made in the report "Quantifying the System Costs of Additional Renewables in 2020" commissioned from consultants ILEX as part of the analysis for the February 2003 Energy White Paper. The report is available on the DTI website at http://www.dti.gov.uk/energy/developep/080scar rcport v2 0.pdf.
Table 12 of the report indicates that the back-up costs of wind power, in terms of generating capacity and system balancing would be of the order of £6 to £7 per MWh of wind generation in 2020. Details of the assumptions used and the analysis applied are contained in the report.
Estimates of the back-up costs of nuclear power have not been made.