I have been monitoring the UK peak power demand every day for the last 12 months, and how that power was delivered. The UK government has invested about £50 billion into Wind energy since 2005, so how has it performed?
The average Wind component of UK peak power demand was 5.7% over a full year. The maximum power output was 6GW on 21 February 2014 at 18:10, while the maximum proportion of demand was 16.8% on Sunday 17th August 2014 at 20:08. The minimum proportion was 0.15% on 31st May 2014 when total Wind output was 49MW (0.05GW).
For comparison Nuclear Power averaged 18.1% of demand and never fell below 15%. The bulk of UK power is still met by fossil fuels and it is impossible to imagine a future Grid based purely on Wind power. The mix of coal and gas is interesting. Coal is dominant in Winter while gas dominates in summer. I also monitored the daily energy “trough” or the lowest demand for electricity which usually occurs each day at around 4am . This is shown below.
It is Coal that keeps the lights on during winter nights! Gas output is ramped down at night, probably because it is easier to regulate power in Gas power stations. The exception to this is during the summer when several coal power stations would appear to be mothballed.
The statistics for Wind power at night appear better because the overall demand is much less. The average contribution of wind power to minimum demand was 9.8%, and the maximum Wind supplied was 22.5% on 2nd February at 05:30 (6GW). However Nuclear also contributes proportionately more at night averaging 30%, which is 10% more than Gas. The difference between the 2 extreme demand curves is shown below over the 13 month period. Note the sharp drop in power demand over the Christmas period.
This analysis makes it clear, to me at least, that the UK should shift the balance of investment towards Nuclear and away from Wind. Even doubling Wind generating capacity to 20GW would still leave some days with essentially zero output, thereby undermining energy security. Furthermore Gas will always be needed with at least the same generating capacity as Wind in order to continuously balance Wind’s erratic output. Nor can energy storage save the day, since it reduces the EROEI for Wind to below sustainable levels.
The data used for this analysis was collected through BM reports – the National Grid balancing mechanism. There are about 10% of wind farms that are not metered by BM so the above figures should probably be adjusted upwards by 10%. The conclusion is the same.
The live monitoring of peak demand over the last 30 days is shown below.