National Grid Seven Year Statement 2008
The National Grid have a Seven Year Statement that gives a useful overview of power generation in the UK and some of the factors that concern people with wind power, particularly comments I see on The Registrar.
Peak unrestricted demand is given as: 61.4GW in 2007/08 rising to 67.3GW by 2014/15.
The aggregate power station capacity rises from 79.9GW in 2008/09 rising to 110.1GW by 2014/15.
"The largest change is due to the 13.9GW increase in CCGT (gas) plant capacity over the period. On this basis, the capacity of CCGT plant will overtake that of coal by 2009/10. By 2014/15, CCGT capacity will exceed coal capacity by 8.2GW and account for 36.0% of the total transmission contracted installed generation capacity.
The second largest increase is due to the growth in Wind generation, with onshore wind accounting for a 7.8% increase and offshore wind accounting for a 7.4% increase in overall capacity. Wind generation capacity (both onshore and offshore) is set to rise to 15.9GW by 2014/15."
The great increase in aggregate power station capacity appears to greatly improve plant margin assumptions for wind generation. 'Plant Margin’ is the amount by which the installed generation capacity exceeds the peak demand
2008/9 plant margin is 28.6 (wind at 100%) 25.7 (wind at 0%)
2014/15 plant margin is 64.3 (wind at 100%) 43.4 (wind at 0%)
As much of the new generation (particularly windpower) is in Scotland they have to plan more grid capacity from North to South, or new generation in Scotland could be rendered "sterile" at they call it. Some of this planned reinforcement appears subject to Public Inquiry, which might delay commissioning dates.
From the Executive Summary they say:
"National Grid’s responsibility in the Balancing Mechanism is to balance generation and demand and to resolve transmission constraints. The persistence effect of wind (i.e. its output is naturally subject to fluctuation and unpredictability relative to the more traditional generation technologies) coupled with the expected significant diversity between regional variations in wind output means that, while the balancing task will become more onerous, the task should remain manageable. Provided that the necessary flexible generation and other balancing service providers remain available, there is no immediate technical reason why a large portfolio of wind generation cannot be managed in balancing timescales.
However, balancing costs would be expected to rise in line with the wind portfolio. Our estimation of balancing cost increases is between £5 and £7.50 per MWh of wind production for 2008/09. As the wind portfolio grows in size, we would anticipate these costs to tend towards a level of between £4 and £7 per MWh of wind production due to greater diversity and geographical location of wind generation of a larger wind portfolio. The increase in the estimates of costs from those reported in previous statements is linked to the rises in market prices for balancing services, in particular reserve and response
In the longer term, we do not think it likely that there will be a technical limit on the amount of wind that may be accommodated as a result of short term balancing issues, but economic and market factors will become increasingly important."