Kleekamp on Wind Power Backup

The following is a comment in response to a question about wind power backup.  The question was posed on the "There Are No Stupid Birds" posting at the blog, "Magic Eye".

The question, posted by "DumbPeople" at 4:44pm on 11/08/05:
If yu [sic] really think wind power will save global warming ... dream on. Wind farms need backup power because they don't always generate anywhere near their capacity. In fact, for every megawatt of wind power there must be a megawatt of backup power. And where do you suppose that will come from?

Response by Charles W. Kleekamp

A note on Wind Power Backup. In answer to a question by a respondent, let me share with you the following facts. If wind were the only source of power on an isolated island, then yes, an equivalent backup would be needed at least for the average power consumed. However, in a grid system like New England’s, most power plants don’t produce the maximum power all the time.

Take the Canal Plant for example. Its base load Unit 1 (designed to run most efficiently at full power) runs about 66% of the time on average. That’s called the capacity factor (CP). Unit 2, a cycling unit (designed to go up and down with the daily load characteristics), runs at a CP of only 50%. The wind farm on Nantucket Sound will have a capacity factor of about 40%. In general, any one power plant can step in or take the place of another if one cannot fulfill its contract obligation for any reason (there is a cost penalty for not delivering). Dispatch to the grid depends largely on who has bid the lowest cost power for that period of the day.

To avoid the sudden unexpected loss of a single large generator in the grid there are pumped storage hydro power plants in Massachusetts like Northfield Mountain at 1,080 MW and Bear Swamp at 625 MW. They were designed and built it the days of burgeoning nuclear power to back up nuclear plants like Pilgrim (660 MW) that do run normally at full power and whose sudden loss would disrupt the grid system. Pumped storage plants now operate using cheap power at night to pump water uphill, and then generate more expensive and profitable power during the day by letting it flow back.

These backup plants can react extremely quickly, certainly more quickly than a dying wind. In addition, there are many so called “peakers” that have an annual CP of about 1%. Powered by diesel or natural gas they are expensive to run. They are seldom used unless the whole grid is under extreme stress. In a grid system with hundred’s of power plants, like the New England grid, there is always plenty of back up available except under crisis conditions. It is doubtful that any new peaker capacity at all would be required unless the total of wind power exceeded perhaps 10 to 20% of the total mix. In Denmark, where wind power provides about 20% of the total, no new backup plants are needed.

Even when our New England system is in a stressed condition, the wind farm could usually provide additional capacity if needed. For example, in the cold snap crisis of January 14-16, 2004 when rolling blackout were on the verge of reality, the wind farm, had it been operational, would have all but alleviated the crisis [1]. During those three days the project would have delivered an average of 396 MW, more that enough to cover the actual ISO New England grid shortfall of 108 MW and more than the import from New York ISO of 350 MW that saved our grid in New England [2]. This is because the wind farm is producing considerable power most of the time.

If in doubt look at the power developed in the last 12 hour period in any day by accessing the Cape Wind meteorological test tower at http://capewind.whgrp.com/ The end of this note is that no new grid backup would be required for the addition of the Nantucket Sound wind farm. In fact, the Massachusetts Energy Facility Siting Board found in its permitting decision that “There is a need for the power provided by the [Nantucket Sound] wind farm beginning in 2007 for [system] reliability purposes.” [3].

Charles W. Kleekamp, P.E. Ret., A Director of Clean Power Now

• Footnote [1]. U.S. Department of Energy, “Diversification Analysis – Natural Gas Supply/Wind Production,” A. Benson, Regional Director, June 6, 2004.
• Footnote [2]. “New England Power System Operations Under Extreme Winter Conditions, January 14-16, 2004,” Stephen G. Whitley, Senior Vice President and COO, ISO New England, March 19,2004, pp. 7-10. Substations were staffed to enable manual curtailment of customer load if necessary.
• Footnote [3]. Findings of the Massachusetts Energy Facility Siting Board, July 2, 2004, p. 188.