HOUSTON — The cold wind from this week’s norther spun turbines that helped keep Texas furnaces running — but also stirred up questions about whether the state counts too much on such a fickle power source.
Amid freezing temperatures statewide Monday morning, Texas generating capacity was just one power plant failure away from falling short of Texans’ demand for power.
Wind power helped keep the lights on, providing about 1,800 megawatts of the 56,000 megawatts of generation capacity available that morning. (One megawatt is enough electricity to power about 200 homes when demand for electricity is highest and 500 homes under normal conditions.)
But the close brush with blackouts Monday has some wondering if the state is depending too much on wind.
“The more the state relies on wind, there is a potential for having a very unstable grid,” said Ed Hirs, an energy economics professor at the University of Houston.
“Wind is not 100 percent reliable,” Hirs continued, “and the capacity variations across wind generation make it inferior to large base load generation facilities and natural-gas fired peaking facilities.”
Base load refers to power generated and used around the clock. Peaking facilities come online as demand exceeds base load.
The state’s grid manager includes a set amount of wind generation when projecting the state’s power capacity. Wind advocates say that grid planners can measure anticipated wind with increasing accuracy, and that wind performed as expected on Monday.
“The wind that morning was exactly what had been anticipated in the forecasting and modeling that takes place in the days prior,” said Jeff Clark, executive director of The Wind Coalition. “This is very much a science.”
In 2012, wind provided about 9 percent of Texas’ power, according to the American Wind Energy Association. But on Monday it only contributed about 3.2 percent of electricity used during peak demand, perhaps tempering any perception that wind saved the day and kept parts of the grid from going dark in rolling blackouts.
“It’s a nice story for wind, but it’s scary that they are relying on it on emergency situations,” said Adam Sinn, a Houston-based independent energy trader. “I think wind should be looked at as a buffer and that the grid should always have fossil fuel resources to prevent an event.”
The number of wind turbines available doesn’t vary much from day to day, but the wind needed to turn them does. For example, a cold front in February 2013 included strong winds. Wind generation ended up providing 28 percent of the system load on Feb. 9, 2013, adding what then was a record 9,481 megawatts of power.
But planners can’t count on such breezy bounty, and instead have to predict how much power to expect from wind-driven generators based on weather conditions.
The state has more than 12,000 megawatts of wind capacity, and that figure is set to reach 14,000 megawatts by the end of this year.
But because of wind’s variable nature, the Electric Reliability Council of Texas, which manages the grid, only includes 8.7 percent of wind generation in estimating available power at peak conditions, even though it frequently generates a much greater amount.
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While Monday morning wind resources were much lower than the previous or following morning, it still exceeded this estimate, providing around 15 percent of wind capacity – and right on target, according to Clark.
“The wind is a variable resource, but the important thing is that it is not a random resource,” Clark said. “It is highly predictable, it is forecastable and in this situation, the forecast and the actual generation were very close together.”
How wind is calculated as an available resource will be key in the debates in the months ahead, as grid managers and lawmakers try to determine if Texas has sufficient resources.
ERCOT had considered a proposal by technical advisors last year to increase the amount of wind capacity in its forecasts to 14.2 percent for non-coastal wind resources and 32.9 percent for coastal wind resources, but has delayed any decisions on the proposal until later this year.
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