Wednesday, August 7, 2013

Wind Energy: Curtailment by Any Other Name Would Be Ordinary

Lowell Mountain Curtailment
During the recent heat wave, Lowell Mountain wind farm was "curtailed" by ISO-NE, the grid operator. In other words, although there was wind available, ISO-NE did not allow Lowell Mountain to send its power to the grid.
After this event, Vermont Governor Peter Shumlin sent a complaining letter to ISO-NE. Fossil plants were putting power on the grid but the wind farm had to stop operating temporarily. Shumlin asked ISO: Doesn't the grid operator understand the importance of Vermont's move to renewables? Note: Andrew Stein has an article about Shumlin's letter at Vermont Digger. There are close to 100 comments.
Many people realize that the grid operator had good reasons not to dispatch the wind power during the heat wave. For example, you might want to read the Burlington Free Press editorial: Not Ready for Prime Time. ( The idea is that renewables are not ready for prime time.) The Burlington Free Press is generally in favor of renewable energy.
Curtailment Means Dispatch
In the meantime--- What is the heck is curtailment? It means that wind was available, but the grid operator did not allow the wind farm to put power on the grid. In other words, the wind farm was not "dispatched." Dispatch is the fate of most plants on the grid. The rules for dispatch include physical imperatives: matching load
not over-loading transmission lines taking into account how quickly various plants can come on-line.
Secondary rules for dispatch include economics and other non-physical issues:
dispatching the least expensive plants first giving renewables a favored position in the line-up.
To keep the grid in balance, the physical imperatives take precedence.
However, the non-physical issues are also part of dispatch. For example, coal is now more expensive than natural gas. Five years ago, our local coal plant, Merrimack Station, ran 75% of the time. Today it runs about 30% of the time. Merrimack Station is no longer one of the least expensive power plants. It's almost a peaking plant, nowadays. (Jeremy Blackman, Concord Monitor, Extreme Weather a Testament to Bow's Plant Relevance?)
Yes, even coal plants only run when dispatched.
Wind Turbines and the Weasel Word
Wind turbines have been high on the list for dispatch, because they are renewables. However, dispatching renewables is a secondary issue, not a physical imperative. Despite this fact, in my opinion, the turbine owners have developed a serious case of entitlement. If the wind turbine doesn't get dispatched, someone is going to hear about it from the Governor.
What an attitude! This attitude isn't good for the future, either. The Vermont Comprehensive Energy Plan says that 90% of all our energy is supposed to come from renewables. Does this mean that people will use the power whenever the renewables can send it? Perhaps we will have alarms in our house: "It's 2 a.m. and the turbines are spinning. Time to do your wash and bake some goodies." Or are the wind turbines willing to be dispatched, just like a power plant?
In my opinion, the first thing we can do to encourage the wind farm owners to understand their place on the grid is is---we can stop using the weasel word, curtailment. We can call the situation what it is. "Due to inadequate transmission capabilities in the area of Lowell Mountain, the wind turbines were not dispatched."
There. Doesn't that sound better?