Thursday, July 8, 2010

Eco-nomics: When Power Comes From Weather

The New York Times' Green blog has an interesting story about the BPA and how it dealt with all of that dang rain we got this Spring. All of a sudden they were faced with much more water than they expected.  Just spill it, you say?  Well, apparently that is no good for the fish.  So they have to scramble to curtail as much energy production as possible.  Now, here is the thing, just because a fossil fuel plant or a nuclear plant is not making as much energy, it is not clear to me that they are burning that much less fuel. I would be interested to know what you all out there know, but I was under the impression that you can't just flip the switch on a coal fired plant - it has to stay hot.  I am sure it has some marginal impact though.
Anyway here is the post:

Engineers say that if the power grid becomes more reliant on renewable energy, a lot of new transmission lines will have to be built at some point or there will be unhappy consequences. Mostly this problem has been predicted rather than experienced. But the future may have arrived last month, when the Bonneville Power Administration, a federal agency that oversees power transmission in the Pacific Northwest, had more energy than it could comfortably use.

The BPA is accustomed to a surplus of hydroelectric power in the spring, as the winter snow pack melts. Last winter there was only about 60 percent as much snow as usual, according to energy experts. But in the late spring heavy rain arrived. Unlike snow melt, which can be predicted by temperature, rainwater gives little warning. And suddenly there was a surplus.

“This year was a little more severe and a little more unexpected,’’ said Michael C. Milstein, a spokesman for the power administration.

In a normal spring, the BPA first shuts down its fossil-powered plants, then exports as much as it can so its neighbors can do the same. This year, he said, “we were essentially asking other utilities to shut down their thermal plants, and most of the coal and gas plants in the region were shut down. They were taking low or no-cost power from us.’’

When it runs out of neighbors that can take the power, the BPA can also let the extra water run down the dams’ spillways, bypassing the power-producing turbines. But that turns out to pose an environmental problem. Water that goes down the spillway gets frothy, and the excess air bubbles can kill salmon and steelheads, an endangered species in the upper Columbia River. So the BPA solved the problem by running all the water through the turbines, making power it didn’t need, Mr. Milstein said.

But beginning around June 8, the rainwater arrived along with an excess of wind power coming from the same storms that brought the rain. Pushing all the power it could to its neighbors, BPA had to turn to the only nuclear plant in the neighborhood, the Columbia Generating Station, and ask the operators to scale back.

This is unusual: nuclear plants are designed to run at 100 percent power and have trouble changing their power settings. “It turns out 100 percent till you shut it down to refuel,’’ said Rochelle Olson, a spokeswoman for the plant.

Columbia is accustomed to reducing power to 85 percent and sometimes 60 percent. In the following days, however, BPA asked the plant operators to go down to just 22 percent. “This year was extraordinary because it all came so heavy and so fast,’’ Mr. Milstein said.

Nuclear operators dislike running at partial power for several reasons. In some cases it makes for less efficient use of the uranium fuel. And one way that they justify their high construction cost is by running as many hours of the year as possible. Some new plant designs are intended to run at partial power at times, but existing plants are not made that way.

The problem seems poised to get worse. BPA is rapidly adding wind power, mostly to meet the renewable portfolio standard in California. But when more spring wind combines with spring runoff, there will be surpluses that cannot be exported over existing power lines, industry officials say.

The BPA is preparing a major report on the event, which lasted until June 13, and will look for solutions. “Maybe transmission lines are where to go next, or the smart grid,’’ Ms. Olson said.

In fact, Mr. Milstein said discussions were under way about beefing up connections to California. Another possibility is asking thousands of homeowners to let their electric companies take control of their electric water heaters, he added. When surplus power exists, the water heaters could heat the water hotter than normal, in effect turning them into storage batteries.

But for now, he said, “we happen to have all these renewable resources, and sometimes they don’t work exactly like we’d want them to.’’

Now I hadn't heard of that one before - taking control of water heaters, what a cool idea. But they can't be that efficient of a storage device. I wonder what else? I always thought of storage solutions to this problem being ones of massive scale, but perhaps if we all had rechargeable batteries attached to our houses that drew in extra energy at low periods and discharged during peak times and had capacity to take extra energy during peak generation times.  I am sure I am not the first to think of this, but it seems like it could work, I wonder what the problems are?


The Oriole Way said...

Big, mobile batteries would be a great idea. Maybe we could put them in our cars... hmmmmm.

Patrick Emerson said...

Yes, I understand that if we all had plug in electric vehicles, they could act as a store of energy, though presumably the discharge would only come from driving (but it wouldn't have to). But this requires us all the have plug in cars. If a battery pack that were attached to a meter were a part of what the electric company provided to each house, then we could assure everyone had it and they would not have to be that big if everyone had them.

ElGordo said...

Thermal power plants have scaling up and down periods that are generally referred to as "ramping". Coal plants like Boardman are meant to act as baseload and, like nuclear, are designed to pretty much run at 100% all of the time (maybe scaling back to 80% at times). So, shutting down a coal plant can create a period of 12-24 hours of ramping down and then back up to get the plant back up to operating temperature.

Natural gas turbines, on the other hand, generally have a smaller capacity and greater flexibility (both in ramping response time and generation variability), so they are the usual choice for backing up renewables.

One option for storage that's getting some decent test projects online soon is compressed air. I think most of the pilot projects are joined to wind turbines. When the turbines are producing more power than is needed on the grid, the compressor can switch on, storing up the energy for later. The compressor can then run a generator when that power is needed for the grid.

Charles B Johnson said...

The genius of storing energy in water heaters is that it doesn't require the design, manufacture, and distribution of a new product to every household. There are ways to "store" energy in everyday devices. For example, there is a WalMart in Las Vegas that allows the local utility company to control the thermostat of its beer coolers. At night, when demand for electricity is lowest and electricity consumption is cheapest, the utility company chills the WalMart beer to just above freezing. In the morning hours, when electricity demand (and cost) peaks, the utility company turns the coolers off - the beer stays cool for hours, and the utility company is not forced to increase its marginal production of electricity by "scaling up" a natural gas plant. WalMart uses the same amount of electricity but at a lower cost, and the utility company saves on marginal costs increasing its profit margin. Everybody wins!