Retired Firefighter    ■    Power Dispatcher    ■    Husband    ■    Daddy    ■    Grandpa    ■    Crazy Man

Friday, April 30, 2010

And Now, More Wind!

Continuing from where I left off after Why wind power is not the (only) answer . . . .

Earlier today I was thinking about where I would go when I came back to the topic of energy future stuff. Then I heard about another new wind farm just approved for construction, over on the west coast.

Hearing about new wind farms is not unusual, but this announcement was a big deal because of its size. Apparently, this new facility will have a capacity of 845MW, which is substantial even by large coal and hydro plant standards. Let me clarify it further: When completed, this new project will reportedly be the largest single wind farm installation in the world, according to its Wikipedia entry.

These things are scary deals for dispatchers. 845MW is about on par with a nuclear plant's output (a point not lost on whoever wrote the announcement I saw), that is a lot of MWs to come from a single location.

The greenies are probably pretty happy about this. And there is no doubt that when those 845MWs are being generated, there will be less MWs coming from pollution-producing plants, so its not all bad.

But folks, it's just not that simple.

If you recall from earlier tutorial posts, there are three major AC interconnections in North America: Eastern (gigantic), Western (fairly big), and Texas (diminutive). The stability of an interconnection is relative to its size in terms of generation capacity and load. The loss of 1,000MW barely causes a burp in the east, while in the west that same loss sets off a few dispatch center alarms and wakes people up. In Texas, the loss of 1,000MW will shake the dust off the rafters and maybe crack a window or two, so to speak.

Texas is where I am going with this. Texas produces more wind power than any other state, with nearly 9,500MW of installed wind capacity. Iowa is a distant second with a little more than 3,500MW installed. But Iowa is in the rock-solid eastern grid. It isn't accurate or relevant to compare wind power by state, anyway, since power grids are not impressed or influenced by state boundaries, right? It has to be done by interconnection.

Presently, the eastern interconnection has about 17,500MW of installed wind power. The western interconnection has a bit more than half that much at about 11,000MW, which is loosely proportional to its strength relative to the east. That's not much more than Texas has all by itself in its tiny little AC grid.

Good for Texas, right? Not so fast. A little over two years ago, the entire Texas grid came perilously close to blacking out. Why? Mainly, because of all of its installed wind power.

From Reuters:
Loss of wind causes Texas power grid emergency

A drop in wind generation late on Tuesday, coupled with colder weather, triggered an electric emergency that caused the Texas grid operator to cut service to some large customers, the grid agency said on Wednesday.
HOUSTON
Wed Feb 27, 2008 8:11pm EST

Electric Reliability Council of Texas (ERCOT) said a decline in wind energy production in west Texas occurred at the same time evening electric demand was building as colder temperatures moved into the state.

The grid operator went directly to the second stage of an emergency plan at 6:41 PM CST (0041 GMT), ERCOT said in a statement.

System operators curtailed power to interruptible customers to shave 1,100 megawatts of demand within 10 minutes, ERCOT said.

(read the rest)
You may not have heard about this when it happened, but it was a very big deal in power dispatcher circles, I can assure you. The article goes on to state that the output of wind power dropped from 1,700MW to 300MW in a very short time, while customer demand increased from 31,200MW to 35,500MW.

Do the math. The little Texas grid lost 1,400MW of generation even as demand increased by 4,300MW. That rapid swing knocked them out of balance by a staggering 5,700MW! Their other resources have enough work cut out for them regulating demand, but picking up that lost wind output nearly created the next big blackout story since the eastern blackout of 2003. The only thing that saved them was dumping over 1,000MW worth of customer load (blacking people out) to make up the difference that their other plants weren't able to cover.

Why did this happen? Well, forecasting wind is still a very inexact science. And even when you know where and when the wind will get you, you still have to have adequate regulation to work around it. They got burned on the forecast and for sure couldn't regulate adequately.

If you keep adding wind generation that makes MWs at the whim of the weather, your regulation demands that need to respond to the scheduled whim of the consumer will also increase to either stay out of the wind's way, or cover for it when it's gone, and eventually you will not be able to keep a decent balance with your other power plants at all. Ergo: brownouts, blackouts, and of course, egregious wear and tear on the overtaxed power plants used for regulation.

Back to today's announcement: The statement indicated that the new Oregon facility is about equal to a nuke plant. The uneducated will rejoice. That's one less nuke or two less coal plants that won't have to run or be built! Hardly. You will rarely get the full capacity from the wind farm except when you have the occasional high sustained winds, and you already know that those high winds aren't going to make appointments to only show up when energy grid demand is high. You'll still need power from somewhere else when the wind is not blowing. So, announcement writers who are supposed to be unbiased: Don't imply it is "equal to a nuclear power plant", because it is anything but.

I'm sure you all get it by now. Wind power is a great source of instability on the AC grid. I'll stop beating that drum so much going forward. Next time I talk about future energy, I'll try to address other renewable sources generating buzz as of late. And there's much more to come after that.


No comments:

Post a Comment