Thursday, February 28, 2008

More wind energy in the news

Sometimes I read McNews (USA Today), especially when it is free at the hotel front desk and the WSJ, NYT, FT and WP are not available.

On a side note, I have spent a lot of time in hotels lately, and learned that you cannot judge a hotel by the name, the fancy woodwork in the lobby, or the price. Instead, hotels get stars in my book by having fluffy (not cardboard-like towels), blackout curtains in the room, free breakfast beginning at a reasonably early hour, a decent selection of newspapers available at the front desk for no charge and free wired and wireless internet in the rooms.

Recently I have learned the value of all these, and the costs of their absence. The most recent hotel I stayed in had great towels, and three per room. That was a good thing since I had to use one to seal the 2 inch gap under the door (yes, I could fit my hand under it). I had to use another to seal the window (dipped in water and frozen in the gap between the window and the sill, the towel stopped the wind from whistling through). The bed was really nice, but the walls were paper-thin so you could hear a normal volume conversation in the next room over. They had wireless internet, which is nice for some things, but there are times I'd rather have a wired connection for security reasons.

At another hotel recently (well, billeting at Keesler AFB), I had another window that would not seal, and every time it rained, the floor got soaked. There were large black blotches of mold on the walls and a huge hole in the ceiling. Interestingly, I had to pay 2 bucks a day for internet, and the room cost me more than a Hotel 6 room would have off base. Oh, and I had to share a bathroom, the emergency lights in the hall were broken, and someone had carved an expletive into the door. I have some pictures to post later. Sort of funny...

Where was I going with all this? Oh yes, energy.

So the USA today had this article about the need for transmission lines brining power from wind areas to areas that need energy. This brings up another major problem with wind energy: production and use are usually geographically separated. The second order cost of this is additional transmission lines. These lines use resources and are an eyesore, they cost a lot to put in, and the costs are not borne by those who benefit. Additionally, they introduce an additional vulnerability to the grid. Saith the USA Today:

Until now, wind developers have piggybacked on existing wires, says analyst Stow Walker of Cambridge Energy Research Associates. But after wind energy soared 45% last year, spare transmission capacity is depleted. Wind power generates more than 1% of U.S. electricity.

Stringing new wires is easier said than done. Wind developers won't go ahead with projects until transmission lines are in place, and utilities are loath to build the lines until they're sure the developers won't back out. Also, the first wind developer in an area is often asked to shoulder much of the $1.5 million-per-mile cost of a high-voltage line.

In Texas, which has about 25% of U.S. wind power, more eye-popping growth in 2008 is expected to push generation past transmission capacity by 65% by year's end, says Bill Bojorquez, vice president of the Electric Reliability Council of Texas, a power-grid manager.

Wind farms will have to compete to be among the lowest bidders to get on the grid, leaving others off. "Clearly we don't want to build wind farms and have them not run," says Horizon Wind Energy executive Denise Hill.

In southwest Minnesota, dozens of wind projects have been proposed to serve the Twin Cities. Even if just 30% of them, with 7,500 megawatts of capacity, are developed, that would far outpace the 2,000 megawatts of transmission capacity planned.

So, diversity is good, but it is important to keep in mind the 2nd and 3rd order effects. There are significant costs to increase the transmission infrastructure capacity, an infrastructure that is already vulnerable to natural disaster and sabotage. Economic incentives are currently focused on generation, not transmission or distribution. In the future we may find this to be a costly oversight.

More energy issues

OK, since I am back on the theme of electric power reliability, here is an interesting tidbit showing why production diversity is good:

ERCOT [Electric Reliability Council of Texas] said the grid's frequency dropped suddenly when wind production fell from more than 1,700 megawatts, before the event, to 300 MW when the emergency was declared.

But they had a plan, and immediately cut 1100MW to interruptible customers, thus saving the grid from going down. Soon they were able to fire up other production facilities and have everyone back on line.

The biggest drawback to wind power (there are a few) is that the wind is notoriously unpredictable. However, as long as there is a backup plan, wind power can be a good additional source.

Tuesday, February 26, 2008

Cascading power

When DX, Troy and I wrote our PAE almost a decade ago we wondered how long it would take for people to understand the concept of a cascading failure. Listening to Fox News today, it sounds like the talking heads have no idea. A small generation or transmission failure in a system running at 90% capacity can quickly cause major failures. July 1996. Aug 1996. Aug 2003. Feb 2008. A few major failures, there have been many smaller ones. It will continue to happen, and we will continue to handle them. So, how does this happen?

A power grid is made up of three parts (yes, it is that simple): generation, transmission and distribution. If any one part fails, power does not move.

The grid always has to be in perfect sync. The amount of power going onto the grid (generation) always has to be exactly the same as the amount coming off (distribution). Transmission is what gets the 'trons from one place to another. Oh, and the frequency and phase of the power entering the grid has to match the grid.

If there is an imbalance, something has to give. Imagine that a section of the city consuming power is suddenly isolated from the rest of the grid (transmission failure or distribution failure). The amount it was consuming suddenly needs to not be put on the grid. The generator (in this case a nuke plant) can't just dump the power into the nearest river. There is no good way of making 'shock absorbers' on a massive scale. In order to protect the generation capability, generators are programed to automatically 'trip' off-line, essentially deactivating the electromagnets producing the power.

When the generator trips off, if the amount it was producing was greater than the amount already shed from the grid, other generators have to spin up and put out more power to make up for the loss. If this surge in demand is too great, generators are put at risk and there is an increased chance of other generation or transmission malfunction. The operating generators are then isolated from the grid, causing another deficit. This deficit causes more distribution problems further away, and the failure propagates rapidly.

In this case, it appears that the system worked as designed. Probably a subsystem transformer (distribution system) or minor transmission line went down, causing a power flux to the power plant. The plant shut down for safety, as it should have. Generators are designed to trip off-line so that they can be rapidly restarted with minimal damage. Yes, people are inconvenienced, but not nearly as much as if the generators were damaged or destroyed.

It is actually pretty hard to get the grid back up and running, which is why they do it one area at a time. Load (toasters, TVs and other powersuckers) must match the available generation. It is more complicated than flipping a switch, and amazing that this fragile system goes down so rarely and comes back so swiftly.

People have been critical of the administration's efforts to get power back up and running in Iraq, but the situation there was terrible. Transmission lines were in poor shape and darn near impossible to defend. Generation was is terrible shape due to 20 years of neglect, and there distribution system was centered around Baghdad and designed not for redundancy or fairness, but rather to let Saddam control the people by giving power to those who were docile and taking it from his enemies. The fact that we have been able to get things running as well as we have is a great tribute to those brave troops (American and Iraqi, as well as some from some other allies) who have toiled long and whose deeds have as long been unheeded in the press reports of the war.