June 05, 2010
Watching California Wind Power Output

The California Independent System Operator (Cal ISO), the organization which manages most of California's wholesale electric power grid, has a page where you can watch recent electric power demand in California. Note the second graph on the page which shows wind power output in California.

For the latest day I see on that page wind power output rises and peaks about 4 hours later than overall electric power demand. So wind power becomes more available when wholesale electric power prices are lower. You will probably see a later day's data by the time you read this post.

You can also load the Daily Renewables Watch PDF file for a picture of all types of renewable electric power output for the previous day.

Hydro can be used to back up less predictable and controllable electric power sources like wind. But since wind power is already generating more electric power than hydro the amount of hydro available in California is not enough to allow hydro by itself to handle wind output variations. Also of note: geothermal outproduces wind in California. Wind way outproduces solar. But what gets the most attention? The opposite order: solar the most, then wind, and geothermal gets the least press attention.

Update: It is less clear to me on inspection about how much of California's electric power comes from hydro. These web pages alternatively refer to hydro and small hydro and it is not clear in all cases when they are referring to total hydro or a subset.

You can also look at past daily renewables watch pages and not just the previous day's page. Try opening a couple of dozen pages in browser tabs and shift between the tabs quickly. A couple of patterns: wind power often peaks around midnite when electric power demand is very low. Wind bottoms out around 7 or 8 AM. Sometimes wind picks up in the late afternoon. But other times it doesn't pick up until the evening. Wind and solar clearly need natural gas electric generators as back-up. During winter the solar contribution is so low that natural gas and other variable power sources have to ramp up during the day.

If one goes thru the daily ouputs for the last couple of weeks and looks at totals then wind's variability becomes clear. On Tuesday June 1, 2010 wind generated 38,341 MWh. By contrast, on Saturday May 29, 2010 wind generated 9,989 MWh. That's almost a factor of 4 swing from Saturday till Tuesday. The managers at Cal ISO must have a hard time managing such a variable power source. In fact, in a meeting at Stanford Jim Detmers of Cal ISO voiced his frustration citing an example of when wind electric power output dropped to one half of one percentage of nameplate (max) capacity. Detmers thinks this variability means wind is costing us more than what the wind generators are getting paid to generate electricity.

Share |      Randall Parker, 2010 June 05 11:45 PM  Energy Electric Generators

Mike Anderson said at June 6, 2010 4:59 AM:

This would be a lot more impressive if their download queries for historical data actually worked.

Patrick Walsh said at June 6, 2010 12:11 PM:

It looks like maybe your comment about hydro power generating less power than wind is referring to the category "small hydro" which is a sub category of renewable energy. When you click on the daily renewables watch pdf it shows a very small band of renewable energy at the bottom of the graph and a much wider band labeled hydro at the top of the graph. In which case hydro (or "big hydro" ) produces about twice what all he renewables do together. Interesting post nonetheless. Thanks.

Harry Schell said at June 6, 2010 12:39 PM:

Any way to see what the installed base of wind power is? And how production compares? In Germany, wind power is averaging production at 8% of the installed base or max capacity...total waste of money. Wonder how CA compares.

EconRob said at June 6, 2010 1:17 PM:

Wind power is ugly.

Randall Parker said at June 6, 2010 1:51 PM:


See this post of mine about wind as a percentage of total US electric power for generation numbers and I include some discussion of capacity. I've read elsewhere that US wind farms overall tends to run at about 30% nameplate capacity. That's because our wind farms tend to get placed in prime high wind areas. America has excellent wind areas down the central plains states.

Germany's problem is that it is not well suited for wind or solar. It is too far north and cloudy for solar. It doesn't have the big plains with high wind levels needed for wind. They ought to build more nukes rather than phase them out. Instead they are banging their heads on the wall trying to do renewables.

Patrick Walsh,

Oops, my mistake. thanks for pointing that out.

ron nord said at June 6, 2010 2:47 PM:

In California wind power kills a lot of birds, there are several studies to that effect. No one likes to mention this but wind power kills. Spain is always pointed out to be one of the leaders in wind power and how wonderful it was and how inexpensive; it was all hype. Wind power is not a viable energy source for an industrial nation, we have to go nuclear, clean and efficient. France and Japan are just about oil free for electrical generation using our technology while we still believe in the "China Syndrome" and Hanoi Jane's portrayal of nuclear disaster. I often think the whole 'green' push is funded by the likes of Saudi Arabia to keep the oil supply at high prices. Funding the 'greens' with $100 million world wide every year would give tremendous returns to OPEC.

Punkindrublic said at June 6, 2010 3:01 PM:

Wind power just isn't the way to go in most conditions. Just ask ANY sailor; you'd be far more efficient burning crappy 151 rum in a gas turbine generator.

BrianE said at June 6, 2010 3:53 PM:

I believe large hydro is not considered a renewable energy source in California.

Ari Tai said at June 6, 2010 7:18 PM:

For scale consider that with traditional hydro, a single dam (given water) will produce some multiple of gigawatts constantly. Bonneville is 1. Hoover is 2. CA totals 4 or 5. Three Gorges is 22.

The California integral of all wind power (assuming its instantaneous availability is offset in reductions of power and cost of power by natural gas peaking units) is maybe 1 gigawatt (if net expenses cannot be offset, using wind is the same excess as using 100 dollar bills to light your cigar).


Afaik, no one has done the surveys and trade studies to compare the return on a dollar invested in wind v. a dollar invested in a new hydroelectric dam. Given they have the Sierras, CA could lead the nation if not the world if it so chose. Granted, dams are not PC today. And clearly Californians must love to sweat (the cost of power being inversely proportional to the quality of life, and even physical security - try waiting for a bus to get out of the way of a looming natural disaster).

peter the bellhop said at June 6, 2010 8:43 PM:

Do y'all have anything to say about vertical wind turbines in city locations?

Among the cows in Iowa said at June 7, 2010 12:46 PM:

California wind farms kill birds because they are old small high speed rotors on lattice towers.

Birds love to roost on lattice towers. Replace the obsolete wind farms with new ones. Problem goes away.

LL said at June 9, 2010 12:14 PM:

It looks like the graph for energy demand if for non wind power... You can see the pattern, as wind power increases there is a dip in the demand.

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