Thursday, March 21, 2002

Hydroelectric power potpourri

Yes, this could be another snooze, but sit still and take your medicine. And beware of the word "potpourri" - it just means that I have abdicated responsibility for a coherent presentation. Thus warned...

An old Dean Martin song starts out with "I'm praying for rain in California, so the grapes can grow and they can make more wine". You may not be a little old winedrinker, but you still probably use a lot of juice.

Yes, I'm talking about electric power. A lot of it depends on the rain too, because a lot of power comes from hydroelectric (hydro) power plants.

Hydro plants use turbines built into dams to harness the energy in flowing water - here's an example. It's clear that the energy available depends on how much water is available. And this in turn depends on gross climatic factors at points upstream.

In addition to the supply of water, good sites for hydro dams usually involve large changes of elevation. One area where both of these are found together is the Pacific Northwest:
Up to 80% of the electricity in the Northwest is produced by hydropower. Historically, hydropower has been one of the most inexpensive and most efficient sources of electricity in the region. In the Northwest, for example, electricity from hydropower typically costs $10 per megawatt hour to produce. This compares to $60, $45 and $25 per megawatt hour to produce electricity, respectively, at nuclear, coal and natural gas plants. To determine these price comparisons, planners calculate what it costs to build, maintain and operate these differing generation facilities.
Scoot the decimal point over three places to the left and you have an idea about utilities' costs for power generation per kilowatt-hour (kWh). At retail you probably pay about a dime a kWh, or about $100 per mWh. (incidentally, I would challenge the figure for nuclear power generation - I think it's high).

The 80% number above is a gross average - it varies with the season, and at times extra is available to ship to power-hungry states like California. A similar situation exists in the Northeast, where the extra power comes from Canada.

But these suppliers have their local consumers too. They don't have to sell their power to the rest of you at all, and definitely not at the prices mentioned above. Sometimes there isn't enough rain, sometimes local demand soars, and the population in the Pacific Northwest is constantly increasing.

Add in some eco-fantasies about removing some existing hydro dams (don't trust anybody who uses the expression "Euro-Americans"), and you can see that this power source is not as reliable as a naive analysis would have you believe. And although it's easy to see that your power demand depends on the local weather, your supply might well depend on the weather somewhere else.

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