Making the most of Solar Energy
Yesterday the Chron ran this article about a new solar plant that is going to be built on the Northwest side of town. NRG is going to spend $40 million to build a 10MW solar plant, and the City will enter into a long-term contract to buy power from the plant at 19 cents per kilowatt hour.
Ouch. 19 cents? That’s extremely high.
This is an interesting article. I’m glad to see the City investing in new energy technology, but I’m not a huge fan of this particular approach.
It strikes me that the best, most effective use of solar power is not as a high-priced central plant, but as a distributed supplementary power system. We’ve seen over and over that solar energy is more expensive than most other kinds of energy.
Even if technology reduced the cost of the solar cells dramatically, solar will never be able to work at night. The only workaround for night-time power is to ramp up the capacity of the plant above daytime demand and store the surplus in batteries – a costly proposition indeed.
As solar technology improves, however, building-integrated solar installations will make more and more sense in the Southwest, because they can provide a big additional spike of energy right when our energy demand is spiking – when it gets really hot in the summer. These systems are much cheaper if their purpose is only to absorb the afternoon demand spike – no batteries are needed for that.
Right now the biggest thing holding back solar tech is the cost of the cells. As that cost goes down it will quickly become practical for businesses to amortize the capital cost of the solar cells in the construction of their buildings, and then be protected from the huge energy bills we all pay in the summer months.
This is the great thing about distributed solar. If we use it right it provides extra boosts of power when they’re needed most. This means we can run a more fuel efficient central plant with less total capacity required. The reduction in energy demand spikes would also help stabilize fuel prices, which benefits everyone. That, to me, is the most concrete long-term justification for solar investment. The sooner we can truly stabilize our energy supply, the better of we’ll all be.
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I was puzzled by the deal, too, until I realized that this is “peaking power”. The greatest loads on electrical systems only last for a few hours, and they are typically powered by gas turbine generators. These can be brought online very quickly when needed. Other kinds of power come from steam turbines, which take time to boil the water and get it up to operating temperature and pressure.
The problem with gas turbines is that they’re inefficient, which makes their power comparatively expensive. In southern parts of the U.S. such as Houston, the times of peak power come on hot summer days, when coincidentally the sun is shining brightly and solar power plants are most effective.
The T.H.Wharton plant where the solar farm will be built is already gas-fired. It’s possible that it’s already reached the maximum capacity of the gas pipelines that provide it with fuel. Building enough gas storage tanks and gas-turbine generators to handle the growth in peak load for Northwest Houston could well be more expensive.
Getting the City of Houston to pay for all this sounds like a good deal all around, helping to promote Houston as the “energy conservation and renewable capital.”
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[...] shouldn’t be too hard to overcome as the technology improves and becomes more widespread, and Andrew Burleson has some ideas on how to make the best use of solar power: As solar technology improves, however, [...]