Michael Kanellos
A 5 GW Solar Plant? Just How Much Land Are You Talking About, Bill? August 8, 2008 at 4:58 PM
The Business Standard, a business paper in India, reported that the Clinton Foundation is considering building an integrated solar city that could generate “5,000 megawatts over a period of time.”
It is unclear whether the plans are to build factories that could churn out 5,000 megawatts, or 5 gigawatts, worth of solar panels, or whether the plan is to build a solar farm that could produce 5 GW of power, or whether the figure includes some combination of the two. It is also unclear whether that means 5 GW of panels and/or power a year or over the lifetime of the project. It could also be an inaccurate report by the paper.
If they are looking at annual figures, though, it’s going to be a tall order either way.
First, the idea of building enough capacity to churn out 5 GW worth of solar panels a year. By the end of the year, there will only be around 10.25 GW worth of capacity worldwide and the figure is expected to only go to aorund 15 GW by 2012, not counting this project. The Clinton project would thus aim at doubling or tripling the world’s capacity. Not easy to do.
Now, let’s look at building a 5 GW solar farm. Solel is currently building a 533-megawatt plant in California that will provide power to PG&E. It is expected to cover 6,000 acres when complete by 2011. There are 640 acres in a squre mile. A 5 GW plant would thus need about 88 square miles. (6,000 divided by 640 gives you 9.375 square miles.Multiply that by 5,000 divided by 533). It would also require plenty of water, which is in short supply in India.
A 5 GW PV solar field would also take up a lot of room. The sun radiates about a kilowatt of energy per square meter on the surface of earth, HelioVolt CEO B.J. Stanbery told me once. There are 2.6 million square meters in a square mile. Thus, every square mile gets about 2.6 gigawatts. But a practical level, solar energy is only going to harvest about 10 percent of the energy that hits a large area, so it takes about 4 square miles of solar panels to generate a gigawatt. That means 20 square miles. India’s huge, but that’s still a lot of room. It could well displace a lot of people. He’d be hugging villagers and feeling their pain through 2016.
I ran out of fingers while doing some of these calculations so if I made an error, please don’t hesitate to call. But hopefully, the Foundation can clarify.
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India and China are and will be for some time primarily net exporters of solar products for the simple reason that the economic bar for solar is a lot lower in Europe and the US. When you can burn coal with impunity and economic growth is the primary imperative, any five gigawatts of product produced in India is going to be finding a home someplace other than India. Five years from now the equation may be different, but I would tend to think more like 10 or 15 years for big domestic solar markets in China and India. I hope I’m wrong.
When Bill does the numbers humself, first blush tends to be a little rosier. Even so, pranning a village -sheltered by- solar concentrators and PV could provide for itself and the cited 5GW surplus over 30 square miles, by 2017, and still be a village. That’s about the limit for village-size, (it will have one child, natch) isn’t it?
They put out for girls with pretty green hygroscopic skins and expect them to show up soon?
w.r.t. serious assumptions:
Water usage in concentrating solar….surely not from water -loose- in cooling towers?
On the other hand, if the town’s occupied as in my assumption (who’s going to prop up the panels and heliotropes, after all) how will water be preserved in the arcology?