Parabolic mirrors in Andalusia

Last December, what is billed as the world’s largest solar plant, Andasol, began operating on Spain’s Gaudix plateau in Andalusia.

It uses 600,000 parabolic mirrors to produce 150 megawatts of electricity, enough to power a city of 500,000. The parabolic mirrors do not operate on the same principles as the more familiar solar panels.

Instead of directly creating electrical current, they absorb heat from the sun, which is transferred to some 30,000 tons of salt for storage. That heat operates steam turbines, meaning that Andasol can continue to produce electricity for about eight hours after sunset.

The Gaudix plateau is about 3600 feet above sea-level. At that altitude, the air is clearer and less turbulent than at lower altitudes. That is why Gaudix captures more energy from the sun than the Saudi Arabian peninsula. A similar and larger project is in the works near Blythe, California.

Both will be dwarfed if an international venture called Desertec Industrial Initiative succeeds in its plans to build a Sahara-wide solar plant. The Sahara receives more energy from the sun in six hours than the entire world uses in a year. The project as planned could produce 15% of Europe’s electricity by mid-century.

Are these massive parabolic mirror projects the future of solar energy? I certainly hope not. They are at once too big and too small. What if every project that anyone has ever thought of gets built and produces the maximum possible amount of electricity? It won’t make enough of a dent in the world’s demands for power to justify the environmental costs of building them.

Obstacles to large parabolic mirror solar power projects

The Gaudix project received massive funding from European governments. By the time it was completed, the governments had begun to scale back their support. The world economy tanked and the euro became threatened by massive debt among some eurozone members. Parabolic mirror projects like Gaudix will find it much more difficult than Gaudix to raise funding.

Besides coming on line in a more favorable economic climate, the Gaudix plateau has important advantages lacking in other sites. Besides receiving 2000 hours of sunlight annually at a fairly high altitude , it has ample underground springs to provide water for the turbines. Even more important, a high-voltage power line already existed nearby.

Even in the California desert, it will be necessary to build the infrastructure necessary to distribute the electricity. America’s antiquated power grid cannot get electricity from remote solar or wind farms to where it is needed without major overhaul. Southern California already has to import massive amounts of water from long distances to support its current population and industry. Where will it get more water to boil for steam turbines?

And the Sahara? As envisioned, the project will begin in relatively stable Morocco. If its developers truly intend to build across the entire Sahara, they will need cooperation from much less stable governments–and the local population. Add security concerns to the lack of water and existing infrastructure. Does anyone seriously expect the people of northern Africa to acquiesce to such a massive project for the benefit of providing electricity to Europe? After all, why should they?

Environmental costs of large parabolic mirror solar power projects

The Gaudix project now produces clean energy. Because of the electricity it provides, it keeps 500,000 tons of carbon dioxide annually from being pumped into the atmosphere. But what about preparing the equivalent of 210 soccer pitches, whatever that is, for construction? What about manufacturing all of that equipment? One California project will cover 7000 acres, and two more farther west will take up 3800 acres and 4640 acres respectively. Using lots of water to produce steam only hints at the environmental downside of building such projects. Here are more causes for concern:

• The first step is to remove all vegetation, which, of course, will no longer remove CO₂ from the atmosphere.
• Whatever other wildlife depends on that vegetation will not survive.
• Making the equipment will require massive amounts of steel. Since the solar plants cannot operate until they are built, making the steel and manufacturing equipment from it will rely on fossil fuels.
• The California project will not use salt to store heat. It will use oil.

Meanwhile, it will take years to build huge projects. At some point, the design will have to be set in concrete, so to speak, while technological innovation will continue. Will the largest of the projects be obsolete by the time they’re ready to go on line? There’s a better way.

Smaller alternatives to large parabolic mirror solar power projects

First, I am not criticizing parabolic mirror technology. It stores heat and can therefore generate electricity at night or otherwise when the sun is not shining. It is much less expensive to store heat than to store electricity. But I have come across lots of Google ads for home parabolic mirror kits as I have worked on this post.

I’ll have to investigate further, but it is quite evident that parabolic mirror technology is already being used for small-scale projects. [You can read my further investigation here.] A multitude of small-scale projects will generate electricity closer to where it is used. We’ll still have to update the grid, but relying on small-scale projects will not require building long transmission lines (over which some of the electricity will dissipate.)

The cost of solar electricity has been declining for some time. Solar energy is now cheaper than nuclear energy. I suppose those figures are based on the simpler solar panel/inverter technology that makes electricity directly from sunlight. Combined with wind turbines, it is already possible to generate electricity all day and in all weather conditions to power either a single building or a small complex of buildings.

Some electric companies themselves are already adding solar power to their technological arsenal. Instead of finding large tracts of land for solar farms, they partner with other businesses, who erect solar equipment on smaller parcel of unused land–or on the roofs of their warehouses or other large buildings. Parabolic mirror solar power projects may or may not be the wave of the future, but for the future to work requires small projects.

It is easy, cheap, and efficient to install millions of small solar projects on private property. It requires sophisticated engineering, expensive construction, and massive government funding to identify the few dozen suitable tracts of public land and build solar projects there.

Sources: World’s largest solar plant powers up / Alasdiar Fotheringham
Solar Showdown: Are New Solar Power Projects Anti-Environmental? / Michael Haederle

Photo credit: Some rights reserved by Tom Raftery