According to the hype, solar energy is both clean and environmentally neutral, if not a positive.

Well, turns out that’s not quite the case.

A fascinating story from Voice of America’s Zulima Palacio points to another side of solar, one that’s neither clean nor green.

The focus of the story is Colorado’s San Luis Valley, the world’s largest mountain valley, and at 7,600 feet the country’s highest major agricultural area.

As it happens, we’re quite familiar with the Valley, since we spent most of our college years there.

The Valley’s flat, dry, hot in summer and bitterly cold in the winter. Our first winter there was marked by an official low of 44 below zero in a week that didn’t get above 10 below. It’s also big — 150 miles from north to south — and wide — 50 miles across. It’s also a desert, with precious little rain and snowfall.

Given such conditions, it’s perhaps surprising that the Valley is also a major agricultural producer. That’s because of a once-plentiful groundwater supply, fed by the surrounding Sangre de Cristo and San Juan mountain ranges.

Back in the early 1960’s water pressure was sufficiently strong to provide that desideratum of well-driven agriculture, an artesian supply with sufficient pressure to bring water to the surface without pumps.

What makes the valley desirable to the solar industry is both the intense sunlight, largely uninterrupted by cloud cover, and the presence of a ready water supply.

But the water’s not infinitely accessible, and therein lies the rub. For contrary to the mythology, solar energy requires water, and lots of it. So much water that the demands of the Valley’s burgeoning solar industry are drawing down the Valley’s once seemingly inexhaustible reserves, threatening the agriculture which has always been the region’s economic driver.

And now for implications, from Palacio’s story:

Steve Vandiver is General Manager of the Rio Grande Water Conservation District. He said, “If agriculture goes away here, we have nothing left.”

Agriculture in this valley is under another threat. The land, rivers and aquifers under the Valley are drying out. That also affects solar power.

“Some of the bigger plants – the solar thermo plants – take a significant amount of water. You have to dry up a lot of farm land in order to create a water supply that is large enough to support those types of plants,” said Vandiver.

Solar panels also need to be washed because dust accumulates on them.

The water shortage has forced authorities to draw up plans that will close hundreds of wells and retire agricultural land.

“Valley wide we are probably looking at 60 to 80,000 acres [24,000 to 32,000 hectares] that will have to come out of production in the long term,” said Vandiver.

Read the rest.

We’ve written extensively about the agrofuel craze, which turns farmland into energy crop plantations. Now we see that the other major non-nuclear alternative to fossil fuels bears also agricultural costs.

And while solar energy may be less polluting than fossil fuel-derived energy, it’s not clean, as Science Daily noted three years ago:

Solar energy has been touted for years as a safer, cleaner alternative to burning fossil fuels to meet rising energy demands. However, environmentalists and others are increasingly concerned about the potential negative impact of solar cell (photovoltaic) technology.

Manufacture of photovoltaic cells requires potentially toxic metals such as lead, mercury and cadmium and produces carbon dioxide, which contributes to global warming.

This is not to say that a shift to solar energy isn’t either desirable or necessary. Rather, it’s a reminder that solar is not an unmixed blessing, and carries with it real environmental costs.