Mexico Notebook: Solar hot water for life

Billboard for housing development in Chihuahua City, Mexico. (© 2008 Photo by Denise Tessier)

CHIHUAHUA CITY, Mexico -- "Free! Hot Water for Life," screams the billboard by the highway.

In the near distance are the boxy-modern condos that spring up like hongos [mushrooms] around virtually every city in Mexico to accommodate their burgeoning populations.

No doubt the company selling this solar water heater -- in this case Signa Hogar -- would like to see a solar boiler atop each one.

Why don't we see signs like that in the States?

The hot topic nowadays in the U.S. is concentrating solar power -- grouping massive solar collectors around concentrators to mimic the large power plants we already have, but harnessing the unlimited power of the sun instead of coal, natural gas or oil. That kind of energy solution, of course, also concentrates the delivery of such systems in the hands of power companies like PNM, which recently put out a request for proposals with three other power companies for construction of a concentrating solar power plant in New Mexico.

While touted as environmentally friendly, these systems also use massive amounts of land [five square miles for a 500-megawatt plant], water for steam and, in some cases, water to clean the solar mirrors on the collectors. In other words, the environmental implications are significant.

Then again, there is the solar-water-heater-on-the-rooftop concept, which certainly isn't new technology -- Jimmy Carter put a system atop the White House in the 1970s; Ronald Reagan took it down.

Sen. Bernie Sanders, I-Vt., wants to see solar panels on top of at least 10 million roofs by the year 2018, and hehas introduced in the Senate the 10 Million Solar Roofs Act, which would require the secretary of energy to set up a program to provide rebates to individuals, businesses and government buildings to spur the installation of solar panels on roofs. That legislation says, "The use of photovoltaics on the roofs of 10 percent of existing buildings could meet 70 percent of peak electric demand."

Meanwhile, researchers at Massachusetts Institute of Technology have proposed turning any window into what they call "solar concentrators," a proposal that appears promising for large office buildings that lose lots of energy through massive use of glass.

Still it turns out the solar billboard in Chihuahua is not a common sight in Mexico, either. And while the thousands of Mexicancondos have black water tanks on their roofs, they aren't heating the water; the black is merely the color of the ABS plastic of which they're made.

Heating water with the sun is simple, available technology. It'd be nice to see more of what the billboard pictured above is touting -- both in the United States and Mexico.

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