Reading the Letters about green power in the June
2004 issue of Physics Today (page
11), I was reminded of an observation I made some
years ago in the Bay Area of San Francisco and in
Los Angeles; there appear to be almost no solar water
heaters on the roofs of buildings there. Many parts
of California enjoy essentially the same sunny weather
as southern European countries such as Greece, where
individual solar water heaters can be seen on the
roofs of almost all buildings. Consisting essentially
of a small black water-storage tank, such solar collectors
are efficient water heaters that offer a low-cost
supplement (not replacement) to more conventional
technologies. Why are they not used in the sunnier
parts of the US? If they were, the financial savings
to each household would be great, and the combined
energy savings across the US would be enormous.
Local energy-saving solutions have enormous potential
to reduce our dependency on fossil fuels. A full account
of the economics of solar water heating is contained
in the publication A Consumer's Guide: Heat
Your Water with the Sun, available from the US
Department of Energy (http://www.nrel.gov/docs/fy04osti/34279.pdf).
According to that document, for homes with electric
water heaters, up to 25% of domestic energy costs
go to heating water. The adoption of local energy-saving
solutions should be considered wherever practical
and built into new homes. The nature of the solutions
depends on the location; excellent insulation and
good use of sunlight should be high on everybody's
list.
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