Storing Solar Energy May Not Be Such a Problem After All

solar-tower.jpgAn article in this week’s Science Times offers an intriguing glimpse of the potential of solar thermal, a form of renewable energy generation that, while not nearly as hyped as PV solar, may ultimately be more feasible for large-scale energy production.

One of the biggest issues with photovoltaic (PV) technology (i.e. - solar panels) has been how to store the energy once it’s generated to meet demand during times of low production, such as at night or on cloudy days. Solar thermal systems avoid this problem because they rely on generating energy from the sun’s heat, which can be more easily stored than the sunlight-generated energy of PV systems. At the core of solar thermal is a surprisingly simple concept: the sun’s rays are used to boil water, which then generates steam to power turbines. The energy is then stored in tanks of molten salt, which can reach about 1,000 degrees Fahrenheit without becoming too pressurized. This allows the energy to be stored for hours, even days, until it is needed. Most current systems achieve this by focusing a field of hundreds to thousands of specially designed lenses on a large water tank or pipe system, then pumping the resulting heat through a closed loop consisting of hot and cold salt tanks, a steam generator and a turbine.

“Nevada Solar One”, the 64 MW Acciona power plant which opened in Boulder City last year and was featured on this very blog just last month, is one such system. The largest solar power plant to be built around the world in the past sixteen years, Nevada Solar One can produce enough energy to power 15,000 households. Now other visionary companies are experimenting with variations of this basic design to further improve efficiency.

Proponents of solar thermal boast other benefits, as well, including greater potential at higher latitudes and other places that don’t get much sun and its greater affordability; solar thermal systems based on a parabolic trough design produce energy at a rate that is 50-75% cheaper than its PV equivalent. As these technologies develop further, different niches may emerge for each. While PV panels may ultimately become the industry standard for individual home-owners and relatively small, off-the-grid systems, solar thermal’s double-barreled promise of storage and price make it a strong candidate for that clean, large-scale power source we’ve all been clamoring for.


Posted on Sunday, April 20th, 2008 at 8:00 am | Tagged in Energy, Technology | posted by Bill

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