The biggest obstacle to alternative energy is storage of the generated electricity. Often enough, the power generated is immediately used in the grid. A recent use of liquid air storage for electricity looks promising. Flywheel based storage is already at use in regulating the grid. Unfortunately, these options are limited to only a few places.
The second biggest issue is how intermittent the generation time lasts. Cloudy days dip solar production. Calm days leave turbines motionless. Recent developments in solar panels have extended the light intensity levels needed to generate power.
Spain's Gemasolar power plant may have solved both issues. This location is the world's first solar thermal plant able to supply 24 hours of uninterrupted electricity. Solar thermal absorbs the sun's rays and uses the heat to generate steam for turbines. Quite different from traditional photovoltaic solar panels that directly converts light to electricity.
The 19.9 MegaWatt facility built by Torresol Energy contains 2,650 heliostats (mirrors) that direct the solar radiation towards the central 120m (450') tower at the center. The concentrated light then heats molten salts that circulate throughout the tower to 500°C (932 °F). The heated molten salts are stored in specially designed insulating canisters that maintain the extreme temperatures. These heated salts can be used for up to up to 15 hours without additional solar input. So, with 12 hours of light and 15 hours of stored energy, the plant can provide uninterrupted power.
"Gemasolar achieved optimal performance in its systems in the last week of June,” said Director of Production at Torresol Energy Diego Ramírez. “The high performance of the installations coincided with several days of excellent solar radiation which made it possible for the hot-salt storage tank to reach full capacity. We're hoping that in the next few days our supply to the network will reach an average of 20 hours a day."
The Gemasolar facility will generate 110 GigaWatt-hours of electricity annually according to Torresol Energy. The power is equivellant to the power necessary for 25,000 homes, and it will save 30,000 tons of CO2 per year.
Terresol Energy hopes that June's demonstration of solar thermal viability will spur on the adoption of the technology. Hopefully no one will walk through a collection of light beams near the center tower. Might end up being bad PR.
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