Now we’re cooking.
Operation of a new Spanish solar thermal plant just kicked into high gear, taking the title as the world’s largest commercial tower-type collector.
The remarkable solar collection facility with the rather unremarkable name – the PS20 – passed its initial trial run with flying colors, surpassing expectations in power production. Located near the ancient city of Seville, it is now the second such tower collector in commercial use.
Abengoa Solar operates the new plant, which has a power capacity of 20 megawatts, enough juice to power about 10,000 homes.
The plant uses 1,255 heliostats (motorized mirrors) to reflect sunshine onto a fixed focal point. The heliostats follow the sun’s path throughout the day to catch maximum rays. Like a legion of faithful followers, the mirrors face upward and pay tribute to the towering idol in their midst. That would be the 531 foot tall collection tower, the object of their reflection.
With a surface area of 1,291 square feet each, the massive mirrors working together focus over a million and a half effective square feet of sunlight on the apex of the tower. It gets hot. Very hot. That heat energy can be used to boil steam to turn turbines, or stored for later use.
Concentrating solar power (CSP) is poised to take the solar industry by storm, offering all the benefits traditionally ascribed to solar – clean, renewable, etc. – with the potential to kick its biggest drawback to the curb.
What to do when the sun’s not shining has forever been solar power’s nemesis. While we can’t alter the sun’s behavior, we can store its power for later use. Electrical batteries have offered somewhat of a solution toward this end, but they are expensive, tough on the environment and impractical for utility-scale power storage.
Heat is another matter entirely.
CSP captures and concentrates the sun’s rays to boil steam, and in turn uses the pressure of that steam to turn a turbine and produce electricity. It’s far easier and more efficient to store the sun’s energy as heat than electricity. The heated fluid can be trapped in insulated storage tanks and then called upon and used to boil water long after stars have begun to shine.
It’s historically been just plain easier to set things on fire – coal, oil, natural gas – and use the heat energy to produce steam to power our stuff.
Easier for now, but perhaps not for much longer.
Current technology can store solar-generated heat for up to seven hours, and the US National Renewable Energy Laboratory is looking forward to stretching that to an amazing 12 hours!
In sum : Concentrating solar power walks very softly yet carries a big stick. It has the potential muscle to compete with fossil fuels in terms of megawatt output, yet treads very lightly indeed on the earth. With its new PS20 plant, Abengoa is making great strides toward this end for the solar industry and clean energy.
Photo Credit: Sandia National Laboratories http://www.nrel.gov/data/pix/Jpegs/00036.jpg