The solar energy industry made a giant step forward yesterday as the largest solar thermal project to date successfully completed its first test run. The Ivanpah Solar Electric Generating System is a collaborative project between BrightSource, NRG Energy and Google, and September 24, 2013, marked the first time the massive solar thermal project in the southeastern California desert delivered electricity to the grid.
At an estimated cost of $2.2 billion – of which $1.6 billion or nearly 73% was provided by the U.S. Department of Energy – construction of the project has been underway since October 2010, with a planned completion date by the end of this year. Once completely online, Ivanpah will generate 377 net megawatts of electricity, enough to power roughly 140,000 homes in the service territories of Pacific Gas and Electric and Southern California Edison. In general terms, that's almost 79% of the generating capacity of the nation's smallest nuclear facility – Fort Calhoun in Nebraska.
How does Ivanpah work?
The Ivanpah Solar Electric Generating System is the largest example of solar thermal power generation the world has ever seen. Rather than the typical solar panel array, Ivanpah has 170,000 heliostat mirrors that redirect sunlight to central towers that create thermal energy from the light.
It's the same concept that let you use a magnifying glass to burn leaves on the sidewalk as a kid. The thermal energy created by concentrating sunlight with the 170,000 heliostat mirrors heats water in the facility's three central towers. The steam produced then rotates turbines which generate electricity.
What makes Ivanpah different
The Ivanpah facility is not the first solar thermal power generating station, but it is the first project of its scale. None of the previous solar thermal facilities have even come close to the output levels of Ivanpah, in part because previous projects were simply less extensive.
The first test of solar thermal power generation was a project called Solar One located outside Barstow, California. Solar One was completed in 1981 and operated until 1986 before the site was revamped through expansion and became Solar Two in 1995. Ivanpah's 170,000 heliostats occupy nearly 3,500 acres, while in comparison, the now decommissioned Solar Two occupied a mere 126 acres and was capable of producing just 10 MW.
Is Ivanpah the beginning of something even bigger?
Anything beyond speculation as to whether or not solar thermal power is a viable alternative to fossil fuel generation for the long term will have to wait. What's exciting about solar thermal as opposed to solar panel technology is its potential to effectively store energy, which is a major limitation of solar panels.
Because of the transition from light to thermal energy inherent to the process, solar thermal power facilities have to solve for a way to effectively store heat, rather than electricity itself, which is a much more manageable proposition. The Solar Two facility pioneered molten salt as a medium for storing solar thermal energy, which was then able to create steam in periods when sunlight was insufficient or unavailable to generate heat, such as cloudy days and overnight periods.
While this technology worked for the 10 MW Solar Two facility, the current plans for Ivanpah do not include a similar storage technique – yet. According to the Nevada Institute for Renewable Energy Commercialization, Mike Bobinecz, vice president of BrightSource, was quoted as saying, "Storage is the next step in our evolution."
No matter what, having a solar thermal generation station as massive as Ivanpah online is an impressive accomplishment for the industry as a whole, and the advancement of renewable energy technology in general. Now we have to wait to see what form of storage technology finds its way to fruition.