In that context, the tower is not only a big step for Solar Reserve, it is also a marker for a new period of accelerated growth in the solar industry, as new advances in solar tech emerge from the lab and achieve their commercial potential with some help from us taxpayers, too.
A government assist for solar power
When President Obama made his pitch for American-made energy, he was including projects like Crescent Dunes. The plant will collect solar energy here in the U.S., obviously, but less evident is its made-in-the-USA pedigree.
The underlying technology was developed in the U.S. through the Solar Two pilot project sponsored by the U.S. Department of Energy in the 1990s, which in turn was based on DOEs Solar One project dating back to the 1980s.
DOEs involvement continues to this day, most recently in the form of a $737 million loan guarantee that enabled Solar Reserve to get financing for the plant.
U.S. takes a lead in global solar industry
The Crescent Dunes plant also provides a much-needed boost for the U.S. solar industry, which just a generation ago was leading the world in photovoltaic cell manufacturing before losing ground to other countries. Based on a solar energy collection and storage system using molten salt, Crescent Dunes boasts the tallest molten salt tower in the world and is the largest power plant of its kind in the world, at least for now.
Pouring salt on a solar power conundrum
Salt may seem like a misfit in the high tech world of todays solar industry, but in its fluid state salt is emerging as a low-cost way to collect and store heat energy from the sun.
As a solar thermal plant, the Crescent Dunes facility does not convert solar energy directly into electricity. Instead, the it uses a circular array of thousands of mirrors called heliostats to reflect and concentrate the suns energy on a central tower.
The walls of the tower are made up of piping. Under the glare from the heliostats, molten salt flowing through the pipes can reach temperatures of more than 1,000 degrees Fahrenheit.
The heated fluid is shunted to a ground-level storage facility. As needed, heat energy is drawn from storage to turn water into steam, which powers a turbine for generating electricity.
Both the cooled salt and the condensed steam are recycled within their respective systems. In the past, water consumption was a major obstacle to the commercialization of large scale solar thermal power plants, so the use of recycled water is a key breakthrough.
More to the point, the combination of an on-demand energy storage system with a solar energy collecting system also solves a problem that dogged the solar industry in its early days, which is the intermittent nature of raw solar energy. The new 110-megawatt plant will have a storage capacity of up to 15 hours, ample time to last through the night.