How To Efficiently Store Solar Power

Can you efficiently store solar power?

One of the biggest challenges facing the solar industry is how to efficiently store solar power.  After all, if you are going to generate clean, renewable energy, you’ll want to have a place to keep it until you use it.  This is particularly so if you harness more solar energy than you need for immediate use.

It’s all possible, said Terry Murphy, president of SolarReserve. The company’s design uses the sun’s heat to boil water and spin a turbine — not unlike other “solar thermal” concepts that are now common. But where a typical system uses mirrors to concentrate sunlight and heat water; SolarReserve uses them to heat a salt, which melts into a liquid about twice as dense as water — and here’s the catch: stored in thermal silo, the melted salt is able to maintain vast amounts of heat, which can be tapped later for use in power production.

Store solar power

Why store solar power in salt?

A fundamental rule is that salt changes the chemistry of heat storage, as well as the freezing point of water (that’s why they salt the roads during winter – salt water freezes at a lower temperature than plain water).  Turns out that with respect to storage of heat, salt loses only 1% of its energy daily.

“Rocketdyne, purchased by United Technologies in 2005, developed the molten salt storage system technology. The Hamilton Sundstrand Rocketdyne segment, which makes liquid metal and molten salt heat transfer systems, is the prime contractor for the International Space Station electric power system.

The project, which is expected to begin generating electricity in three or four years, would produce up to 500 megawatts of peak power a year. That’s enough to supply electricity to about 250,000 to 500,000 homes, depending on time of day, according to the U.S. Department of Energy.”

Researchers are working on ways to use molten salt to store solar energy that could produce enough electricity to power 250,000 to 500,000 homes a year.  I could try to explain how molten salt will efficiently store solar power, but since I didn’t major in chemistry, its best if I just quote from another source.  Here’s a thumbnail sketch of how it works:

“Molten salt, a mixture of sodium and potassium nitrate, circulates through a central receiver, is heated by sunlight to more than 1,000 degrees, stored in a tank and dispatched into a steam generator. The steam drives a turbine that generates electricity. The cooled salt re-circulates and the process begins again.”

In short, technology is progressing on the solar power front.  Storage of extra generated energy will both encourage more people to convert to solar energy and allow for the savings of money that would otherwise be directed towards utility bills.

Want to know more about efficiently storing solar power?  Do you have a success story to share?   Please let me know in the comments below.

Tags: how to efficiently store solar power, molten salt, solar power batteries, solarreserve, store solar power in salt