As I sat in my seat, baking in the hot San Diego sun, grains of salt from my delicious snack fell inconsequentially into my lap. I brushed them off, thinking nothing of it. Had I known, I wouldn't have...I would have...
My God, what have I done?
According to SolarReserve CEO Kevin Smith, "It's really the ability to provide renewable energy that's available on demand 24 hours a day," using molten salt to store heat when the sun isn't shining.
But before we jump into salt, let's make an important distinction.
What is CSP?
We're talking mirrors. Large, parabolic mirrors that concentrate sunlight into super intense heat. That heat is used to create steam, which powers conventional steam engines.
This technology has been around since 1866, when a French genius named Auguste Mouchout, using the powers derived from his incredible mustache, invented the world's first parabolic mirror.
Since then, the technology has gotten much sleeker, and more ubiquitous in the field of solar. Here's a CSP plant in Spain. Here's one in Arizona.
The Storage Problem
Highly pressurized water was circulates through pipes that are heated by 136 acres of parabolic troughs. These pipes are fed into a heat exchanger, that feeds into a saturated-steam receiver that powers a turbine.
But what happens at night, you ask? Great question.
This is the question that stumped early CSP engineers, and forced them to start playing with mediums other than water that are better equipped to stay hot after the sun goes down.
What would happen if you take all of that salt, and super-heat it into a liquid form using the power of concentrated sunlight? You would probably need a lot more pretzels, and a lot more salt.
But eventually, you would get molten salt, which, in the right conditions, is capable of storing a lot of heat with very little heat loss, even throughout the night.
In fact, the SolarReserve project will be able to store the heat generated by hot molten salt in tanks at over 1000⁰F, with losses of only 1⁰F per day! That's a 99.9% efficiency rating, which, 999 out of 1000 dentists agree, is very high.
At night, or during very cloudy days, you can deploy that stored heat to power those steam engines. When the sun shines again, rinse and repeat.
- Molten salt is circulated through highly specialized piping in the receiver (heat exchanger) during the day, and held in storage tanks at night – requiring no fossil fuels.
- The tanks store the salt at atmospheric pressure.
- Use of molten salt for both heat transfer and thermal energy storage minimizes number of storage tanks and salt volumes needed.
- Molten salt is stored at 1050⁰F (566⁰C) until electricity is needed – day or night, whether or not the sun is shining.
- As electricity is needed, molten salt is dispatched from the hot tank through a heat exchanger to create super-heated steam which then powers a conventional steam turbine.
The SolarReserve project won't begin construction for another two to three years. According to Smith, it will create approximately 3,000 jobs over the following 7 years, and generate about 1.5 to 2 GW of power.
Go to EcoWatch.com for more info about this project.