Can we use solar power overnight?
As more and more people turn to solar energy for reliable, clean renewable power, there is still one major stumbling block. You can only tap into solar power when the sun is shining. But what if you could use solar power overnight? How could that work?
Scientists at SolarReserve have come up with the antidote to night skies and overcast days. A solar energy farm can store solar energy in heated molten salt. Up to 7 hours of stored solar energy is held by the heated salt, which creates steam to generate an electrical turbine.
The technology is similar to concentrated solar power (aka solar thermal power). Giant mirrors, called heliostats, follow the path of the sun and reflect sunlight toward a 500-foot tower holding millions of gallons of liquid molten salt. The heliostat field is approximately 2 square miles in size.
As described on SolarReserve’s website:
A tower resides in the center of the heliostat field. The heliostats focus concentrated sunlight on a receiver which sits on top of the tower.
Within the receiver, the concentrated sunlight heats molten salt to over 1000 degrees Fahrenheit. The heated molten salt then flows into a thermal storage tank where it is stored, maintaining 98% thermal efficiency, and eventually pumped to a steam generator. The steam drives a standard turbine to generate electricity. This process, also known as the “Rankine cycle” is similar to a standard coal-fired power plant, except it is fueled by clean and free solar energy.
Heliostat field
Researchers believe that the energy generated by the solar power towers will be cheaper than coal or natural gas. The clean electricity is fed back into the grid and purchased by utilities for sale to their end customers. Lest you question the “green-ness” of storing solar power overnight in molten salt, the technology is both safe and inexpensive – not to mention reliable:
The molten salt storage loop enables the plant to generate electricity whenever it is needed – 24 hours per day or during “peak demand” periods. Molten salt is an efficient and inexpensive medium to store energy. The salt used in the process is an environmentally friendly mixture of sodium and potassium nitrate, the same ingredients used in garden fertilizer.
Solar Reserve’s plant will generate between 100-600 megawatts of electricity, depending on the configuration of power load that the utility requires. A single megawatt is enough power to supply approximately 1,000 households. That’s some serious juice!
Talk about solar technology that’s worth its salt!
Tags: concentrated solar power, heliostats, solar energy farm, solar power overnight, solar power towers, solar reserve, solar thermal power, storing solar power
Storing energy in molten salt is what interest me the most here. The major power providers need to be able to do the same thing we do with our own home systems. Make more then we need, hold it in batteries. Great video!
Wow, molten salt! That’s really cool. I love heliostats. They’re such an awesome invention. The only potential drawback that I can see is with only 7 hours of energy availability, what happens during overcast days that and then nighttime where the system could go a whole 24 hours without sunlight?