From Guest Blogger Mathias: Breakthrough in Thermal Energy Storage for Solar Power?

Solar power is known for being a fluctuating source of energy. Predicting good weather and sunshine seems to be impossible, and there isn’t any solar energy available during the early morning hours and the night at all.

According to REN21 Renewable Energy Policy Network for the 21st Century (November 2010), wind, solar, biomass and geothermal power only accounts for about 0.7% of the total power generation worldwide. The unpredictability of solar power is therefore not a big concern yet, but as more capacity is being added to the grid, we eventually will need energy storage for solar.

This is where a research team at the University of Arkansas comes in. They have developed a solar thermal storage system that has the potential to take over for conventional and storage systems. Molten salt and storage tanks filled with oils and packed rock are typically being used today. However, these storage methods are expensive and risky:

“Filler material used in the conventional method stresses and degrades the walls of storage tanks. This creates inefficiencies that aren’t calculated and, more importantly, could lead to catastrophic rupture of a tank,” says Panneer Selvam, professor in Civil Engineering and the leader of the small research team.

Prof. Selvam and doctorial student Matt Strasser has together created a storage system that builds on the same principles as the old methods, but with concrete plates and thermocline units – bodies of fluids or gases that causes much less damage to the storage tank.

The team has estimated the efficiency of energy storage at 93.9%, which means that most of the energy that is sent into the storage tank can be turned into useful power through a generator. Costs will likely end at $0.78 per kilowatt-hour of energy storage – almost 20 times less than Department of Energy’s price goal for energy storage systems.

Gary Tulie says:

November 30, 2012 at 11:42 am

This is excellent news for concentrated solar thermal systems where solar heat generates steam which in turn spins a steam turbine, and can greatly increase the viability of storage in such systems.

I could also see this storage method being used as a bolt on extra with existing high efficiency fossil fuel plant to deliver peaking service without the efficiency compromises of conventional peaking plant. This arrangement could allow a higher penetration of intermittent renewable energy without destabilising the grid.

Dennis Miles says:

December 1, 2012 at 10:33 am

With a sterling engine powered generator to use the heat directly it allows greatly increased efficiency in the solar collectors also, in fact a glass encased PV panel will get quite hot and collecting that heat for storage is an excellent efficiency increasing technology although the PA solar panels mus be kept below 500 degrees and special solders used at even that temp. as solder melts at 360 degrees typically. The combination of 20% directly produced electricity and the 80% heat stored to offset other energy utility purchase , the system becomes VERY efficient.

Another alternative is using the electricity to make Hydrogen then using the Hydrogen like natural gas is used for water heating, cooking, refrigeration, and such. Hydrogen is much safer in a home than natural gas because if there is a leak it won’t stay trapped in the basement, but rises thru common building materials to the open sky then up-and-away clear of the home and is not explosive, even mixed with oxygen it simply burns fast , it does not explode.