San Diego zoo debuts energy storage

It converts sunlight into energy, charges electric vehicles and delivers access power to the grid. And it keeps your car cool while you go feed the elephants. The newly unveiled parking lot at San Diego zoo has solar canopies that can produce up to 90kW of electricity, five car-charging stations and the possibility to deliver energy to the grid. Best of all, it has two lithium-polymer storage units, with a total capacity of 100kW.

According to an article on the KPBS site, the energy storage element is a first for this type of project. And the installation has so impressed the University of California in San Diego that it is considering building a similar power hub on campus.


US molten salt project gets green light

The US solar developer SolarReserve this weekconfirmed it has received the final Arizona State approval required to go ahead with its Crossroads Solar Energy Project. This aims to supply approximately 500,000MW annually of reliable, sustainable, zero-emission electricity to Arizona or California, enough to power up to 100,000 homes during peak electricity periods, says the company.

The project comprises 150MW of electrical generating capacity using concentrating solar power, plus 65MW of additional solar photovoltaic technology. Up to 10 hours of solar energy per day will be stored using the company’s molten salt power tower technology, says SolarReserve. Construction of the site, near Gila Bend, should begin late this year, or in early 2013.

New solar storage possibilities from MIT

Scientists at the prestigious Massachusetts Institute of Technology (MIT) have produced modified carbon nanotubes that can store solar energy indefinitely after being charged up by sunlight, says the university.

Although nano materials that store sunlight in chemical bonds have been produced before, researchers on this project say that the new material, which is made using carbon nanotubes in combination with a compound called azobenzene, has a much higher energy density than earlier solutions. In fact the energy density of this solutions is comparable to that of lithium-ion batteries.

Areva teams with Sandia for CSP storage

Areva Solar has announced it is collaborating with Sandia National Laboratories on a new concentrated solar power (CSP) installation with thermal energy storage. As the company’s online video shows, the CSP storage project combines Areva’s modular compact linear fresnel reflector solar design with Sandia Labs’ molten-salt storage system.

This will be the first CSP integration with Sandia Labs’ Molten Salt Test Loop System, located at the US Department of Energy’s National Solar Thermal Test Facility in Albuquerque, New Mexico, says the company.

Researchers trust rust for energy storage

An integrated solar cell that produces hydrogen as a form of energy storage is being investigated by researchers at the Ecole Polytechnique Fédérale de Lausanne (EPFL), in Switzerland. Converting solar to hydrogen is hardly a new idea, but so far solutions to the problem have been very costly. The EPFL system sidesteps this problem by using iron oxide, better known as rust, and water.

Of course, this is not common-or-garden rust but ‘nanostructured rust’: enhanced with silicon oxide and covered with a nanometer-thin layer of aluminum oxide and cobalt oxide. But it is still cheap to produce, say scientists at EPFL. The one drawback is low efficiency. At 1.4% to 3.6%, the prototype is not going into production anytime soon.

However, researchers are confident they can attain efficiencies of 10% in a few years, for less than USD$80 per square metre.

Concrete steps forward in thermal energy storage

It is cheaper than molten salt and causes less damage to heat tank walls than packed rocks, say engineering researchers at the University of Arkansas, who have developed concrete layers as a means of capturing heat from solar energy. reports that the concrete plates conduct heat with an efficiency of 93.9%.

Although this is slightly less efficient than the packed rock method, the specially developed concrete avoids the stress caused to tank walls because of the expansion and contraction of storage tanks during thermal cycling. In addition, energy storage using the new technique costs only USD$0.78 per kilowatt-hour, far below the US Department of Energy’s benchmark figure of $15 per kilowatt-hour.

Plant power to store energy?

Premier Global Holdings Corporation holds the rights to a pending patent for a combined solar power generation and storage unit based on photosynthesis, the process plants use to convert the sun’s rays into chemical energy.

Now DayStar Technologies, a developer of thin film photovoltaic solutions, has acquired the rights to the technology through its purchase of 100% of the outstanding shares in Premier, reports Solar Thermal Magazine.

The technology itself was originally developed at the University of British Columbia and consists of light-harvesting molecules suspended in an electrolyte and mediator molecules which store charge until extracted via electrodes. Needless to say, if DayStar can find a commercial application for the technology it would be a real game-changer.