Physics! Redefining Batteries

August 2, 2013 by Taylor Studios in Professional & Industry Tips

In a much earlier blog entry, I mentioned how battery technology was a crucial next step in making solar and wind power comparable to power derived from fossil fuels. At that time, I was focused on the types of chemical batteries being produced or researched. However, through my reading and wandering through the internet, I have expanded my definition of a battery. For my purposes, I now consider a battery an energy storage system. Why so broad? Because there are several technologies in development and in use that use chemical and physical energy storage, but have little to do with the heavy cylinders we put in flashlights.

A crucial aspect to consider about energy storage is scale. D-cell batteries are very small-scale energy storage. When you start talking about megawatts/hour (MWh) or gigawatts/hour (GWh), even your car’s lead-acid battery is small. If you are living off the grid and have a small wind turbine or a solar array, you probably use a multiple lead-acid battery system. At the other end of the scale are power companies trying to integrate fossil fuel power and renewable power. When the wind is blowing or the sun is shining, some of that energy is stored by the power company using several different technologies. The most popular is , which uses two water reservoirs at different elevations. At times of high electricity production, water is pumped from the lower reservoir to the upper. When the demand for power peaks, the water is released from the upper reservoir and heads down to turbines at the level of the lower reservoir.

Large solar arrays use a in which concentrated solar reflectors heat a non-toxic salt mixture to over a 1,000 degrees Fahrenheit. This super-hot liquid can then be stored in well-insulated tanks for up to a week before being pumped out as needed. The hot salts are used to create super-heated steam that drives a turbine. Another mid-scale technology is a flywheel system, which accelerates a large flywheel to top speed when electricity is plentiful. At peak demand, the system uses the spin of the flywheel to generate electricity, which slows the wheel down.

A new twist for the mid-scale market is using automated train cars that run on a closed rail system on an incline. This concept is being developed by . Each weighted car is in contact with a parallel conductor rail, which powers the car’s electrical motor to move it up the incline, and then also transmits the power created by the car’s regenerative braking when it rolls down the incline. In the rendering above, the solar power moves the cars up the incline. When the clouds move in, cars move back down the rail, transmitting electricity as they move. In this way, electrical energy is stored as potential energy in the mass of the car. To scale the system up, add more tracks and more train cars.

I am rather pumped about all the options, and it gives me a lot more hope that renewable energy is here for the long haul. Did any of these technologies give you a “Wow!” moment?