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Where will we store our extra electrons?

July 15, 2010

Many people talk about energy shortages, but the reality is the US enjoys a surplus of electricity. That’s good and bad news. The good news is we don’t have an immediate need to build large scale base load capacity. The bad news is electrons can be very difficult to inventory in their native state. How best to do this was the subject of Storage Week hosted by InfoCast. This meeting discussed options for grid-scale electricity storage and also how to integrate this with the growing renewable energy base. The options are dizzying: Lithium-Ion or lead acid battery or super capacitors? Pumped hydro or compressed air? Stationary battery or flywheel? Do you need peak load relief or frequency leveling? Storage for hours of energy or only a few seconds?


The good news is we have lots of options and they all have strong merits for any situation. Most of our excess electricity is “stored” in retention lakes at high elevations where water is pumped up until it is needed. It is then released through a turbine and converted to electricity. The classic potential-to-kinetic energy conversion. Some electricity is used to spin up and maintain flywheels until loads dictate that it be released through generators to stabilize a drooping frequency when loads are high. The bottom line is we enjoy a nearly uninterrupted flow of electricity and this background technology enables us to turn on our AC, cook dinner, watch the HD TVs we all enjoy. As we add renewables to our electricity supply, especially wind and solar, these storage options will play more important roles since these sources are “spiky” in output and will need to be collected before they are used on the grid. And they may end up literally in your backyard as another option, Community Energy Storage, adds another utility box in your landscaping.



Photo courtesy of PJM




Union Station – Washington D.C. – erected in 1907 and still holding true in 2010



Submitted by: Kevin Arnold P.E.

EWI Energy Center