February 11, 2013

Low Cost, Scalable Energy Storage for renewables

I'd encourage you to take a look at this idea for low cost, scalable energy storage. 

Here is a link to the video from Google's Solving for X series

Danielle Fong dropped out of middle school at age 12 - to enroll at Princeton where she graduated at age 17. Now at age 24, she is running a company that is funded by Vinod Khosla called LightSail Energy

LIghtSail Energy plans to lower the cost of energy storage so that the cost of Wind Power + Energy Storage is less than the cost of electricity generated by gas peaking power plants. 

Her company, LightSail Energy, is working on technology to create easier storage of energy created from renewable resources.

"We're tackling what some call the holy grail of green energy: how to economically and efficiently store energy such that intermittent renewables such as solar and wind can reliably and economically power our electrical grid," Fong tells MNN. 

To do that, Fong and her team hope to store energy using compressed air. On the conceptual level, that idea works but on the practical level, there are several obstacles.

The challenge
The overriding problem in using compressed air for energy storage is the high temperature produced during the compression and expansion process.

"Hotter air is at a higher pressure, and requires more energy to compress the same charge of air into a given volume," Fong explains. "When the air cools, the pressure diminishes and accessible energy is lost. This is the main inefficiency with previous attempts at air energy storage."

Fong's concept, and the process used at LightSail Energy, is to spray a fine mist of water during the compression or expansion process. The water captures the heat, keeps the temperature at a constant low level, and can be held in a water tank or routed into a building for usage.

The process is called regenerative air energy storage, or RAES for short, because it regenerates usable energy from the heat generated during compression. This bonus output nearly doubles the efficiency of compressed air storage to 70 percent in both directions — compression and expansion.

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