Will Gravel Batteries Improve The Energy Efficiency of Solar Panels and Wind Turbines?

Salvatore Cardoni holds a political science degree from the George Washington University. He's written about all things environment since 2007.

Two clean energy technologies long thought to be the silver bullet in the heart of climate change—solar and wind power—have an inherit flaw: intermittency.

What to do when the sun goes down and or the wind stops blowing?

Install a giant battery that can store the energy using gravel, says Isentropic, the British energy company behind the new idea.

"If you bolt this to a wind farm, you could store the intermittent and relatively erratic energy and give it back in a reliable and controlled manner," said Jonathan Howes, Isentropic’s founder, to The Guardian.

The step-by-step process behind the technology is a bit complicated, so bear with us:

1) Two silos filled with rock, such as gravel, would be installed on a solar or wind farm.

2) A gas is fed into one of the silos, heating the gravel to around 932 Fahrenheit.

3) After leaving the first silo, the gas then enters the second silo, where it expands back to normal atmospheric pressure. This gas-swapping process acts like a refrigerator, forcing the gravel inside the second chamber to drop to -256 Fahrenheit.

4) The energy—which originated from the solar panel or wind turbine—is then stored as a temperature difference between the two silos.

5) To release the energy, the cycle is simply reversed, thereby powering an attached generator that producing electricity.


Don't be, as all the lay person really needs to grasp is that this complicated process is economically simple.

Isentropic says that the gravel-storage is a far cheaper method than the alternative: pumped hydro – where leftover electricity is used to pump water up a hill. "The water is impeded by a dam until the energy is needed, when it is released down the hill, turning turbines and generating electricity," reports the Guardian.

Quick Study: Energy Efficiency | Solar Energy | Wind Energy

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