Critics of renewable energy always bring our the 'red herrings' of what if the wind does not blow? or the sun doesn't shine?

Or what if everybody had electric cars, how would the grid couple at night if you wanted to use only renewable energy?

Lithium iron-based batteries are getting cheaper and can smooth the grid, but longer-term cheap storage of excess renewable energy is also required. Pumped hydro is restricted to specific locations and is expensive to set up, although very cheap to run once it's going.

What is the solution? SAND! Polar Night Energy is developing a way of storing cheaply produced renewable energy in common sand. Heating it up to 500 degrees, it can be tapped into months later as required. For example, during the long and cold Finnish winters, where Polar Energy is based.


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