Renewable energy storage is mostly about banking some form of solar energy. It may seem simple, but exactly how do you save energy for use later, or for use in some other location? It is a big problem.
With non-renewable energy, trees, shrubs and other plants concentrated sunlight into wood and other biomass. Entire forests grew, died, got compacted, then were turned into coal, gas, and oil and stored in rocks. These fuels packed lots of energy in portable places and stored well until needed.
It took millions of years to consolidate vast quantities of this natural plant energy. This is natural renewable energy storage. However, over the past few thousand years, people have been using this energy at an ever increasing rate. Burning all that fuel in a fraction of the time it took to make it has put a lot of smoke and other junk into the air faster than it can be dispersed. Cough, cough.
Now that a big chunk of the saved energy is burned up, the problem facing people is how to build that solar energy account back up that took nature such a long time to accumulate.
We can generate electric energy all kinds of ways including hydroelectric, windmills, solar panels, tidal energy, and geothermal wells to name some. The problem is: How do you save the electricity you just generated, or move it a long way to use it somewhere else? This is the problem of renewable energy storage.
Since people didn’t really need to, they didn’t work too hard in the past to bank energy in a big way. Recently a few tried and true methods have been expanded, and a few new methods have been devised to store energy.
A few of the more commonly used renewable energy storage methods are electrical and thermal. This generally means batteries and some kind of hot fluid.
Storage Batteries: Storage batteries have been around for the past 150 years or so. Recent developments in utility scale storage batteries may be helping store renewable energy. Technical details are here.
Storing energy in grid facilities may be another way to go. This is the so called Smart Grid.
One other practical storage device might turn out to be the capacitor, though currently the resident time of energy stored this way is pretty short.
There is some research being done on storing mechanical energy as well. This would include mechanical flywheel devices. One interesting proposal in progress is compressed air storage.
Lithium Ion storage facilities are underway. A 32 megawatt project in West Virginia takes wind energy and stores it in a bank utility scale of Li-Ion batteries. EV company Electrovaya has deployed 1.5 MW Li-Ion leveling batteries in the US.
