How we get there

We need to continue out investment in renewable energy technologies and also Cap Carbon to put a price on emissions. Both of these things will make wasting energy and using inefficient power sources more expensive and encourage the building of large scale storage systems.

We also need to advance the technologies being considered for large scale storage systems. Below you can learn about all the major systems being described. Contact your utility company to see if it takes advantage of any of these technologies or intends to in the near future.

Pumped Water

This system uses two reservoirs, one higher than the other. It pumps water up into one of them with excess energy and then uses it like a traditional hydroelectric source when demand is high. This system recovers 75% of energy stored, is currently most cost effective method, and can come online in 15 seconds. There are 90GW energy stored around world, which represents 3% of world's current instantaneous generation capacity. There is also talk of using wind directly to move water uphill to let it fall and collect the energy later. This sort of system is limited by geography, as you need two large bodies of water separated by a reasonable height.

Compressed Air

Compressed air storage consists of using electricity to force air into space, raising its pressure, and then releasing it from the high pressure vessel to power a turbine or compressed air engine. Large scale storage could be underwater or underground in old mines. This is one of the more viable technologies out there currently, but is limited due to geography.

Thermal

Storing energy as thermal energy, or heat, usually involves storing energy in water, salts, citric acid, or any number of other materials. These systems add heat to a material using excess energy and then later remove it and turn it into steam. One of the methods of thermal storage is something called Phase Changing Materials, that turn from solid to liquid when heat is added. Most thermal storage systems require very high temperatures and so need very well insulated storage tanks. They also may need a lot of a material to be able to store significant energy.

Batteries

Another option for large scale energy storage that is actually being implemented in some test cases is the use of batteries. These systems require truck-sized batteries often at the point of generation. The battery technologies being discussed are Lithium Ion batteries, which are also being researched for electric vehicles, and sodium-sulfur batteries that are supposed to be more durable and less expensive. Also a part of the battery option is the potential to use electric vehicles plugged into the grid for evening out demand spikes. For example, if your refrigerator kicks on, it can pull the energy for that spike from your car, and then the electrical grid can just take a couple extra minutes to recharge your car at its own pace. You can read more about this in the Smart Grid and Electric Cars sections.

Flywheel

A flywheel setup has an electric motor turns large wheel, which can then be slowed down and produce energy through a generator. They are made of benign materials and and have limited overall negative impacts, but their size and cost limits their usefulness in utility-scale storage. Still, they are a focus of many for providing some storage capacity.

Hydrogen

Hydrogen energy storage is just that, energy storage, not a means of creating energy. It involves using electrolysis to split water into H2 and O2 which then must be stored before being recombined to create energy, a process with about a 50-60% total efficiency as a best case scenario. Hydrogen storage is a fairly simple process and does not lose energy by being stored over time, but does require rather large storage tanks and has a relatively low overall efficiency.