The relative cost-effectiveness of fossil fuels (which are often cheaper than alternative energy sources) are keeping the world in a state of dependence on coal, oil and gas. The current state of energy consumption is far from static, however. All of the various sources of energy are experiencing major technological breakthroughs, with none more significant than in the field of energy storage.
The transition from fossil fuels to clean energy would be expedited if renewable energy storage was simply more affordable. The long-term cost-efficiency of clean energy, the obvious benefit of minimizing damage to the earth’s environment, and advancements in new production and storage technologies are undeniable positives. Storage continues to make the progression toward renewable energy and away from fossil fuels more and more of a fluid evolution.
Widespread future use of renewable energy sources such as sun and wind seem dependent on the development of effective, affordable means to store excess energy. The primary means of r.e. storage depend on the energy source, and therefore vary greatly. However, some of the most utilized methods include:
1. Pumped storage (PH - pumped hydro)
2. (CAES) - compressed air energy storage
3. Batteries (lithium-ion, nickel-iron, flow etc...)
4. Hydrogen/ fuel cell *
5. Ice/ thermal storage technologies**
7. Capacitor/ supercapacitor***
Pumped hydro remains the most popular means for storing clean energy for utilities. Pumped hydro is often the most cost-effective means of storage for large-scale projects. CAES (compressed air energy storage) is dependent on having a underground chamber, mine or locale for storing the compressed air, but is also a method of energy storage which is growing in popularity. CAES is more location-dependent then pumped hydro. To implement pumped hydro, all that is needed is an area in which both a higher and a lower reservoir can be developed. As these areas are relatively easy to discover, this technique is more widely used than CAES.
Two technologies which seem very promising, but need to be developed more to become cost-effective, are electric vehicle (EV) storage (using the EV's battery) and hydrogen storage. The good news is that EV's are gaining in popularity world-wide. It remains essential that the energy to charge the EV comes from a renewable energy source.
* hydrogen is discussed further in the Clean Hydrogen in European Cities (CHIC) article
*** yet to be addressed here