Renewables, such as wind and solar, are by their very nature only able to generate power intermittently. Without a cost-effective method of large-scale energy storage and recovery, renewable energy sources will never be viable.
Other non-fossil fuel-based sources of power generation, nuclear in particular, are not able to operate at varying power levels. Even if nuclear power alone were to replace fossil fuel-based generation, the only method of handling variations in user demand, without widespread use of a suitable storage technology, would be to create an excess of generation capacity to handle peak load, then simply dump this excess when it is not required. This is both wasteful of equipment and an inefficient use of energy.
Nuclear plants also have very high capital and de-commissioning costs. It is more cost-effective to have a smaller number of plants operating at peak efficiency 24-hours a day, with demand variability accommodated by energy storage.
Pumped Hydro is a well-proven technology where the local geography allows its use. It currently accounts for 99% of all large-scale electricity storage. However, there is a diminishing number of suitable sites and the sites are rarely co-located with the best grid points for storage.
Other forms of storage such as flow batteries are significantly more expensive than PHES and often involve the use of environmentally harmful chemicals, some of which are of very limited availability.
Isentropic's PHES uses conventional metals within the machine and the storage medium is very lightly processed (crushed, graded and cleaned) mineral particulate.
Effective energy storage is required to: