Renewable energy is growing but storage is one of it’s biggest problems. We need to be able to store turbine energy for windless days and solar energy for rainy days otherwise we can never discount dependency on fossil fuels.
Present technologies for storage include: (a) pumped hydroelectricity schemes where water is pumped back up into a vast reservoir and stored as potential energy then released through turbine generators, but here there is little potential or inclination for new reservoirs, and installation costs are high.
(b) Lithium-ion or Lead-acid batteries are quick to respond to demand but are not seen as long term solutions – cost $154/kW year ($187 for lead-acid)
(c) Compressed air energy storage is another possibility where compressed air is stored underground but has disadvantages of heat generation on compression lowering efficiency to 50% – adiabatic compression raises it to 62% but this is still quite low – advantage high storage capacity – cost unknown
(d) Gravitricity utilises old disused coal or metal mine shafts by suspending weights of 500 to 3000 tonnes which are raised by motors to the top gaining potential energy, then lowered to release energy through generators – cost $141/kW year
(e) Flywheel energy storage whereupon mass flywheels are run up to speed, usually in a vacuum, via motors then energy is released when switched to generator mode that slows them down – cost $312/kW year
The consensus of opinion is to use a combination of all technologies to supply quick energy response along with longer term storage capabilities, whereupon the technologies are also linked and managed.
Option (d) I find personally interesting because it is efficient, has a relatively quick response time and utilises an old and redundant fossil fuel industry, bringing some employment back to potentially deprived area. In a word ‘regeneration’ !
Hope you have a good month
All the best
“Failure is simply the opportunity to begin again, this time more intelligently.”
“Stay away from negative people. They have a problem for every solution.”
ps If you have enjoyed the blog please forward to those who might be interested, many thanks in advance, Mike