Page 46 - Impiantistica industriale Luglio Agosto 20147

fexibility including their ability to daily availability of a suitable technologies at competitive
cycling capital and maintenance costs.
- improve coal fred units load change Energy storage plants may be essential when
rate to higher value (about 8%/min) and managing large quantities of variable renewable
combining this modifcation with steam generation as well as to supply peak loads.
turbine manufacturers In addition enabling wind integration into the
- reduce once through coal fred boiler generation mix, energy storage can help utilities to
minimum load to 10-15% from present 35%. reduce GreenHouse Gas (GHG) emissions.
Large-scale storage has in the past usually meant
Being the capital cost and O&M of the energy pumped hydro or compressed air. Sites for
storages high, the improvement of fexibility and constructing new large pumped hydro storage are
availability also to daily cycling of existing and few, limited by topography and consideration of
new fossil power generation units could be the the environmental impact of such large schemes.
alternative to the increase of energy storages. Compressed air energy storage is also constrained
In the case 4) power generation is almost totally by the availability of suitable caverns or rock media
supplied by renewables and integration from other for the air storage. But today due to the large
sources will be not required. impact of renewables within power grids, it is also
Authorities must defne what is the most competitive becoming very important the ability of the storage
case for their network, comparing the costs of the systems to switch rapidly from charge to discharge
different solutions. and to supply real and reactive power within the
same time within distribution grids. In addition for
2. Classifcation of the this new service the above mentioned mechanical
technologies (pumped hydro storage and air
different energy storage storage) are no more suitable in many cases due
systems (including hydro, to their delay in response time.
In addition pumped hydro storage and air storage
chemical, cryogenic, gravity usually are not suitable to store the not needed
power modules, CAES, energy produced by renewables, being mainly
located far from the RES (Renewable Energies
capacitors etc.) Storage) plants.
The classifcation of EES is usually made according
Table 1 - Different energy The increased use of energy storage on power to the form of energy used.
storage technologies networks has been limited up to day by the Table 1 indicates the long list of possible different

Mechanical electrical
Fly Wheels Adiabatic Compressed Super Capacitors Superconductivity
Air (CAES) Magnetic Energy
Storage (SMES)
Hydro Pumped Diabatic cheMical
Storage Compressed Air
Gravity Hydro Liquid Air Storage Hydrogen Natural Gas
Power Module
Pumped Heat
Electrical Storage
therMal
Heat (Hot Water - PCM -Phase Change Material) Molten Salt (CSP - Concentrated Solar Power)
Packed -Bed Heat Storage Smart Electrical Thermal Storage

electrocheMical
classic Batteries Flow Batteries
Lead Acid Li-ion Vanadium Zn-Br
Li-Polymer Li-S Red-Ox
Metal Air Na-Ion
Na- NiCl Na-S
Ni-Cd Ni-MH

42 Impiantistica Italiana - Luglio-Agosto 2014