Definition of Electrical energy storage:
1- EES technology refers to the process of converting energy
from one form (mainly electrical energy) to a storable form and reserving it in
various mediums; then the stored energy can be converted back into electrical
energy when needed(1). Such a process enables electricity to be produced at
times of either low request, low production cost or from intermittent energy
sources and to be used at times of high demand, high generation cost or when no
other generation means is available.
provides options to offset the mismatch between demand and
supply and to operate the distribution system in a more efficient, economic,
and environmentally sound manner(1.1). Lastly, with smart grid technologies and
energy storage in place, benefits to residential consumers will include cost
savings from peak load management, energy efficiency, and increasingly
affordable distributed renewable energy systems. On the other hand, smart grid
in turn also provides opportunities for load control and dispatch of storage
units making renewable sources such as solar PV and wind more valuable to the
For an example If your home is connected to the grid, an
electricity battery will help you make the most of your renewable electricity,
meaning your electricity bills will be cheaper and your CO2 emissions will be
lower(1.1.1). In an off-grid
home, battery storage can reduce your reliance on an alternative fossil
fuel electricity generator.
Another benefit of storing energy systems is their
resilience. About the old system to produce electricity systems can be knocked
out by earthquakes, cyclones, floods and terrorism; decentralized systems are
less likely to be affected.
EES can have many attractive value propositions to power
network function and load balancing, such as(2):
Helping in meeting peak
electrical load demands.
Providing time varying
intermittence of renewable source power generation
Meeting remote and vehicle
Supporting the realization
of smart grids
Helping with the management
of distributed/standby power generation
Reducing electrical energy
import during peak demand periods.
Applications and benefits of energy storage
Apply energy storage to supply ancillary services such as
frequency regulation or to act as spinning reserves for the electrical grid is
proving to be a successful business model that has minimal operation and
maintenance costs – with a significantly lower carbon footprint than
conventional generation. For frequency regulation applications, the ESS is
charged or discharged in response to an increase or decrease, respectively, in
grid frequency caused by a sudden misalignment of energy supply and demand.
This approach is particularly attractive due to its rapid response time and
effective spinning reserve, the ESS is maintained at a level of charge ready to
respond to a generation or transmission outage. The system could react within
milliseconds to supply power to enable network continuity while the backup
generator is started and brought online. This will enable the generator to work
at optimum power output, without the need to keep idle capacity for spinning
The load level usually involves storing power during periods
of light loading on the system and delivering it during periods of high demand.
The beneficial must design their network according to the peak
power usage capacity, having energy storage strategically located next to the
load allows for the postponement of investments in grid upgrades or new
Load leveling and Peak shaving is similar but is for
reducing peak demand rather than for economy of power system operation. Peak
shaving installations are often owned by the electricity consumer rather than
by the utility. Commercial and industrial customers benefit from optimized
time-of-use energy cost and demand charge management.
Downstream loads against short period events can be
protected by having an energy storage system which is widely used in quality
applications. For instance, voltage fluctuations due to events such as power
equipment failure, tree branches falling on the power line or the variability
of power output from solar photovoltaic (PV) plants and wind farms, can have
adverse impacts on the quality of power delivered to electricity consumers.
These power quality issues can lead to brownouts and
possibly a complete power interruption. ESSs can provide instantaneous voltage
support by injecting or absorbing both active and reactive power. In addition
to voltage support, the ESS may serve as an uninterruptible power supply (UPS)
that can bridge unplanned disruptions in service, thus further enhancing the
quality of power supplied to the energy consumers.
Maintaining the variable, intermittent power output from a
renewable power plant at a committed (firm) level for a period is called capacity
firming. The Electrical Storage systems smoothes the output and controls the
ramp rate (MW/min) to eliminate rapid voltage and power swings on the