Environmental Engineering Reference
In-Depth Information
and the speed of the rotation determines the amount of energy stored; smaller flywheels are
used to stabilize voltage and frequency while larger flywheels can be used to dampen load
fluctuations.
Other energy storage technologies include thermal energy storage, in which energy is
stored in heat either collected in molten salts or synthetic oil, or - in the case of end-use
thermal - in hot or cold storage in underground aquifers, or water or ice tanks. The
ultracapacitor is another technology useful for backup power during brief interruptions;
this electrical device can store energy by increasing the electric charge accumulation on
its metal plates and can discharge the energy by releasing the electric charge on the metal
plates. A final energy storage technology is superconducting magnetic storage, which is a
winding coil of superconducting wire; changing the current in the wire can add or release
energy from the magnetic field. Advantages of this technology are that energy can be
stored indefinitely with minimal losses, high reliability, and low maintenance because the
parts are motionless and at steady state the wires release no energy. A disadvantage of
superconductors is the refrigeration required.
These energy storage technologies all have potential, but are also all associated with a
wide spectrum of costs and distributed benefits among actors (the next chapter describes
the main categories of different actors). The different technologies have different salience
in different contexts, and there is no “one-size-fits-all” approach to valuing the benefits of
these technologies (California PUC 2010 ) .
While energy storage technologies are a potential game-changer for electricity systems
and these technologies have critical potential as smart grid technologies, many remain too
costly for widespread deployment. These technologies are important not only because of
their impact on enabling renewable integration, but also to allow a lower overall cost of
electricity. The system flexibility provided by energy storage could be valuable in multiple
ways.
3.3.4 Distribution Network Technologies for Smart Grid
Multiple smart grid technologies focus on enhancing the efficiency and resilience of
distribution networks. Microgrids and substation automation are two broad categories of
technologythatofferimportantsmartgridpotential.Microgridsaregenerallyconsideredas
anyconfiguration oftechnologies that forms asingle electrical power subsystem associated
with distributed energy resources (Mariam 2013 ). Microgrids offer self-reliance and the
potential for “islanding,” which means the ability to separate completely from the larger
grid under certain circumstances.
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