Environmental Engineering Reference
In-Depth Information
5.6 Renewable energy integration
In order to aid the integration of renewable resources, energy storage can be used to:
1.
Store renewable energy during off-peak time periods for use during peak hours
(diurnal time-scale)
Match the output from renewable resources to the load required in the electric-
2.
ity market time-scale (quarter hour)
Smooth output fl uctuations from a renewable resource in the millisecond to
3.
second time-scale
Signifi cantly enhance the capacity factor (output which can be considered reli-
4.
able) and associated payments attributable to wind
Facilitate the maximum inclusion of renewable electricity, by storing electricity
5.
from conventional generation for periods when total generating capacity cannot
supply demand
A storage system used with renewable technology must have a power capacity of
10 kW to 100 MW, have fast response times (in some cases less than a second),
excellent cycling characteristics (100-1000 cycles per year) and a good lifespan.
5.7 End-use applications
A survey in the US estimated that losses due to end-use and UPS applications were
between $119 billion and $189 billion [2]. The most common end-use application
is power quality which primarily consists of voltage and frequency control. Transit
and end-use ride-through are applications requiring short power durations and fast
response times, in order to level fl uctuations, prevent voltage irregularities and provide
frequency regulation. This is primarily used on sensitive processing equipment.
5.8 Emergency backup
This is a type of UPS except the units must have longer energy storage capacities.
The energy storage device must be able to provide power while generation is cut
altogether. Power ratings of 1 MW for durations up to 1 day are most common. For
outages of several hours, days or weeks, diesel generators are more cost effective.
5.9 Demand side management
Demand side management (DSM) involves actions that encourage end-users to
modify their level and pattern of energy usage. Energy storage can be used to
provide a suitable sink or source in order to facilitate the integration of DSM.
Conversely, DSM can be used to reduce the amount of energy storage capacity
required in order to improve the network. Ultimately, the goal is to match con-
sumption with generation by attributing some intelligence and control ability to
the consumer, fi rst at the industrial-scale and then domestic with tariff and other
incentives for peak avoidance.
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