Page 19 - Vol 33 Issue 34 2021

mining

At the point of use, for large power uses
like industrial and manufacturing facilities and
commercial hubs, ES plants can improve power
quality and reliability, provide un-interruptible
back-up power and reduce grid interconnection
and energy cost by shifting their power
consumption away from times with high grid
congestion and corresponding high peak power
and capacity rates. ES plants can also open the
door for facilities to build their own wind or solar
plants to store and smooth the produced energy
for their own use or to export to the grid at peak
demand times. Some ES plants, like liquid air
technology, can also utilize waste heat and cold
produced at the site to further lower the overall
cost of energy for the site.
During a sunny day, there is an overabundance dition to our example of time shifting re newable Technology Choices
of energy from solar plants, well beyond that power, ES plants can be used to improve the
needed to serve load. The first job of an ES plant ramping response of slower power plants to for Energy Storage
is to store the excess solar energy over the 11- balance the minute-by-minute up and down
hour daytime period and then release it later output of wind and solar plants. No single technology can provide all the needed
in the evening and in the early morning of the ES plants can also provide both real and ES services. A portfolio of ES technologies placed
following day. This allows full utilization of the reactive power for fast acting voltage and at optimal locations across the grid or behind-
energy produced by the solar plants with the frequency control. Those ES plants utilizing the-meter (BTM) is needed to achieve the most
beneficial market result of smoothing out energy spinning AC generators can also provide inertia reliable, flexible and economical solution.
prices over the entire 24-hour period. for grid stability and black start services needed Optimum spots for ES plants will depend on grid
But the solution needs to go beyond just to establish the reference grid frequency to re- design and the distribution of generating plants
smoothing out energy supply, it also needs to energize a grid after a complete black-out. and loads unique to each grid.
maintain or restore grid stability. Since the ES At the transmission and distribution level, The services, range of capacity and energy
plant allowed the full utilization of the available ES plants can relieve congestion and avoid discharge duration best suited for each ES
solar energy, for the entire 24hour period most technologies available today, both from an
of the energy on the grid will be coming from curtailment of wind and solar plants by storing economic and functional capability aspect. They
asynchronous power sources which lacks the electricity during periods when grid congestion is are all needed to even-out power, reduce grid
inertia provided by synchronous power. high and then releasing it at off peak times. ES congestion, provide inertia for stability, control
If a grid upset were to occur over this period, it plants can also provide reactive power for local voltage and frequency to support the expansion
would be very difficult to control and likely would voltage control and those with AC generators can of wind and solar.
result into an extended upset, tripping additional add inertia to improve stability at points across
plants and loads off the grid as frequency and the entire T&D network. In many cases, ES plants (To be continued in next edition)
voltage levels exceed predetermined safe levels. can be a faster, lower cost and more flexible
ES technologies that connect AC motors and alternative to traditional T&D solutions of adding
generators to the grid need to be an important more cables, towers and substations.
part of the complete solution.
In essence, ES plants need to
restore the inertia lost from the
continued retirement of fossil
and nuclear steam power plants.
Beyond this one solar inte-
gra tion example, there are ma-
ny other ways ES can help us
achieve high levels of renewable
ener gy across the entire elec-
tri city supply chain. ES can be
ap plied to the beginning of the
supply chain at the point of
power generation, to the trans-
mission and distribution net-
work and finally at the point of
electricity use.
At the generation level, in ad-

AFRICAN POWER Mining & Oil Review Vol33 Issue 34 2021 | 19