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FUTURE-PROOFING
faster and has 50 times the cycle life. It operates safely
at temperatures of up to 40oC, slashing air conditioning
costs and even potentially eliminating the need for any
separate battery room. Li-ion batteries also have a 10-15
year lifespan, during which an SLA block would probably
require replacing up to three times. Overall, the total cost of
ownership for Li-ion could be anywhere from 10-40% less, so
any greater up-front investment is balanced out over time.
Exploring the possibilities
Despite ongoing uncertainty regarding the
Capacity Market, which was temporarily
suspended in November after a European
Court of Justice ruling found it breached state
aid rules, there are still a variety of incentives
provided by the National Grid to help balance
the electricity network. Its range of Reserve
Services cover any unexpected increases in
demand or a lack of generation. Under the
Short Term Operating Reserve (STOR), energy
users get guaranteed payments for two
years to either reduce demand or increase
generation at 10 minutes’ notice.
There’s Demand Turn-Up, which offers a fee
to encourage energy use at times of surplus,
for example overnight. And there’s Fast
Reserve, which helps balance out the demand
surges such as times where everyone goes and
turns the kettle on during advertising breaks
of massively watched TV events such as a
Royal Wedding or football World Cup. For data
centres though, probably the most viable and
rewarding entry point is Frequency Response, which aims to
deliver a consistent grid frequency of 50 Hz, with one hertz
latitude either side.
Firm Frequency Response (FFR) isn’t easy, as you must
be capable of feeding into the grid or reducing demand
by 10 MW within 30 seconds of an event such as a power
station tripping out. But Li-ion batteries are ideally suited
for this task thanks to their rapid response, fast ramp times,
and capacity to continually generate and absorb power. On
average the National Grid needs 800 MW of FFR capacity.
That’s an ongoing, consistent demand securing data centres
a strong return on the investment of deploying battery
storage in this way.
"The financial advantages for
a data centre of turning their
UPS into a ‘virtual power plant’
are obvious"
Reaping the rewards
The financial advantages for a data centre of turning their
UPS into a ‘virtual power plant’ are obvious – cash incentives
plus lower energy bills because the mains supply isn’t
needed during peak times. But think back to what the main
perceived barrier to participation is – the idea that using
batteries for anything other than an emergency backup
would compromise resilience. In fact, battery failure is one
of the most common reasons why a UPS doesn’t spring into
action when needed. That’s because SLA cells are hard to
monitor, so if they haven’t been called upon for a while, are
you certain they’ll be functional when you really need them?
On the other hand, Li-ion packs require advanced battery
monitoring, with each individual cell analysed to maintain
balanced stats of charge. As a consequence, this ongoing
monitoring ensures overall reliability is actually enhanced,
even though the batteries are being used for DSR too.
With one eye on the future, which data centre operator
wouldn’t want their UPS systems to be more than just
a simple, passive insurance policy when it’s clear they
can offer far greater value than that? Embracing battery
storage could give them a competitive edge, not to mention
future-proofing against what’s likely to be increasingly
stringent environmental rules and regulations. According
to the Renewable Energy Association and the All-Party
Parliamentary Group on Energy Storage, UK battery storage
capacity will top 8 GW by 2021. Now’s the time for data
centres to fully embrace the potential and reap the rewards,
not just today, but for years to come. n
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