Tech Briefs Magazine - July 2021 - 41

Power & Energy
Flywheel Energy Storage Continues to Advance
Green Initiatives
Flywheels offer an environmentally and financially sound choice for protecting critical operations.
VYCON, Inc., Cerritos, California
E
nsuring continuous electrical power
within mission-critical facilities is top
of mind for today's facility managers, data
center operators, hospital IT managers,
and electrical engineers. Thoughtful
planning, design, equipment selection,
and maintenance of an organization's
power infrastructure is vital for continuous
operations. According to U.S. Energy
Information Administration findings,
typical utility customers experienced
nearly six hours of power interruptions
in 2018 in the U.S., largely a result of
severe weather or devastating wildfires.
With businesses losing upwards of $150
million as a result of blackouts (according
to the U.S. Department of Energy),
protecting against power outages and
disturbances is essential. Equally important
is incorporating environmentally
friendly power solutions to advance
organizations' green initiatives.
Uninterruptable Power Systems (UPS)
with valve-regulated lead-acid (VRLA)
batteries have traditionally met needs
for instantaneous backup power during
a power event. Although lead-acid
batteries are a known resource, they
have high environmental and operational
costs. Main tenance, frequent
replacement, spill containment, and
environmentally responsible disposal are
also considerations.
More recently, Lithium-ion batteries
serve as an energy storage option with
UPS. Lithium batteries have higher
energy density and longer life than
VRLA batteries; however, they have disadvantages,
including initial cost, and
may require extra floor space for potential
fire spread.
The chemical nature of batteries
means there is no commercially available
" perfect " battery - yet. Every
chemical type has considerations. But
mechanical-based energy storage solutions
can offer a safer and environmentally
greener approach.
During a power disturbance, a flywheel
system provides instant backup
Tech Briefs, July 2021
Cov
Genset
AC
UPS System of Choice
Static By-Pass
Automatic Transfer
Switch
Utility
AC
DC
AC
Rectifier
AC/DC
DC Bus
Inverter
DC/AC
Critical AC
Output
VYCON VDC
Figure 1. Flywheel system interface.
power to seamlessly bridge the critical
gap in power until the facility's generator
comes online. A flywheel operates
like a dynamic battery that stores energy
kinetically, spinning a mass around an
axis. Electrical input spins the flywheel
rotor up to speed and a standby charge
keeps it going until called upon to re -
lease the stored energy.
Flywheel systems connect to the UPS's
DC bus just like a battery bank, receiving
charging current from the UPS and providing
DC to the UPS inverter during
discharge (Figure 1). Upon loss of utility
power, up to 450 kW of regulated DC
power per flywheel is delivered instantly
to the UPS. This provides the power
needed to start and transition to the gen -
erators during a prolonged outage.
Multiple flywheels can be paralleled for
longer run times or N+1 redundancy.
The highest-reliability flywheels offer a
20-year operational life and feature a
high-speed permanent magnet motorgenerator,
fast recharge, magnetic levitation,
no bearing replacements, and an
intelligent monitoring system. For an
added layer of protection, flywheels can
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ToC
Figure 2. VYCON's VDC XXT Flywheel System.
41

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