Georgia Magazine - May 2019 - 24

GEORGIA'S Energy Outlook

By Alan C. Shedd

TESLA

Battery storage units charged by solar
arrays help to power Kauai.

Utility-scale energy
storage solutions

n last month's article about energy storage (see bit.ly/geapr19), we
looked at some of the applications for energy storage, the history of battery development and why battery storage technology is important to
consumers and your electric membership cooperative (EMC).
Now let's dig a little deeper into battery technology, discuss the most
common and promising battery types and take a look at how an EMC is
using a large utility-scale battery to meet energy demands and save
members money.
Rechargeable lead-acid batteries have been used for a century to store
the electricity needed to crank a car's engine, power a golf cart and provide
backup power. These batteries are readily available and inexpensive, but
they are heavy and-depending on their use-have a limited "cycle life"
(the number of times they can be recharged). Over the past 30 years, other
types of batteries have been used increasingly in rechargeable tools, toys
and consumer electronics. Nickel-cadmium, nickel-metal hydride and
lithium-ion batteries weigh less, store more energy per pound and have
longer cycle lives, but they cost more.
Today's cellphones, laptops and electric vehicles are powered by
lithium-ion batteries. The cost of these batteries has dropped 70 percent
over the past six years due to increased production. Falling battery prices
have made it economical to build large, utility-scale lithium-ion batteries
capable of storing energy and delivering it, as needed, to the electric grid
and consumers.
A lithium-ion battery provided a utility-scale solution on the Hawaiian
island of Kauai, where the Kauai Island Utility Cooperative (KIUC) supplies power to 33,000 electric accounts. In 2010, 92 percent of the island's
electricity came from generators operating on imported fuel oil, resulting
in an electricity cost of 37 cents per kilowatt-hour-three to four times what
we pay in Georgia.

Georgia Magazine

May 2019

Recently, KIUC has added more
solar power, which is good for the environment, reduces oil imports and can
lower electricity costs. During the day,
solar now supplies up to 90 percent of the
island's energy needs, but there's a catch:
Hawaii is in the tropics, and the sunny
skies are punctuated with puffy white
clouds. Each time a cloud passes over a
solar field, power output drops suddenly,
then bounces back. To fill in the demand
for power during these brief periods, the
cooperative has kept conventional power
plants running. This is expensive and
has created problems for the island's
electric grid.
In 2016, KIUC installed its first large
battery as part of a solar project. The battery, manufactured by Tesla, is charged
by a 13-megawatt (MW) solar array and
can store 52 megawatt-hours (MWh) of
electricity, which is enough to power 52
homes for a month or 1,500 homes for 24
hours. When needed, the battery delivers
power for up to four hours for the co-op's
consumer-members. Based on the success of that project, the electric cooperative installed a second, larger solar array
and battery system in 2018 that is capable
of producing 20 MW of solar power and
storing 100 MWh. A third system is being
constructed.
These systems and other projects
undertaken by the electric cooperative
have helped reduce its members' average
power bill by 26 percent, reduced dependence on imported oil and are helping
KIUC meet its goal of generating at least
70 percent of the co-op's electricity from
cost-effective, renewable sources by 2030.
Here in Georgia, the state's EMCs are
deploying solar resources and researching energy storage systems and other
high-efficiency electric technologies to
help provide safe, reliable and affordable
electricity to members.
Alan C. Shedd is the director of
sustainability for Tucker-based Oglethorpe
Power Corp.

http://www.bit.ly/geapr19

Georgia Magazine - May 2019

Table of Contents for the Digital Edition of Georgia Magazine - May 2019