POWER August 2017 - 40

RESILIENCY
3. Producing energy in the desert.
This solar array is part of a microgrid project
operated by Italian energy giant Enel. The
project, in the Atacama Desert in Chile, was
commissioned earlier this year. It merges 125
kW (peak) of solar PV with two energy storage
systems, one based on hydrogen and the
other lithium-ion battery storage. Courtesy:
Enel
used to heat living and working quarters, and
the balance released to the atmosphere.
The plant had been operating for more
Microgrids Are Old, and New
Microgrids could be the next big thing in electric
power generation, but they are not new.
The modern power business began more than
a hundred years ago with a bunch of small,
unconnected grids serving cities around the
country. Some were investor-owned, and
some were owned by local governments.
These early systems expanded until the favorable
economics of interconnection into a
large grid became clear.
Power systems to serve remote locations
unable to connect to a conventional grid, or
needing continuous power for critical operations,
have been around for more than
50 years and continue to prosper. Military
bases and hospitals were among the earliest
of microgrid projects, and the military took
the lead.
In the 1950s and 1960s, the Atomic Energy
Commission (AEC, predecessor to
the U.S. Department of Energy) and the
Department of Defense (DOD) put significant
resources into finding ways to provide
remote military bases with reliable electric
power when those bases were unable
to connect to a grid. The AEC developed a
prototype small nuclear generating plant at
the Idaho National Reactor Testing Station
(NRTS) in Idaho's remote eastern desert.
That was the site of what nuclear engineer
and historian James Mahaffey describes in
his 2014 book Atomic Accidents as " the
strangest and most tragic reactor accident
in American history. "
The AEC and DOD developed a reactor
design, called SL-1 ( " stationary low-power
reactor, version one " ) aimed at powering distant
early warning system (or " DEW Line " )
radar stations inside the Arctic Circle aimed
at detecting incoming Soviet missiles during
the Cold War. A demonstration plant went up
at NRTS. As Mahaffey details, the plant was
a 3-MW (thermal) boiling water reactor, with
200 kW converted into electricity, 400 kW
40
than two years when on the night of January
3, 1961, a crew of two operators and a
trainee were killed. One of the operators-
against all instructions-physically lifted
the main control rod on top of the reactor
far more than was safe. The machine went
prompt critical in 2 milliseconds, a steam
explosion resulted, and all three men in the
plant perished, one of them pinned to the
ceiling by the control rod.
The military's attitude toward small reactors
dimmed, although the Army did deploy
small units in Greenland, Antarctica, Alaska,
Wyoming, and Panama. The military and
other users of self-generation then turned to
diesel engines for generation at internal microgrids.
While reliable, diesels use expensive
fuel and create polluting exhaust gases.
The Pentagon is now looking at microgrid
systems for its bases that couple natural gas
generation, along with solar and wind, with
battery storage.
restructuring law, which removed generation
from the control of the utility. Exelon has
faced similar concerns in Illinois.
An Oncor project in Texas also has experienced
regulatory obstacles. Texas classifies
energy storage as generation. The state's
deregulated market means that distribution
companies such as Oncor can't sell excess
power from storage into the Electric Reliability
Council of Texas (ERCOT) wholesale
power market.
Some conventional utilities are also skeptical
of the impact of microgrids. An official
from Pittsburgh's Duquesne Light Co. told a
recent conference organized by the Harvard
Business Review that microgrids could lead
to a " death spiral " for conventional utilities,
with fewer people relying on the macrogrid
left to pay for conventional grid upgrades.
" Those customers who are able to afford
distributed generation are now paying for a
smaller portion of the electric grid, " said a
senior manager, " which means the customers
who cannot afford to install their own distributed
generation are paying for a larger share
The converging technologies of solar PV
and battery storage are driving the
current enthusiasm for microgrids.
The converging technologies of solar PV
and battery storage are driving the current
enthusiasm for microgrids. PV arrays have
become much cheaper and operate well
(when the sun is shining), with no fuel or
emissions control costs. Battery technology
developments, particularly the increased
power density of lithium-ion technology,
may provide the answer to the variability of
sun power. Lithium-ion batteries, however,
have inherent limitations, including catching
on fire under some circumstances. They
also have limited lifetime, meaning they
have to be replaced.
Microgrid Challenges
Regulatory challenges to microgrid projects
could slow development. In 2016 the
Maryland Public Service Commission (PSC)
denied Baltimore Gas and Electric cost recovery
for two microgrid projects, one in the
city of Baltimore and the other in suburban
Howard County. The utility-an Exelon subsidiary-wanted
to impose a surcharge on
all customers to pay for a $7 million, 2-MW
microgrid, and a $9.2 million, 3-MW microgrid.
The PSC said the microgrid projects
conflicted with the state's 1999 electricity
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of the electrical grid. "
APPA's Hyland, while positive about microgrids,
stresses caution and careful analysis
about projects, particularly because the economics
of batteries are dicey. Often, he said,
the " numbers don't add up " when it comes to
battery storage cost projections.
" Microgrids are not for everybody, " he
said. " They make sense in certain conditions. "
Utilities pondering microgrids, he
said, " need to look at empirical data, need
to look at all the facts, and need to ensure
that customers know what the costs will be.
There's lots of hype, and I like the hype, but
at the end of the day, it's got to be driven by
facts and hard data. "
Nevertheless, optimism about microgrids
is high and growing. At the Harvard Business
Review meeting, Gregory Unruh from
George Mason University in Virginia, as
reported by the Thomson Reuters Foundation,
said, " We are witnessing perhaps the
twilight of the macrogrid and...the dawn of
the microgrid. "
Or maybe not. ■
-Kennedy Maize is a long-time
energy journalist and frequent
contributor to POWER.
POWER | August 2017
http://www.powermag.com
POWER August 2017

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