Seeking resilience, organizations turn to microgrids
Supported by renewables and clean-burning propane or natural gas,
microgrids produce power cleanly and affordably while protecting the
reliability of the power supply.
By Jeffrey Lee
Uninterrupted power is becoming an essential
component of the resilience strategy for many organizations.
In an era where the electrical grid is aging
and under threat from storms and disasters, power for data centers or emergency
operations is more critical than ever. While individual buildings typically
meet those needs with standby generators, larger organizations and campuses are
turning to a more advanced solution: microgrids.
Microgrids go several steps further than a
standby generator by incorporating multiple sources and uses of power, says
Philip Barton, director of Schneider Electric's North American Microgrid Competency Center in La Vergne, Tennessee.
These "distributed energy resources" (DERs)
can include batteries, propane- or gas-fueled generation, and renewable power
such as solar. Microgrids integrate these resources into a reliable system that
can run in parallel with the grid or, in the case of an outage, separate from it.
As organizations become more familiar with the
capabilities of microgrids, analysts expect usage of the technology to grow
rapidly. According to Navigant Research, global microgrid capacity is expected to
grow from 1.4 gigawatts in 2015 to 7.6 gigawatts in 2024.
Reliability, efficiency, sustainability
An infographic from Schneider Electric highlights the benefits of microgrids.
Because they incorporate multiple sources of
power, microgrids make facilities more resilient in the event of an emergency.
But in many cases, they also offer a more efficient and sustainable source of
power, Barton says. That's because they're able to incorporate clean or
renewable inverter-based resources like solar power, battery energy storage,
and propane microturbines, which wouldn't normally work without the grid.
A standard called UL 1741 requires that these
inverter-based resources turn off when the grid goes down, so that they don't
backfeed the grid and present a risk to workers. "That's why microgrids are so
compelling," Barton says. "We just need to open the main breaker and control
those resources, and then we can run without the grid. It allows you to keep
the solar on or any other inverter-based resources, including propane
microturbines or fuel cells."
Microgrids may also be able to produce power
at a lower cost than the electric utility. By producing power onsite, instead
of at a centralized utility, microgrids can eliminate the transmission and
distribution losses associated with the grid. They can also utilize the heat
generated from producing power as thermal energy for nearby buildings, an
application known as combined heat and power, or CHP. Such systems can operate at efficiency
levels of 70 to 80 percent.
Organizations with large or critical power
needs are some of the best candidates to utilize the advantages of a microgrid,
Barton says. That could include corporate or university campuses, as well as
municipalities, emergency operation centers, military bases, and hospitals.
The easy button
Click to enlarge
Although they include multiple energy
resources, microgrids require an anchor resource that provides a stable source
of voltage and frequency. Gas-fueled onsite generation options, such as
microturbines or standby generators, are excellent anchor resources, says Jim
Crouse, executive vice president of sales and marketing for Capstone, a
"Because you can control the output, they can
support the intermittency of other renewable sources like solar and wind,"
Crouse says. "They can also easily be incorporated into microgrids where
there's renewables, storage, and some onsite generation."
For projects in locations that lack affordable
access to natural gas, propane is a natural fit as a contributing or anchor
resource. That was the case at Oncor, a regulated electric utility business in
Texas. To demonstrate how microgrids and distributed energy resources can
improve the grid, and to protect the critical loads at its System Operating
Services Facility, Oncor worked with Schneider Electric to design a
sophisticated microgrid that incorporated a variety of energy resources,
including a 65-kW Capstone microturbine fueled by propane. (Check out a video about the microgrid here.)
"Propane was definitely the ‘easy button' for
Oncor," Barton says. "They couldn't get the natural gas line there to
sufficient pressure for a reasonable amount of money, so propane was the way to
If Oncor is a small-scale microgrid, the one
on Catalina Island in Southern California is a much larger example. Southern
California Edison provides all
of the island's power, and with no access to natural gas, it used to rely
solely on dirty diesel internal combustion engines for electricity. To update
its outdated grid and meet California's strict air quality standards, the
utility added 23 Capstone propane microturbines, which can be turned on and off
in increments of 65 kW.
The microturbines reduced diesel fuel usage by
about 10 percent, or 200,000 gallons, annually, according to Capstone. And the
island's overall emissions profile improved, with annual reductions of about 8
percent for smog-forming nitrogen oxide emissions and about 9.5 percent for diesel
Backup energy storage
Even for projects with access to natural gas,
propane may be the best choice for backup energy storage in the event of a
natural gas outage. At Syracuse University's Green Data Center in New York, for example, 12 65-kW natural
gas microturbines generate power alongside the grid. But instead of using
diesel generators as backup, the microturbines can simply switch to a
propane-air mixture from a storage tank onsite.
One reason to turn to propane is that it can
be easier to store onsite than diesel, Crouse says. "Propane doesn't get algae
growth, it doesn't need to be filtered or treated, it doesn't get old and wear
out," he explains.
"Propane was definitely the ‘easy
button' for Oncor."
Battery energy storage is also gaining
popularity as the batteries become smaller and cheaper, but it remains an
expensive option overall, Barton says. "We find sometimes that a propane system
is a more cost-effective way to do energy storage and to be an anchor for the
microgrid than the battery energy storage system," he says.
Organizations may turn to microgrids for a
variety of reasons — storm hardening, increasing their use of renewables, or
lowering their carbon footprint. But resilience is a growing concern for
everyone. "It's been a growing trend, but after Superstorm Sandy and some of
the natural disasters that have occurred, people are looking to make sure that
in spite of their local electric utility, they have the ability to stay in
business," Crouse says. "It's really about business continuity."