At 6:44 a.m. Dec. 23, 2022, when power went out in portions of Long Island because of the bad weather sweeping the US, utility Public Service Electric & Gas (PSEG) Long Island notified a ShopRite grocery store that a line was down that served the feed to the store.
But thanks to a microgrid, the lights were on and the refrigerators were powered at the Lake Ronkonkoma, New York, store, even though nearby buildings went dark.
During the PSEG outage, which lasted about 34 hours, the ShopRite store was powered by a microgrid from Unison Energy. The microgrid’s controls sensed that utility power was out and seamlessly put the microgrid in island mode, said Scott Fiveland, vice president of operations for Unison Energy.
Charles Gallagher, owner of three ShopRite stores on Long Island, said that the day of the storm he received several texts from PSEG Long Island about high winds, flooding and possible long-duration outages.
“I deleted all of them and was able to rest easy, knowing our Unison microgrids would keep our stores open and power us through any utility outages during the storm,” he said. ShopRite has two other stores with microgrids on Long Island.
A microgrid made up of two combined heat and power units that produce 216 kW – plus controls – powered the Lake Ronkonkoma store. The store not only was able to sell groceries to the local community, but avoided losing food that needed refrigeration.
“If power is lost, millions in dollars of inventory is at risk,” said Leslie Meyer, director of marketing for Unison Energy. Without the microgrid, the store would have had to scramble for dry ice and backup generators and to obtain fuel for the generators.
Microgrids at their best
It wasn’t only energy users like ShopRite that benefited from microgrids during the Christmas week storm, dubbed Winter Storm Elliott. So did the electric grid as severe cold whipped up a bomb cyclone in the Midwest, left more than 50 inches of snow in Buffalo, New York, and sent frigid temperatures southward, fueling tornados. Demand for electricity intensified, and some utilities and grid operators had to institute rolling blackouts or call for conservation to keep the grid in balance.
When the grid is strained, distributed energy resources such as microgrids play an important role, providing much needed power that helps the grid keep supply and demand in balance.
The grid’s winter woes also revealed themselves on Dec. 23 when real-time prices jumped to more than $4,000/MWh (see graphic below) in the territories of two grid operators, the Midcontinent Independent System Operator (MISO), which spans 15 states and the Canadian province of Manitoba, and the Electric Reliability Council of Texas (ERCOT).
“The real-time prices were a good measure of grid stress,” said Allan Schurr, chief commercial officer at Enchanted Rock. Enchanted Rock helped out by providing about 460 MW to the southern region of MISO and ERCOT, calling upon its portfolio of microgrids located in many different parts of the two territories.
“This is the value of microgrids at their best, distributed energy, close to the load, with a diversity of locations and equipment types. The central grid needs distributed energy to perform during the energy transition to immediately fill in and quickly balance supply and demand,” said Schurr.
About 97% of the output of Enchanted Rock’s microgrid portfolio was available on Dec. 23, when the grid started to teeter, he said.
Additionally, the week before Christmas, Enchanted Rock counted 46 separate utility outages at customers' sites, half of them on Dec. 22, said Schurr.
“We were running the microgrids for the value of displacing load and exporting from the microgrid to the grid,” he said.
And this wasn’t the first time microgrids helped out during times of grid stress. During last summer’s heat wave, multitasking microgrids kept the lights on in a small California community surrounded by wildfire, supported the Texas grid during power emergencies, islanded to relieve stress on the California power system and helped an Oregon military facility meet its air conditioning needs when temperatures soared.
Enchanted Rock was prepared for the most recent grid stress because it learned from its experiences during Winter Storm Uri, said Schurr.
“We learned a lot from Uri and were ready for this one as the forecast started showing widespread cold,” he said.
ERCOT underforecasted some of the energy demand on the morning of Dec. 23, which meant that it had to recover in real time, and the microgrids were especially helpful.
“I think we were an important contributor to the grid,” said Schurr. “There are a lot of moving parts when ERCOT is up against these weather events.”
When the microgrids stepped in to help, in some cases, they were making up for low renewable energy availability. For example, the week before Christmas, wind production dropped substantially in Texas, and the microgrids were available to start quickly and cover that shortfall, he said.
Even when its microgrid customers experience outages, Enchanted Rock can provide the needed customer backup and also serve the grid. That’s because it has 1,150 generating units in ERCOT and MISO South located in diverse locations. If some microgrids are providing backup, others can serve the grid. In part, that’s because the company has gas-powered microgrids in many different gas distribution areas, said Schurr.
PowerSecure microgrids help avert potential catastrophe
Microgrid provider PowerSecure also stepped in to help during the Christmas storm. Its team entered storm mode operations a week before Christmas to make sure the microgrids were tested and fueled, said Debra Phipps, director of PowerControl for PowerSecure. The company put 190 operations into standby mode at 123 different locations. The company also managed more than 570 load management events triggered by utilities during the Christmas week storm, Phipps said.
During a load management event, utilities seek help from customers who can reduce their loads or provide extra power with microgrids or other equipment.
The storm presented a unique set of challenges, said Phipps.
During a hurricane, the hot weather temperatures will cool down enough so little load management is required. This allows PowerSecure to focus on utility power outages and keep customers up to date with information about outages.
But during winter storms, the situation can be dicey. The national grid was in peril Christmas week for numerous reasons. A few utilities proactively shut down wind turbines to prevent damage from high winds. In addition, heavy snow and cloudy weather undermined solar output. The lack of wind and solar contributed to utilities calling for demand response load management events, said Phipps.
PowerSecure responded to two major load management events in Tennessee – the first such events in 18 years. PowerSecure was required to dispatch its microgrids within five minutes of being notified by utilities. The PowerSecure microgrids were available within two to three minutes of the notifications, she said.
PowerSecure microgrids also kept the lights on for customers in North Carolina and South Carolina, where Duke Energy implemented rolling blackouts.
When areas of the northeast issued their first-ever emergency demand response event, PowerSecure responded with help from its microgrids. After the storm, Phipps was happy to receive a message from the utility saying, “Your participation in this critical program serves as a front line of defense and your response to the recent events helped prevent what could have been a catastrophic grid situation.”
Interested in learning about more microgrids? Join us May 16-17 in Anaheim, California for Microgrid Knowledge 2023: Lights On!