There’s a good reason that traditional demand response (DR) programs only ask C&I customers to curtail energy usage a few times each year. Traditional DR is painful. It’s a no-holds-barred, shut down that conveyor belt, stop production, turn off the air conditioner and send people home kind of deal. It is, by definition, disruptive. And, frankly, not every organization can afford to have its business endure even a few interruptions a year.
But, DR doesn’t need to be disruptive, and to get the most out of today’s demand management technology, we really need to think of curtailment events as a day-to-day method of grid support instead of troublesome headaches that must be painfully tolerated.
That’s what one East Coast utility is doing with the Symphony by EnbalaTM distributed energy resource management platform (DERMS). By aggregating small amounts of response from many different devices in one site, a promising pilot is showing that curtailment can be both effective and invisible to customers.
One site, one hour, 186 kWh of curtailment
The curtailment in question is a pilot being conducted at a large employee-development center owned by a multinational conglomerate. The site has eight buildings on its campus and, currently, there are 103 assets being controlled by the DERMS. Some, such as chillers, are sizeable. Many are smaller loads, such as air handling units with blowers, coolers and heating elements, roof-top units that perform the same functions as the inside air handling units and packaged terminal air conditioners (PTACs), which combine air conditioning and heating into one wall-mounted unit. These are the same kinds of heating and cooling units often found in hotels.
The site also has seven building meters and three submeters for certain asset types. All told, the platform is gathering approximately 800 data points. When combined with customer-defined pre-set parameters on the assets under control, some 1,200 data points are relayed to a GE Digital Predix system every second. The Predix is a platform for building applications that connect to industrial assets, collect and analyze data, and deliver real-time insights for optimizing industrial infrastructure and operations.
Working in tandem with the Predix, the Enbala platform juggles control of those 103 assets to deliver very precise reductions in power without creating any discomfort for people working in the building. In contrast to traditional DR, rather than shutting off all the air handlers, the system may turn off a few at a time. It also makes use of any variable frequency drive motors to turn equipment down, not off, and it cycles equipment on and off very quickly.
There are many other ways in which this curtailment differs from most C&I demand response programs. For one, it’s automated. It doesn’t begin with the utility calling or emailing building site managers to let them know a DR event has been called for the next day.
In addition, this curtailment doesn’t require action on the part of site inhabitants and building managers. No one has to reschedule work because an important piece of industrial equipment must be shut down. No one needs to manage various building functions, like shutting down nonessential elevators or turning off drinking fountains and decorative water fountain pumps. There’s no switch to back-up generation. The site can deliver enough response simply by allowing many small assets to be connected to the DERMS.
Best of all, the curtailment events in which this site participated were essentially invisible and unfelt by the people who work at the facility. Sure, the building manager knew what was up, but the many company managers participating in vital training exercises at this educational facility never noticed when the site participated in curtailment two days in a row this summer.
The curtailment events called by the utility lasted four hours each. On the first day, the site delivered 186 kWh between the times of 7 and 8 p.m. On the next day, it gave the grid 108 kWh during the same time frame.
Unexpected Insights Sweeten the ROI
Along with load shedding, all the data collected by the DERMS delivered valuable energy efficiency insight and cost-savings potential that might well have gone undetected. The 2.5 gigabytes of data collected and analyzed daily during the pilot revealed that some 50% of the facility’s air conditioning units with economizers had non-functioning dampers. The dampers were allowing too much outside air to be pumped into the room when fans were running and ACs were off, causing rooms to heat up quickly as soon as they had been cooled down.
Now, that’s something building managers DID notice, even though they did not notice the inobtrusive curtailment technology that enabled the facility to fix this costly problem.
For more information on the contrast between traditional DR and more advanced solutions for demand curtailment, we invite you to read our white paper that explores the topic “Is DR Dead?”