Smart thermostat

Major California utility tests automated emissions signaling, affirms it can reduce device-level emissions from associated electricity use

 March 12, 2020 

At this very moment, even the most-efficient appliances are sucking up energy indiscriminately from their local grid—clean, dirty, whatever’s on tap at the moment. Until recently, there’s been little choice in the matter. Now however, it’s possible to get choosy about how we power up the machines and devices we depend on, from electric vehicles to smart thermostats. And major utility providers are taking note.

Here at WattTime, we’ve been advancing a capability we call Automated Emissions Reduction (AER). It provides a software signal that allows smart energy-using devices, from EVs to thermostats, to sync with clean energy and avoid dirty energy. By operating with the intelligence of real-time marginal emissions data, our software tells devices if using power now (or later) will in-turn cause a high-emitting power plant to respond, or maybe zero-carbon wind or solar, and it automatically opts for those low or no-carbon moments. All this takes place with zero negative impact for the end user. The technology has increasingly been battled-tested and -proven.

Now, California utility PG&E has conducted a rigorous analysis of WattTime's AER software. The results? In short: AER works. The 50-plus-page assessment is no light read, but it indicates growing industry interest in effective new ways of meeting emissions-reduction targets and driving other strategic goals, like demand response programs and renewable integration.
Four device-level examples of AER in action
To understand how AER supports broad utility strategy, it’s useful to consider first how AER works for the average device. PG&E’s analysis looked at four everyday appliances, in a laboratory setting, concluding that WattTime software effectively supports control of end-use energy consumption for each. By using AER technology to control their own versions of these appliances, people can…

  1. Curb heating and cooling emissions with smart thermostat controls. Global energy demand for air conditioning is expected to triple by 2050, making AC one of the top drivers of global electricity demand in the years ahead, according to the U.S. Energy Information Administration (EIA). In California, for instance, PG&E notes that AC usage often coincides with higher GHG intensity on the grid. Meanwhile, the EIA residential energy survey reports that space heating accounts for roughly 15% of an average home’s annual energy use. So it’s meaningful that utilities can take more ownership over the kind of power people use to heat or cool their homes. With WattTime’s AER solution, PG&E simulations found that the average homeowner could trim HVAC-related emissions by 7.5–13.2% per year.
  2. Maintain a water heater’s warmth, while cutting back on associated emissions. Water heating makes up 15% of a home’s energy use, according to the EIA survey cited above. With AER water heater load control, homeowners can make sure they’re using more of the clean energy that’s available from their utility. Per PG&E’s assessment, the water heater load controller “performed well” in controlling temperature and, in some cases, could reduce emissions by as much as 20% per day while maintaining desired water temperature.
  3. Ease up on the refrigerator’s carbon footprint with an AER-powered smart plug. Refrigerators may be a quiet but steady energy suck, constituting about 7% of the average home’s energy use. But it’s a myth that they’re always consuming power. In fact, refrigerator compressors only have to consume power in little bursts of cooling that happen about every 30 minutes or so—during which time, the grid’s supply can vary greatly. AER can help find the cleanest five-minute period within that window, supporting demand-response programs while enabling homeowners to keep both food and appliance in good shape. In PG&E’s simulation, this approach cut carbon emissions by 1.3% on average per day.
  4. Give EVs an instant ‘MPGe boost’ with AER service equipment. WattTime research shows that smart timing of EV charging can reduce associated emissions by as much as 20% annually, and up to 90% on some days. This will vary by location and grid. For example, PG&E’s California-based simulation team found they were able to shift charging time to achieve a 13% per day average reduction in GHG emissions.

The big picture: AER can help utilities achieve climate goals

Utilities working toward ambitious carbon emissions targets are increasingly seeing the broader benefits of adding AER to their toolbox.

For starters, AER aids renewable energy grid integration—and helps avert undesirable renewable energy curtailment—by using more surplus renewable energy. It does this not only by shifting flexible demand to windy and sunny times, but by especially targeting times when renewable energy is on the margin and at risk of being wasted.

AER also gets more out of demand response programs, especially when emissions rates and electricity prices are aligned. With AER, utilities can turn DR offerings into a year-round feature that truly appeal to customers. Our research shows AER boosts DR program enrollment and retention.

As California’s largest electric utility, PG&E’s report is another major affirmation that AER works not just for the individual devices people depend on everyday—but for the larger utilities that bring them to life, too. In a world of ever-more sophisticated demand response and renewable energy efforts, AER is proving a game-changing tool that grid operators can increasingly appreciate, and adopt.