TRC is working with Entergy Texas on a Grid-Enabled Heat Pump Water Heater Pilot Program, an innovative measure that offers multiple benefits to both customers and the utility: energy efficiency, voltage regulation, load shifting, and peak-demand load shedding. This technology offers new ways to provide residential customers with energy savings, cost savings, and a more resilient grid.
Entergy Texas provides electricity to more than 430,000 customers in Southeast Texas. Since 2019, TRC’s Advanced Energy team has implemented residential energy efficiency and demand reduction programs to help the utility reach its objectives. A key component to our work for the utility is a new construction program which offers incentives directly to home builders to encourage the development of highly efficient, above-code new homes.
As part of this residential new construction program, TRC worked with Entergy Texas to develop a pilot program to further capture energy savings in the residential market through heat pump water heater (HPWH) technology. Compared to traditional electric water heaters, HPWHs are two to four times as energy efficient, and represent significant energy savings potential when used in housing stock in place of traditional water heaters.
Heat Pump Water Heater Technology
Heat pump water heaters (HPWH) work much like a refrigerator in reverse. The heat pump extracts the heat from surrounding warm air, intensifies the heat with a compressor, delivers the heat to the water, and exhausts the cooler air. Because it uses warm ambient air temperature to do most of the work, it is a very efficient way to heat water, using less than half the energy of standard electric water heaters. During periods of high hot water demand, HPWHs switch to standard electric resistance heat — which is why they are often referred to as “hybrid” hot water heaters. HPWHs also have programmable settings; “economy” mode which uses only the heat pump setting, and “vacation” mode which shuts down the heater for a set amount of time. (Source: EnergyStar.gov)
Heat pump water heaters are not only energy efficient, but they are designed to be grid-enabled, allowing for installation in utility demand management programs. As a result, this technology delivers multiple benefits to the customer and utility:
- Energy efficiency (kWh savings): energy usage reduced in comparison to less efficient technology
- Grid resilience: HPWHs are capable of storing thermal energy and reducing strain on the grid during peak electricity demand, including the critical Winter Peak in Texas
- Demand response (kW savings): this recurring benefit comes from Demand Response and/or Load Shifting actions. When combined with software capable of deploying event actions, a connected HPWH can provide the grid with load management or emergency response services. Further, grid-level deployment can happen at the grid operator level (e.g. ERCOT) or at the utility level (e.g. Oncor).
Demand actions can be accomplished using one or more methodologies, including pre-heating water and using mixing valves, adjusting set points, preventing the use of electric resistance heating elements in HPWHs, or interrupting power to all heating elements. Demand reduction analysis from HPWH is an emerging field of research, with few completed studies. Part of the goal of the TRC and Entergy Texas HPWH Pilot Program is to demonstrate, record and analyze the technology’s peak demand reduction capabilities in real-world applications, including:
- The HPWH pilot program hopes to show that Winter Peak demand savings will be significant – and as shown by the Texas grid disruptions during Winter Storm Uri of February 2021, this benefit is critical to the local grid. HPWH technology relies on an electric resistance heating element to provide back-up heat when temperatures are less than ideal for operation in heat-pump mode.
- A pilot rollout of Heat Pump Water Heater technology will also be a way apply thermal energy storage as a vehicle for distributed energy resources, such as functioning as part of a virtual power plant. HPWH technology will also be tested as a resource for ancillary services like voltage regulation.
TRC and Entergy Texas are conducting the pilot program with participation from industry partners including homebuilders, technology manufacturers, and grid management software providers. As we achieve results from the demonstration project, we will share these results with the industry and evaluate the potential for heat pump water heaters as a scalable resource for grid resilience, energy efficiency, and Integrated Demand Side Management (IDSM).
“We’re excited to participate in this pilot study, because heat pump water heater technology will provide Entergy Texas with new ways to provide our customers with energy savings, cost savings, and a more resilient grid.”
– Mark Delavan, Program Manager, Entergy Texas