Stor4Build heats up thermal energy storage solutions for buildings and grids
by Jennifer Burke for ORNL News
Oak Ridge TN (SPX) December 23, 2024
In the United States, more than 100 million buildings use electrical energy to keep heating, ventilation, air conditioning, and refrigeration equipment operating. HVAC systems account for the majority of peak demand on the power grid; One way to reduce the load on the grid is to develop new storage options for heat and cold.
As a partner in the Department of Energy's Stor4Build consortium, Oak Ridge National Laboratory, along with the National Renewable Energy Laboratory, Lawrence Berkeley National Laboratory, Pacific Northwest National Laboratory, and the American Council for an Energy-Efficient Economy, leads research to develop thermal energy storage as a supplement to electric battery storage.
ORNL Director Stephen Streiffer welcomed colleagues and industry stakeholders to the two-day Stor4Build workshop, which focused on future paths for the development, demonstration and deployment of novel building services technologies and materials that harness thermal energy.
“ORNL exists to solve big problems that address national needs, such as developing solutions that improve the electric grid,” Streiffer said. “The Stor4Build consortium will play a critical role in shaping the future of the country’s energy systems.”
Sven Mumme, co-director of Stor4Build and DOE technology manager for research and development in opaque shells and thermal energy storage, said thermal energy storage has many advantages. “Thermal energy, for example, can improve the performance of heat pumps and make them easier to market, and using low-carbon materials can also reduce the carbon impact of a building,” Mumme said.
Energy on demand
Thermal energy storage (TES) works like a battery and stores the energy stored in a material as a source of heat or cold that can be reserved for later use in buildings. Researchers are optimizing the performance of phase change materials such as wax and salt hydrates, which can store and release energy when converted from a solid to a liquid or from a liquid to a solid.
Because TES can store or release heat depending on immediate needs, it can be coupled with a building's HVAC system to reduce demand for electricity from the grid during peak periods, such as late afternoon in summer or early morning in winter . while the room temperature is maintained at the thermostat setting. TES also allows heat pumps to function more effectively in extreme weather conditions.
The main goal of Stor4Build is to find ways to cost-effectively integrate TES into HVAC systems and the building envelope or walls and roof. To reduce costs and enable broader adoption, new approaches to TES are needed, said ORNL's Kyle Gluesenkamp, co-director of Stor4Build and a distinguished research and development scientist.
“Today’s TES products are primarily used to cool large commercial spaces,” he said. “If we want this technology to be widespread and benefit everyone, no matter where you live, we need to reduce costs, develop more powerful storage materials, and design components and modular packaging that integrate seamlessly with all types of HVAC systems, heat pumps and building envelopes.”
Expanding acceptance of heat pumps
Heat pumps represent an energy-efficient alternative to conventional furnaces and air conditioning systems. The heat pump transfers heat energy to cool and warm rooms using a refrigeration cycle.
As part of Stor4Build, Gluesenkamp led a research team to design, manufacture and evaluate a novel heat pump prototype that can shift electricity demand using TES. By modifying a heat pump using only off-the-shelf components, the team was able to reduce costs. Through funding from DOE's Building Technologies Office, Gluesenkamp leveraged the resources of the Building Technologies Research and Integration Center at ORNL to develop the prototype.
“If deployed at scale, our TES-enabled heat pump promises to reduce the need for electrical infrastructure upgrades and shift peak demand more cost-effectively than electric batteries alone,” said Gluesenkamp. “We have built a prototype that shows that a heat pump with TES can reduce electrical heating demand during peak network times by three times compared to commercially available heat pumps today.”
The achievement is significant, he emphasized, because it represents a proof of concept to inform utilities and industry about what is achievable with heat pumps and TES. In addition to the prototype, Gluesenkamp's team also demonstrated a new defrosting method using TES that avoids a common complaint with heat pumps. Heat pumps tend to periodically blow out cold air during the defrost phase. However, defrosting is necessary to prevent the outdoor coils from becoming clogged with frost.
“By de-icing with TES, we have shortened the duration and improved comfort for the occupants,” he said. “Defrosting can be completed in three minutes, compared to the usual five to 10 minutes. This means that there is no cold blow effect indoors, the efficiency of the heat pump is higher and the peak electricity demand is lower.”
Ultimately, reducing cold air injection results in greater comfort for residents and reduces strain on the power grid as minimal electricity is used – all positive attributes that could further enable the mass deployment of heat pumps.
Change the market
ORNL's heat pump research is just one of many avenues Stor4Build will use over the next few years to advance potential TES solutions from early to mid-stage development through market launch. By 2028, the program aims to conduct field evaluations of novel packaged or integrated TES solutions to validate the benefits of the new technologies when installed in homes. In addition, the program envisions a community-wide demonstration that can demonstrate a 50-100 kilowatt reduction in aggregate peak demand in 20 to 50 homes while reducing individual household thermal load power consumption by at least 50% over a period of four to six Hours.
Mumme, who shared expected 2025 achievements with participants at the Stor4Build workshop at ORNL, noted that the national laboratories will undertake projects in five areas: TES-enabled residential heat pumps; TES-enabled equipment for commercial buildings; active TES in building envelopes that improve resilience, reduce peak loads and save energy; Open source TES sizing, benefits and decision-making tools; and standard testing protocols and procedures for TES products.
“Stor4Build unites stakeholders, including the HVAC industry and utilities, as well as our academic and research communities, to share knowledge and collaborate on common goals to accelerate the scaled adoption of TES technologies in buildings,” said Mumme.
“It will take cross-functional teams to develop equitable solutions that ensure the benefits of TES are clear to everyone,” he added.
In addition to Mumme and Gluesenkamp, Stor4Build co-directors include Sumanjeet Kaur, materials scientist and thermal energy group leader at Lawrence Berkeley National Laboratory; and Tim LaClair, distinguished scientist in building thermal energy at the National Renewable Energy Laboratory.
Related links
Oak Ridge National Laboratory
Powering the world in the 21st century at Energy-Daily.com