In direct support of the GEB Initiative and Energy Storage Grand Challenge (ESGC), the Building Technologies Office (BTO) is focused on thermal storage research, development and field validation, seeking to accelerate the commercialization and utilization of next-generation energy storage technologies and sustain American global leadership in energy storage. In general over 50% of building energy consumption can be attributed to thermal loads; making thermal energy storage a natural fit for the built environment. BTO is focusing on developing thermal energy storage technologies, including materials, equipment, and systems, for building applications. Thermal energy storage materials have the opportunity to increase energy savings and flexibility for shedding and shifting building loads. Future materials can further optimize utilization of storage capacity through improved temporal and spatial control of heat flows.
Phase change materials (PCMs) are a class of thermal energy storage materials that absorb and release thermal energy during the process of melting and freezing. When a PCM melts, it absorbs a large amount of energy. Conversely, when a PCM freezes it releases a large amount of energy in the form of latent heat at a relatively constant temperature. These materials can thus reduce and shift the timing of heating or cooling energy demand. The primary grid benefit of thermal storage is load shifting and shedding by supplanting HVAC system operation during peak hours and using the HVAC system to recharge the storage during off-peak hours. Additional efficiency benefits come from shifting HVAC system operation to periods when the system can operate more efficiently (because of ambient conditions and/or thermostat set point) or charging using ambient conditions (similar to free cooling).
Some of the next-generation thermal storage technologies BTO is pursuing include thermally anisotropic materials, envelope thermal storage, tunable thermal conductivity materials, liquid desiccant thermal energy storage, and embedded thermal energy storage. More detailed information about these technologies can be found in the Windows and Opaque Envelope GEB Technical Report and the HVAC, Water Heating, Appliances and Refrigeration GEB Technical Report.
R&D targets for next-generation thermal storage materials: