Abstracts

“Thermal Reservoir Networks for Modularly Expandable Thermal Microgrids” by Dr. Michael Wetter (EW23-7686)

Thermal microgrids are a cost-effective solution to electrify heating and provide cooling for buildings using heat pumps and storage. Reservoir networks are a specific type of 5th generation thermal energy networks for providing heating and cooling. They support large-scale integration of renewables and storage, increase load flexibility, and provide resilience to climate events and technology changes. Their modularity allows a phased investment and build-out.

This presentation explains reservoir networks. It introduces a workflow that was developed as part of our project to standardize design and operation, and manage complexity, technical risks, and costs. The workflow consists of techno-economic multi-objective optimization to generate promising configurations of storage and energy conversion technologies for a given site. Next, for candidate solutions, detailed coupled thermal, fluid, and control models will be used to reduce design and operation risks. These models conduct dynamic system-level verification of the performance including testing of the control logic. They identify technical risks and opportunities that need to be managed to achieve the desired performance. The models provide a clear specification for construction and operation. Lastly, via proposed American Society of Heating, Refrigerating, and Air-Conditioning Engineers Standards 231P and 223P for digitalized workflows and digital twin technologies, the workflow supports highly digitalized control deployment. The presentation includes a demonstration of the workflow’s application to Joint Base Andrews.

“Technology Evaluation for Beneficial Electrification of Thermal Microgrids for Decarbonization and Energy Cost Savings” by Dr. Amy Allen (EW23-7632)

This ultimate goal of this project is implementation of a thermal microgrid at a U.S. DoD installation, supporting ESTCP’s goals of promoting efficiency, resilience, and improved performance of heating, ventilation, and air conditioning (HVAC) systems. Thermal microgrids are a type of district energy system and use water loops at near-ambient temperatures and distributed heat pumps to provide heating and cooling in a highly efficient way. The current phase of this project is on feasibility studies of thermal microgrids at two DoD installations in Germany.

The presentation will summarize the scope of the feasibility study, including evaluation of the expected energy and life cycle cost performance of thermal microgrids at these sites. Energy performance is being evaluated through the National Renewable Energy Laboratory’s URBANopt™ platform and URBANopt’s™ District Energy Systems module. The feasibility study will also address guidance for practical implementation of a thermal microgrid, including compatibility with existing building HVAC systems, as well as integration of waste heat.

In suitable applications, thermal microgrids operate very efficiently, due to their moderate temperatures and ability to integrate environmental heat sources and sinks (such as ground heat exchangers), as well as waste heat. Thermal microgrids can also leverage the inertia of a thermal loop to reduce and shift electrical demand, providing further savings and resilience opportunities.

Speaker Biographies

Dr. Amy Allen is a mechanical engineering researcher at the National Renewable Energy Laboratory in Golden, Colorado. Her work focuses on advanced district thermal energy systems and applied heat pump and heat recovery systems, as well as de-risking of such systems through laboratory experimentation. Amy’s research interests also include development of flexible modeling and analysis tools for district thermal energy systems. Amy is currently the principal investigator of an ESTCP project focused on feasibility studies of thermal microgrids for two DoD installations. She is especially interested in addressing challenges to adoption of advanced district energy systems in older existing buildings. Amy received her bachelor’s degree in civil engineering from the University of Illinois, her master’s degree in civil engineering from Stanford University, and a doctoral degree in architectural engineering from the University of Colorado at Boulder, where her research focused on network topology optimization for advanced district thermal energy systems.

Dr. Michael Wetter is a Senior Scientist in the Building Technology and Urban Systems Division at Lawrence Berkeley National Laboratory in Berkeley, California. His research includes integrating building performance simulation tools into the research process, as well as their use for design and operation. He is leading the development of Spawn of EnergyPlus, a next-generation simulation engine for building and district energy and control systems, OpenBuildingControl, a project that digitalizes the control delivery process, and the Modelica Buildings Library, the largest Modelica library for building energy and control systems. He was the co-operating agent of the International Building Performance Simulation Association (IBPSA) Project 1 and of the International Energy Agency Energy in Buildings and Communities (IEA EBC) Annex 60, two multinational collaborations that developed new generation computational tools for energy systems between 2013 and 2022. Michael has a bachelor’s degree in energy and building technologies from the University of Applied Sciences at Luzern, Switzerland, and a doctoral degree in mechanical engineering from the University of California, Berkeley.