REopt Goes Underground To Elevate Facility Energy Savings and Resilience

A New Geothermal Heat Pump Module Enables REopt Web Tool To Evaluate Individual Facility Energy, Cost, and Emissions Impacts of Converting Conventional Heating and Cooling Systems to Ground-Source Heat Pumps

Jan. 10, 2022

You are hearing it straight from the (ground) source: A geothermal heat pump (GHP) technology module has been added to the REopt® web tool, used for feasibility analysis and comparison of a wide range of clean energy technology investments.

Developed by the National Renewable Energy Laboratory (NREL), the REopt web tool enables users anywhere to optimize system sizes and battery dispatch strategies to minimize energy costs by entering their facility data, including utility rates, billing history, and local weather. REopt can also be used to estimate how long a system can sustain critical loads during a grid outage, informing resiliency strategies.

Dig Deeper: Geothermal Heat Pump Basics

GHPs use a ground heat exchanger to take advantage of the more constant temperatures a few feet below the earth's surface to warm a building in the winter and cool it during the summer. They are a highly efficient energy technology currently deployed in all 50 states and serving 2 million households, and they are gaining wide recognition as a critical technology to decarbonize residential and commercial buildings as well as entire campuses.

GHPs can be used for commercial and residential applications, and configured both horizontally and vertically. Learn more about GHPs.

Weighing the Benefits of Geothermal Heat Without Breaking a Sweat

Through the REopt web tool, users can now simulate the impact that converting conventional heating and cooling systems to GHPs may have on on-site consumption of fuels and electricity, utility costs, and CO2 emissions. Additionally, users can leverage REopt’s existing distributed energy resource models to study the impact and interaction of a GHP retrofit with solar photovoltaics, batteries, combined heat and power, and other technologies.

NREL Research Engineer Bill Becker said, “GHPs are a way to electrify heating loads, which are typically served by a natural gas-fueled boiler or heater, more efficiently than air-source heat pumps, and it improves the efficiency of serving cooling loads. By electrifying heating, GHPs enable renewable electric technologies like solar photovoltaic to effectively serve the site’s heating needs.”

As Renewable Resources Vie for Viability, REopt Helps Find Site-Specific Solutions

As with many distributed energy resources and energy conservation measures, the viability of GHPs depends on site-specific factors. NREL Research Engineer Dan Olis said there are many critical considerations that the new module uses to perform an analysis.

“What are the energy needs for a facility?” Olis said. “How much is used for heating and how much is used for cooling? Do cooling and heating needs occur simultaneously, or do they differ considerably based on time of day or time of year? How much does electricity and fuel cost, and what are the specific climate and geotechnical conditions? In addition to these technical questions, it is important to consider the goals of the facility owners. Is the primary objective to reduce operating cost, or is reducing the carbon footprint important as well?”

The REopt web tool models each of these variables and site priorities—and how they all interact—to enable facility owners, technology vendors, and policymakers to identify site-specific needs and opportunities.

Development of the new REopt web tool GHP module was funded by the U.S. Department of Energy’s Federal Energy Management Program (FEMP) and Geothermal Technologies Office. According to Data, Modeling, and Analysis Program Lead Sean Porse, the Geothermal Technologies Office funded the project to advance understanding and commercial deployment of GHP systems.

“We were thrilled to collaborate with FEMP and NREL in order to see GHPs integrated into more lab-developed tools, like REopt, as we pursue ways to raise the profile of GHPs as an important clean energy technology,” Porse said. “GHPs should be a first-order consideration for any commercial facility seeking to save energy, enhance their resiliency, reduce their greenhouse gas footprint, and lower operating costs.”

Learn more about REopt and NREL geothermal research.