Putting Groundwater
to Work
Darcy’s groundwater-sourced geothermal technology delivers the most cost effective, most energy efficient, and most environmentally friendly heating and cooling for buildings.
Darcy Solutions addresses the two biggest challenges for geothermal ground source heating and cooling – cost and footprint.
Our patent-pending approach harnesses the thermal advantages of water and consistent temperature of shallow Earth to make sustainable heating and cooling practical and financially attractive for commercial and residential buildings.
Our technology dramatically improves system efficiency, lowering energy use and reducing site footprint requirements up to 95%.
By offering project paybacks under 10 years and the greatest reduction in carbon emissions, Darcy makes its environmentally friendly heating and cooling solution viable for new construction and retrofit projects.
Save Energy & Reduce Emissions
Darcy Solutions provides a practical and financially compelling option.
We deliver the most energy-efficient and economical HVAC system for both heating and cooling.
Our solution reduces CO2 emissions well below other HVAC solutions and cost-effectively meets efficiency standards and sustainability goals.
Our Partners
Darcy has established deep working relationships with several industry-leading experts and complements their well-established practices with our hydrological and geological expertise to create and deliver the most cost effective, most energy efficiency, and most environmentally friendly heating and cooling for buildings. Read more about our partners.
Traditional geothermal/ground source heat pump systems rely on conduction-based heat exchange. They do this by pumping a heat exchange fluid (typically water mixed with anti-freeze such as glycol) through a closed-loop system consisting of a number of u-shaped plastic pipes. These pipes are placed in boreholes (typically 200-250 feet deep) that enable heat exchange with the surrounding earth. Because plastic piping and the cement grout surrounding it doesn’t exchange heat quickly, a large amount of piping is needed to provide the heating and cooling capacity necessary for a building. Over the course of a heating (or cooling) season, the earth surrounding the piping will gradually cool down (or heat up), decreasing system efficiency.
A Darcy system takes advantage of convection-based heat exchange, providing a much faster and higher capacity approach. Darcy also uses a closed-loop system and a heat exchange fluid. Our system pumps water through plastic piping and does not use anti-freeze. A heat exchanger replaces the u-shaped bend in a traditional system. This heat exchanger is positioned in an aquifer to take advantage of the superior heat exchange benefits of flowing groundwater to heat or cool the closed-loop fluid (water). As a result, a single Darcy borehole can deliver 20 times the heat exchange capacity of a traditional geothermal borehole. Darcy’s system sustains a relatively constant temperature throughout the year and maintains its efficiency throughout a heating or cooling season. This is because the massive quantity of flowing groundwater has high heat capacity to dissipate the heat.
Heat pumps are essentially air conditioners that can be operated in one direction to provide cooling and operated in the opposite direction to provide heating. Heat pumps use refrigerants, which take advantage of the ideal gas law (PV = nRT) and move heat around through 4 steps.
For cooling, a heat pump works as laid out in this table.
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The system works in reverse when the building needs to be heated.
There are two major benefits.
The first benefit is that a system does not lose efficiency over the course of a season due to the gradual decrease in temperature while heating or a gradual increase in ground temperature while cooling (as happens in traditional geothermal). Maintaining consistent efficiency helps reduce electricity use and cost.
The second benefit is that a system can be designed to deliver cooling only or heating only without concern for gradual increase (or decrease) in underground temperature over years of operation. This flexibility enables the incorporation of creative heating or cooling systems (e.g., a cooling only system with the use of chilled beams, a DOAS, and no heat pump) for which energy savings can be significant, sometimes as much as a 70% reduction vs. conventional systems.
Darcy’s technology was developed at the University of Minnesota by a team of expert hydrogeologists. One of these hydrogeologists is our co-founder, Dr. Jimmy Randolph. Darcy supplements its hydrogeologic expertise with the help of our industry partners.
Darcy complements this expertise with a monitoring system that helps ensure each wellbore is performing as intended. Monitoring information is also available to the building operators and the HVAC contractor to provide early identification of maintenance needs. In addition, because the heat exchanger installed in each wellbore is readily accessible and removable, we can quickly remedy underperforming wellbores and/or heat exchangers.
While traditional geothermal systems typically deliver 1 – 2 tons per borehole on average, each Darcy borehole can deliver 20 tons or more. As an example, a building that needs 200 tons of heating/cooling capacity may require 175-200 boreholes spaced every 15-20 feet on a grid. Using a Darcy system would likely require 8-10 boreholes spaced every 50 feet in a line. This line of wellbores could run along one length of the building or parking lot. This reduction in footprint requirements enables the Darcy system to readily fit in constrained outside spaces, making it appropriate for new builds and retrofits alike even in the densest urban environments.
Each Darcy wellbore will have a header that extends approximately 12 inches out of the ground. These headers can easily be incorporated into the landscaping. They offer the benefit of ready access to the well for maintenance. Another aspect is what you don’t see — the outside appearance of a building and rooftop. By using a Darcy system, unsightly cooling towers and other rooftop units can be eliminated. The elimination of these components provides the additional benefit of making rooftop space readily available for solar installations.
Darcy is currently focused on systems requiring 20 tons of heating/cooling capacity or more. (A single Darcy wellbore can typically deliver 20 tons of capacity.) To be cost effective a project should utilize the majority of this capacity. This means commercial and multi-unit residential buildings are well-suited to take full advantage of the economic benefits of a Darcy system. Single family homes can also benefit when connected to a community/district system.
Darcy’s closed loop system only interaction with groundwater is the transfer of heat. The massive volume of water and surrounding earth readily and quickly dissipates/restores the impact of the exchanged energy. The water that circulates through the closed loop does not come into direct contact with the groundwater. These designs do not consume groundwater, remove it from the subsurface, move it between aquifers, or introduce contaminants.
Roughly two thirds of the US population live in an area with suitable groundwater availability and surface proximity for Darcy’s technology. The glaciated regions of the country running from the upper Midwest to New England are particularly well-suited for this technology. Additionally, there are many other areas in the U.S., including the PNW and SE U.S. with suitable groundwater resources. Please contact us for an initial assessment of your region’s suitability.
We are in various stages of projects in multiple states currently. Please contact us if you have a project for which you think our technology may be a good fit. info@darcysolutions.com
As a relatively new company, we have not developed the resources for international operations. However, we’d still love to hear from you as this will inform our expansion plans in the future. info@darcysolutions.com
There are several important considerations when thinking about de-carbonizing building heating and cooling and the electrification of HVAC technology. Providing the most energy efficient technology can help reduce system load and avoid the need for additional power. generation and transmission investments. Similarly, utilizing technology that helps reduce peak electrical demand and smooth energy use can also enhance system load factors and mitigate the need for additional generation and transmission capacity.
Air source heat pumps (ASHPs) represent an increasingly popular HVAC technology that supports electrification and eliminates the emissions from fossil fuels burned for heating. In addition, they offer attractive improvements in efficiency vs. conventional HVAC technologies, and their relatively small premium in installation cost makes them a viable alternative. Geothermal heat pumps provide greater energy efficiency (2-3x) and a flatter usage profile, mitigating the challenges of summer and potential winter demand peaks.
The geothermal energy that occurs across various parts of the globe, such as Iceland, can offer 2 important and beneficial uses. High temperature geothermal (>360 F) can be used to create steam which in turn can be used to generate electricity. Lower temperature (68 – 302 F) geothermal can be used for direct heating, as the ancient Romans did.
Darcy’s technology utilizes what is really a form of solar energy that is stored in the shallow earth. Groundwater temperatures are relatively stable year-round, and typically reflect the average annual temperature for the area, ranging from 45 degrees F in the northern part of the continental U.S. to 75 degrees F in the southern part of the country. HVAC equipment, such as a heat pump, is designed to supplement these temperatures to provide the desired level of heating or cooling.