HS TV Ep 8: 1/2 the Drilling Depth, 1/3 the Footprint, SCW vs. Closed Loop Geothermal Systems

Standing column well geothermal projects have significant advantages over closed geothermal projects in certain circumstances. Standing column wells typically need half the amount of drilling then traditional closed systems, because they can transfer heat so much faster. Also, they be installed in places with extremely limited space, in cities for example. Lastly, they can be used in rural areas in conjunction with potable water wells.

The problem is that because even closed loop geothermal systems are foreign to many HVAC and drilling contractors, standing column well systems seem like they’re on another planet. We’d like to change this.

We’ve been writing heavily about standing well systems, how they’re designed, their difference between closed system systems. See below for some review articles if you’re brand new.

• The 4 Differences Between Geothermal Standing Column Well and Closed Loop Systems
• What You Need to know About Quoting and Selling Standing Column Well Systems
• 13 Steps to Basic Standing Column Well Geothermal Design

I also wanted to speak with Dr. Albert Koenig, a standing column well expert, to get his opinion on the technology, if he feels it get be relegated from a niche technology and what he is doing to demystifying the design and installation process so more contractors will feel comfortable designing and installing the technology.

Here are the highlights. 

• SCW systems typically need 1/2 the drilling length of comparable closed loop systems, because the thermal conductivity is extremely high in SCW systems.
• SCW typically take 1/3 the foot print of closed systems, if you’re space constrain this will be extremely attractive.
• SCW systems can typically 12 to 15 tons of heating and cooling capacity for each well, compared with 2 tons be average for closed system systems.
• Most well drillers know 80% of what they need to drill and installed SCW wells.
• You can retrofit existing water wells for a SCW project, but you may need to increase the depth of the well.

Here is the full agenda

• Standing column well 101. Why is it a great technology and what fascinates you about it?
• What is the main difference between closed loop geothermal projects and SCW?
• The closed loop industry has created a standard design and installation process that contractors can follow, why does SCW lack this and how is it being created?
• What do you see is the huge benefit of SCW over closed loop systems?
• Do you tend to find that people in rural areas, that are already drilling water wells, are attractive for SCW systems?
• What are the rules of thumb for drilling the well? How do you manage the game between drilling depth and minimizing capital costs?
• Do you think SCW can have a standard process like closed loop systems or do you think SCW is limited by the technology and each system will always be customer?
• Most drillers now how to put in water wells, but they may not know how to put a SCW design modification into that well for heating and cooling as well as potable water use.
• What is your advice for New England drillers that want to get into SCW? What does a driller need to learn to understand SCW systems?
• What are the two things contractors that are serious about SCW need to understand about the technology so they quote jobs correctly, win business, and make a profit as well?
• Answer. First is the ability to measure the conductivity of the well. Everyone is guessing on residential SCW projects to create the proper depth. So, we need to create a standard process to understand conductivity, diffusivity, and thermal response rates based on soil conditions will impact well depth.
• What are the conservative rules of thumb for SCW systems?
• What do you see are the difference between the residential and commercial SCW markets? Where do you the market opportunity for residential and commercial?
• Answer: The residential market has been dominated by closed loop projects. They have not need for a submersible pump. Their is a fantastic opportunity for SCW projects in places where wells already existing or its common for them to go in.
• Answer: For commercial, it’s based on a specific price point. It needs a 10% IRR and based on available land. It needs 1/3 of the foot print of closed loop projects for the same BTUS. Urban areas are extremely attractive for SCW because often time you’re drilling through sidewalks.
• One well will provide 12 to 15 tons of HVAC capacity, closed loop systems typically provide 2 tons per well.
• Can you retrofit an existing well to use SCW projects? Can it be done on a 10 year old well, or does it need to be done when the well is first drilled?