How Geothermal Heat Pumps Can Soar Like Solar

Posted: Feb 28 2014, 9:36am CST | by , Updated: Mar 1 2014, 12:57am CST, in News | Misc


How Geothermal Heat Pumps Can Soar Like Solar
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Geothermal Heat Pumps (GHP) are a niche market.  They shouldn’t be.

A Better Mousetrap?

Ralph Waldo Emerson never said “Build a better mousetrap, and the world will beat a path to your door.”  The mousetrap that likely inspired the misquote was invented seven years after his death.  Unfortunately, many people take it literally.  GHPs have all the hallmarks of a better mousetrap: They do the job of heating and cooling a building more efficiently than any other option.  Despite the larger up-front cost, they are a mature technology and usually the most economic option in for buildings that can accommodate them.

Not only can GHPs cut energy costs for heating and cooling by up to 80%, they can also provide other benefits such as essentially free hot water in cooling mode, lower reliance on fossil fuels, and the elimination of above ground outdoor equipment.  These advantages have earned GHPs a small but dedicated cult of true believers, but not broad market acceptance.

The world has not yet beaten a path to the GHP door.  Instead, GHPs have a slim and only modestly growing market share.  The North American geothermal market was only $102 million in 2012.  Frost and Sullivan projects it to reach $148 million by 2017.  The entire market for climate control products was $13 billion in 2012, and they project  it to reach $15 billion in 2017.  That gives GHPs a 0.8% market share in 2012, growing to a 1% market share in 2017.  While the GHP market is projected to grow at a 7.8% annualized rate, much of that is due to overall market growth.  GHP’s market share is only expected to grow at a 4.7% annual rate.

Although that estimate of market share is biased downward because not all buildings can accommodate GHPs, this does not bias the calculations of annual growth rate in market share.  Less than 5% annual market share growth is clearly not the type of market transformation many would expect from a “better mousetrap.”

Siege Mentality

I struck a few raw nerves when I asked if air source heat pumps are a threat to geothermal heat pump suppliers last month, despite the fact that I answered my own question with a “No.”

Except in moderate climates, super-insulated homes, or situations where the installation of a geothermal heat pump (GHP) would be particularly difficult, GHPs have the better economics.  This is despite recent advances in air source heat pump (ASHP) technology, which led me to ask the question in the first place.  ASHPs don’t provide hot water, while man  GHP systems can.  Also, as the recent heavy snows in the Northeast demonstrated, there are some advantages to having a heat exchanger which is not exposed to the elements (see pic).

Given all these advantages, why the raw nerves? I suspect it’s because geothermal heat pump sales continue to disappoint and proponents are looking for someone to blame.

ASHPs in Net-Zero Buildings

Another target of geothermal advocates’ ire is Marc Rosenbaum (who teaches the online Net Zero Energy Homes course in the Northeast Sustainable Energy Association’s Building Energy Masters Series.)  He also raised hackles when he recommended minisplit air source heat pumps (ASHPs) for most single family net zero homes (I quoted Rosenbaum extensively in the previous article.)

Marc relates the story of the Putney School’s 16,000-square-foot Net-Zero Field House.  The team designing this building modeled its heating costs using a GHP, and also using an ASHPs with additional solar photovoltaics  sufficient to provide the extra electricity needed to run the ASHPs.  They found that it was cheaper to expand the solar system to power the ASHPs than it would have been to pay the extra installation costs of a GHP.   Furthermore, the price of solar has fallen significantly since the Putney Field House was built; the price of the ground loop for a GHP has not.

Nevertheless, Rosenbaum’s preference for ASHPs in highly insulated buildings does nothing to explain GHPs’ low market share growth rate.  Net Zero buildings are the exception, not the rule, and have a far lower market share than geothermal heat pumps.  When the heating load is very low, the operating cost advantage from the greater efficiency of GHPs is not enough to repay the additional installation costs.  That is not the case in 99.9% of new and existing buildings today.

GHPs Almost Everywhere Else 

My own home, a farmhouse built in 1930, is much less efficient and requires a lot more heat than a Net Zero home, despite my own significant improvements.  I don’t have enough suitable roof space for photovoltaics to make up for the extra energy ASHPs would require, even if that could be done economically.  I opted for four ductless minisplit ASHPs rather than a GHP system, but it was because the minisplits allowed me to do the install without adding air ducts.  Adding air ducts to my 85 year old home would have significantly increased the cost and disruption of installing a GHP system.

There are not currently any ductless geothermal systems on the market, although it’s possible that my needs could have been met with a water-to-water GHP using my existing radiators for heating and small air handler units in various rooms for cooling.  Unfortunately, the best water-to-water GHPs are significantly less efficient than the industry standard water-to-air units, reducing the advantage of going with geothermal in the first place.  I would have also lost the significant efficiency gains I achieve with zoning and only heating rooms when they are in use.   Finding a contractor willing an able to cost-effectively install such a complex system would have been a daunting task as well.


Since GHPs are economic in most situations, other factors must be holding them back.

The relative complexity of a geothermal system is one likely suspect.  As Rosenbaum says about ASHP minisplits,

“[O]ne thing I really like about the minisplits is how they are packaged systems from a single supplier, and are highly engineered as a system and therefore very reliable. GSHP systems are, at least where I have practiced, essentially custom engineered and installed, usually by several entities who have a shared responsibility to make sure the systems perform.”

Given the large up-front cost of a GHP system, the risk of a poor installation is likely to deter nonprofessionals from using GHPs even more than it deters experienced professionals like Rosenbaum.

The Curse of Complexity 

The only cure for installation risk would be a way to validate the performance of GHPs in the field, and track problems back to their source.  When contractors lose the ability to blame others for their mistakes, they quickly stop making those mistakes or they go out of business.

I recently spoke to Matt Davis, the co-founder of Ground Energy Support and a professor of hydrology at the University of New Hampshire.  Ground Energy Support provides GHP monitoring to GHP owners and contractors, as well as data and analysis to support the development of the industry.

Ground Energy Support recently published a 14 page Homeowner Guide to Geothermal Heat Pump Systems.  While I found the guide easy to understand, it makes clear that GHPs are not for everyone.  The start of the guide directly helps homeowners decide if they and homes are suitable for a GHP, while its length indirectly makes the point that GHPs are not always “plug and play.”  The six pages dedicated to finding and selecting a suitable GHP installer indirectly makes clear that the process is not for anyone with only casual interest in GHPs and their savings they bring.

If GHPs are to become commonplace, the process of financing and purchasing a reliable GHP system have to be simplified to the point where it becomes a matter of calling a name in the phone book.  The success of SolarCity Corporation (NASD:SCTY) in providing solar to homeowners who are more interested in the green in their checking account than the green of their electricity shows the potential.  That success is based on SolarCity’s ability to provide financing, installation, maintenance, and performance verification services internally.  All the homeowner needs to do is pay the monthly bill for electricity production.  The value proposition is simple: a hassle-free installation and savings from day one.

The SolarCity of Geothermal

Geothermal heat pumps also have the economic potential to deliver that same value proposition: hassle free installations, and reliable savings from day one.  But if the industry is to achieve this potential, several things have to come together:

  • A single company responsible for the entire installation, from engineering to installation to maintenance.
  • Reliable monitoring of heat production from the ground loop.
  • A financing tied to the geothermal installation itself, to allow a lease-like structure which allows homeowners to see the benefits from day one.

We already have the corporate and financial structures to bring the solar lease model to GHPs.  In fact, it takes little stretch of the imagination to see a solar lease company acquiring or partnering with GHP installers and offering a geothermal lease along with the solar lease to its customers.  In cold climates not known for their sunny winters such as the Northeast US, the underlying economics of GHPs are far superior to those of solar photovoltaics.  These economics should enable very attractive GHP leases, as soon as the other pieces are in place.

First, the homeowner and the geothermal lease company would have to have a reliable, objective way to monitor the performance of the GHP system.

Geothermal Monitoring

Ground Energy Support is tackling this problem with its GXTracker, which monitors the heat output of the ground loop and monitors or models the electricity consumption of the pump itself.  Heat production monitoring lets everyone know if a system is operating as designed, and helps diagnose the problem when it is not.

Of the 30 GHP systems Ground Energy Support has been monitoring for the last two and a half years, 60% have had some operational, maintenance or mechanical issue.  Most of these were minor maintenance issues or improper settings which caused only minor drops in performance, but which would have gotten worse if undetected. But 17% of the systems had significant design or installation problems, although a third of these were oversized systems which can lead to higher energy costs but were likely the result of homeowner preferences.  Another third were easily fixable and not the fault of the installer: a failed heat pump (covered under warranty), and an air duct which was left open to an unfinished garage.  The rest (high pumping penalty caused by too large a pump or too small pipes, and an undersized ground loop) could have been avoided if the homeowner had been able to vet the installers’ track records – another potential benefit of ubiquitous monitoring.

One other way proper monitoring of GHPs might help the industry is enabling the implementation of incentives for renewable heat production from geothermal ground loops, analogous to the incentives for photovoltaics.  The Massachusetts legislature currently working on a bill to allow heating and cooling with renewable fuels to benefit from the same incentives the state give to renewable electricity.  The bill states that the heat must be “verified through an on-site utility grade meter” or similar means.


Advocates of geothermal heat pumps should spend less time discussing the well established attractive economics of GHPs in theory, and more time delivering those economics.  The key to this is making the buying process simple for the customer while providing verification and taking responsibility if those economics fail the be acheived .  While GHPs are not the best fit for every home, in many climates the majority of such homes will benefit more from a GHP system than a new conventional heating and cooling system.

The solar lease is an excellent model for taking a renewable energy system and making it attractive to the general public.  The GHP industry can follow down this path, but first it has to adopt reliable monitoring as a standard feature.  This will hold installers to account for their design and implementation, while giving customers confidence that they will get what they pay for.

Adopting monitoring could start with customers wanting to know that their systems are operating as designed.  It could also begin with states like Massachusetts giving incentives for verifiable renewable heat production, or an installer deciding to break open the market by offering a geothermal lease.

It seems to me that the group that has both the most to gain and the most power to affect change is GHP manufacturers.  If they were to include monitoring as a standard feature, they might be able to catalyze this market themselves.

To Davis’ knowledge, only Waterfurnace Renewable Energy (TSX:WFI, OTC:WFIFF. Disclosure: I own this stock.) and  Modine Manufacturing Company (NYSE:MOD) currently offer any sort of energy monitoring, and only as part of their optional Aurora and Orb controllers.  I suspect the extra costs of making such monitoring standard would be more than compensated by greater customer satisfaction and increasing sales.

Will one of these manufacturers make the first move, or will change come from the bottom up?  If geothermal heat pump sales are going to soar, someone will have to make the first move.

Source: Forbes

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