We cant have confusion hamper uptake of geo-exchange technology. That matters, because the technology has the potential to be a key contributor to decarbonization efforts and offers real benefits to American businesses, households and grid operators.

Geo-exchange: Green Potential Muddied by Misconceptions

Kevin Stickney | Erda Energy

Decarbonization is coming. The United States is strewn with ever-more renewable generation; Tesla and Electrify America are leading the charge on decarbonizing the auto-industry and States like California are setting fiercely ambitious climate policies. But if there’s one area there needs improvement, it’s in heating and cooling.

In 2015, Americans used 3945 trillion British Thermal Units (BTUs) heating their homes and a further 731 trillion on air conditioning to cool them. Much of that heating demand was met by high carbon fuels extracted from the ground.

This needs to change – not just in homes but in commercial premises too. And it will. The questions are how and when. The answers will depend on what technologies are used to get there.

One option that already exists is geo-exchange, also known as both ground source heat and as geothermal. It’s a proven technology in the field with a strong track record. But it’s underutilized, at least in part due to some stubborn misconceptions about what it is and what it does.

Geo-exchange – a good grounding for decarbonization

Geo-exchange is a powerful technology. It works on the basis that, below the earth, temperatures are consistently between 50°F and 60°F all year round. For most places, this means that the ground is warmer than the surface in winter, and cooler in summer.

Geo-exchange runs with this principle. A heat-conductive liquid is circulated through boreholes into the earth, either picking up or getting rid of heat.  An electric heat pump, like a reverse air conditioner, concentrates this heat and circulates it throughout the building. Or, just like a regular air conditioner, it collects this heat from the building’s air and expels it into the ground. Nothing is burned and the only input is electricity. Along with air source heat pumps (ASHPs), geo-exchange is an important technology for electrifying heat.

And that’s important for decarbonization. The logic of electrification is simple: one area we know how to decarbonize on a mass scale is power. Therefore, if we can run other energy processes using electricity rather than by burning something (e.g. in a car engine or a natural gas boiler), we have a route to decarbonization. Electric technologies are as clean as the power that runs them, so as time goes by and renewable generation spreads, they will get cleaner. California, for example, has pledged to decarbonize power completely by 2045.

Widespread benefits

But it’s not just about the environment. Geo-exchange has a lot of other benefits too. For domestic customers, the chief ones are cost and comfort.

In areas such as the North East, businesses and households face an energy bill double-threat: they spend a lot heating their spaces during very cold winters and a small fortune again on air conditioning over hot summers. Americans spent over $27 billion on air conditioning in 2015. Well-designed geo-exchange, on the other hand, typically lowers cost on an annual basis, as you are no longer paying for fuel and the related infrastructure. This reduces any trade-off between comfort and cost.

For businesses, this is a powerful commercial proposition. We may have the option to don an extra sweater at home to save on heating but businesses have a responsibility to provide their staff and customers with a temperate environment.

Locations with high energy needs such as supermarkets and hotels are especially well-suited to geo-exchange. Here, not only can systems harness heat from the earth, but also from other equipment such as freezers and refrigerators that produce a lot of heat as a by-product, boosting efficiency and adding to the financial benefit.

Businesses can also enjoy secondary benefits such as the reputational boost that comes from low-carbon heating (potentially zero carbon if combined with onsite renewables). Consumers increasingly factor social and environmental issues into their buying decisions and business customers are doing the same with their supply chains.

Homeowners can enjoy the same benefits but may be less able to afford the upfront expenditure. Fortunately, many states are throwing in a raft of financial incentives to sweeten the deal. For example, New York state homeowners can claim a $1,500/ton incentive for home geo-exchange installations from NYSERDA, as well as a 30 percent federal tax credit.

It’s not just the end-users of energy that can benefit though – the suppliers and distributors of it can too. Independent Systems Operators (ISOs) and Regional Transmission Organizations (RTOs), tasked with balancing the grid and keeping the lights on, are watching trends such as renewable energy and electrification carefully. In California, the famous duck-curve is an example where non-dispatchable renewables create a mis-match between times of high supply and high demand that must be managed. Electrifying our cars and heat would also add load to the grid.

However, the ability to time-shift electricity use with geo-exchange systems means that they can in fact be a smart tool to support grid operators, helping them to smooth peaks and troughs in supply and demand.

Ground source heat: thinking deeply

Despite these benefits, geo-exchange and GSHPs have had limited uptake. The opportunity is far larger. Partly, this can be attributed to the marginally higher upfront costs and longer wait on ROI compared to fuel technologies that enjoy economies of scale and rich subsidies. Better technologies and installation techniques have chipped away at these factors and continue to do so.

But another problem is that geo-exchange has struggled to shake some stubborn misconceptions.

In no small part, these stem from loose terminology. Both consumers and the industry alike will often use the terms geo-exchange, ground source heat pump (GSHP) and geothermal interchangeably.

Though not technically incorrect, this is unhelpful and out of keeping with how the terms are used elsewhere in the world. Geo-exchange is in fact an advanced form of GSHP, but geothermal typically refers to a different technology which uses ultra-deep boreholes to access heat from the Earth’s core or in areas of volcanic activity. This extreme heat can then be used as heat or as steam put through a turbine to produce power. Think Iceland (which does this) or somewhere like Yellowstone (which, in theory, could). In contrast, GSHPs typically drill down around 50-400 ft and the heat they draw has typically been contributed by the sun rather than the Earth itself.

Geo-exchange is then an evolution of the GSHP concept, typically drilling much deeper (around 650ft) and capable of using the ground as a thermal battery in order to produce both heating and cooling. Engineering advances and better modelling allow for better heat exchange and more efficient systems.

If this sounds like a pedantic distinction, it’s not. It can lead to real confusion. For example, potential geo-exchange users may mistakenly think they need to sit atop an area of volcanic activity and discard the option without properly considering it. Or they might see frozen ground and dismiss the idea of subterranean heat. Equally, the mix-up can obscure the great ability of geo-exchange to provide cooling as well as heating – increasingly important with a warming climate. After all, geothermal contains the world ‘thermal’, which implies ‘heat’ to most people. Geo-exchange is heat/cooling neutral.

In short, in an age of fast-paced energy transition, terminology matters. Where climate change really should be referred to as climate breakdown, the same is true of our solutions to this problem: We can’t have confusion hamper uptake of geo-exchange technology. That matters, because the technology has the potential to be a key contributor to decarbonization efforts and offers real benefits to American businesses, households and grid operators. We need to stop geo-exchange’s commercial and green potential being muddied by misconceptions.

About Kevin Stickney​

Kevin is the managing director of Erda Energy’s London office. He has pioneered innovative technology and clean energy solutions for Greenfield Energy, which was acquired by Erda Energy in July 2017, for more than a decade. Kevin contributed to the invention of many of the Erda Energy patents, installed the systems required to operate Erda solutions and develops and delivers strategy for the company. 


  1. https://www.eia.gov/consumption/residential/data/2015/c&e/pdf/ce3.1.pdf
  2. https://www.eia.gov/consumption/residential/data/2015/c&e/pdf/ce5.5a.pdf


The content & opinions in this article are the author’s and do not necessarily represent the views of AltEnergyMag

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