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Debunking the Myths - GeoExchange and the Electrification of Buildings

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Jon Mesquita's picture
COO Diverso Energy

Jon is a co-founder and COO with Diverso Energy. Jon leads the business management of Diverso Energy including business operations, business development and legal negotiations.Jon has over 15...

  • Member since 2021
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  • Mar 16, 2021
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With the world-wide pressure to reduce carbon emissions in the fight against climate change, the electrification of buildings has become a hot topic for many states. This has led to multiple studies to explore the idea of “beneficial electrification” and the impact on utilities. Much has been discussed on this topic and Dunsky recently released a report, clearly outlining the positive impact geothermal has on the cost of electrification and the overall impact on the electrical grid.  

The report can be found here: https://www.hrai.ca/uploads/userfiles/files/Dunsky__HRAI_Benefits%20of%20GSHPs_(2020-10-30)_F.PDF

As a result, the interest in Geothermal or GeoExchange Heating and Cooling continues to grow exponentially with most developers seriously considering the switch for their next project. For years, the Geothermal industry has been fighting for relevance and now the discussion has shifted to debunking the myths.  

It’s often said that as long as a borefield is sized properly and the driller does a good job of installing the pipes, the geothermal system will perform consistently for the life of the building. Unfortunately, while those are both important steps, it’s a short-sighted approach and is not enough to guarantee success.

One of the most common ways to size a borefield is based on using a rule of thumb approach relying on peak heating or cooling loads. This would be like sizing a fuel tank for a car based on how much power it has rather than how far it needs to travel between fill-ups. In reality, a successful geothermal borefield is dependent on how the building operates just as much as car’s fuel consumption is dependent the type of driving and distance travelled. You have to understand both or you won’t get it right. 

Once the borefield is designed and installed properly, you’re only half way there. Borefields use the ground as a large thermal battery where the heat is rejected from the building and most of it is stored in the ground during the summer months and then extracted in the winter to be used for heating.

Think of the heat in the borefield like water in a leaky bucket: If the amount going in is more or less than what’s coming out, eventually you with either end up with an empty bucket or one that’s overflowing. The challenge is that buildings very rarely have naturally balanced heating and cooling loads and if left unattended, you will either freeze the borefield or in most cases have a borefield that overheats.

That sounds simple enough: just monitor the borefield and keep it at the right temperature. Unfortunately, the tricky part is knowing how to interpret the data and knowing what to do and when. Temperatures that may seem normal, might actually be a sign of future problems and like many things in life, the key is to take action early when changes are simple and cheap, not later when the costs sky rocket.

Fortunately, there are ways to balance the loads utilizing equipment that that most buildings already have. Connecting the geothermal system to the snow melt system for the parkade ramps for example, proper integration of the ventilation system or DHW pre-heat are important resources that allow the geothermal operator to reject excess heat and keep the borefield at the right temperature without adding expensive equipment like cooling towers that offer no value to the building. This takes us back to the importance of design. Too often geothermal designers either don’t understand the importance of integration into the mechanical system or there’s a lack of knowledge of building science. Gone are the days of geothermal design being only about the number of pipes in the ground or the tons of cooling or heating required.

So, as you can see, although Geothermal is the future for mid to high rise buildings, it isn’t as simple as many would like to believe it is and requires a specialized skill set to successfully install and manage a borefield under the footprint of the building. Its easy to look at Geothermal as just another technology or piece of infrastructure and oversimplify it. Fortunately, there are a number of experienced Energy as a Service companies in North America who focus on Geothermal who are leading the charge in the Commercial Real-Estate Space.

 

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Matt Chester's picture
Matt Chester on Mar 16, 2021

What type of maintenance specialization or repair expertise would be needed in this type of technology? I imagine it wouldn't be as easy as it is to get someone to look at your gas heater or electric AC systems today?

Jon Mesquita's picture
Jon Mesquita on Mar 17, 2021

Great question Matt. Fortunately, if implemented well, GeoExchange has a limited number of moving parts and so the maintenance and repair costs are not significant. However, the real challenge is in the management of the energy going into and out of the ground. If this isn’t well balanced, in a few years the borefield will fail and you’ll be forced to replace it with other equipment.

Matt Chester's picture
Matt Chester on Mar 17, 2021

What exactly does it mean when a borefield fails-- that geothermal is no longer able to be extracted from the site? When that happens, is it just done completely or is there any way to adjust and still make use of it (though likely at a cost, I'm sure)?

Jon Mesquita's picture
Jon Mesquita on Mar 17, 2021

When the temperature of the group loop exceeds the range in which mechanical equipment in the building can utilize to generate heating or cooling. The only way to "fix" the borefield is to let it rest and over time it will return to its natural state. However, this means that you would need to install cooling towers and boilers for an extended period of time to allow the borefield to "rest".

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