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The integral role of geothermal heat pumps in beneficial electrification - Renewable Energy World

Last updated: 02-01-2021

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The integral role of geothermal heat pumps in beneficial electrification - Renewable Energy World

Based on an article that appeared in Plumbing Engineer Magazine

Design professional have perhaps the most difficult task when trying to adapt to new industry goals.  When the standard has been combustion furnaces, boilers, and combined heat and power systems, the request to switch new (and retrofit) buildings to all electric heat pumps can seem daunting.  Modular chillers and heat recover equipment can bring a whole new set of obstacles in the design process. The fact is, it’s the new normal, so the sooner we’re all on board with beneficial electrification, the better

The topic of beneficial electrification has been a difficult topic since I started writing back in 2009. One of my first articles, written for National Geographic simply talked about heat pump efficiency. Using the Coefficient of Performance (COP) measurement, I went on to explain that a geothermal heat pump has an efficiency of 500%, meaning that it delivered 5 units of heat for every unit of electricity used by the heat pump. The comments resulting from that article were abrasive to say the least. The most typical comment said something like this; “…how can something even be 100% efficient? It’s impossible. Nothing can be more than 100% efficient.”

It simply is not intuitive to state that something is more than 100% efficient. It’s better to explain that a heat pump is a device that pumps energy from one location to another. Sometimes it can pump heat from the outside, or ambient-air into a home, other times it can pump heat from the Earth into a building. It just depends on how the heat pump is designed.

Beneficial electrification is used to describe the need and the benefit to our society to electrify all of our buildings.  The main purpose for doing this is to reduce the emissions coming from combustion heating of those homes and businesses. There are actually more emissions from the heating of homes and commercial buildings than there are emissions from internal combustion engines involved in transportation. This is speaking typically for the cities and areas that have cold winters, and high populations.

Many people are concerned about emissions from transportation. The fact of the matter is that we cannot reduce emissions to a point where our goals can be achieved without the elimination of combustion heating for homes and buildings. Some of the figures that we see indicate that 40% to 45% of the CO2 emissions are coming from heating buildings and power generation, while only 28% is coming from transportation. So in order to reduce emissions 80% by 2030 and 100% by 2040, buildings must switch from furnaces and boilers to electric heat pumps. There is a lot of Education that needs to be done.

First let’s talk about the public perception. There are a certain number of us that wish to have nothing to do with anything that involves reduction of fossil fuel combustion. They simply do not believe that that is part of the problem. However, most of this sector of the population is quite good with electrification if it can be proven to them that a heat pump will reduce their overall Energy bill. The fact is that the benefit is there, but it’s still an educational process, and we are in the midst of it right now.

The next part of the public perception has to do with comprehension of heat pumps. The Carnot refrigeration cycle is simply not intuitive, and too often, we wish to help consumers understand how it is that a compressor, an expansion valve, a condenser, and an evaporator can manipulate the movement of heat from one space to another. Probably the best analogy is to just point to a common kitchen refrigerator. It is a heat pump that is electrically powered that pumps heat out of the refrigerator box and into the kitchen. Similarly, a heat pump can pump heat out of the cold outdoors and into the building that needs to be heated.

The next hurdle to overcome has to do with explaining that the CO2 emissions come from combustion. That combustion can be coal, oil, Natural Gas, Propane, or any other combustible source that is used for heating. The average American will say that as they think of the thousands of years of human beings who have been warmed by the fireplace on cold winter days, while reading bedtime stories to their children, or enjoying idle chit-chat. This quaint picture is hard to paint as a bad thing.

However, the fact is, combustion heating adds to CO2 emissions, and does not help us in our goal toward emissions reductions. These are the people that will have serious reservations about anybody turning off the gas to their home. I’ve dealt with it many times in high rise apartments and office Buildings. The primary question asked is, what do I do if the heat breaks down. Fortunately there is an easy answer. What’s an electrically powered heat pump, emergency and backup resistance heat strips are “standard” option. That usually satisfies just about anybody.

Another fact that few people have been able to wrap their heads around is that Natural Gas, or Methane is a more potent greenhouse gas than we could have ever imagined. It has 84 times the impact of CO2. Basically, that means that as far as greenhouse gas emissions go, unburnt natural gas is far more damaging by a factor of 84 then combusted natural gas. Go figure?

With about 45% of admissions coming from burning fossil fuels to make energy including heat and electricity, having a fully electric Society and no longer using combustion Heat is the direction we want to go. Air-source in geothermal heat pumps are absolutely necessary in helping us attain the goal of no on-site admissions, and provide a terrific amount of sight sourced energy from the ambient air, and from the earth beneath our buildings.

Just because we state that we want an all-electric Society, doesn’t make it all that easy to do. I’ve used the analogy of a family who truly thinks they’re doing the right thing for the environment when they purchase an electric car and put photovoltaic panels on their home. Most people think but that is all that is needed to be as environmentally conscious & active as possible. A certain degree of consumer education is needed to explain what we’ve been talking about so far in this article. Not only do the furnaces need to be converted to heat pumps, but also the stoves and cooktops, as well as the domestic hot water tanks.

Folks who are used to cooking with gas have quite an aversion to electric cooking. The group Mothers out Front has been extraordinarily helpful in educating the public on the virtues of induction cooking. I don’t have time to talk about it too much here, but if you go to the link you can see a little bit about what they’re doing.

Another part of the important education is that the natural gas infrastructure in the US is becoming very aged. So much so that in many City centers throughout the United States, $$ double-digit billions of dollars are needed to upgrade the old natural gas piping infrastructure. This is an opportunity for beneficial electrification. The opportunity comes as we educate consumers, regulators, and utilities that while the natural gas pipelines must be upgraded, they can be upgraded to geothermal micro districts, which will provide the ground coupling service to geothermal heat pumps as easily as new natural gas pipelines could be put in. This is a perfect scenario or example of installing infrastructure that will not become a Stranded asset.

Stranded asset is a term used to describe the installation of a system that will be obsolete or illegal at some point before the end of its usable life span. Indeed, many state laws have outlawed combustion heating in buildings after the year 2050. Putting in a natural gas pipeline now, with a lifespan estimated at 60 years, is a waste of money, or a stranded asset. Putting in a geothermal micro District now, which takes about the same footprint, about the same or less in construction cost, and will be a permanent asset are conserved homes and businesses and coming Generations is the answer toward electrification. There have been several studies done on this electrification effort and the conversion of a natural gas pipe grid over to geothermal many districts, the most recent being in Massachusetts. For more information on that, read this article from Plumbing Engineer entitled, The $9 Billion Question: Stranded Assets or #Geothermal MicroDistricts?. Read this article; it has quite a bit of information that can make a believer out of just about anyone.

Air source heat pumps and geothermal heat pumps work very well when installed correctly. Like anything, it takes due attention and training to manufacturer’s instructions, and operational settings to ensure a great system install. I recognized this as a young contractor 35 years ago when I started installing geothermal heat pumps in homes. I was being interviewed on a network in Tampa Florida, and they asked me where I thought the geothermal heat pump market was going. It’s important to note here that geothermal heat pumps work very effectively for cooling, and there are quite literally hundreds of thousands of them installed in hot, tropical climates.  I said that I believed that much like utilities supplied electricity, drinking water, and wastewater drains to buildings, I believed that geothermal exchange means would be installed in neighborhoods and cities, making installation of geothermal heat pumps as simple as hooking up a dishwasher or washing machine. My point on this is that the consumer is using BTUs, which are quite similar to a utility charging for electricity or anything else of that nature. Why would a utility not want to sell BTUs to consumers? Why would a consumer not want to purchase BTUs from a utility whose responsibility it is to make certain the energy is always there?

If you think about the logic in this, it’s simpler for a consumer to hook to a geothermal district main than it is to hire a well driller, and have them drill a 500-foot bore hole in their yard. That would be as silly as having every customer drill their own water well when there is a water main running right through the property.

Building electrification is not a new idea. If you look at the image above, you can see Ronald Reagan right between two ladies as a paid spokesman for the National Electrical Manufacturers Association (NEMA), the group that was pushing for building all electric homes. The point was that it is safer and easier to provide only one source of energy to a home. I think this effort will gain traction again nationally and internationally, and we might even have a medallion that goes on new homes similar to the total electric award Medallion you see in the image. It would be sort of like a “LEED” rating.

As far as building electrification goes, the big picture is that electricity utilities have to watch the load profile of the grid. Currently, in heating dominant areas, most utilities provide electricity and natural gas or other combustible fuel for heating. So as a result, we see a peak in electrical consumption in the middle of the summer for air conditioning, while electrical consumption drops in the winter and you see a peak for natural gas consumption. This situation, in and of itself, has become a problem in many places where they’ve had to enact natural gas moratoriums because consumption is outpacing the deliverables.

When heat pumps are introduced into this same Community or City, the summertime Peak would generally stay about the same, but the winter time which is normally low on electrical demand would become better balanced. The potential problem as you can see in this image of the load profiles for the ASHRAE building in Atlanta is that the winter time peak usage could far outweigh the summertime Peak. With most Electric utilities built to the design capacity of the summertime peak, a much increased wintertime Peak as a result of building electrification would result in overwhelming expenditures of new power generating facilities. That is central to the strategy of demand-side management focusing on geothermal heat pumps to level the load profile. As you look at this image of the ASHRAE building in Atlanta, you can see that the blue lines indicate the geothermal heat pumps load profile, and it actually comes in under the summertime Peak by a good margin. This clearly illustrates that the geothermal heat pumps can increase the productivity of the grid, while reducing demand in the summertime, which will give a greater capacity overall for heating and cooling. In fact, full penetration of heat pumps into the market with prescribed numbers of geothermal heat pumps could realistically provide a reduction in demand overall that could offset the need for new electrical power generation facilities well into the future. That equates to a very good use of resources.

Beyond the financial benefits that are realized by building electrification, some of the other benefits include reduced reliance on fossil fuels, which is obvious, but reduced-price risk is another remarkable benefit. Those of us with any experience with natural gas cost fluctuations know that the cost for this fuel can vary dramatically. Just 10 years ago, NG cost three times what it cost today. Electricity on the other hand has always been fairly stable. That is because electricity can be generated from a number of different sources including hydroelectric, photovoltaic, wind power, nuclear, and even natural gas-fired power plants. By the way, the use of natural gas to generate electricity is its most effective use. It creates more benefit with fewer emissions in the process of making electricity than in any other way. You could say that the COP is higher.

Another benefit of a hydronically based geothermal micro district is something called load diversification. This has been proven out in applications throughout the world. The study done by Stanford in theory and then in practice is remarkable illustration, one that can be understood by anyone. Prior to upgrading their campus, they had electrically driven chillers that provided all of the cooling for the campus, and combustion boilers that provided all of the heating cooling and heating systems. As you can see in the image, all the combustion heating below the central line is in red, and all the electrical consumption for cooling is in blue. When they converted to heat recovery Chillers at the central energy plant, all the waste heat that normally went out the cooling towers was then pumped over to be used in heat recovery operations for the heating system. By the same token, heat recovery chillers strip the heat out of the fluid in the hydronic pipe-lines, providing essentially free Cooling, while in the process of heating other systems. This is called thermal load diversification, and you can see represented by the yellow in the image the amount of heat that was shared between Heating and Cooling operations. This is also true in geothermal districts for towns and communities. The BuroHappold study completed in Massachusetts shows many examples of thermal diversification that can be applied.

Recently, the New York State Electric Research and Development Authority (NYSERDA) created an insightful poster that showed the benefits of building electrification as you can see in the illustration. Building electrification provides more comfortable homes, less maintenance, safer and emissions-free, and much lower operating costs.

Back in 2010, Oak Ridge National Laboratories performed a study on a geothermal heating and cooling neighborhood and was able to report that full building electrification using geothermal heat pumps would reduce carbon emissions in the United States by 45%, and reduce summer Peak electrical Demand by 56%. of course this translates into remarkable Energy savings for consumers, but did you catch that 56% reduction in summer electrical Peak? That means that electrical generation facilities will not need to be upgraded for quite some time to come; another great point for strategic building electrification.

It has been my experience that among the largest Natural Gas Distribution companies in North America are keenly aware of the benefits of geothermal districts. If you look at the image below, you can see that both Distribution Systems require pipelines. The big difference is that the Natural Gas Distribution pipeline needs Source energy, meaning it needs a constant supply of natural gas, and it does not deliver a product that is capable of cooling the building. Meanwhile the similar infrastructure of geothermal micro District provides a renewable energy source, one that needs no Source energy because it’s exchanging heat with the Earth and other utilities, and it’s deliverable is both Heating and Cooling, and of course domestic hot water.

As we develop this technology for full integration as we move toward building electrification, the workforce is going to shift its talents a little bit. It’s helpful to our workforce and economy to know that the pipelines that need to be replaced for natural gas systems will simply be replaced with a material similar to what natural gas distribution lines are made of currently, and that is high-density polyethylene (HDPE). The heat pumps that are installed in the buildings will be put in by cross-trained plumbers and heating contractors. Geothermal heat pumps are an appliance as simple as a window air conditioner in principle. The difference is, they need to be installed in cooperation with a competent duct distribution system, electrical services and controls for monitoring the temperature of the space.

Most utilities have begun to recognize energy in the form of BTUs, rather than kilowatt-hours and therms. Whatever measure you use, the image above represents the result of transportation and building electrification.  In the first slide you can see that the peach and pink represent the number of gas furnaces and boilers, and the blue represents the number of electric heat pumps. Overall electric consumption increases annually, while peak demand is reduced, resulting in an overall energy reduction of nearly 50% in total energy consumption. That is due to the fact that heat pumps use 1 unit of electricity to create 3 to 5 units of heating or cooling. This is the image that reflects building electrification and deep decarbonization. This is it. This works. This is where we’re going.

Special Thanks to HEET, Mothers Out Front & BuroHappold

Jay Egg is a geothermal consultant, speaker, writer, and the owner of Egg Geo. He has co-authored two textbooks on geothermal HVAC systems published by McGraw-Hill Professional. He can be reached at jayegg.geo@gmail.com.

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