Geothermal heat pumps seem to be a bit of a dark horse in the Big Apple, which these days has aspirations of becoming a Green Apple. In some respects the reasons for it are unclear, because there have certainly been successful geothermal projects. On the most practical level the obstacles seem to be mostly lack of knowledge as well as some quasi-regulatory issues. But geothermal heat pumps are probably the single most strategic renewable energy technology in the City, and it is gratifying to see that City Hall is finally studying the technology.
Lack of knowledge about geothermal heat pumps begins with the fact that people are uninformed about the different geothermal technologies that exist, and what their applications are. There is deep geothermal, and if you are in Iceland, and you have a geyser or lava stream in your backyard, you may have an opportunity to exploit that technology. This is not what we do in urban environments. The shallow varieties of geothermal are really forms of heat exchange that exploit the largest solar collector in the world: the earth's crust. Below the frost line it is permanently 52 degrees Fahrenheit in NYC, and that is enough to set up a heat exchange which can provide cooling in summer and heating in winter, (HVAC), and perhaps Domestic Hot Water (DHW), and it might be able to heat your pool water, or provide an ice-melt system for your driveway.
NYSERDA MPP hampers geothermal heat pumps
The most practical problem that is holding up geothermal heat pumps may seem to be the difficulty of retrofits. Obviously, new construction is easier, but that issue is not as large as it seems, for the payoff from geothermal can be significant, particularly in the city, where space is a problem and we need to exploit every available angle if we want to generate our own energy. The most practical impediment to geothermal deployment is the NYSERDA MPP program, which penalizes a project (building) for adding any load to the grid. Their objective is reducing load. Besides all the other reasons why this program is an impediment to green energy technology deployment, here is yet another one.
From the standpoint of the overall improvement of the energy economics of buildings, there are few more powerful solutions around, however we've stacked the deck against it, because the focus of the NYSERDA MPP is narrowly defined by reducing electrical demand. This is yet another case where these kinds of programs are targeted to get building owners to do what is good for the utility in the short run, not even in the longer run. As a result, building owners are missing out, and so is the overall energy household of the city.
Geothermal heat pumps: the multiplier effect
The reason geothermal heat pumps are such a strategic technology, is because they create a multiplier effect, which can create compound returns from a renewable energy retrofit. At a Coefficient of Performance of around 4.0, which is the terminology the geothermal industry uses, they return 400% on their energy input. To put it differently, for every one BTU equivalent input, you get 4 BTUs out. Now that's a good trade! It may be marginally economic with grid power, depending on your rates, but you can boost the economics by leveraging time of use rates (for your geothermal field needs recovery time anyway, and you're designing around the objection mentioned above, against increasing demand from a building). Then, if you can generate some serious power from wind or solar, you can create a very powerful, and totally renewable, solution.
In short, if you can cover part of your BTU load from geothermal energy today, you have the option to generate more of your own energy with other means, either solar PV, or a wind turbine (there are more and more building mounted options coming on the market), so that if the electricity prices become to high to your taste, you can probably cover your requirements for your geothermal heat pumps, as well as taking part of your building off line, and there you will have a permanent energy price hedge. And remember, you are competing with retail electricity in your home or apartment building, and in NYC the rates are sky high, because we are far away from power generation, and the long haul transportation is expensive. Only Long Island is higher than the City. In either case the cost of transport is 60-70% of the bill in most cases.
Geothermal Heat Pumps for Multi-family Buildings
In a traditional multi-family building, the most obvious strategy is to replace the Domestic Hot Water (DHW) with either geothermal heat pumps or a solar thermal system. It usually represents 30-50% of the BTU load in the building, at least the for the building owner, who is responsible for heat and hot water.
With the proliferation of building mounted wind turbines, wind energy becomes a logical complement to the geothermal solution, particularly because pre-heated hot water becomes an effective storage solution, and that is the single most difficult aspect of creating an effective green energy infrastructure. It explains why we can create compound investment returns with these types of integrated green energy retrofits. This way multiple green energy technologies can be exploited within one building and taken together, they produce superior investment returns, while providing enhanced building resiliency.
Conclusion: green energy and property values
The reason geothermal heat pumps are so strategic for a green energy infrastructure in a building is because they represent a multiplier with which you can build an effective energy price hedge into your building, and create a compound return on integrated green energy technology which will accrue to you by raising property values.
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