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Geothermal Energy’s Implications for Buildings and Homes

Did you know that the US spends between $30 and $50 billion every month on foreign oil?  I find that number to be huge and think that we need to reduce that amount if we want to remain competitive, independent, and environmentally friendly. It doesn’t make long-term economic sense to spend so many of our resources on an environmentally toxic substance that also needs to be transported halfway around the world. If the goals are energy independence, sustainability and local jobs, some say the US should drill for domestic oil and other fossil fuel resources that are within US borders.

In a recent interview I had with T.Boone Pickens, he mentioned that if we switched large trucks to natural gas instead of diesel we could reduce foreign oil dependency by 50 percent. I agree with him, but also think we should focus more on geothermal energy and call for a “drill, baby, drill” campaign that all political parties can endorse as it will save money and help our environment, while creating domestic jobs that would be difficult to outsource to other countries. To accomplish this requires a slight change in policy to remove some unfair barriers, but let me first explain the benefits of geothermal.

Geothermal Quick Facts

Geothermal energy is the only commercially available renewable energy that offers 100 percent uptime reliability. It uses extremely simple technology, has low operating maintenance costs and results in far fewer emissions by using the earth’s thermal energy instead of fossil fuels. Geothermal energy represents a broad spectrum of applications, including utility scale power as well as solutions for buildings and homes.

For example, utilities use hot spots in the earth’s crust to make steam and then drive a turbine to make electricity. In addition to using our US-based resources to make kWhs, utility-scale geothermal steam generation plants are also eligible for Renewable Energy Credits (RECs), just like solar and wind energy projects.

Where I want to focus your attention is on another example of geothermal energy — the Ground Source Heat Pump (GSHP) which uses the ground as a moderate temperature heat source during the winter and a heat sink during the summer. Basically, during the summer, it is easier to reject heat from the building to the ground (~60oF) versus the outside air (~80oF). The same concept is true in the winter — easier to recover heat from the ground (~60oF) versus the outside air (~40oF).

GSHPs are an example of renewable energy technology that is also distributed, which reduces the strain on our electrical grid. According to the Department of Energy, the U.S. had over 600,000 GSHPs installed and operating by 2008, so the technology is proven and GSHPs are being installed by countries all over the world.

The Economics of Ground Source Heat Pumps
I am surprised Ground Source Heat Pumps are not more popular. GSHPs reduce the kWhs required for air conditioning. When you also consider that when a utility promotes GSHP applications (for example as a Demand-Side Management method), the utility will have reduced demand during peak periods, requiring fewer generation plants and less pollution.

As our world’s overall energy consumption increases, we should be promoting GSHPs to help us satisfy our needs because a GSHP only costs about $.8 million/MW to build, as opposed to a new fossil-fueled power plant ~$2 million/MW.

I acknowledge that GSHPs do have higher installation costs to the building owner than a traditional air conditioner (air to air heat pump). The main reason is due to the infrastructure cost of drilling the GSHP boreholes and installing the ground heat exchanger.

However, the ground loop will last more than 50 years, so perhaps utilities should treat this as “infrastructure” the same way that they evaluate transmission lines. In addition, because these systems last 50+ years and we pay the operating costs every year, the life-cycle costs should be compared. When this is done in combination with the economic benefits to the utility, GSHPs are a no brainer and offer the lowest life cycle cost.

They have shorter payback periods than other renewable technologies and do not require back-up infrastructure, wind and solar energy generators need back-up generation when it is cloudy or calm.). GSHPs provide 100 percent uptime. Because the ground loop has a long life and is hidden and quiet, it is an asset to the building/home that should add value the same way that a solar array on the roof does.

Let’s look at some sample numbers using these equations relating to Energy Efficiency Ratio “EER” and Coefficient of Performance “COP”.

EER = (COP * 3.412) = (BTU per hourmoved/wattsin).

Example: If you had a 5-ton air-to-air heat pump, we would be moving 5 x 12,000 BTU/hour, which equals 60,000 BTUs per hour. If the air-air Seasonal Energy Efficiency Ratio (SEER) is 10, that means we use ~6 kW every hour we run the air-air heat pump.

In contrast, a GSHP would have a SEER of 20 during the summer, which means you would only need ~3 kW. Thus, the GSHP reduces demand by ~3 kW, reducing emissions and helping the utility shave peak demand during the summer. In the winter, the SEER of the GSHP drops from 20 to 13.65 (COP = 4), meaning that the unit will draw 4.4 kW to move 60,000 BTU/hour. 4.4 kW equals about 15,000 BTU/hr of input energy, with the remaining 45,000 BTU/hr coming from the earth.

The total fuel/energy usage is still less than conventional sources (fossil fuels) because the GSHP gets ~75% of the energy from the earth (~45,000 BTU/hr), which avoids fuel that could be going into a natural gas fired heater/boiler. In addition, most utilities are not hitting their kW peak load during the winter, thus GSHPs do help the utility level their kW load throughout the year, which is an effective demand side management function.

Call to Action

Although GSHPs leverage a renewable energy resource, it does not currently allow the user to obtain RECs. I think we should change that.

Due to population and general trends utilities need to prepare for higher demand, why not get that energy from a renewable source at a reduced overall capital investment as well as reduced operating costs? Why shouldn’t the GSHPs get RECs if they are literally using the earth’s natural energy to avoid MW, just the same way that solar, wind and hydro technologies do?

With respect to Renewable Energy Credits, we should find a way to allow GSHPs to achieve them.Why does US policy grant RECs for Utility-Scale Geothermal generating steam from the earth’s hot spots, but not for GSHPs at the building level? Shouldn’t a BTU from the ground be able to become a REC in all designs? If the utilities could get RECs, maybe they would be able to subsidize GSHPs as a Demand Side Management strategy.

The above reasons are why I support drilling for natural and environmentally friendly geothermal energy. If you would like to help get utilities to install geothermal systems as an alternative to more fossil fuel generation, let me know. I would like to hear your ideas on how we can get this done. I think the energy policy needs to be updated, and this would help us all over the long term.

Eric A. Woodroof, Ph.D., is the founder of Profitable Green Solutions, and is completely committed to helping businesses and organizations “go green,” while improving profits.  For more than 20 years, he has helped over 400 organizations and governments improve profits with energy-environmental solutions, generating over $100 million in savings. He is the Chairman of the Board for the Certified Carbon Reduction Manager (CRM) program and he has been a board member of the Certified Energy Manager (CEM) Program since 1999. His clients include government agencies, airports, utilities, cities, universities and foreign governments. Private clients include IBM, Pepsi, GM, Verizon, Hertz, Visteon, JP Morgan-Chase, and Lockheed Martin.

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