Final Report Mt Hope Geothermal

8/7/2019 Final Report Mt Hope Geothermal

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GEOTHERMAL POND OPTIONS FORMOUNT HOPE FARM

Bart Johnsen-Harris

Diego Wedgwood


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Table of Contents

Introduction. p. 3

Objectives 4

Glossary of Terms.. 5

Fundamentals of Ground Source Heat Pumps... 6-9

Financing .. 10-12

Reclamation and Aquaculture . 13

Findings 14

Recommendations and Alternatives. 15

Conclusion and Acknowledgements. 16


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Introduction

Mt. Hope Farm is a 200 acre farm located in Bristol Rhode Island. Located adjacent to Browns

Haffenreffer estate, the farm has a long-standing relationship with the Brown community and the

town of Bristol. The farm is officially a land trust and thus there are many stakeholders involved

in approving any project. However, this also means that the farm has an increased capability for

educational and experimental projects, as opposed to the average farm. The land is used a

fully-functioning farm, but with the additional usage of various retreats, educational seminars,

weddings, and children-oriented programs among a random assortment of other community

events.

Recently under new leadership, Mount Hope farm has taken initiative towards reaching out into

the local farming community. It is becoming a hub of sustainable agriculture in the region, and

has a variety of projects in mind to further this goal. Most recently, the farm has received

funding towards becoming a research and educational center where local farmers can come

and learn the best ways to grow vegetables over the winter. They have just completed

construction of a traditional greenhouse to study various techniques currently in practice, but arehoping to construct other, potentially cheaper and more eco-friendly, alternatives in the future.

Additionally, they have expressed interest in constructing a new visitor center that could serve

as overnight accommodation for both farmers studying greenhouse growing, as well as event

guests at the farm. This building or compound would combine both the rustic and historical

aesthetic currently in place with cutting edge green building technology.

Existing buildings on the premises include an inn, a greenhouse, and a welcoming center,

among other structures. Near these structures is a small pond, currently in poor environmental

health. The pond is highly eutrophied and does not support much, if any, actual wildlife.

However, there is potential to utilize the pond to install HVAC system that could be used to heat

and cool current and future buildings on the premises. The area of the pond is approximately2.5 acres, well over the minimum 1/2 acre required for a closed loop geothermal pond system1.

In fact, at over 107,209 sq ft, one could theoretically fit at 35-ton system, provided the pond was

deep enough2. However, at the present time we lack the resources necessary to determine the

depth of the pond, and so for the purpose of this report all recommendations are based on the

assumption that it is deep enough for such a system.

1 WaterFurnace Installation

2 GIS Analysis of topographical map of Bristol. RIGIS. Accessed: November 2010.


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Objectives

Primary Goal: To assess the feasibility of -- and give a recommendation on -- theinstallation of a ground source heat pump (GSHP) in an onsite pond at Mount Hope

Farm. This system would be intended to heat one or more of the following:

A) a proposed event and visitor center where farm guests or studentscan host a variety of events and spend the nightB) the existing historical farm buildings, including the Gov. Bradshaw

House, the Cove House, the newly constructed greenhouse, and/or others inthe vicinity

C) a new, alternative, winter-growing greenhouse that is more energyefficient and eco-friendly than the current structure

Secondary Goal: Address the eutrophication of the freshwater pond on the premises,

as well as assessing the possibility of pond reclamation tied with the installation of theGSHP (e.g. a filtration unit incorporated into the loop system) to establish a aquaculturalfood production


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Glossary of Terms

In any discussion of geothermal technologies it is necessary to define certain terms to

differentiate between the various systems. For example, the geothermal systems described in

this report are not to be confused with geothermal electricity generation

COP Coefficient of Performance

A unit less ratio of energy output to energy input

EER Energy Efficiency Ration

Equivalent of COP but for cooling (Btu/hr/W)

GSHP - Ground Source Heat Pump (aka Geoexchange)

Any heating/cooling system that utilizes temperature exchange within theenvironment

GCHP - Ground Coupled Heat Pump (aka Closed Loop)

Uses tube with no open ends to transport heated/cooled fluid- fluid never enters or

leaves system

GWHP - Ground Water Heat Pump (aka Open Loop) or

Tube has two open ends, one which takes in water and one which deposits water

SWHP - Surface Water Heat Pump (aka Pond Loop)

Typically closed-loop, uses coil installed at the bottom of a pond to freeze surrounding

water and extract heat

Direct Use

An open-loop system which utilizes naturally hot water, which eliminates the need for

pre-heating

Standing Column

A geothermal well system drilled into confined aquifer, utilizing the vertical temperaturegradient for heat exchange


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Figure 1.

Source: http://www.heat-pumps-systems.com/

Fundamentals of Ground Source Heat Pumps

For a developer deciding on an HVAC system for a project, GSHPs can be an attractive option

due to their associated energy savings and environmental benefits. According to the EPA,

GSHPS have been shown to be 22-44% more energy efficient than top line ASHPs and 63-72%

more efficient than standard electrical heating and air-conditioning systems3. The key to this

energy efficiency of a GSHP lies in its ability to harness the free and constant energy of the

earth to buffer the temperature requirements of the HVAC system. Unlike air source heat

pumps, which are subject to the fluctuations of ambient atmospheric temperatures, GSHPs can

utilize the near constant temperature of the ground (~55F for GCHPS) as an effective heat

source and sink. This translates into much smaller energy expenditure is needed to heat and

cool the refrigerant (see below) to usable temperatures.

The same principle applies to SWHPs, to a

slightly lesser extent. Due its unique molecular

properties, water is densest at 39-40F. This

means that no matter how much a body of

water is heated or cooled, a sufficiently large

pond will maintain a constant temperature at its

bed as cool water sinks and warmer water rise,

creating a constant convection current (Figure

1). It is this current that ensures that even in

the coldest winters, water will not freeze deeper

than 4-6 ft allowing for use year-round.

In a typical pond-loop system, a closed and pressurized length of piping is laid at the bottom ofa pond connected to a heat pump inside the structure. Through this pipe an anti-freeze solution

is pumped with a sub-freezing temperature, which allows it to be heated to 40F by the water at

the bed of the pond before returning to the heat pump for HVAC utilization (See below). The

same principle applies to all GSHPs: passive heating allows heat pumps to achieve efficiencies

of 300%-600% of energy normally required, or COPs of 3.0-6.0. However, surface water

systems are on the low end of this spectrum due to the lower temperature compared to

subterranean wells in GWHPS and GCHPS (40F vesus 55F).

Nevertheless, pond systems are not without their advantages4. Installation costs are relatively

lower, since there is minimal excavation compared to GCHPS and no drilling at all. By the same

token, operating costs and pumping energy are minimal, as is maintenance. Additionally, bymaintaining a closed loop of relatively pure anti-freeze solution, systems avoid potential fouling

and damage from water with less than ideal pH or biomass, a potential problem for open loop

systems like GWHPs. There are certain trade-offs, however, beginning with the fact that pump

3 Office of Geothermal Technologies. September 1998. Environmental and Energy Benefits of

Geothermal Heat Pumps. National Renewable Energy Laboratory. DOE/GO-10098-653.

41999 ASHRAE Applications Handbook. Chapter 31 Geothermal Energy.


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Source: http://www.heat-pumps-systems.com/

Figure 2.

efficiency drops slightly due to the lower temperature of the antifreeze (4-12F below water

temperature). Secondly, anti-freeze is often corrosive over time, and the lightweight

polyethylene piping of most systems is more susceptible to this wear than heavier copper or

steel piping. A study of 6 types of anti-freeze against 7 criteria like corrosion, leakage, and

environmental risk found none to be completely satisfactory5. Similarly, there is always risk of

damage to these pipes -especially in mixed use ponds- that could result in environmentally toxicleaks (a catastrophe if the pond is used for aquaculture).Finally, it should be noted that if the

pond is shallow it more susceptible to temperature variation, most drastically during periods of

drought if there is risk or the pond drying up completely. Therefore, it is crucial that the body of

water be sufficiently deep enough to prevent both this occurrence and the freezing of the water.

Heat Pump Basics

A heat pump is essentially a refrigeration unit -like an air conditioner or freezer- that it

relies on heat transfer to draw heat from one space and eject it to another. The difference lies in

heat pumps are reversible: like an A/C, they can remove heat in the summer but are also

capable of discharging heat into a room in winter. This versatility makes heat pumps a desirablechoice for any HVAC system.

In any thermodynamic

system heat naturally flows

downhill from a warm heat source

to a colder heat sink, which is why

houses tend to lose heat in winter to

the outside air, and gain unwanted

in summer. With a heat pump,

however, one can use a small

amount of energy from the grid toreverse this process. The way this

is accomplished varies slightly for

different types of heat pumps, but

almost always involves the

compression and condensation of a

refrigerant to manipulate

temperature gradients so that heat

flows in a desirable direction. Most

closed loop GSHPs use a water-to-

air heat transfer, described in Table

1(below):

Table 1.

5 Heinonen, EW and RE Tapscott. 1996. Assessment of anti-freeze solutions for ground-source

heat pump systems. New Mexico Engineering Research Institute for ASHRAE RP-863. ASHRAE.


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3-TON SYSTEM

[36,000 Btu/hr] HEATING CYCLE COOLING CYCLE

Evaporator

Cold water or anti freeze solutionin geothermal loop is heated by

earth. Heat vaporizes refrigerant in

sealed and pressurized loop[3 COP system = 24,000 Btu/hr]

Hot indoor temperature raisesthe heat of the air coil

Air coil heat vaporizes therefrigerant, drawing heat fromthe house

[ ~50,000 Btu/hr]

Reversible Valve Determines which direction vaportravels, depending on cycle

Same as Left

Compressor Vapor is pressurized, raising

temperature[3 COP = 12,000 Btu/hr]

Same as Left

Desuperheater

(Optional)

A small fraction of this heat isexchanged with a water loop fordomestic hot water

Same as Left

[12,000 15,000 Btu/hr]

Condenser

Hot vapor passes through air coiland heat is extracted

Fan blows this heat throughoutthe structure

Vapor condenses to a liquid

Heat from vapor is exchangedwith cool geoexchange loop,warming solution

Heat is rejected into the coolearth, re-cooling the anti-freeze

Vapor condenses into a liquidExpander/ Meter Liquid cooled and depressurized Same as Left

Sizing and Installation

The sizing of a geothermal system is heavily dependent on the energy requirements of

the structure in question. It is very important to size the GSHP system correctly to avoid either

uncomfortable climatic conditions if undersized, or wasted energy and undue strain on the

system if oversized, followed subsequent loss of efficiency and longevity. Depending on the

climatic conditions of the area, however, it may be advantageous to oversize a system for

heating load provided this is limited to 10-25% of the cooling load6.

6 National Rural Electric Cooperative Association. Closed-Loop-Ground-Source Heat Pump

Systems: Installation Guide. Oklahoma: 40-41.


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Figure 3.8

As a general benchmark a 3-ton system is approximately sufficient to serve the needs a

typical residential home7. However, this is only a basic rule of thumb, and should not be applied

universally. Lacking exact structural data for the site, it is not possible to determine the exact

system sizing in this report. If such a system were to be pursued, it is therefore recommended to

seek the counsel of an experienced geothermal contractor to calculate the design, energy, and

ground loads specific for the site and project. Similarly, proper installation is crucial to ensurethe system functions well, so should not be attempted by anyone other than a professional.

Typically, pond loops utilize a number of 300-foot coils of narrow diameter (0.75-1

depending on material) for the bottom of the lake, which are connected to wider (1.25 or more,

depending on volume) headers that connect back to the heat pump through a straight buried

channel8. The lake coils can be spaced in various arrangements depending on the situation.

They can be stacked on-top of each other (Figure 3.) or spread out slinky-style. Regardless, it is

advisable to create separation between the coils in some fashion - through barriers or spacing-

to ensure that there is minimal horizontal transfer of heat between pipes that reduces system

efficiency and COP. The material used in these piping varies, but in general high resin

polyethylene (PE3408) that has been thermally socket fused and UV-protected are idealbecause they are much more resistant to damage than copper, PVC, or clamped jointed tubing4.

However, since the PE coils are less dense than water even when flushed with anti-freeze it is

necessary to weigh them down. This can be accomplished by cinderblocks5, tires6, or even

concrete telephone poles9.

7 http://www.energysavers.gov/your_home/space_heating_cooling/index.cfm/mytopic=12670

8 WaterFurnace International, Inc.Pond/Lake Loop Installation. 900 Conservation Way, Ft.

9 Zimmerman, Mike. Personal Interview. Dec. 1, 2010.


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Financing

The breakdown for what is needed for financing falls into three categories: materials costs and

labor costs, and operating costs.

Materials costs

This would include the costs of any necessary purchases before the project commences. As

such, any necessary piping would fall into this category, as would the heat pump itself. Both of

these device purchases are dependent on the intended load of the heating system, which

cannot be predicted at this time for this project. However, according to energysavers.gov, a

typical rule of thumb is a $2,500 investment per ton of capacity for a geothermal system.

Additionally, any other necessary purchases would be added into this category, such as the

purchase of cement to weigh down the coils. In general, this investment is larger than that of

comparable fossil fuel systems.

Labor costs

This subsection includes the costs of installation. This is highly dependent on the type of project

in question. If the intention is to bury the coils under the pond bed, which would increase

efficiency somewhat, the labor costs are much higher, as they include dredging. This also

includes the cost of hooking the retrofit geothermal system up to the existing heating system.

Operating costs

These costs are not part of the initial investment, but are associated with running the system.

These costs are based upon the heating load of the house. However, they are generally lower

than the associated intervallic costs of fossil fuel systems. For a typical geothermal ground-

based system, this can range from 30%-60% savings, based on information fromenergysavers.gov. However, this is a higher efficiency than would be obtained by a pond loop

system, even including all the proper installation, sizing, and pre-emptive research to guarantee

a successful location. A successful pond loop, however, would still obtain higher efficiency than

a fossil fuel system. Thus, while operating costs are uncertain, they would illustrate some level

of savings over a conventional heating system.

Financial incentives in Rhode Island are applicable to this kind of project. Generally, labor costs

are fixed but, materials costs can be alleviated when these incentives are utilized. Additionally,

the incentives can be applied in other realms, such as a tax credit, which would create net

savings, but which cannot be directly applied to either the materials or labor costs.

Incentives in Rhode Island with relevance to this project include 10:

10All information in this list was taken from the Database of State Incentives for Renewables & Efficiency(DSIRE). Additional information on each of these incentives can be found there, athttp://www.dsireusa.org/
http://www.dsireusa.org/http://www.dsireusa.org/http://www.dsireusa.org/


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National Grid Commercial Energy Efficiency Incentives Program

Utility Rebate ProgramEligible Technologies: Lighting, Lighting Controls/Sensors, Chillers, Furnaces, Boilers,Heat pumps, Central Air conditioners, Compressed air, Motors, Motor-ASDs/VSDs,Custom/Others pending approval, Led Exit Signs, Commercial Refrigeration Equipment,Dry Type Transformers, Time Clocks, Occupancy Sensors, Walk-in CoolersApplicable Sectors: Commercial, Industrial, Schools, Local Government, StateGovernment, Multi-Family Residential, Institutional, Retail SupplierAmount: Schools and New buildings (custom): 75% of additional cost for efficiencyupgradesExisting buildings (custom): 50% of the project costSmall business: 80% of equipment installation costVariable Speed Drive: $1700 -$10,200Fluorescent Fixture Replacements: $10-$50/fixtureLED Exit Fixtures: $10/fixtureMetal Halide and High Intensity: $50-$100/fixtureLEDs: $15-$150/fixtureControls/Sensors: $20-$60

Air Compressors: $180-$280/HPHotel Occupancy Sensors: $75/sensorEnergy Management Systems: $200-$300/ EMS strategy point

RIEDC Renewable Energy Fund Loans

State Loan ProgramEligible Technologies: Solar Water Heat, Solar Space Heat, Solar Thermal Electric,Photovoltaics, Landfill Gas, Wind, Biomass, Hydroelectric, Geothermal Electric,Anaerobic Digestion, Tidal Energy, Wave Energy, Ocean Thermal, Fuel Cells usingRenewable FuelsApplicable Sectors: Commercial, Industrial, Nonprofit, Schools, Local Government,Multi-Family Residential, Low-Income Residential, Agricultural, InstitutionalAmount: Varies by projectFunding Source: Rhode Island Renewable Energy Fund (RIREF)

RIEDC Renewable Energy Fund Grants

State Grant ProgramEligible Technologies: Solar Water Heat, Solar Space Heat, Solar Thermal Electric,Photovoltaics, Landfill Gas, Wind, Biomass, Hydroelectric, Geothermal Electric,Anaerobic Digestion, Tidal Energy, Wave Energy, Ocean Thermal, Fuel Cells usingRenewable FuelsApplicable Sectors: Commercial, Industrial, Nonprofit, Schools, Local Government,Multi-Family Residential, Low-Income Residential, Agricultural, InstitutionalAmount: Varies by projectFunding Source: Rhode Island Renewable Energy Fund (RIREF)

Renewable Energy Sales Tax Exemption

Sales Tax IncentiveEligible Technologies: Solar Water Heat, Solar Space Heat, Solar Thermal Electric,Photovoltaics, Wind, Geothermal Heat Pumps, Solar Pool HeatingApplicable Sectors: Commercial, Residential, General Public/ConsumerAmount: 100% exemption


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Additionally, there some federally applicable programs:

U.S. Department of Treasury Renewable Energy Grants

Federal Grant ProgramEligible Technologies: Solar Water Heat, Solar Space Heat, Solar Thermal Electric,

Solar Thermal Process Heat, Photovoltaics, Landfill Gas, Wind, Biomass, Hydroelectric,Geothermal Electric, Fuel Cells, Geothermal Heat Pumps, Municipal Solid Waste,CHP/Cogeneration, Solar Hybrid Lighting, Hydrokinetic, Anaerobic Digestion, TidalEnergy, Wave Energy, Ocean Thermal, MicroturbinesApplicable Sectors: Commercial, Industrial, AgriculturalAmount: 30% of property that is part of a qualified facility, qualified fuel cell property,solar property, or qualified small wind property10% of all other propertyFunding Source: The American Recovery and Reinvestment Act (ARRA)

USDA Rural Energy for America Program (REAP) Grants

Federal Grant ProgramEligible Technologies: Solar Water Heat, Solar Space Heat, Solar Thermal Electric,Photovoltaics, Wind, Biomass, Hydroelectric, Geothermal Electric, Geothermal HeatPumps, CHP/Cogeneration, Hydrogen, Anaerobic Digestion, Small Hydroelectric, TidalEnergy, Wave Energy, Ocean Thermal, Renewable Fuels, Fuel Cells using RenewableFuels, Microturbines, Geothermal Direct-UseApplicable Sectors: Commercial, Schools, Local Government, State Government,Tribal Government, Rural Electric Cooperative, Agricultural, Public Power EntitiesAmount: Varies

USDA Rural Energy for America Program (REAP) Loan Guarantees

Federal Loan ProgramEligible Efficiency Technologies: Solar Water Heat, Solar Space Heat, Solar ThermalElectric, Photovoltaics, Wind, Biomass, Hydroelectric, Geothermal Electric, Geothermal

Heat Pumps, CHP/Cogeneration, Hydrogen, Anaerobic Digestion, Small Hydroelectric,Tidal Energy, Wave Energy, Ocean Thermal, Renewable Fuels, Fuel Cells usingRenewable Fuels, Microturbines, Geothermal Direct-UseApplicable Sectors: Commercial, AgriculturalAmount: Varies

The possibility of an Energy Efficient Mortgage (EEM) also exists. The theory behind the

program is that increased efficiency of a system, and the associated savings, are factored into

the income of a borrower. This increases the purchasing power of the borrower. The value of

the system is then included in mortgage payments. In this way, it can often make the project

free, or even have a positive cash flow, since the annual savings can exceed the annual costs

factored into the mortgage. This program can be applicable in certain cases, depending on the

system in question, location, and the lender. For more information,http://geothermal-house.com

recommends EEM expert Bill Sweitzer at National City Bank ([email protected] or 815-

788-2701)
http://geothermal-house.com/http://geothermal-house.com/http://geothermal-house.com/mailto:[email protected]:[email protected]:[email protected]://geothermal-house.com/


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Reclamation and Aquaculture

In general, the eutrophication of the pond can be thought of as a positive aspect in this

circumstance, since there are so many roadblocks in place when installing systems in

functioning ecosystems. This is due to conservation of existing species. One example of this

kind of barrier can be seen with Narragansett Bay, which we targeted for a short while during

the planning process. We thought that because of the proximity, if the pond proved infeasible,

we could look into the possibility of using Narragansett Bay as a source of geothermal energy.

According to Mike Zimmerman, an expert in geothermal energy and installation, the bay would

be able to provide enough energy to heat all of Rhode Island, thanks to ideal temperatures and

scale. However, the Army Corps of Engineers prohibits any such use of these waters, under the

ideology that it would harm the ecosystem. This is strictly enforced.

Because there seem to be no fauna in the pond in question, these roadblocks do not exist in

this situation. Thus, at the very least, the project is legally plausible. However, one of the

questions we originally posed related to the dual usage of the pond by both installing a

geothermal heat exchanger system AND rehabilitating the pond. There were a couple problemswe ran into.

One of our original ideas was to install some kind of filtration as part of our geothermal loop

system. However, once we settled upon a closed loop system as being a better option for this

instance, the possibility of incorporating a filtration unit was ruled out automatically. Our

proposed system does not actually draw water from the pond, and thus cannot be coupled with

any kind of water treatment device.

Furthermore, we were not able to discover anything with regards to the initial cause of

eutrofication. We reasoned that before reclamation is to take place, the source of the problem

must be addressed. If this source is, for example, the farm itself, then reclamation may not bean option at all. This could very well be the case, as farms are often sources of runoff. There are

many known cases in which fertilizers have been attributed to algae blooms, due to increased

nitrogen. The algae bloom then depletes the water of oxygen and makes it unlivable for most

other inhabitants.

The last problem was estimating the impact of the heat exchanger itself on aquaculture, .if all

other factors were accounted for and fixed. In the winter, the piping would be effectively freezing

surrounding water to draw heat energy for use in the building(s). Jack Hermance, Professor of

Hydrology at Brown, expressed much concern about the introduction of an additional variable

into an already volatile system. Aquaculture has, in fact, been coupled with geothermal systems

in ponds, but the examples we found applied to engineered ponds, as opposed to existing ones.Additionally, geothermal systems are often used in productive larger bodies of water, such as

lakes, but in these examples the heat exchange has a much lower impact than it would in a

smaller ecosystem. There are fish that would be able to survive more extreme circumstances.

Karp, for example, have the ability to freeze in winter and reanimate in the spring. However,

Mike Zimmerman advised us not to aim for creating a habitat. In general, it is not accomplished

with existing small ponds.


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At this point, we ruled out the possibility of accomplishing both reclamation and geothermal

usage in the pond.

Findings

Most of the following data was drawn from a conversation with Mark Zimmerman

The Coefficient of Performance (COP) mentioned earlier plays are large role in the findings of

our study. In essence, COP represents a multiplier for the efficiency of a system, comparing the

input electrical energy and output heat energy. As an example, in approximately 30 degree

Fahrenheit water, the COP is 3.

As a rule of thumb, the temperature at the bottom of a body of water remains at 40 degrees

Fahrenheit. This is because H2O is densest at 40 degrees. This is assuming that the water is

deep enough, approximately 10ft, that it will not be affected by air temperature in winter. In

winter, the surface will freeze, creating a buffer layer of ice. This ice proves to be a very good

insulator, keeps deeper water temperatures relatively unchanged.

In this example, it is also important to look at the chemical formulas for burning and thus

extracting energy fromfossil fuels. In the case of coal, for instance, each particle is simply a

carbon atom with covalent bonds to 4 hydrogen atoms. When it burns, it comb ines with

oxygen to for CO2. The remaining hydrogen atoms combine with oxygen to form 2 H2O

molecules. This reaction gives off a certain amount of energy, based off the breaking and

creation of old and new bonds. A different proportion of energy to CO 2 is resultant with oil, as is

a third proportion with natural gas. To paraphrase, the when it comes to harvesting energy with

the smallest release of carbon dioxide, natural gas is more efficient than oil, which in turn is

more efficient than coal.

This relationship is important, since one must remember that harvesting geothermal heat energyrequires an electrical input. In the end, if the COP is below 4, efficiency of burning methane

(natural gas) is about equal to the geothermal unit. The COP at 40 degrees, which is the

temperature at the bottom of this pond, is about 4. Additionally, with this COP, the amount of

carbon being emitted (by the power plant where the electricity for the geothermal system is

produced) is about equal to the carbon emitted by burning natural gas on site as a heat source,

as opposed to geothermal energy.

The conclusions that can be drawn are that the geothermal system would be inefficient on two

fronts. One, it would not be more productive than a natural gas-powered system. Two, the

system would not have a net positive environmental impact, since the carbon emitted to power

the system would equal that of a comparable natural gas system. The circumstances underwhich such a pond loop would be efficient are that natural gas is not an option- however, in

Rhode Island, it is.


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Recommendations and Alternatives

Unsuitable productivity makes this project questionable, but does not rule it out. If it were to

have an environmentally beneficial purpose, it may prove a handy educational tool, for instance,

especially for a group such as the people on Mount Hope Farm who have further goals than

maximum immediate economic gain. However with the projects environmentally benign

outcome at best, these conclusions lead us to say that a pond loop system at Mount Hope Farm

is a poor investment.

That said, there are other factors to consider. Earlier, it was mentioned that a pond loop system

in this circumstance should not be attempted with the additional goal of pond reclamation.

However, since the pond loop system has been ruled out, reclamation presents itself as

potentially attainable once again. Initial research would need to be done on the cause of the

eutrophication in the first place, to ensure that work put in to cleaning up the pond is not in vain.

If the initial source is not ongoing, or if it persists but can be counteracted or compensated for,

then reclamation can move to the next step. We would urge careful planning when it comes to

floral and faunal species to be introduced to the ecosystem. However, with proper preparationand implementation, we see the possibility for a thriving ecosystem, with aesthetic benefits,

environmental benefits, and educational benefits. Thus, we would advise that the concept of

pond reclamation is not ruled out simply because it shall not be coupled with a geothermal

system.

Furthermore, there are many other options for geothermal energy that we did not get the chance

to investigate in depth. The prospect for using Narragansett Bay must be ruled out, as

mentioned earlier, but there are other sources that could definitely be harnessed. First, if a pond

system is still desired, a man-made pond might be a good alternative if other uses for the pond,

such as agricultural irrigation or aquaculture, are integrated into the design. The multiple other

benefits associated would make such backfilling cost-effective and a pond loop could beinstalled for minimal cost. Alternately, if enough initial capital could be obtained, an open loop

system or a standing column well might be a more efficient geothermal option. Mount Hope

Farm sits on a bedrock of granite, which though expensive to drill through, has good thermal

conductivity compared to the soil heavy wells in most of the extant studies. This would require

significant water testing to ensure proper pH and water hardness, but conceivably water

pumped from a well could be flushed into the pond in a fashion that might allow for aeration and

reclamation. If an open GWHP is not feasible, it is possible to have a two column well to ensure

proper flow, but this would need to be done very carefully to prevent salt-water intrusion. Finally,

if by some chance an underground hot-spring fissure is located or deep enough well is drilled, a

direct use system could conceivably be installed. This would be a ideal, if admittedly unlikely,

situation as the hot water from the well could be used to heat a sustainable greenhouse, warm

the necessary structures, and heat a significant warm-water aquaculture operation, as has been

demonstrated in places like the Gone Fishing aquaculture farm in Klamath Falls, Oregon 11.

11 Geo-Heat Center. October 2005. Geothermal Direct-Use Case Studies. Oregon Institute of

Technology. Klamath Falls, OR.


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Conclusion

In this study of the functionality of a pond loop geothermal system on Mount Hope farm, we

found the system to be an inefficient expenditure on multiple fronts. This inefficiency factors in

both financial opportunities and external benefits. There are many other opportunities for

geothermal energy that we were unable to look into fully, however, and would urge an

investigation into other techniques on Mount Hope farm. Additionally, we think it is important not

to give up on the possibility of revitalizing the pond in question, even if it is not usable in terms of

heating.

Acknowledgements

We enjoyed working with the people at Mount Hope farm very much, are enthusiastic about the

many great projects going on within the grounds. Our thanks to David Ford and Nancy Stratton

for allowing us to participate in this planning phase. Also, many thanks to our other references:

Jack Hermance and Mike Zimmerman without whose help this project would not have been

possible. Finally, thanks to Kurt, Rob, and Emelia for allowing us the opportunity to learn in

such an free and interesting manner.

Title Image: Heat Spring Institue and Kevin Rafferty. 2008.

Closing Logo: http://www.northcoastirwmp.net/Content/10360/2/Geothermal_Energy.html

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Final Report Mt Hope Geothermal