Geothermal Basicsjkjhbmn

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GEOTHERMAL ENERGY 1

Chapter

11.1

Geothermal BasicsThe word geothermal comes from the Greek words geo (earth) and therme (heat). So, geothermalenergy is heat from within the Earth. We can recover this heat as steam or hot water and use it toheat buildings or generate electricity.

Geothermal energy is a renewable energy source because the heat is continuously producedinside the Earth.

Geothermal Energy Is Generated Deep Inside the Earth

Sobhasaria Engineering college


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Geothermal energy is generated in the Earth's core. Temperatures hotter than the sun's surface arecontinuously produced inside the Earth by the slow decay of radioactive particles, a process thathappens in all rocks. The Earth has a number of different layers:

The core itself has two layers: a solid iron core and an outer core made of very hot melted rock,called magma.

The mantle surrounds the core and is about 1,800 miles thick. It is made up of magma and rock.

The crust is the outermost layer of the Earth, the land that forms the continents and ocean floors.It can be 3 to 5 miles thick under the oceans and 15 to 35 miles thick on the continents.

The Earth's crust is broken into pieces called plates. Magma comes close to the Earth's surfacenear the edges of these plates. This is where volcanoes occur. The lava that erupts fromvolcanoes is partly magma. Deep underground, the rocks and water absorb the heat from thismagma. The temperature of the rocks and water gets hotter and hotter as you go deeper

underground.People around the world use geothermal energy to heat their homes and to produce electricity bydigging deep wells and pumping the heated underground water or steam to the surface. We canalso make use of the stable temperatures near the surface of the Earth to heat and cool buildings.

1.2 Where Geothermal Energy is Found



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The ring of fire goes around the edges of the Pacific. The map shows that volcanic activityoccurs around the Pacific rim.

Naturally occurring large areas of hydrothermal resources are called geothermal reservoirs. Mostgeothermal reservoirs are deep underground with no visible clues showing above ground. Butgeothermal energy sometimes finds its way to the surface in the form of:

Volcanoes and fumaroles (holes where volcanic gases are released)

Hot springsGeysers

Most Geothermal Resources Are Near Plate Boundaries

The most active geothermal resources are usually found along major plate boundaries whereearthquakes and volcanoes are concentrated. Most of the geothermal activity in the world occursin an area called the Ring of Fire. This area encircles the Pacific Ocean.

U.S. Geothermal Resource Map

Source: U.S. Department of Energy, Energy Efficiency & Renewable Energy

When magma comes close to the surface, it heats ground water found trapped in porous rock orwater running along fractured rock surfaces and faults. These features are called hydrothermal.They have two common ingredients: water (hydro) and heat (thermal).

U.S. Geothermal Is Mostly in the West

Most of the geothermal reservoirs in the United States are located in the western States andHawaii. California generates the most electricity from geothermal energy. "The Geysers" drysteam reservoir in northern California is the largest known dry steam field in the world and hasbeen producing electricity since 1960.

1.3 History:



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In the 20th century, demand for electricity led to the consideration of geothermal power as agenerating source. Prince Piero Ginori Conti tested the first geothermal power generator on 4July 1904 in Larderello Italy. It successfully lit four light bulbs.[ Later, in 1911, the world's firstcommercial geothermal power plant was built there. Experimental generators were built inBeppu, Japan and the Geysers California, in the 1920s, but Italy was the world's only industrial

producer of geothermal electricity until 1958.n 1958, New Zealand became the second major industrial producer of geothermal electricitywhen its Wairakei station was commissioned. Wairakei was the first plant to use flash steamtechnology.

In 1960 Pacific Gas and Electric began operation of the first successful geothermal electricpower plant in the United States at The Geysers in California. The original turbine lasted formore than 30 years and produced 11MW net power

The binary cycle power plant was first demonstrated in 1967 in Russia and later introduced to theUSA in 1981 This technology allows the use of much lower temperature resources than werepreviously recoverable. In 2006, a binary cycle plant in Chena Hot Springs, Alaska, cameon-line, producing electricity from a record low fluid temperature of 57C

Geothermal electric plants have until recently been built exclusively where high temperaturegeothermal resources are available near the surface. The development ofbinary cycle powerplants and improvements in drilling and extraction technology may enable enhancedgeothermal systems over a much greater geographical range. Demonstration projects areoperational in Landau-Pfalz, Germany, and Soultz-sous-Forts, France, while an earliereffort inBasel, Switzerland was shut down after it triggered earthquakes. Other demonstrationprojects are under construction in Australia, the United Kingdom, and the United Statesof America

The thermal efficiency of geothermal electric plants is low, around 10-23%,becausegeothermal fluids are at a low temperature compared to steam from boilers. By the laws ofthermodynamics this low temperature limits the efficiency of heat engines in extracting

useful energy during the generation of electricity. Exhaust heat is wasted, unless it can be useddirectly and locally, for example in greenhouses, timber mills, and district heating. The efficiencyof the system does not affect operational costs as it would for a coal or other fossil fuel plant, butit does factor into the viability of the plant. In order to produce more energy than the pumpsconsume, electricity generation requires high temperature geothermal fields and specialized heatcycles. Because geothermal power does not rely on variable sources of energy, unlike, forexample, wind or solar, its capacity factor can be quite large up to 96% has beendemonstrated. The global average was 73% in 2005h

1.4 Use of Geothermal Energy

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GEOTHERMAL ENERGY 5

Some applications of geothermal energy use the Earth's temperatures near the surface, whileothers require drilling miles into the Earth. The three main uses of geothermal energy are:

Direct use and district heating systems use hot water from springs or reservoirs near the surface.

Electricity generation power plants require water or steam at very high temperature (300 to700F). Geothermal power plants are generally built where geothermal reservoirs are located

within a mile or two of the surface.Geothermal heat pumps use stable ground or water temperatures near the Earth's surface tocontrol building temperatures above ground.

1.5 Direct Use of Geothermal Energy

There have been direct uses of hot water as an energy source since ancient times. AncientRomans, Chinese, and Native American cultures used hot mineral springs for bathing, cooking,and heating. Today, many hot springs are still used for bathing, and many people believe the hot,mineral-rich waters have natural healing powers.

After bathing, the most common direct use of geothermal energy is for heating buildings throughdistrict heating systems. Hot water near the Earth's surface can be piped directly into buildings

and industries for heat. A district heating system provides heat for 95% of the buildings inReykjavik, Iceland.

Industrial applications of geothermal energy include food dehydration, gold mining, and milkpasteurizing. Dehydration, or the drying of vegetable and fruit products, is the most commonindustrial use of geothermal energy.

The United States Is the Leader in Geothermal Power Generation

The United States leads the world in electricity generation with geothermal power. In 2008, U.S.geothermal power plants produced 14.86 billion kilowatt-hours, or 0.4% of total U.S. electricitygeneration. Seven States have geothermal power plants:

California has 34 geothermal power plants, which produce almost 90% of U.S. geothermal

electricity. Nevada has 16 geothermal power plants. Hawaii, Idaho, Montana, and Utah eachhave one geothermal plant.

Chapter 2

2.1 A Geothermic Power Station



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Geothermal power plants use hydrothermal resources that have two common ingredients: water(hydro) and heat (thermal). Geothermal plants require high temperature (300F to 700F)hydrothermal resources that may come from either dry steam wells or hot water wells. We canuse these resources by drilling wells into the Earth and piping the steam or hot water to thesurface. Geothermal wells are one to two miles deep.

Types of Geothermal Plants

There are three basic types of geothermal power plants:

Dry steam plants

Flash steam plants

Binary cycle power plants

Dry steam plants. Produce energy directly from the steam generated underground. In this case wedo not need additional boilers and boiler fuels because the steam (and no water) directly fill upthe wells, passing through a rock catcher and directly operate the turbines. The using of suchtype is not popular because the natural dry steam hydrothermal reservoirs are very rare.

This was the original, and the least common type of geothermal power plant, utilizing the drysteam straight from the production well, drilled into the geothermal reservoir. The high pressuredry steam passes up the production well and through a rock catcher; a series of mesh filters

which catch any rocks, stones or other debris, which would damage the turbine blades. Thesteam then passes through a steam turbine that drives an electrical generator, which produceselectricity for the grid.

The steam exits the LP stage of the turbine and into the turbine condenser, that is under avacuum. From here the condensate is pumped through a series of scrubbing towers that removeany residual non-condensable gasses. The condensate is then pumped to the water coolingtowers, where it is cooled, with any remaining incondensable gasses re-circulated to thescrubbers before being re-injected with the cooled condensate down the injection well into thegeothermal reservoir.

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GEOTHERMAL ENERGY 7

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2.2 Flash steam plants

Flash steam plants take high-pressure hot water from deep inside the Earth and convert it to

steam to drive the generator turbines. When the steam cools, it condenses to water and is injectedback into the ground to be used over and over again. Most geothermal power plants are flashsteam plants

This type of plant injects water and condensate into the geothermal reservoir through theinjection well that forces water at a high temperature (360F) up through the production well.From the production well it is pumped through a series of pressure vessels which being at alower internal pressure than the hot geothermal fluid, causes the water to flash off into low,medium and high pressure steam. The steam then passes through the steam turbine, condensing



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GEOTHERMAL ENERGY 8

and being treated as per a dry steam plant, returning to the geothermal reservoir along with thenon-condensable gasses through the injection well.

2.3Binary cycle power plants

Binary cycle power plantstransfer the heat from geothermal hot water to another liquid. The heatcauses the second liquid to turn to steam which is used to drive a generator turbine. it isemployed when the hydrothermal resource is with lower temperature (100 F). The hot water ispassed to a heat exchanger where it is compound with secondary liquid with lower boiling point(hydrocarbon like isobutene or izopentane). This mixture vapor and its steam run the turbine.The waste mixture is recycled trough the heat exchanger. The geothermal fluid is condensed andit is returned to the hydrothermal resource. Since the most resources are with lower temperaturethe binary steam power plants are more common.



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GEOTHERMAL ENERGY 9

Chapter 3

3.1 Geothermal Heat Pumps

A geothermal heat pump or ground source heat pump (GSHP) is a central heating and/or coolingsystem that pumps heat to or from the ground. It uses the earth as a heat source (in the winter) ora heat sink (in the summer). This design takes advantage of the moderate temperatures in the

ground to boost efficiency and reduce the operational costs of heating and cooling systems, andmay be combined with solar heating to form a geosolar system with even greater efficiency.Geothermal heat pumps are also known by a variety of other names, including geoexchange,earth-coupled, earth energy or water-source heat pumps. The engineering and scientificcommunities prefer the terms "geoexchange" or "ground source heat pumps" to avoid confusionwith traditional geothermal power, which uses a high temperature heat source to generateelectricity. Ground source heat pumps harvest a combination of geothermal energy (from theearth's core) and solar energy (heat absorbed at the earth's surface) when heating, but workagainst these heat sources when used for air conditioning.

Depending on latitude, the upper 3 meters (9.8 ft) of Earth's surface maintains a nearly constanttemperature between 10 and 16 C (50 and 60 F). Like a refrigerator or air conditioner, these

systems use a heat pump to force the transfer of heat from there. Heat pumps can transfer heatfrom a cool space to a warm space, against the natural direction of flow, or they can enhance thenatural flow of heat from a warm area to a cool one. The core of the heat pump is a loop ofrefrigerant pumped through a vapor-compression refrigeration cycle that moves heat. Heatpumps are always more efficient at heating than pure electric heaters, even when extracting heatfrom cold winter air. But unlike an air-source heat pump, which transfers heat to or from theoutside air, a ground source heat pump exchanges heat with the ground. This is much moreenergy-efficient because underground temperatures are more stable than air temperatures throughthe year. Seasonal variations drop off with depth and disappear below seven meters due tothermal inertia. Like a cave, the shallow ground temperature is warmer than the air above duringthe winter and cooler than the air in the summer. A ground source heat pump extracts ground heat

in the winter (for heating) and transfers heat back into the ground in the summer (for cooling).Some systems are designed to operate in one mode only, heating or cooling, depending onclimate.

The geothermal pump systems reach fairly high Coefficient of performance (Cop), 3-6, on thecoldest of winter nights, compared to 1.75-2.5 for air-source heat pumps on cool days. Groundsource heat pumps (GSHPs) are among the most energy efficient technologies for providingHVAC and water heating. Actual Cop of a geothermal system which includes the power requiredto circulate the fluid through the underground tubes can be lower than 2.5. The setup costs arehigher than for conventional systems, but the difference is usually returned in energy savings in 3to 10 years. System life is estimated at 25 years for inside components and 50+ years for theground loop. As of 2004, there are over a million units installed worldwide providing 12 GW of

thermal capacity, with an annual growth rate of 10%.

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GEOTHERMAL ENERGY 10

3.2 Using the Earth's Constant Temperatures for Heating and Cooling

While temperatures above ground change a lot from day to day and season to season,temperatures 10 feet below the Earth's surface hold nearly constant between 50 and 60F. Formost areas, this means that soil temperatures are usually warmer than the air in winter and cooler

than the air in summer. Geothermal heat pumps use the Earth's constant temperatures to heat andcool buildings. They transfer heat from the ground (or water) into buildings in winter and reversethe process in the summer.

Geothermal Heat Pumps Are Energy Efficient and Cost Effective

According to the U.S. Environmental Protection Agency (EPA), geothermal heat pumps are themost energy efficient, environmentally clean, and cost effective systems for temperature control.Although most homes still use traditional furnaces and air conditioners, geothermal heat pumpsare becoming more popular. In recent years, the U.S. Department of Energy and the EPA havepartnered with industry to promote the use of geothermal heat pumps.

3.4 Geothermal Energy & the Environment

The environmental impact of geothermal energy depends on how it is being used. Direct use andheating applications have almost no negative impact on the environment.

Grand Prismatic Spring, Yellowstone National Park, Wyoming

Geothermal Power Plants Have Low Emission Levels

Geothermal power plants do not burn fuel to generate electricity, so their emission levels are verylow. They release less than 1% of the carbon dioxide emissions of a fossil fuel plant. Geothermalplants use scrubber systems to clean the air of hydrogen sulfide that is naturally found in thesteam and hot water.

Geothermal plants emit 97% less acid rain-causing sulfur compounds than are emitted by fossilfuel plants. After the steam and water from a geothermal reservoir have been used, they areinjected back into the Earth.

Many Geothermal Features Are National Treasures

Geothermal features in national parks, such as geysers and fumaroles in Yellowstone NationalPark, are protected by law, to prevent them from being disturbed.



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Chapter 4

Geothermal heating - Advantages4.1 ADVANTEGES:-

The advantages of geothermal systems boil down to efficiency advantages, reliability and safetyadvantages, flexibility and convenience, renewable energy advantages, and financial advantages

Geothermal energy or geothermal power is in fact Earth's thermal energy that is generated byheat stored beneath the Earth's surface. Since geothermal power has great potential, we'll take alook here at its main advantages and disadvantages when used for heating.

Probably the biggest advantages of geothermal heating are low heating costs (cost savings can beas much as 80% over the fossil fuels) and it also uses significantly less electricity than standardheating systems. Geothermal heating uses Earth's heat which is a renewable energy source.

When it comes to efficiency geothermal energy is 48% more efficient than gas furnaces and even75% more efficient than oil furnaces. There are also very low levels (sometimes none) of the airpollutants and greenhouse gases making it from this point of view as highly ecologicallyacceptable solution.

Not only that geothermal heating system heats the house but it cools it as well and operates veryquietly. There is also uniform heating meaning there's no cold and hot spots and of course thereare no furnaces or chimney to clean after. Maintenance of geothermal heating system is also verycheap since it requires only changing the heat pump units air filter. Geothermal heating systemcan be also introduced into the existing home, especially if there's forced air duct system and itsunderground piping has lifetime of over 50 years. When a power station harnesses geothermalpower in the correct manner, there are no by products, which are harmful to the environment.Environmentalists should be happy about that!

There is also no consumption of any type of fossil fuels. In addition, geothermal energy does notoutput any type ofgreenhouse effect. After the construction of a geothermal power plant, there islittle maintenance to contend with. In terms ofenergy consumption, a geothermal power plant isself-sufficient.

Another advantage to geothermal energy is that the power plants do not have to be huge which isgreat for protecting the natural environment

4.2 Efficiency advantages of geothermal systems

Geothermal heating systems can extract up to six times the heat energy they use in electricalenergy. In other words, compared to electrical heating, they are at least three and up to six timesmore efficient.

Geothermal heating systems use far less electricity than traditional electric heating systems - aslittle as one sixth as much.

Savings in heating mode can be up to 3/4 of the cost of electrical heating, and savings in cooling

mode can be up to 1/4 to 1/2 of the costs of running a traditional air conditioner. When you factorin virtually free hot water, the overall efficiency can be even higher.

A 1500 square foot house equipped with a geothermal heating and cooling system costs $30 to$50 per month to heat or cool in most US climates.

Reliability and safety advantages of geothermal systems

Geothermal heating and cooling systems have few moving parts, so they are highly reliable.Failures are rare and minimal maintenance is required, other than regular forced air system

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maintenance (fan, filters) and some maintenance on the water loop in open loop systems due tomineral and sediment in the water.

Unlike central air conditioning systems, geothermal cooling systems have no parts outside. Thereis no wear and tear on an outdoor condenser. You do not need to worry about leaves, plants, ordirt getting onto the condenser fan. There is no risk of vandalism.

Geothermal heating systems can last far longer than most heating systems. The polyethylene pipein most loop fields typically has a 25 or 50 year warranty and estimates are that it can last up to200 years.

A geothermal heating and hot water system eliminates the risk of carbon monoxide poisoningassociated with natural gas heating and hot water. The risk of fires is also much lower than in ahouse equipped with a gas furnace and/or gas water heater.

Flexibility and convenience advantages of geothermal systems

Geothermal heat pumps can be set up to supply hot water as well as space heating and cooling.In some cases (for example, with a de-super-heater that extracts heat out of the system when youare cooling your home), the hot water comes at no additional energy cost. Otherwise geothermalhot water can cost just pennies a day.

Geothermal heating systems can easily be extended to heat a pool, since they can heat water aswell as heat and cool your home.

Geothermal heating and cooling systems create no noise outside the home, and almost no noiseinside either.

The hardware for heating and cooling within your house requires less space than a conventionalfurnace or air conditioner (or combination furnace and air conditioner), so your equipment roomcan be greatly scaled down in size.

Renewable energy advantages of geothermal systems

Geothermal is a renewable source of energy for heating, cooling, and air conditioning. There isno pollution caused by home geothermal systems; even in an open loop water system that isproperly designed, the small amount of heat extracted from your home during the hot weathercooling system is not enough to cause any adverse effects on flora or fauna.

If you buy your electricity from a green electricity supplier, you can heat and cool your homewithout creating any greenhouse gas emissions.

Geothermal heating and cooling systems do not contribute to global warming. Even with aconversion from a forced air natural gas heating system, to a geothermal heating system wherethe electricity is generated from coal, net CO2 emissions go down. See more on the CO2emissions of geothermal heating and cooling below.

Financial advantages of geothermal

Although geothermal systems can cost several times what a conventional system costs, paybackcan be within 2-10 years according to some estimates. Obviously, the payback period depends oninstallation costs, which vary greatly by area, as well as on energy costs, which vary over time.Remember when calculating your payback (how long it takes for the energy savings to pay forthe more expensive system) that energy costs keep going up faster than we expect.

Installations in the US may be eligible for up to a $300 Federal Energy Tax Credit as well as atax credit of up to $2,000 through the Emergency Economic Stabilization Act of October 2008.

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Chapter 55.1 Geothermal heating Disadvantages

The disadvantages of geothermal systems are up-front costs, disturbances to your land duringinstallation, environmental risks of direct exchange systems, legal conformance risks relating toopen loop systems, and maintenance issues relating to open loop systems.

There are several disadvantages to geothermal energy. First, you cannot just build a geothermalpower plant in some vacant land plot somewhere. The area where a geothermal energy powerplant would be built should consist of those suitable hot rocks at just the right depth for drilling.In addition, the type of rock must be easy to drill into. It is important to take care of a geothermalsite because if the holes were drilled improperly, then potentially harmful minerals and gas couldescape from underground. These hazardous materials are nearly impossible to get rid of properly.Pollution may occur due to improper drilling at geothermal stations. Unbelievably, it is alsopossible for a specific geothermal area to run dry or lose steam.

Main disadvantages of geothermal heating are very high installation costs and its positioning,since it requires big yard for horizontal installation and a bedrock-free ground for verticalinstallation or a well or pond. The Department of Energy estimates that the installation cost on a

retrofit can be recouped in two to ten years and sometimes as some experts say payback can beeven more than 20 years long.

Installation of geothermal system can be also quite tricky so it's needed (and very muchsuggested) to hire a certified installer which of course costs more than regular installation andinstallation in cities is sometimes not possible because of small lots and more often than notgeothermal units are not compatible with the existing heating units such as radiators.

There's also the fact that geothermal energy isn't 100 percent clean energy source because of thegeothermal pumps. Geothermal pumps are using coal based electricity and coal isn't ecologicallyacceptable fuel since it releases carbon dioxide that causes the global warming.

So here are the advantages and disadvantages of geothermal heating and basically if you canafford it go with it despite the high initial costs and the long-term payback because its advantagesoutweigh its bad sides. This particularly applies to the low heating costs and excellent efficiencyof geothermal heating systems. Installation cost disadvantages of geothermal systems

These systems can be very expensive to install. Price estimates for total systems for a typical UShome range from $5,000 to $20,000 (there are wide variations in estimates from differentsources). There may be other energy efficiency upgrades you can do in your home that cost asimilar amount but have as great or greater an impact on your energy bill over the next twentyyears. If you live in a leaky, poorly insulated house, you may be better off spending that kind ofmoney on better insulation and draft sealing, energy efficient windows and doors, and otherupgrades that reduce the amount of energy required to heat and cool your home. In fact, it's agood idea to do this first even if you do install a geothermal system, since you can install asmaller geothermal system if you reduce the heating and cooling load through efficiencyupgrades.

5.2Installation disturbance disadvantages of geothermal systems

Because horizontal systems are the most cost effective, and because of the extensive trenchingrequired for horizontal systems, most geothermal installations require some level of disturbanceof the land around your home. Even open loop systems and closed loop pond or lake systemsrequire some trenching to keep the water loop pipes buried below the frost line.



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The installation type that causes the most disruption to your landscape is a horizontal installation,either in standard loops or in a Slinky configuration. This is because of the long, wide, and deep(4-6 feet) trench that needs to be dug to accommodate the heat bed. If you have a vacant lot andare building a new home, this type of installation is more cost effective and you may not mindthe disturbance to soil and the possible damage to tree roots of surrounding trees.

If you are concerned about damaging the landscape or flora of your property, a verticalinstallation is more appropriate. Vertical installations require minimal disturbance to yourlandscaping other than a clear access path for the bore drilling equipment to the heat bed, andspace to temporarily store for the bore holes and the material removed from the bore holes.However, vertical installations are typically much more expensive than horizontal installationsbecause of the cost of drilling several hundred feet underground.

Environmental disadvantages of geothermal systems using direct exchange (DX)

Direct exchange geothermal systems are the cheapest to install and some installers claim they arethe most efficient. In a direct exchange system, a single loop circulates a refrigerant such as thatused in an air conditioner or refrigerator between the heat pump in your house and thegeothermal sink or source under ground. There are two problems with direct exchange systems.

First, they use copper pipes to circulate the refrigerant, and copper pipes buried under ground caneasily corrode over time, leading to leaks that are hard to locate and almost impossible to fix.

Second, they use up to 100 times more ozone-depleting CFCs or HCFCs than a double loopsystem, because the liquid circulating in the geothermal heat source or sink is a refrigerant. (In adouble loop system, virtually all of the liquid circulates in the geothermal loop, not therefrigerant loop, and this liquid is a benign blend of water and antifreeze.) So if you install adirect exchange system you run the risk of a short-lived heat exchange system, and of releasingvast amounts of ozone-depleting chemicals into the atmosphere.

Building a new home

The perfect time to install a geothermal heating and cooling system is when you're building anew home. There are two major types of geothermal installations: horizontal and vertical.

In horizontal installations, the geothermal pipes are placed underground on a horizontal planethrough your yard, in a network of trenches dug in your yard. The pipes are buried deep enough -usually six feet or more - that there's little risk of damaging the pipes if you are digging after thehouse is finished, unless you're out there with your back hoe!

Vertical installations are more suitable where you have limited yard space, or where you don'twant to dig a lot of trenches, for example if you want to protect trees or other natural features ofthe landscape. The problem with vertical installations is that they are considerably moreexpensive to install, because of the deep drilling involved.

You need to replace your existing heating or cooling system

You may need to replace your existing heating or cooling system because it uses too much

energy, or because it's so old the maintenance costs are escalating. If you need to replace bothyour heating and cooling systems, geothermal is a great option because you can replace twoexisting, inefficient or failure-prone systems with a single new one.

When you do a payback analysis on geothermal, it always helps the geothermal side's case if youwould otherwise have to buy a new furnace and/or air conditioner in the new future. It is muchharder to justify a geothermal heating and cooling system when your current system is workingjust fine. If the system works well but is energy-inefficient, then your payback analysis shouldinclude a full life cycle cost for both a more traditional replacement system (e.g. forced air



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natural gas system and traditional central air conditioner) and for a geothermal heating andcooling system. Remember that geothermal systems have lower maintenance costs and lowerenergy costs once installed.

You want the most energy efficient home heating and cooling system, at any cost

If you have relatively speaking unlimited financial resources and want the most energy efficient

home heating and cooling system at any cost, geothermal heating and cooling is the way to go. Ifyou make your home extremely energy efficient in terms of passive lighting, heating andcooling, using the most energy efficient lights and appliances, and installing solar electricity forhomes or wind generation capacity, you may be able to install a geothermal heating and coolingsystem and make your home entirely self-sufficient in energy.

CO2 emissions of geothermal heating and cooling systems

Does a geothermal heating and cooling system contribute to global warming?

It's true that you don't use any natural gas to run your geothermal system. But you do useelectricity. Where is that electricity coming from? If it's coming from a coal-fired or natural-gasfired power plant, the generation of that electricity still contributes to global warming - but lessso than heating with natural gas or cooling with central or room air conditioners. Let's consider

this scenario:You currently heat with gas, using an 80% efficient gas furnace.

You switch to a geothermal heat pump, which produces 4 units of heat per 1 unit of electricity

The gas you no longer use is now used to generate the electricity to run your heat pump. Gaselectrical turbines operate at about a 40% efficiency, meaning 60% of the energy in the burninggas is lost as heat.

You were getting 80% of the gas energy as heat with your gas furnace. You are now getting 40%of the gas energy as electricity from the natural gas generator. That 40% is then extracting 4 unitsof heat from the ground for each unit of electricity. So your net is 40% X 4, or 1.6 units of heatenergy per unit of natural gas. Since originally you were producing 0.8 units of heat energy, youhave effectively cut your CO2 emissions in half even assuming the same fossil fuel is used togenerate your electricity as was used for your furnace. Of course, if you switch to a Greenelectricity supplierat the same time that you switch to geothermal, you'll not only eliminate allCO2 emissions from your heating and air conditioning system, but you'll probably still wind upsaving on your monthly bills even with the premium green electricity suppliers charge for theirfossil-fuel-free electricity.

5.3 Alternative uses for Geothermal Energy

Besides power resources, geothermal energy can be harnessed for other means as well. Thanks togeothermal water, there are natural hot springs all over the world and many people enjoy thewarm waters and its restorative effects. Geothermal water can also be beneficial for growingagricultural products in a greenhouse within a cold or icy climate. Geothermal waters can be

harnessed to create space heating in buildings or even to keep streets and sidewalks warmenough to prevent icing over. Several cities have actually used geothermal energy in this uniquemanner.

Because geothermal energy is reliable and renewable, this alternative power source will start toenjoy more growth. However, just remember that geothermal energy will not necessarily beavailable in many areas due to its volatile needs. Areas like California, Iceland, Hawaii and Japanare just a few places where geothermal energy is being used, many due to earthquakes and theunderground volcanic activity.

http://www.green-energy-efficient-homes.com/solar-electricity-for-homes.htmlhttp://www.green-energy-efficient-homes.com/solar-electricity-for-homes.htmlhttp://www.green-energy-efficient-homes.com/green-electricity.htmlhttp://www.green-energy-efficient-homes.com/green-electricity.htmlhttp://www.green-energy-efficient-homes.com/solar-electricity-for-homes.htmlhttp://www.green-energy-efficient-homes.com/solar-electricity-for-homes.htmlhttp://www.green-energy-efficient-homes.com/green-electricity.htmlhttp://www.green-energy-efficient-homes.com/green-electricity.html


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The biggest disadvantages of building a geothermal energy plant is the time it takes toexploration the perfect land. While exploring the suitable place, researchers will do a landsurvey, which may take several years to complete. Thus if a company wishes to build a plant, itmay have to wait for several years before the researchers reply whether the land is suitable ornot. Moreover, most companies that order surveys are often disappointed, as the land they were

interested is incapable of supporting a geothermal energy plant. In order to extract the heatrequired, we have to find certain hot spots within the earths crust, which are quite commonaround volcanoes and fault lines, which are obviously very difficult places to build a geothermalenergy plant. However, there are certain land areas that may have the sufficient hot rocks to heatup the water to generate power. Some great spots have been found in New Zealand, Iceland,Norway and Sweden.

Some common questions that are answered in a survey include; whether the rock is soft enoughto drill through, do the rocks contain sufficient heat, will the heat be sustainable for a significantamount of time, and lastly, is the environment fit for a power plant? If most of these answers arepositive, then a more in depth survey is conducted.

One of the other biggest disadvantage of geothermal energy extraction is that many times, a site

that constantly produces steam and turns it into power for many years, may suddenly stopproducing steam. This is possible to last for around 10 years in some cases.

The constructors should also be aware of the harmful gases that can escape from deep within theearth, through the holes drilled by the constructors. Disposing of the gas can be very tricky andthe developers should take measures to do it safely.

Geothermal heat is mostly available miles beneath the earth's surface, and it's often hard to findsuitable locations for geothermal power plants. Those who are interested in building geothermalplants may find out that the land may not be able to support a geothermal power plant. There aremany factors that need to be considered before a geothermal power plant is built. Rocks must besoft enough to drill through and must contain sufficient heat. It's also important that this heat issustainable for a long period of time and that the environment where drilling is going to be done

is fit for a power plant.Putting up a geothermal power plant to make use of geothermal energy for electricity can alsohave negative effects on land stability. Although geothermal sites can provide energy enough forelectricity that will last several decades, these locations may also cool down. This is why only asmall part of the world makes use of geothermal power for electricity. Those who want to usegeothermal energy can just opt for the installation of geothermal heat pumps for their property.

The drain on the earth's resources is one of the largest disadvantages of geothermal energy. Oncethe heat source starts to cool down, there is no way to reverse it. Although these types of energyplants can provide stable energy for an extended period of time, there is a definite end date. Inorder to replace that energy source, a new location would need to be identified and a new plantbuilt.

Chapter 6

How much does a geothermal power plant cost



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According to studies, an economically competitive geothermal power plant can cost as low as$3400 per kilowatt installed. (1) While the cost of a new geothermal power plant is higher thanthat of a comparable natural gas facility, in the long run the two are similar over time. This isbecause natural gas construction costs account for only one third of the total price of the facility,while the cost of the fuel at a natural gas facility represents two thirds of the cost. The initial

construction costs of a geothermal facility, in contrast, represent two thirds or more of total costs.So although initial investment is high for geothermal, natural gas and geothermal are stilleconomically comparable over a long term.

California Energy Commission (CEC) 2007 estimates place the levelized (2) generation costs fora 50 MW geothermal binary plant at $92 per megawatt hour (3) and for a 50 MW dual flashgeothermal plant at $88 per megawatt hour, which over the lifetime of the plant can becompetitive with a variety of technologies, including natural gas. (4) According to the CECreport, natural gas costs $101 per megawatt hour for a 500 MW combined cycle power plant and$586 per megawatt hour for a 100 MW simple cycle plant. On average the cost for newgeothermal projects ranged from 6 tp 8 cents per kilowatt hour according to a 2006 report,including the production tax credit. (5) But, it should be noted that the cost for individual

geothermal projects can vary significantly based upon a series of factors discussed below, andthat costs for all power projects change over time with economic conditions."However, it mustbe remembered that a major impact on geothermal power cost is the local, regional, national, andglobal competition for commodities such as steel, cement, and construction equipment.Geothermal power is competing against other renewable and non-renewable power development,building construction, road and infrastructure improvements, and all other projects that use thesame commodities and services. Until equipment and plant inventories rise to meet the increasein demand for these commodities and services, project developers can expect the costs to risewell above the background inflation level."Costs for geothermal generation at some facilitieshave decreased to half the original price per kilowatt hour of power in 1980 , compared to whenthe first independent geothermal plants were installed. (10) Their cost falling at a faster rate than

coal over this same period. The current price for extensions onto existing projects can becompetitive with polluting coal-fired plants. While geothermals costs have steadily decreasedthroughout the years, those of natural gas have increased, often experiencing boom and bust typecycles that can negatively impact the economy.

California Energy Commission (CEC) analysis examines what it estimates are the cost ofdifferent technologies based upon levelized cost which includes both capital and fuel costs.Their study places geothermal energy at a lower levelized cost ($/MWh) than many other typesof merchant owned power plants including: Natural Gas Combined-Cycle, Wind, BiomassCombustion, Nuclear, Solar Thermal, and Photovoltaic. Many industry experts agree thatgeothermal is one of only a few alternative technologies that will compete economically withpolluting technologies in the near termeven without considering the additional benefits of

geothermal production

Chapter 77.1 What factors influence the cost of a geothermal power plant

There are many factors that influence the cost of a geothermal power plant. In general,geothermal plants are affected by the cost of steel, other metals and labor, which are universal tothe power industry. However, drilling costs may vary as well. Geothermal projects are site-



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specific, thus the costs to connect to the electric grid vary from project to project. Also, whetherthe project is the first in a particular area or reservoir impacts both risks and costs. Theacquisition and leasing of land also varies, because to fully explore a geothermal resource adeveloper is required to lease the rights to 2,000 acres or more. Challenges to leasing andpermitting vary from project to project; especially on federal lands. These factors include:

Size of the plant Power plant technology

Knowledge of the resource

Temperature of the resource

Chemistry of the geothermal water

Resource depth and permeability

Environmental policies

Tax incentives

Markets

Financing options and cost

Time delays7.2 What types of jobs are created by the geothermal sector, and how long will they last

According to an employment study, an overwhelming majority of geothermal jobs (86%) are fulltime, permanent positions. Geothermal provides quality wages to people living in depressedeconomic communities and provides a stable source of employment.Geothermal provides long-term income for people with a diversity of job skills. People directlyemployed by the sector include welders, mechanics, pipe fitters, plumbers, machinists,electricians, carpenters, construction and drilling equipment operators and excavators, surveyors,architects and designers, geologists, hydrologists, electrical, mechanical, and structuralengineers, HVAC technicians, food processing specialists, aquaculture and horticulturespecialists, resort managers, spa developers, researchers, and government employees.

7.3 How many people currently work in the U.S. geothermal industryIn answering this question, most organizations focus upon the total number of direct and indirectjobs created by their industry. For geothermal, direct jobs relate to the construction andmaintenance of geothermal power plants, while indirect jobs provide goods and services to theindustries directly involved in power plant construction or operation and maintenance. Thenumber of indirect jobs within a particular sector is largely theoretical, and changes according tothe preferred method of analysis. So while indirect impacts should certainly be consideredanyinvestment in a particular sector of the economy will impact other sectorsit is also important todistinguish between these two types of employment impacts.

Power plant or direct employment was estimated to be 4,583 full-time positions.As the reportnotes, Employment in the industry is probably at a historic low since power plant construction

has been minimal between 1993 and 2004 as state and federal policies underwent significantchanges. Also, because federal research support is at a historically low level, associated researchemployment is low.Based upon our 2004 analysis, GEA estimates that the geothermal industrydirectly employed about 25,000 people in 2008. This is roughly 9,000 direct jobs in operating,construction and manufacturing and an additional 16,000 indirect and supporting jobs.

7.4 How many jobs will be supported by the geothermal industry in the future?

Many new projects are under development and will likely come on line within the next fewyears, which will significantly expand geothermal employment. According to a report by the



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Western Governors Association (WGA), development of near-term geothermal potential of 5,600MW of geothermal energy would result in the creation of almost 100,000 jobs. The chart belowsummarizes that estimate of geothermal employment potential.

Geothermal energy provides low cost, reliable, environmentally friendly fuel; supplies thousandsof quality jobs; boosts rural economies; increases tax bases; reduces foreign oil imports;

stabilizes prices; and diversifies the fuel supply.Unlike coal and natural gas, geothermal incurs no hidden costs such as land degradation, highair emissions, forced extinction and destruction of animals and plants, and health impacts tohumans.

According to a 2006 GEA publication, "besides the costs expended through the development andconstruction of a power plant, geothermal developers often make significant contributions to thecommunities in which they are located, as well as to the local, state, and federal governmentsunder whose jurisdiction they operate. Some contributions come as royalties or taxes, which aremandated by the government, while some come voluntarily from the geothermal company.

In addition, wages paid to geothermal employees often circulate back through the community.For an example, if New Mexico brought 80 MW of geothermal power on line it would contribute

340 full time jobs/1,280 person*yrs and $1.2 billion economic output over a 30 year periodGeothermal power plants can be a tourist draw when students, scientists, or interested individualsvisit the site of a power plant, thereby bringing business to the local community. This not onlyoccurs in the U.S. but also in other countries like Iceland. Iceland is unique in that geothermalcontributes 26 % of the country's total energy supply through five geothermal power plants.Because of geothermal energy's impact on the country it is not rare for tourism companies toadvertise tours of the plants as well as a visit to Iceland's largest tourist destination, the BlueLagoon, which is a geothermal spa located in southwestern Iceland

Summary of Western States' Near-Term Geothermal Potential and Resulting Employment

and Economic Contribution

New Power

Capacity

(MWs)

Direct and Indirect and Induced

Employment

(Power Plant Jobs/Construction &

Manufacturing Employment)**

30 Year Economic

Output (nominal) +

California 2,400 10,200 ft jobs/38,400 person*yrs $36 billion

Nevada 1,500 6,375 ft jobs/24,000 person*yrs $22.5 billion

Oregon 380 1,615 ft jobs/6,080 person*yrs $5.7 billion

Washington 50 212 ft jobs/800 person*yrs $749 million

Alaska 25 106 ft jobs/400 person*yrs $375 millionArizona 20 85 ft jobs/320 person*yrs $300 million

Colorado 20 85 ft jobs/320 person*yrs $300 million

Hawaii 70 298 ft jobs/1,120 person*yrs $1 billion

Idaho 860 3,655 ft jobs/13,760 person*yrs $12.9 billion

New Mexico 80 340 ft jobs/1,280 person*yrs $1.2 billion

Utah 230 978 ft jobs/3,680 person*yrs $3.4 billion



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Wyoming ,

Montana ,

Texas ,

Kansas ,

Nebraska ,

South Dakota ,North Dakota

Potential Exists;Resource notstudied in WGAReport

Not Studied Not Studied

Total Western

States

(additional tocurrent)

5,635 MW

23,949 fulltime jobs/90,160

person*years of construction and

manufacturing employment

84,410,046,000.00

Almost 85 billion dollars

to the U.S. economy over

30 years

** Power plant jobs are the direct, indirect and induced full-time jobs (ft jobs) created byreaching the full power production capacity indicated. Construction and manufacturing jobs arethe direct, indirect and induced jobs necessary to build and supply the power plants at the fullpower capacity indicated. Construction and manufacturing jobs are expressed as full-timepositions for one year (person*years), however these jobs will be spread out over several years

depending upon the development time frame for new projects. Direct employment results in 1.7full time positions and 6.4 person*years per megawatt. Induced and indirect impacts werecalculated assuming a 2.5% multiplier; for a total direct, indirect, and induced employmentimpact of 4.25 full time positions and 16 person*years per megawatt.



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Chapter 8

Geothermal Energy and the Environment8.1Applicable Environmental Regulations . An Overview

To understand geothermal energy and its impact on the environment, a brief overview ofapplicable regulations is necessary. Many regulations, such as the Clean Air Act (CAA),apply to

all sources of emissions, including emissions from renewable technologies such as geothermal.These environmental regulations dictate specific levels of allowable air emissions, how permitscan be issued, what sorts of environmental reviews must take place, and what land types may beapproved for development. Development of any kind will impact the environment, and thus mustfollow specific regulations.

Clean Air Act Regulations

Several pollutants discussed in the subsequent section of this paper are regulated under the CleanAir Act (CAA) as criteria pollutants. A criteria pollutant is a principal pollutant identified as mostharmful to people and the environment. The Clean Air Act sets National Ambient Air QualityStandards (NAAQS) to regulate emissions of criteria pollutants on a federal level. The sixcriteria pollutants regulated by NAAQS are carbon monoxide, lead, nitrogen dioxide, particulatematter, ozone, and sulfur dioxides. States containing nonattainment areas. Geographic areas thatdo not meet NAAQS standards are required to develop a State Implementation Plan (SIP), astrategy to meet NAAQ standards at the local and state level. States and tribes are responsible formeeting NAAQS standards under U.S. Environmental Protection Agency (EPA) oversight. State

and local governments issue most of the air permits required by Title V of the Clean Air Act.These air permits include enforceable air emissions limitations and standards as established bythe state or local government. Title V permits are issued to certain air pollution sources after theyhave begun to operate. In certain circumstances, for example on tribal lands, EPA may issue TitleV permits as needed. EPA permits do not supersede state permits but rather serve areas not undertraditional state and local government jurisdictions.All emitting facilities must comply withfederal emission standards under sections 111 and 112 of the Clean Air Act. Under section 111,sources built after September 18, 1978 are subject to particulate matter, sulfur dioxide, andnitrogen oxides standards established by the new source performance standards (NSPS), whilethose built before 1978 are not subject to federal regulation unless significant renovations occurat the facility. The uncertainty of what constitutes a significant renovation or modification to apower plant has been the subject of recent controversy. Under section 112, "major" industrialfacilities that emit one or more of 188 listed hazardous air pollutants, or air toxics, must be EPA

regulated. EPA defines .air toxics. as those pollutants that are known or suspected of causingcancer or other serious health effects, such as developmental effects or birth defects.Becausegeothermal power plants emit pollutants at lower levels than those regulated by the Clean AirAct, they do not face the same constraints as new fossil fuel facilities seeking air and operatingpermits from state governments.In California, the state with more geothermal electricitygeneration than any other area of the world, ambient air quality standards are stricter thannational standards. Air districts in California with geothermal electricity production are requiredto comply with those strict air quality standards. Details about California air regulations areprovided by the California Air Resources Board (CARB) and are web-accessible.



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8.2Additional Regulations

Under the National Environmental Policy Act (NEPA), any geothermal project selling power to afederal entity, moving power over a federal transmission line, or using federal funding or federalland must undergo an environmental analysis in order to determine potential environmentimpact. Power plants constructed on private or state lands are usually subject to similar state

requirements. Depending upon the conclusions reached by the environmental review, additionalstudies, public hearings and documentation may be required before construction can begin. Anysignificant environmental impacts identified in an Environmental Assessment (EA) orEnvironmental Impact Statement (EIS) must be accompanied by a plan for monitored mitigationmeasures.Other environmental regulations that address geothermal development include theClean Water Act, the National Pollutant Discharge Elimination System Permitting Program(NPDES), the Safe Drinking Water Act (Underground Injection Control Regulations),heResource Conservation and Recovery Act (RCRA), the Toxic Substance ControlAct,theNoiseControl Act, the Endangered Species Act, the Archaeological ResourceProtectionAct, Hazardous Waste and Materials Regulations, the Occupational Health and SafetyAct, and the Indian Religious Freedom Act. The federal regulatory agencies involved in the

geothermal development process include the Bureau of Land Management (BLM), the ForestService, the Federal Energy Regulatory Commission (FERC), and the Fish and

8.3Air Emissions

Geothermal power plants release very few air emissions because they do not burn fuel like fossilfuel plants. Most fossil fuel power plant emissions are either a product of fuel combustion or awaste-product from that process. Geothermal plants avoid both environmental impacts associatedwith burning fuels as well as those associated with transporting and processing fuel sources.Geothermal plants emit only trace amounts of nitrogen oxides, almost no sulfur dioxide orparticulate matter, and small amounts of carbon dioxide. The primary pollutant some geothermalplants must sometimes abate is hydrogen sulfide, which is naturally present in many subsurface

geothermal reservoirs. With the use of advanced abatement equipment, however, emissions ofhydrogen sulfide are regularly maintained below even California state standards. It is importantto note that air emissions from all power plants. Including but not limited to geothermal. Comefrom a variety of sources. For example, additional fossil fuel emissions, which come from thetransportation of fuel to the power plant, are often omitted from emissions data. Unfortunately,air emissions comparisons are sometimes misleading, because the emissions data from ageothermal plant typically includes all emission sources from the well field through the powerplant. A better comparison would include the complete range of emissions from fossil fuel plants.The lack of such data means that the comparisons that follow generally overstate the comparative

emissions from geothermal power, and while this analytical problem cannot be resolved withinthe confines of this paper, it should be noted by the reader. Average life cycle emissions at coal

facilities are substantially higher than their average operational emissions, Operational emissionsdo not consider the effects of coal mining, transport, construction, and decommissioning. Lifecycle emissions from geothermal facilities, in contrast, generally remain in the same range as

operational emissions.

8.4 Nitrogen Oxides

Nitrogen oxides (NOx) are often colorless and odorless, or reddish brown as nitrogen

Dioxide. Nitrogen oxides form during high temperature combustion processes from the



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Oxidation of nitrogen in the air. Motor vehicles are the major source of these pollutants, followedby industrial fuel-burning sources such as fossil fuel-fired power plants. Fossil fuel-fired powerplants are responsible for 23 percent of nitrogen oxide emissions

Nitrogen oxides contribute to smog formation, acid rain, water quality deterioration, global

warming, and visibility impairment. Health effects include lung irritation and respiratoryailments such as infections, coughing, chest pain, and breathing difficulty. Geothermal energyproduced in the United States, when compared to coal, offsets approximately 32 thousand tons ofnitrogen oxide emissions each year. This is substantial considering that even brief exposure tohigh levels of nitrogen oxides may cause human respiratory problems, and airborne levels ofnitrogen oxides above the EPA established average allowable concentration of 0.053 parts permillion48 can cause ecosystem damage. Nitrogen dioxide is a federally regulated criteriapollutant. Power plants built after September 17, 1978 must comply with federal nitrogen oxidestandards; those built before may be subject to state or local standards. Because geothermalpower plants do not burn fuel, they emit very low levels of nitrogen oxides. In most cases,geothermal facilities emit no nitrogen oxides at all. The small amounts of nitrogen oxides

released by some geothermal facilities result from the combustion of hydrogen sulfide.Geothermal plants are generally required by law (with some variation from state to state) tomaintain hydrogen sulfide abatement systems that capture hydrogen sulfide emissions and eitherburn the gas or convert it to elemental sulfur. During combustion, small amounts of nitrogenoxides are sometimes formed, but these amounts are miniscule. Average nitrogen oxideemissions are zero,

8.5 Hydrogen Sulfide

Hydrogen sulfide (H2S) is a colorless gas that is harmless in small quantities, but is oftenregarded as an .annoyance. due to its distinctive .rotten-egg. smell. Hydrogen sulfide can belethal in high doses. Natural sources of hydrogen sulfide include volcanic gases, petroleum

deposits, natural gas, geothermal fluids, hot springs, and fumaroles. Hydrogen sulfide may alsoform from the decomposition of sewage and animal manure, and can be emitted from sewagetreatment facilities, aquaculture facilities, pulp and paper mills, petroleum refineries, compostingfacilities, dairies, and animal feedlot operations. Individuals living near a gas and oil drillingoperation may be exposed to higher levels of hydrogen sulfide.Anthropogenic (manmade)sources of hydrogen sulfide account for approximately 5 percent of total hydrogen sulfideemissions. Health impacts from high concentrations include Hydrogen sulfide remains in theatmosphere for about 18 hours. Though hydrogen sulfide is not a criteria pollutant, it is listed asa .regulated air pollutant.. Hydrogen sulfide remains the pollutant generally considered to be ofgreatest concern for the geothermal community. However, it is now routinely abated atgeothermal power plants. The two most commonly used vent gas hydrogen sulfide abatement

systems are the Stratford and LO-CAT. Both systems convert over 99.9 percent of the hydrogensulfide from geothermal no condensable gases to elemental sulfur, which can then be used as asoil amendment and fertilizer feedstock. The cost to transport and sell the sulfur as a soilamendment is about equal to the revenue gained from the transaction. As a result of abatementmeasures, geothermal steam- and flash-type power plants produce only minimal hydrogensulfide emissions. Hydrogen sulfide emissions from California geothermal plants are reported asbelow the limits set by all California air pollution control districts. This is significant,considering that Californias clean air standards tend to be more restrictive than federal



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standards. Binary and flash/binary combined cycle geothermal power plants do not emit anyhydrogen sulfide at all.In terms of dry gas by volume, a California study cites, as an example,that hydrogen sulfide could comprise around 1 percent of no condensable dry gas emitted by agiven geothermal power plant. Considering all types of geothermal plants, that translates into anoverall average of about 0.187 lbs per megawatt hour.Since 1976, hydrogen sulfide emissions

from geothermal sources have declined from 1,900 lbs/hr to 200 lbs/hr or less, althoughgeothermal power production has increased from 500 megawatts (MW) to over 2,000 MW.

8.6 Sulfur Dioxide

Sulfur dioxide belongs to the family of SOx gases that form when fuel containing sulfur (mainlycoal and oil) is burned at power plants. Fossil fuel-fired power plants are responsible for 67percent of the nations sulfur dioxide emissions. High concentrations of sulfur dioxide canproduce temporary breathing impairment for asthmatic children and adults who are activeoutdoors. Health impacts from short-term exposures included nausea, headache, and eyeirritation; extremely high levels can result in death. wheezing, chest tightness, shortness ofbreath, aggravation of existing cardiovascular disease, and respiratory illness. Sulfur oxideemissions injure vegetation, damage freshwater lake and stream ecosystems, decrease species

variety and abundance, and create hazy conditions.There are both short- and long-term primary NAAQS for sulfur dioxide. The short term (24-hour) and secondary (3-hour) standards are not to be exceeded more than once per year. Thecurrent regulations were finalized in 1972. While geothermal plants do not emit sulfur dioxidedirectly, once hydrogen sulfide is released as a gas into the atmosphere, it spreads into the air andeventually changes into sulfur dioxide and sulfuric acid. Therefore, any sulfur dioxide emissionsassociated with geothermal energy derive from hydrogen sulfide emissions. When comparinggeothermal energy to coal, the average geothermal generation of 15 billion kilowatt hours avoidsthe potential release of 78 thousand tons of sulfur oxides per year.

8.7 Particulate Matter

Particulate matter (PM) is a broad term for a range of substances that exist as discrete particles.Particulate matter includes liquid droplets or particles from smoke, dust, or fly ash. .Primary.particles such as soot or smoke come from a variety of sources where fuel is burned, includingfossil fuel power plants and vehicles. .Secondary. Particles form when gases of burned fuel reactwith water vapor and sunlight. Secondary particulate matter can be formed by NOx, SOx, andVolatile Organic Compounds (VOCs). Large particulates in the form of soot or smoke can bedetected by the naked eye, while small particulates (PM2.5) require a microscope for viewing.PM10 refers to all particulates less than or equal to 10 microns in diameter of particulate massper volume of air. Particulate matter is emitted through the full process of fossil fuel electricityproduction, particularly coal mining. Health effects from particulate matter include eye irritation,

asthma, bronchitis, lung damage, cancer, heavy metal poisoning, and cardiovascular

complications. Particulate matter contributes to atmospheric deposition, visibility impairment,and aesthetic damage. Power plants built after September 17, 1978 must comply with federalPM10 standards; those built before that date may be subject to state or local standards.

Although coal and oil plants produce hundreds of short tons on an annual basis (where one shortton equals 2,000 pounds), geothermal plants emit almost no particulate matter. Water-cooledgeothermal plants do emit small amounts of particulate matter from the cooling tower whensteam condensate is evaporated as part of the cooling cycle. However, the amount of particulatematter given off from the cooling tower is quite small when compared to coal or oil plants which



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8.9 Mercury

The majority of mercury emissions derive from natural sources. Mercury occurs naturally insoils, groundwater, and streams, but human activity can release additional mercury into the air,water, and soil. Coal-fired power plants are the largest source of additional mercury of anyenergy source, because the mercury naturally contained in coal is released during combustion.

Currently, the coal industry contributes 32.7 percent of the nations anthropogenic mercuryemissions.

Mercury emissions from coal vary both day to day and from plant to plant. According to a recentEPRI study, mercury emissions vary significantly over a one month period. Snapshot mercuryemissions information, taken over a 1-2 hour period, does not always accurately reflect long termmercury emissions. Hourly averages can vary by almost an order of magnitude. In addition,mercury emissions from certain types of coal plants,such as bituminous plants, tend to be greaterthan from other types of coal plants. It is estimated that bituminous plants emit 52 percent of coalmercury emissions, while lignite coal plants emit only 9 percent. Those plants with emissionstechnologies in place, such as combined selective catalytic reduction (SCR) and wet flue gasdesulphurization (FGD), tend to emit the lowest levels of mercury. This means that those plants

built before 1978 that are not subject to Clean Air Act guidelines, and thus function withoutemissions control technologies, can emit ten times more mercury than newer, pollutioncontrolled coal plants. Mercury emissions from power plants pose a significant risk to humanhealth. When mercury enters water, biological processes transform it to a highly toxic form,methyl mercury, which builds up in fish and animals that eat fish. People are exposed to mercuryprimarily by eating fish or by drinking contaminated water. Mercury is especially harmful towomen: in February 2003, a draft report about mercury contamination noted that eight percent ofwomen between the ages of 16 and 49 have mercury levels in the blood that could lead toreduced IQ and motor skills in their offspring. Mercury and mercury compounds are consideredone of 188 Hazardous Air Pollutants (HAPs) and one of 33 urban HAPs under section 112 of theClean Air Act. Urban HAPs are considered to present the greatest threat to public health in the

largest number of urban areas. To date, EPA has established National Emission Standards forHazardous Air Pollutants (NESHAPs) for mercury emissions, but these standards only apply tofacilities such as mercury ore processing centers with high concentrations of mercury. Individualstates can mandate specific regulations for individual facilities. In addition, the EPA issued draftregulations on March 15, 2005, under The Clean Air Mercury Rule, which limits federal mercuryemissions through a market-based regulatory program. Mercury is not present in everygeothermal resource. However, if mercury is present in a geothermal resource, using thatresource for power production could result in mercury emissions, depending upon the technologyused. Because binary plants pass geothermal fluid through a heat exchanger and then return all ofit to the reservoir, binary plants do not emit any mercury. In the United States, The Geysers is themain geothermal field known to emit small quantities of mercury in the atmosphere. The

Geysers, however, was also m mercury emissions would exist independently of geothermaldevelopment. Within The Geysers, the presence of mercury in the steam varies dramatically, asaround 80 percent of mercury emissions derive from only two facilities. These individual highmercury facilities are scheduled to install mercury abatement equipment in 2005 that willsignificantly reduce the overall geothermal mercury emissions.83 Furthermore, mercuryemissions from The Geysers are below the amount required to trigger a health risk analysis underexisting California regulations governments have also introduced measures to reduce mercuryemissions from other sources. As a result, mercury abatement measures are already in place at



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most geothermal facilities. The abatement measures that reduce mercury also reduce theemissions of sulfur generated as a byproduct of hydrogen sulfide abatement: after hydrogensulfide is removed from geothermal steam, the gas is run through a mercury filter that absorbsmercury from the gas. In removing mercury, the sulfur that is created from the abatement processcan then be used as an agricultural product. The rate of mercury abatement within a facility,

which varies according to the efficiency of the activated carbon mercury absorber, is typicallynear 90 percent, and is always efficient enough to ensure that the sulfur byproduct is nothazardous. The activated carbon media is changed out periodically and is disposed of as ahazardous waste.

U.S GOETHERMAL POTENTIAL



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WORLD GEOTHERMAL POTENTIAL

NITROGEN OXIDE COMPARISON



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SULFUR DIOXIDE COMPARISON

PARTICULAR MATTER COMPARISON



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Installedgeothermal

electric capacity

Country Capacity (MW)2007[19] Capacity (MW)2010[42]

USA 2687 3086

Philippines 1969.7 1904

Indonesia 992 1197

Mexico 953 958

Italy 810.5 843

New Zealand 471.6 628

Iceland 421.2 575

Japan 535.2 536

El Salvador 204.2 204Kenya 128.8 167

Costa Rica 162.5 166

Nicaragua 87.4 88

Russia 79 82

Turkey 38 82

Papua-New Guinea 56 56

Guatemala 53 52

Portugal 23 29

China 27.8 24

France 14.7 16Ethiopia 7.3 7.3

Germany 8.4 6.6

Austria 1.1 1.4

Australia 0.2 1.1

Thailand 0.3 0.3

TOTAL 9,731.9 10,709.7
http://en.wikipedia.org/wiki/Geothermal_energy_in_the_United_Stateshttp://en.wikipedia.org/wiki/Geothermal_power_in_the_Philippineshttp://en.wikipedia.org/wiki/Geothermal_power_in_Indonesiahttp://en.wikipedia.org/wiki/Geothermal_power_in_Mexicohttp://en.wikipedia.org/w/index.php?title=Geothermal_power_in_Italy&action=edit&redlink=1http://en.wikipedia.org/wiki/Geothermal_power_in_New_Zealandhttp://en.wikipedia.org/wiki/Geothermal_power_in_Icelandhttp://en.wikipedia.org/wiki/Geothermal_power_in_Japanhttp://en.wikipedia.org/wiki/Geothermal_energy_in_El_Salvadorhttp://en.wikipedia.org/wiki/Geothermal_power_in_Kenyahttp://en.wikipedia.org/w/index.php?title=Geothermal_energy_in_Costa_Rica&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Geothermal_power_in_Nicaragua&action=edit&redlink=1http://en.wikipedia.org/wiki/Geothermal_power_in_Russiahttp://en.wikipedia.org/wiki/Geothermal_power_in_Turkeyhttp://en.wikipedia.org/w/index.php?title=Geothermal_power_in_Papua-New_Guinea&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Geothermal_power_in_Guatemala&action=edit&redlink=1http://en.wikipedia.org/wiki/Geothermal_power_in_Portugalhttp://en.wikipedia.org/wiki/Geothermal_power_in_Chinahttp://en.wikipedia.org/w/index.php?title=Geothermal_power_in_France&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Geothermal_power_in_Ethiopia&action=edit&redlink=1http://en.wikipedia.org/wiki/Geothermal_power_in_Germanyhttp://en.wikipedia.org/w/index.php?title=Geothermal_power_in_Austria&action=edit&redlink=1http://en.wikipedia.org/wiki/Geothermal_power_in_Australiahttp://en.wikipedia.org/w/index.php?title=Geothermal_power_in_Thailand&action=edit&redlink=1http://en.wikipedia.org/wiki/Geothermal_energy_in_the_United_Stateshttp://en.wikipedia.org/wiki/Geothermal_power_in_the_Philippineshttp://en.wikipedia.org/wiki/Geothermal_power_in_Indonesiahttp://en.wikipedia.org/wiki/Geothermal_power_in_Mexicohttp://en.wikipedia.org/w/index.php?title=Geothermal_power_in_Italy&action=edit&redlink=1http://en.wikipedia.org/wiki/Geothermal_power_in_New_Zealandhttp://en.wikipedia.org/wiki/Geothermal_power_in_Icelandhttp://en.wikipedia.org/wiki/Geothermal_power_in_Japanhttp://en.wikipedia.org/wiki/Geothermal_energy_in_El_Salvadorhttp://en.wikipedia.org/wiki/Geothermal_power_in_Kenyahttp://en.wikipedia.org/w/index.php?title=Geothermal_energy_in_Costa_Rica&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Geothermal_power_in_Nicaragua&action=edit&redlink=1http://en.wikipedia.org/wiki/Geothermal_power_in_Russiahttp://en.wikipedia.org/wiki/Geothermal_power_in_Turkeyhttp://en.wikipedia.org/w/index.php?title=Geothermal_power_in_Papua-New_Guinea&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Geothermal_power_in_Guatemala&action=edit&redlink=1http://en.wikipedia.org/wiki/Geothermal_power_in_Portugalhttp://en.wikipedia.org/wiki/Geothermal_power_in_Chinahttp://en.wikipedia.org/w/index.php?title=Geothermal_power_in_France&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Geothermal_power_in_Ethiopia&action=edit&redlink=1http://en.wikipedia.org/wiki/Geothermal_power_in_Germanyhttp://en.wikipedia.org/w/index.php?title=Geothermal_power_in_Austria&action=edit&redlink=1http://en.wikipedia.org/wiki/Geothermal_power_in_Australiahttp://en.wikipedia.org/w/index.php?title=Geothermal_power_in_Thailand&action=edit&redlink=1

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