Geothermal Energy: Clean, Reliable, and Sustainable Power Source

1. INTRODUCTION • The word ‘Geothermal’ originates from the Greek roots geo, meaning earth, and thermos, meaning heat. • Geothermal energy is the earth’s natural heat available inside the earth. • Geothermal power is cost effective, reliable, sustainable, and environmentally friendly. • Geothermal energy is an enormous, underused heat and power resource that is clean (emits little or no greenhouse gases), reliable and home-grown. • Geothermal power has the potential to help mitigate global warming if widely deployed in place of fossil fuels.

2. INTRODUCTION • High-pressure, high-temperature steam fields exist below the earth’s surface. • Recently, geothermal energy has been used in electric power production, industrial processing, space heating, agriculture, and aquaculture. • Geothermal energy is the natural heat of the Earth, originating at the Earth’s core and flowing outward to the surface.

3. This heat can be used in its unchanged form to heat homes or it can be harnessed in the form of steam to turn turbines and generate electricity. WHAT DO WE USE GEOTHERMAL ENERGY FOR?

4. Animation of geothermal power plant HOW DOES A GEOTHERMAL POWER PLANT WORK?

5. ADVANTAGES OF GEOTHERMAL POWER • Unlimited source of cheap energy. • Geothermal energy does not produce any pollution, and does not contribute to the greenhouse effect. • The power stations do not take up much room, so there is not much impact on the environment. • No fuel is needed.

6. ADVANTAGES OF GEOTHERMAL POWER • Have long life span. • No mining needs. • Little waste disposal.

7. >BENEFITS OF GEOTHERMAL POWER • Emission free (if binary plant) • 100 MW eliminates 560,000 tons of CO2 • No SOx, NOx, or particulates • Generates continuous, reliable “baseload” power • Renewable and Sustainable • Full scheduable output during peak hours • Fuel Hedge (Contract for insurance on price changes) • 100MW replaces about 6 BCF of natural gas per year • Not subject to spot market, seasonal, or other price excursions • No drought years

8. DISADVANTAGES OF GEOTHERMAL • The big problem is that there are not many places where you can build a geothermal power station. • Drilling wells is very expensive. • Potential danger of noxious gases. • Noise problems from steam valves.

9. IS GEOTHERMAL RENEWABLE OR NON RENEWABLE? • Geothermal energy is renewable. • The energy keeps on coming, as long as we don't pump too much cold water down and cool the rocks too much.

10. WHAT DEFINES A COMMERCIAL GEOTHERMAL RESOURCE • Viable Resource • Temperature, Permeability, Working Fluid, and Depth. • Together these define the Capital cost of wells, pipeline, and power plant. • Market • Transmission: Access to customer(s) • Reach investment criteria

11. RESOURCE DISCOVERY & EXPLORATION • Usually surface manifestation (generally the features that first stimulate exploration) leads to resource investigation. • Raft River side discovered by drilling a hot stock water well – no surface manifestation. • Exploration tools: • Geothermometry • Geophysics: magnetics, self-potential, resistivity, microgravity, seismic (rare) • Bottom Line: Drilling and flow testing

12. Geoscience and surface investigations Temperature gradient holes Slim hole Production size well Additional wells Flow tests Other Corporate costs ========== Financeable Project $ 300,000 .2 – 2 yr $ 300,000 $1,000,000 $2,000,000 1 – 4 yr $4,000,000 $ 600,000 .2 - .5 yr $1,500,000 ================ $9,700,000 1.5 – 7 yr COST OF EXPLORATION & DISCOVERY

13. BALANCE OF COST TO BUILD • Installed Cost of Plant • $4,000 - $4,500 per kW of capacity • Exploration and Discovery • $10M • For a 25MW Plant • $100M total cost • ($10M Exploration) • ================== • $90M to be financed

14. COST AND TIME IMPLICATIONS OF GEOTHERMAL EXPLORATION • 1-3 years for any new resource in North America and Northwest • Discovery cost is far higher than other renewable resources • Is always done on equity alone • Cannot get loans • Needs a PSA(Purchase Sharing Agreement) in hand to get financing beyond temperature gradient holes • Not all exploration programs lead to commercial resources

15. GEOTHERMAL COSTS INCREASE AS RESOURCE TEMPERATURE DECREASES

16. PLANT ONLINE Raft River Geothermal Project

17. HYBRID AIR COOLING Cooler air going in to condenser means lower condenser pressure and therefore higher generator output. Air Cooled Condenser “Swamp Cooler” Hybrid Air Cooler Conventional Air Cooler

18. SUMMARY OF GEO POWER • Has great characteristics for a utility • Shape, generation forecasting, environmental • Exploration is risky and expensive • Needs a PPA early to eliminate market risk • The PPA is not a price or delivery certain contract, as it is with other generators • Risk of discovery and price escalation • Geothermal PPAs need unique terms

19. HISTORY • The presence of volcanoes, hot springs, and other thermal phenomena must have led our ancestors to surmise that parts of the interior of the Earth were hot. • It has been used for bathing since Palaeolithic times and for space heating since ancient Roman times, but is now better known for generating electricity. • The oldest known spa is a stone pool on China’s Lisan mountain built in the Qin dynasty in the 3rd century BC.

20. SOURCES OF EARTH’S INTERNAL ENERGY • Earth's core maintains temperatures in excess of 5000°C • Heat gradual radioactive decay of elements • Heat energy continuously flows from hot core • Conductive heat flow • Convective flows of molten mantle beneath the crust. • The Earth's internal heat naturally flows to the surface by conduction at a rate of 44.2 terawatts, (TW,) and is replenished by radioactive decay of minerals at a rate of 30 TW.  • Volcanic activity transports hot material to near the surface • Only a small fraction of molten rock actually reaches surface. • Most is left at depths of 5-20 km beneath the surface, • Hydrological convection forms high temperature geothermal systems at shallow depths of 500-3000m.

21. AVAILABILITY OF GEOTHERMAL ENERGY • On average, the Earth emits 1/16 W/m2. However, this number can be much higher in areas such as regions near volcanoes, hot springs and fumaroles. • As a rough rule, 1 km3 of hot rock cooled by 1000C will yield 30 MW of electricity over thirty years. • It is estimated that the world could produce 600,000 EJ over 5 million years. • There is believed to be enough heat radiating from the center of the Earth to fulfill human energy demands for the remainder of the biosphere’s lifetime.

22. GLOBAL GEOTHERMAL SITES

23. IDENTIFICATION OF GEOTHERMAL SITES

24. EXTRACTING GEOTHERMAL ENERGY

26. METHODS OF HEAT EXTRACTION

27. DRY STEAM SCHEMATIC

28. DRY STEAM POWER PLANTS • “Dry” steam extracted from natural reservoir • 180-225 ºC ( 356-437 ºF) • 4-8 MPa (580-1160 psi) • 200+ km/hr (100+ mph) • Steam is used to drive a turbo-generator. • Steam is condensed and pumped back into the ground. • Can achieve 1 kWh per 6.5 kg of steam • A 55 MW plant requires 100 kg/s of steam

29. SINGLE FLASH STEAM SCHEMATIC

30. SINGLE FLASH STEAM POWER PLANTS • Steam with water is extracted from the ground. • Pressure of mixture drops at the surface and more water “flashes” to steam. • Steam is separated from water . • Steam drives a turbine . • Turbine drives an electric generator. • Generate between 5 and 100 MW. • Use 6 to 9 tones of steam per hour.

31. DOUBLE FLASH POWER PLANTS • Similar to single flash operation. • Unflashed liquid flows to low-pressure tank – where it flashes to steam. • Steam drives a second-stage turbine • Also uses exhaust from first turbine • Increases output 20-25% for 5% increase in plant costs.

32. BINARY CYCLE SCHEMATIC

33. BINARY CYCLE POWER PLANTS • This system passes moderately hot geothermal water past a liquid, usually an organic fluid, that has a lower boiling point. • The resulting steam from the organic liquid drives the turbines. • This process does not produce any emissions and the water temperature needed for the water is lower than that needed in the Flash Steam Plants (2500F – 3600F).

34. HOT DRY ROCK TECHNOLOGY

35. HOT DRY ROCK TECHNOLOGY • The simplest models have one injection well and two production wells. • Pressurized cold water is sent down the injection well where the hot rocks heat the water up. • Then pressurized water of temperatures greater than 2000F is brought to the surface and passed near a liquid with a lower boiling temperature, such as an organic liquid like butane. • The ensuing steam turns the turbines. • Then, the cool water is again injected to be heated. This system does not produce any emissions. • US geothermal industries are making plans to commercialize this new technology.

36. APPLICATIONS

37. 1. AQUACULTURE, HORTICULTURE, AND THERMOCULTURE • This renewable energy can be used to raise marine life that needs warm waters and a tropical environment. • Geothermal renewable energy is used to heat the worlds only geothermally warmed prawn farm, and in the year two thousand and five this prawn farm sold twenty tons of prawns raised on the farm.

38. 2. INDUSTRIAL AND AGRICULTURAL USES • Geothermal power generation can play a big part in industrial and agricultural operations around the world. • Timber can be dried using heat from geothermal energy, and paper mills like one that is located on a geothermal field in New Zealand can use this energy in almost every stage of paper processing. • There are thousands of industrial and agricultural uses that geothermal energy may be perfect for, and the cost of this energy is very low once the geothermal power generation facility is in place and operating.

40. 3. FOOD PROCESSING • One way that this energy source can be invaluable is as steam for sterilizing food processing facilities. • The earth naturally contains high levels of heat and steam, and releasing this steam can sterilize equipment and rooms without using drugs or chemicals. • Geothermal energy can also help dry out plants, making powders and concentrates that are used in food processing, and at times these substances can be used to add flavors or preserve foods without any unnatural additives. • Foods can be cooked, steamed, or prepared in other ways using geothermal energy as well.

41. 4. PROVIDING HEAT FOR RESIDENTIAL AND COMMERCIAL USE • Geothermal renewable energy can be used to provide heat for all types of buildings, from homes to businesses to farms, barns, and other types of buildings. • Using this energy does not just provide heat, it is a complete temperature control system which can help cool your home as well. • With a geothermal heating and cooling system you will see much lower energy bills, because a furnace or air conditioner is not needed. • Geothermal temperature control units can add heat or pull it out of your home or other type of building, keeping it comfortable all year long.

43. 5. ELECTRICITY GENERATION • A geothermal power station can provide a large amount of electricity, with many benefits that using fossil fuels for electricity generation do not offer. • Geothermal power generation is very clean, because it uses the heat and steam trapped in the earth to produce electricity. • There are no harmful gas emissions or high carbon levels, and these power generation plants do not contribute to air pollution. • This energy source is renewable, and does not depend on fossil fuels or foreign countries to supply energy the country needs. • Geothermal energy can add stability to both the cost and the availability of electricity and heat for the entire world.

45. OVERVIEW OF APPLICATIONS

46. GEOTHERMAL’S POSITIVE ATTRIBUTES • Useful minerals, such as zinc and silica, can be extracted from underground water. • Geothermal energy is “homegrown.” This will create jobs, a better global trading position and less reliance on oil producing countries. • Geothermal plants do not require a lot of land, 400m2 can produce a gigawatt of energy over 30 years. • In large plants the cost is 4-8 cents per kilowatt hour. This cost is almost competitive with conventional energy sources. • Geothermal plants can be online 100%-90% of the time. Coal plants can only be online 75% of the time and nuclear plants can only be online 65% of the time. • Flash and Dry Steam Power Plants emit 1000x to 2000x less carbon dioxide than fossil fuel plants, no nitrogen oxides and little SO2.

47. GEOTHERMAL’S HARMFUL EFFECTS • Brine can salinate soil if the water is not injected back into the reserve after the heat is extracted. • Extracting large amounts of water can cause land subsidence, and this can lead to an increase in seismic activity. To prevented this the cooled water must be injected back into the reserve in order to keep the water pressure constant underground. • Power plants that do not inject the cooled water back into the ground can release H2S, the “rotten eggs” gas. This gas can cause problems if large quantities escape because inhaling too much is fatal. • There is the fear of noise pollution during the drilling of wells.

48. ENVIRONMENTAL IMPACTS • Land • Vegetation loss • Soil erosion • Landslides • Air • Slight air heating • Local fogging • Ground • Reservoir cooling