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Geothermal

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Information about Geothermal
Science-Technology

Published on March 10, 2009

Author: arasarn

Source: authorstream.com

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Geothermal++++++“Earth Energy” : Geothermal++++++“Earth Energy” Slide 2: “Geo” means Earth “Thermal” means Heat Geothermal energy is the natural heat of the Earth Earth energy is sub-surface heat from the Sun Slide 3: Heat Flows outward from the Earth’s Interior The Curst insulates us from Earth’s interior heat The Mantle is semi-molten, the outer core is liquid and the inner core is solid Source of Geothermal Energy Difference between Earth Energy and Geothermal : Earth Absorption 700 – 3,000 nm Surface Heat Reservoir Earth Energy ? Heat Difference between Earth Energy and Geothermal Core Deep Earth Reservoir Very Hot Heat Steam “Geothermal” Energy : “Geothermal” Energy Deep Geothermal Basics : Deep Geothermal Basics Capturing “Geothermal” EnergyThe 1st System : Capturing “Geothermal” EnergyThe 1st System In 1904 1st demonstration. Emerging steam powered a turbine to light 5 light bulbs World’s 1st Geothermal Power Station. 1911 in Tuscany, Italy By 1913 a 250 kW power station had been built and was used to power the Italian electric railway system. Today world production is 5 TWh, or 10% Capturing “Geothermal” EnergyModern Integrated Community System : Capturing “Geothermal” EnergyModern Integrated Community System Earth Energy : Earth Energy Heat Spectra Earth Energy ? Heat Pump : Earth Energy ? Heat Pump A heat pump is an electrical device that extracts heat from one place and transfers it to another Capturing “Earth” Energy I : Capturing “Earth” Energy I Geothermal Heat Pumps can provide heat in the winter and cool air in the summer – best of both worlds Residential and commercial/institutional scale is available. Geothermal heat pumps can be used anywhere in the world without a geothermal reservoir. The insulating properties of the earth, just below our feet, can keep us warm or cool !! Slide 14: Energy Under Our Feet 47% of Solar Energy is Absorbed By the Ground 19% Absorbed by Water Vapor & Dust 4% Absorbed By Clouds 17% Reflected By Clouds 6% Absorbed By Surface Technology & OperationBasic System Components : Technology & OperationBasic System Components 3 Basic Components A ground loop A heat pump A heat distribution system Ground Loop: a series of high density polyethylene or copper pipes in soil or water A water and antifreeze mix circulates through the pipes and is pumped directly into the heat pump in the home. Since the ground and air outside always contain some heat, a heat pump can supply heat to a house even on cold winter days……in fact, air at -18°C contains about 85% of the heat it contained at 21°C Terms to Know : Terms to Know Refrigerant. Liquid/gaseous substance that circulates through the heat pump, alternately adsorbing, transferring and releasing heat. Commonly used refrigerants are distinguished by the fact that over a relatively moderate range of elevated pressures, they vaporize and condense at temperatures that can generate spontaneous heat flow to maintain interior building comfort Classified as hydro-chloro-fluoro-carbons (HCFC), or chloro-fluoro-carbons (CFC). Today’s refrigerants are designed to have minimal impact on the atmosphere by eliminating the chlorine (hydro-fluoro-carbons) COP. Coefficient of Performance is a measure of a heat pump’s efficiency. It is determined by dividing the energy output or the heat pump in BTU/hr by the electrical energy needed in watts to run the pump, at a specific temperature. The higher the COP, the more efficient the pump. EER. Energy Efficiency Ratio measures the steady state cooling efficiency of a heat pump. It is determined by dividing the cooling capacity of the pump in BTU/hr by the electrical energy input in watts at a specific temperature More Terms to Know : More Terms to Know Compressor. It “squeezes” the molecules of the refrigerant, gas together, increasing the temperature of the refrigerant shifting it to a vapor phase Evaporator. A coil in which the refrigerant absorbs heat from the soil/water and boils to become a low temperature vapor. Condenser. A coil in which the refrigerant gives off heat to its surroundings as it condenses back into a liquid. Expansion Device. Lowers the pressure created by the compressor. This causes the temperature to drop, and the refrigerant becomes a low temperature vapor/liquid mixture. Evaporator Condenser Expansion Evaporation Condensation Compression Expansion Device Compressor “Air Source” Heat Pumps : “Air Source” Heat Pumps Air source heat pumps draw heat from the outside air during the heating season and eject heat outside during the summer season. Air to Air. Extracts heat directly from the air and dispatches it inside or outside, depending on the season. Air to Water. Used in homes with hydronic heat distribution systems. Heat from warm outside air is transferred to heat water which is distributed to radiators within the home to provide convective heat. New. Ductless Mini-split Heat Pump. Ideal for retrofits having hydronic or electrical resistance baseboard systems Wall mounted and installed in individual rooms Note: Our focus will be on ground source heat pumps (Earth Energy Systems) which are better suited to the climate in northern Ontario. “Ground Source” Heat Pumps : “Ground Source” Heat Pumps Source. A ground source heat uses the earth or ground water or both as the sources of heat in the winter, and as a sink for heat removed from your home in summer. Access. The heat is extracted from the earth (land or water) using a liquid, “antifreeze” solution, or refrigerant (direct expansion system) The temperature of the antifreeze is raised by the heat pump The heat is transferred to the indoor air Summer reversal ? heat is taken from indoor air and transferred to the ground Delivery. Forced air Hydronic radiant Electrical resistance base board Ground Source Operation I : Ground Source Operation I Location Entire pump system is inside, unlike air source in which one of the heat exchangers, usually the compressor is outside Open System Open System takes advantage of the heat retained in underground body of water, usually a well. Water is drawn up directly to the heat exchanger where heat is extracted Discharge is to a stream, lake or pond, where permitted, or a discharge well. Closed System Collects the heat through an underground system of piping. An antifreeze solution, or refrigerant, which has been chilled by the heat pumps refrigeration system to several degrees colder than the soil/water circulates through the piping and absorbs heat from the soil Ground Source Operation II : Ground Source Operation II Heat Cycle The antifreeze solution or refrigerant (heat carrier) which has circulated through the piping and absorbed heat is brought back to the heat pump in the building. In the ground water or antifreeze system the carrier passes through the refrigerant filled primary heat exchanger and transfers the heat In the direct expansion (DX) system the refrigerant enters the compressor directly with no intermediate heat exchanger The heat is transferred to the refrigerant, which “boils” to become a low temperature vapor - it then goes to the compressor In the open system the ground water is pumped back to the discharge well In the closed system the heat carrier is pumped through the outdoor piping to be reheated again Ground Source Operation III : Ground Source Operation III A reversing valve directs the refrigerant vapor to the compressor at which point the vapor is compressed by reducing the volume and increasing its temperature. The reversing value then directs the hotter vapor (gas) to the condenser coils. Here it gives up heat to: Air blowing across the coil and through the duct system to heat the home Water flowing across the coils and to the radiators in the rooms Having given up the heat, the refrigerant passes through the expansion device where the temperature and pressure are decreased further before returning the the first heat exchanger, or to the DX system, to begin the cycle again Technology & OperationHow the Heat Pump Works : Technology & OperationHow the Heat Pump Works Heat pumps transfer heat by circulating refrigerant through a cycle of alternating evaporation and condensation. A compressor pumps the refrigerant between 2 heat exchanger coils. In one coil, the refrigerant is evaporated at low pressure and absorbs heat from its surroundings (blue – in the soil/water). The refrigerant is then compressed in route to the other coil where it condenses at high pressure (red) At this point, it releases the heat it absorbed earlier in the cycle (into the home) Earth Home Compression Condensation Expansion Evaporation Evaporator Condenser Low Pressure Low Temperature Liquid High Pressure High Temperature Liquid Low Pressure Low Temperature Liquid Low Pressure Low Temperature Liquid Heat Pump Ground Loops I : Heat Pump Ground Loops I Points to Consider Size of the system Ground loop design Soil Type, Depth and Consistency Land area available Heat Pump Ground Loops II : Heat Pump Ground Loops II Vertical Most appropriate for suburban homes where lot space may be restricted. Pipe inserted into bore holes 6 inches by 60-200 feet, depending on soil type and system size 100 m piping per ton of heat capacity (3.5kW or 12,000 BTU) DX systems smaller holes, less cost Horizontal Rural areas with more property Piping in trenches 3 to 6 m deep 150 m piping per ton of heat capacity Well insulated 2,000 sq.ft. home would use 360 to 540 m pipe Heat Pump Ground Loops III : Heat Pump Ground Loops III Regardless of the arrangement chosen, all piping for refrigerant or antifreeze solution systems must be polyethylene or polybutylene with thermally fused joints to ensure leak free connections for life of the pipe, or 25 to 75 years. DX systems use copper pipe that is of refrigeration grade. Or Polyethylene Copper Heat Pump Ground LoopsMulti-Unit Dwellings : Heat Pump Ground LoopsMulti-Unit Dwellings Same principles apply for commercial/institutional settings In room systems compartmentalized and operate independently Integration with Solar PV can help optimize benefits Pipe Installation : Pipe Installation New Construction Sites More Rural Retro-fit Construction Sites More Urban Pipe Installation – Lesson 1 : Pipe Installation – Lesson 1 Oh hi honey, Yeah I told the backhoe guy about your garden Plan Ahead ! Pipe Installation – Lesson 2 : Pipe Installation – Lesson 2 Yeah boss, I got the geothermal system up and running just great But it’s Going to be hell laying pipe Look at the Plan ! Odds & Ends IHot Water System : Odds & Ends IHot Water System Dedicated heat pump water heaters are heat pumps designed solely to heat water. They can be used in any building space heating and/or cooling system, providing on demand, high efficiency water heat year around. Heat pumps can be water or air source. Water is best because of it takes 4x less energy to move an equivalent amount of heat. Water units best for GHP systems, where ground loop is the heat source for the heat pump. Odds & Ends II“Residential Geo-Electric -- No Hot Steam Source” : Odds & Ends II“Residential Geo-Electric -- No Hot Steam Source” Binary cycle geothermal power plants are a viable option for residential without a hot steam source at temperatures below 200?F. Hot geothermal fluid and a second (binary) fluid with a much lower boiling point than water pass through the heat exchanger. Iso-butane or Iso-pentane Heat from the geothermal fluid causes the binary fluid to flash to vapor, which drives the turbine. The closed loop nature of the system greatly reduces emissions. Production Well Rock Layers Injection Well Heat Exchanger Load Generator Turbine Binary Cycle Power Plant Earth Energy - Advantages : Earth Energy - Advantages Uses 25% - 50% less energy than conventional heating and cooling Improved humidity control Can be retrofitted Long lasting, quiet and easily accessible Less expensive to operate and maintain Investment return of 3 to 10 years….or less It can work in land or water – lots’ of flexibility They conserve fossil fuel reserves and enable their use for higher value products They provide clean heating and cooling with no emissions from burning fuels Earth Energy - Disadvantages : Earth Energy - Disadvantages High initial cost, particularly for retrofitting Horizontal ground loop systems which are the least expensive require a hectare This can be addressed by combining vertical and slinky systems to reduce spatial requirements A qualified installer is recommended. However, this does open the door to financial grants that do not come with a “do it yourself” operation Benefits of Heat Pumps : Benefits of Heat Pumps They can be used almost everywhere world wide They are energy and cost efficient They conserve fossil fuel reserves and enable their use for higher value products They provide clean heating and cooling with no emissions from burning fuels (depending on electricity source) Geothermal Benefits : Geothermal Benefits Replacing your natural gas furnace is equivalent to parking 2 cars for a year. EPA: Geothermal heat pump systems are the most energy efficient, environmentally clean, and cost effective space conditioning systems available Originates from the electricity source Questions : 95% of people who installed a heat pump said they would recommend heat pumps….and do it again ! Questions The Refrigerator – Simple SystemFour Main Components : The Refrigerator – Simple SystemFour Main Components Compressor. Increases the pressure of the an refrigerant vapor, pushing it through the system, and increasing the vapor’s temperature above that of the surrounding kitchen air. Condenser. Behind the refrigerator where the refrigereant vapor condenses to a liquid. Expansion Value. Causes a sudden drop in refrigerant pressure, causing it to boil – passes only as much liquid as can be completely vaporized in the evaporator. Evaporator. Latent heat of refrigerant vaporization is absorbed from the cold box Virginia Tech Site ?? Summer/Winter Operation : Summer/Winter Operation Winter Heating Cycle Winter Cooling Cycle

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