Andy
Well-Known Member
- Joined
- Jan 6, 2008
- Messages
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Geo-power and why it is not a long term solution. Thanks Sil for inspiring me to write this.
Before I begin, some say the US is behind the world in geo-power and alternative energies. The truth is we lead the world in Geothermal power. As shown on the chart, the USA leads the world with installed Geothermal capacity at 2,687 MWs. Holding the number 2 spot is the Philippines with less than half of our capacity. Actual source for the chart numbers from European Geothermal Congress 2007 (pdf format)
This will cover the following points
1. Cost, both in capital investment (price to build), and operational upkeep.
2. Limited potential, both in viable locations and limited size.
3. Potential dangers, in possible air polution and earthquakes.
4. Common rebuttals.
1. COST
Capital investment, is the cost that must be paid in order to take a concept to operational power plant. Initial cost is compared in the form of $$$/per kW of installed capacity. Example: Solar Photovoltaic cells are averaging $7,000 / per kW of installed capacity. (1 MegaWatt = 1,000 KiloWatts)
Thus, a 25 MW Solar PV plant would cost 25,000 kW X $7,000 = $175 Million.
Since the size of the plants differ in output, the comparison is merely how much it costs per kW of installed capacity. Proponents often cite low cost of Geothermal power plants by conveniently ignoring the limited electrical production. Yes, a Geo-plant may cost a fraction of a nuclear one, but the power produced is also a fraction.
Average cost per kW of installed Capacity:
Nuclear Power Plant = $3,000 (Likely lower, save it for another thread)
Hydro Power Plant = $2,000
Traditional Coal Plant = $1,900
Natural Gas Plant = $ 750
Geothermal Plant = $3,700
Source is NGSA.org in PDF format
In order to validate the estimate, I found supporting evidence.
Wikinvest claims $2500
The DOE claims $3000 to $5000 (oddly cited by Wiki, as saying $2500)
Better still, some real life examples.
PacifiCorp Energy attempted to sell a Geothermal plant to Public Service Commission of Utah. Estimated cost = $5,538 per kilowatt. The plan was rejected.
Queensland Australia, Geothermal proposal. Cost = $7,000 per kW.
US Geothermal Inc. presentation for proposed Geothermal plants. Estimated cost on current projects = $4,000 - $4,500 per kW.
Capital investment varies dramatically depending on the specific location. The cheapest being to tap an existing geothermal system, like Old Faithful at Yellowstone. Cost skyrockets when the heat source is deep, when exploratory wells must be drilled to find the heat, when the heat is dry and water must be added, when the heat is too low, when there is acidic elements to the soil or water table.
Operational cost, is the amount of money required to run the plant. In theory, this should be very low. In practice, estimates are not so low. NGSA.org has their estimation of yearly operational cost:
(chart located in PDF of first link)
Nuclear Power Plant = $170K
Hydro Power Plant = $72K
Traditional Coal Plant = $67K
Natural Gas Plant = $47K
Geothermal Plant = $331K
Information on operational costs of Geo-plants is limited. That said, the GEOTHERMAL ENERGY ASSOCIATION, released a document in PDF format. It relates the following reason for Operational expenses.
Chemicals 1% - 15% pollution reducers, cleaning agents for wells
Other-Misc 6% - 41% repairs - routine maintenance
Labor 8% - 32% twenty to forty employees vs. power production
Steam 42% - 74% Cost of producing steam
MYTH: Geothermal plants have no fuel costs. While on a pure technical level this is true, obviously without water, there is no steam. Steam fields must be supplied with water continuously. This could be, by proxy, considered 'fuel'.
Another major operational cost of producing steam, is the fact that every steam field will go through a decline of production. This requires more injection and retrieval wells be built.
From the same document:
LIMITATION ON SIZE AND VIABILITY
Size, is the key to electrical generation. Nuclear is not cost effective because it's cheap to build, but rather, it is because of the massive output that can be produced. However, according to Wiki, most Geothermal plants are under 50 MW, and only 8 break the 100 MW range. As opposed to Nuclear that defaults at 1 GW. (see chart Nameplate Capacity Range by Generator Type)
The reason for this is that a geothermal heat source is not exactly infinite. As stated by Valgerdur Sverrisdottir (I can type it, not say it), Minister of Industry and Commerce in Iceland
There is a great danger in over tapping a heat source, either by making the plant too big, or by having too many power plants tapping the same general spot.
For example, The Geysers of California in 1989 had an installed capacity of 2043 MW from 22 plants. Yet current output is 750 MW. This article, written in the late 80s, details how production dropped consistently as each new well and power plant came online. This makes geothermal risky to investors.
Viability, is where a heat source can be economically tapped. This ignores how long it can be tapped and at what power out put can be accomplished, which is a problem as list above.
This is where it can be tapped at all. The GEOTHERMAL ENERGY ASSOCIATION, in the PDF listed above, shows the following factors that can place a heat our out of economic viability.
Knowing exactly where the heat is. Unknown heat sources require expensive exploratory drilling.
The depth of the heat. How far down you must go, add onto the cost exponentially.
Supply of water. Water at the heat source reducing the cost of supplying water.
Acidity. If the area around the heat source has high acidic qualities, this can damage equipment. That requires expensive counter-measures.
Amount of heat available. Overestimating the heat available, results in the Iceland and The Geysers situations, where production is less than half the installed capacity.
All of these factors and more can quickly result in a heat source being uneconomically viable.
POLLUTION AND EARTHQUAKES
Pollution, from Geothermal plants comes from the production wells. The water from the geothermal source is normally saturated with different elements. The steam is vented, thus releasing those elements. Arizona State University says that pollution includes radon gas, hydrogen sulfide (H2S), CO2, methane, and ammonia. This was supported by information from France, but I could not find the link at this time. (Please duly note the supposed green house gasses we are not using "fossil fuels" in order to avoid releasing)
Before I begin, some say the US is behind the world in geo-power and alternative energies. The truth is we lead the world in Geothermal power. As shown on the chart, the USA leads the world with installed Geothermal capacity at 2,687 MWs. Holding the number 2 spot is the Philippines with less than half of our capacity. Actual source for the chart numbers from European Geothermal Congress 2007 (pdf format)
This will cover the following points
1. Cost, both in capital investment (price to build), and operational upkeep.
2. Limited potential, both in viable locations and limited size.
3. Potential dangers, in possible air polution and earthquakes.
4. Common rebuttals.
1. COST
Capital investment, is the cost that must be paid in order to take a concept to operational power plant. Initial cost is compared in the form of $$$/per kW of installed capacity. Example: Solar Photovoltaic cells are averaging $7,000 / per kW of installed capacity. (1 MegaWatt = 1,000 KiloWatts)
Thus, a 25 MW Solar PV plant would cost 25,000 kW X $7,000 = $175 Million.
Since the size of the plants differ in output, the comparison is merely how much it costs per kW of installed capacity. Proponents often cite low cost of Geothermal power plants by conveniently ignoring the limited electrical production. Yes, a Geo-plant may cost a fraction of a nuclear one, but the power produced is also a fraction.
Average cost per kW of installed Capacity:
Nuclear Power Plant = $3,000 (Likely lower, save it for another thread)
Hydro Power Plant = $2,000
Traditional Coal Plant = $1,900
Natural Gas Plant = $ 750
Geothermal Plant = $3,700
Source is NGSA.org in PDF format
In order to validate the estimate, I found supporting evidence.
Wikinvest claims $2500
The DOE claims $3000 to $5000 (oddly cited by Wiki, as saying $2500)
Better still, some real life examples.
PacifiCorp Energy attempted to sell a Geothermal plant to Public Service Commission of Utah. Estimated cost = $5,538 per kilowatt. The plan was rejected.
Queensland Australia, Geothermal proposal. Cost = $7,000 per kW.
US Geothermal Inc. presentation for proposed Geothermal plants. Estimated cost on current projects = $4,000 - $4,500 per kW.
Capital investment varies dramatically depending on the specific location. The cheapest being to tap an existing geothermal system, like Old Faithful at Yellowstone. Cost skyrockets when the heat source is deep, when exploratory wells must be drilled to find the heat, when the heat is dry and water must be added, when the heat is too low, when there is acidic elements to the soil or water table.
Operational cost, is the amount of money required to run the plant. In theory, this should be very low. In practice, estimates are not so low. NGSA.org has their estimation of yearly operational cost:
(chart located in PDF of first link)
Nuclear Power Plant = $170K
Hydro Power Plant = $72K
Traditional Coal Plant = $67K
Natural Gas Plant = $47K
Geothermal Plant = $331K
Information on operational costs of Geo-plants is limited. That said, the GEOTHERMAL ENERGY ASSOCIATION, released a document in PDF format. It relates the following reason for Operational expenses.
Chemicals 1% - 15% pollution reducers, cleaning agents for wells
Other-Misc 6% - 41% repairs - routine maintenance
Labor 8% - 32% twenty to forty employees vs. power production
Steam 42% - 74% Cost of producing steam
MYTH: Geothermal plants have no fuel costs. While on a pure technical level this is true, obviously without water, there is no steam. Steam fields must be supplied with water continuously. This could be, by proxy, considered 'fuel'.
Another major operational cost of producing steam, is the fact that every steam field will go through a decline of production. This requires more injection and retrieval wells be built.
From the same document:
LIMITATION ON SIZE AND VIABILITY
Size, is the key to electrical generation. Nuclear is not cost effective because it's cheap to build, but rather, it is because of the massive output that can be produced. However, according to Wiki, most Geothermal plants are under 50 MW, and only 8 break the 100 MW range. As opposed to Nuclear that defaults at 1 GW. (see chart Nameplate Capacity Range by Generator Type)
The reason for this is that a geothermal heat source is not exactly infinite. As stated by Valgerdur Sverrisdottir (I can type it, not say it), Minister of Industry and Commerce in Iceland
There is a great danger in over tapping a heat source, either by making the plant too big, or by having too many power plants tapping the same general spot.
For example, The Geysers of California in 1989 had an installed capacity of 2043 MW from 22 plants. Yet current output is 750 MW. This article, written in the late 80s, details how production dropped consistently as each new well and power plant came online. This makes geothermal risky to investors.
Viability, is where a heat source can be economically tapped. This ignores how long it can be tapped and at what power out put can be accomplished, which is a problem as list above.
This is where it can be tapped at all. The GEOTHERMAL ENERGY ASSOCIATION, in the PDF listed above, shows the following factors that can place a heat our out of economic viability.
Knowing exactly where the heat is. Unknown heat sources require expensive exploratory drilling.
The depth of the heat. How far down you must go, add onto the cost exponentially.
Supply of water. Water at the heat source reducing the cost of supplying water.
Acidity. If the area around the heat source has high acidic qualities, this can damage equipment. That requires expensive counter-measures.
Amount of heat available. Overestimating the heat available, results in the Iceland and The Geysers situations, where production is less than half the installed capacity.
All of these factors and more can quickly result in a heat source being uneconomically viable.
POLLUTION AND EARTHQUAKES
Pollution, from Geothermal plants comes from the production wells. The water from the geothermal source is normally saturated with different elements. The steam is vented, thus releasing those elements. Arizona State University says that pollution includes radon gas, hydrogen sulfide (H2S), CO2, methane, and ammonia. This was supported by information from France, but I could not find the link at this time. (Please duly note the supposed green house gasses we are not using "fossil fuels" in order to avoid releasing)
Geothermal plants cause earthquakes? 
