"Geothermal" is an extremely large umbrella under which many different types of systems are developed. I am a field supervisor for a company that specializes in the development high temperature geothermal aquifers. Right now (like tonight) I'm drilling in the Ohaaki-Broadlands field in New Zealand. I'll be leaving here to return to Iceland where they've been developing the Reykjanes (Blue Lagoon) and Hellisheidi fields.
This is (at least) the second time these "hot rock" systems have been mentioned on Slashdot. Each time this type of geothermal power is mentioned as being "first", it means that it is the first of its kind to be commercially viable. It involves (at a MINIMUM of 2 wells - one to inject and one to drain - for a heat transfer loop to occur from the temperature of the surrounding rock. A "path" for the water to move from one well to the other is where the "art" or science comes into play. I'm really speculating now but from what I gathered between the lines of the article was that where they drilled the injection well was along a natural fault. This would save them the cost of a "frac" job to create a path between the injection and the recovery well. (I'm leaving out the possibility of a reverse circulation well which would pump down the outside of a tubing string and recover up through it). http://ec.europa.eu/research/energy/nn/nn_rt/nn_rt _geo/article_1136_en.htm
These projects are the "first" of it's type (to be commercially viable (in the future)). Geothermal power generation has been in production (on a large, commercial scale) from the late '40s and early '50s.
The power generation wells we drill typically flow "water" at 290-315C - you can tell (on surface while drilling) how hot they get by indicator minerals and their melting points. When we drill into one of these aquifers the "water" wants to become 100C and "steam" at atmosphere - that's where the energy to power turbines comes in. I'm leaving out the "typical" production figures since this varies from country to country - some fields produce 8-10MW/well and others can produce 35-40MW/well - that's alot of power to be coming out of the ground from a single hole (usually 12 1/4" or 8 5/8")!
The wells then get tied into a pipeline system and feed a turbine generating station (after pre-plant treatment if required). This is similar to how oil/gas wells are tied into a refinery. In most cases the water outflow from these plants are re-injected into wells that are drilled for this purpose on the edge of the aquifer systems. I just wanted to throw some point of view out there for this stuff - I can try to answer other questions related to geothermal power (since it's kinda my "hobby" now like Linux was when I was dd'ing onto 14 floppies back in '94). I didn't write the book on this stuff but I work along side the people who did. Cheers
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"Geothermal" is an extremely large umbrella under which many different types of systems are developed. I am a field supervisor for a company that specializes in the development high temperature geothermal aquifers. Right now (like tonight) I'm drilling in the Ohaaki-Broadlands field in New Zealand. I'll be leaving here to return to Iceland where they've been developing the Reykjanes (Blue Lagoon) and Hellisheidi fields.
t _geo/article_1136_en.htm
This is (at least) the second time these "hot rock" systems have been mentioned on Slashdot. Each time this type of geothermal power is mentioned as being "first", it means that it is the first of its kind to be commercially viable. It involves (at a MINIMUM of 2 wells - one to inject and one to drain - for a heat transfer loop to occur from the temperature of the surrounding rock. A "path" for the water to move from one well to the other is where the "art" or science comes into play. I'm really speculating now but from what I gathered between the lines of the article was that where they drilled the injection well was along a natural fault. This would save them the cost of a "frac" job to create a path between the injection and the recovery well.
(I'm leaving out the possibility of a reverse circulation well which would pump down the outside of a tubing string and recover up through it).
http://ec.europa.eu/research/energy/nn/nn_rt/nn_r
These projects are the "first" of it's type (to be commercially viable (in the future)). Geothermal power generation has been in production (on a large, commercial scale) from the late '40s and early '50s.
The power generation wells we drill typically flow "water" at 290-315C - you can tell (on surface while drilling) how hot they get by indicator minerals and their melting points. When we drill into one of these aquifers the "water" wants to become 100C and "steam" at atmosphere - that's where the energy to power turbines comes in. I'm leaving out the "typical" production figures since this varies from country to country - some fields produce 8-10MW/well and others can produce 35-40MW/well - that's alot of power to be coming out of the ground from a single hole (usually 12 1/4" or 8 5/8")!
The wells then get tied into a pipeline system and feed a turbine generating station (after pre-plant treatment if required). This is similar to how oil/gas wells are tied into a refinery. In most cases the water outflow from these plants are re-injected into wells that are drilled for this purpose on the edge of the aquifer systems.
I just wanted to throw some point of view out there for this stuff - I can try to answer other questions related to geothermal power (since it's kinda my "hobby" now like Linux was when I was dd'ing onto 14 floppies back in '94). I didn't write the book on this stuff but I work along side the people who did.
Cheers