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Recycling Old Wells for New Power
10/12/2012 11:30 am EST
A new breakthrough in geothermal power could democratize the energy source in the US, and also add enormous value to thousands of abandoned wells across the country, observes energy expert Tom Drolet of Drolet Energy Services.
Gregg Early: We're here with Tom Drolet, president of Drolet Energy Services. Tom, you are a veteran of the energy industry on all sorts of different levels, and you have been talking about geothermal recently.
I was interested in getting your take, and maybe you could explain what the advantages are for geothermal, how we're using it in the US, and what's to come. We'll take this one step at a time. What is geothermal energy?
Tom Drolet: Well, good morning, Gregg. Geothermal energy is-basically, the meaning of the word is the combination of two words, geological and thermal. It's heat from the earth; heat from the ground.
Geothermal as we know it and practice it today really comes in two packages. There's the retail homeowners way. Some homeowners have bought into geothermal heat pumps to help offset costs of electricity in their house.
All you do there is drill a hole down, say 100 feet on average, and take the temperature difference between the ground-which is pretty static at 100 feet down-and the surface air, and you drive a heat pump. It's sort of a reverse engine, and uses that temperature difference between the surface and the ground at 100 feet to offset some of your electricity costs. A lot of people have done that along the East Coast, Northeast, Southeast, and across the top of the country.
The other big use of geothermal today is predominantly along the West Coast of the US, and right around the Ring of Fire around the Pacific, where you get tectonic plate movements which allow the magma-or the hot, hot lava, if you will-from deep below in the earth to approach the surface of the earth.
For instance, in the geyser fields north of San Francisco, geothermal is generating today about 1,000 megawatts of energy. What they do there is they drill down about a mile to two miles with a series of production wells. That taps the heat, the hot rock that's down there, and the interstitial water, and water comes up the well bores, flashes to steam in a turbine, and makes electricity.
That's conventional geothermal, as we know it today. Around the world, in total, there are some 3,000-plus megawatts of electricity being generated by geothermal. That spot north of San Francisco that I mentioned doing is about one-third. The US is right in there tight with conventional geothermal.
Gregg Early: Would this be possible, say...I know that there's the New Madrid plate on the Mississippi, but is the US just out of this market moving to the east from the west-is the only plate that really works in the West at this point?
Tom Drolet: Yes, it is the only plate, because the predominant cost of this conventional deep geothermal is the drilling. That drilling represents about half the capital cost of the facility, and if you have to go any deeper-which you do as you come eastward from California-then you're having to go deeper and deeper.
Frankly, right now, conventional geothermal is only economic along that west coast and in some parts of Nevada, where they've come up with some good reservoirs. Also, bits of Oregon, Utah, southern California along the Imperial Valley, along the Mexican border where some of that San Andreas fault fissures go sideways to the east. But generally speaking, it's a "westward young man" type of energy source.
Gregg Early: Are there any technologies on the horizon that are going to change that dynamic somewhat?
Tom Drolet: Yes, Gregg. This is the exciting part. There is a new source that's been known for decades, and in fact our government, the US Department of Energy, spent approximately $180 million some two decades ago looking into the thermal energy that exists at the bottom of some abandoned oil and gas wells.
They focused their efforts in Texas and in some places, under some of those 1 million-plus abandoned oil and gas wells. There are reservoirs of hot brine or hot sea water, if you will, down about two miles, and that seawater also contains residual amounts of natural gas.
So what they did is they mounted a rather intensive two-decade-long program to see if they could get that hot brine to come up those abandoned well bores and make electricity through pretty conventional technologies where you flash off the natural gas, make steam, turn to turbine electricity, and then use the thermal energy from that brine to make electricity again in another sort of engine.
That program has spawned a couple of companies that are now looking at doing that in a practical, commercial way. Those companies are Greenwell Power Corporation of Canada and SolaGen Renewable Energy down in San Antonio, Texas. They're looking at starting a program of putting in three different types of machines, which will allow that electricity to be generated from the hot brine.
Gregg Early: Are there any publicly-traded companies that we should look to? Those are-neither of those are publicly traded at this point, correct?
Tom Drolet: No, that's correct. There's no publicly traded companies that are actively looking at that, at the moment. So these two private companies are putting together their first project, hopefully for late spring next year, with the first well to generate 3 megawatts of energy down in that San Antonio region, along the coast where some of these brine reservoirs exist.
Their plans are to do approximately 75 of those wells, and if you look at 3 megawatts per well, then that's a heck of a lot of power from a reservoir source of renewable energy that was abandoned. It was thrown away. It was thought to never be useful, and now we've got a new type of renewable energy source, a geothermal type, that can be used from throwaway facilities. It's a real breakthrough, as far as I can see.
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