Geothermal energy interest grows in Alaska
October 10, 2011
By Ed Schoenfeld, CoastAlaska: When you’re trying to tap geothermal energy, for heating or electrical generation, you’ve got to consider a number of factors.
“The temperature is the obvious one. Flow rate is really important too,” says Gwen Holdmann, director of the University of Alaska’s Center for Power and Energy. She spoke at the recent Rural Alaska Energy Conference in Juneau.
“You might have a really high temperature resource and one good example that’s pretty close by here (Juneau) is Tenakee Springs. They have a fairly high temperature but they have an extremely low flow rate,” she says.
You also need to know the extent of the hot-water reservoir, its depth and the rate it recharges itself.
Another importation factor is location. Being close to a city or transmission lines make tapping power more affordable.
That’s why the Aleutian Islands city of Akutan, and the local Trident Seafoods plant, are looking at nearby Hot Springs Valley.
“We hit water as hot as 350 (degrees)-plus at 500 feet,” says Ray Mann, a consultant for the city of Akutan, northeast of Unalaska.
“But according to the studies that have been done that’s the outflow resource and we probably will not get the flow and the capacity we need. So we have to go further up the valley to the upflow zone. And the estimate is we could achieve anything between 15 and 100 megawatts, with a minimum of 8 megawatts, to provide power,” Mann says.
Outflow is where water comes from the ground. Inflow is the subterranean area where it travels to near the surface.
There’s been interest in the Akutan site for at least 30 years. New wells were drilled this and last year, one finding water up to 500 degrees. Deep water is under enough pressure that it does not boil off at those temperatures. And other studies further defined the resource.
Mann says the city is committed to building an approximately $60 million plant, including about 5 miles of road and transmission lines. Read more