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Chena Hot Springs - geothermal power, plus more

April 24, 2012

The Chena Hot Springs is a complex of tourist attractions and greenhouses all tapping into thermal energy. The Chena Hot Springs are located about 60 miles North and east of Fairbanks.

The Chena Hot Springs Geothermal Resource, like all interior Alaskan hot springs, is located along the margins of a granite pluton. These plutons are ancient (cooled) magmatic bodies that have pushed up into the surrounding rock at some time in the distance past (at least 80 million years ago). The geothermal water source, 700 feet underground, is taken at 165 degrees F, below the boiling point of water 212 degrees F. A secondary fluid, R-134a, which has a lower boiling point is used to turn the turbines and generate electricity. The Hot Springs generate enough electricity for the entire complex, and could easily export electricity if it were connected to an energy grid. The Chena geothermal power plant came online in late July 2006, putting Alaska squarely on the map for new geothermal technologies. Chena Hot Springs is the lowest temperature geothermal resource to be used for commercial power production in the world. The cost of power production, even in semi-remote locations such as Chena is about 7¢ per kWh.

The power plant itself is the heart of a much larger project. In order to operate the plant, we need to pump 500+gpm of geothermal water from our production well, which is located 3/4 of a mile from the power plant. We do this via an insulated and buried 8inch line. The production well itself took almost a month to complete. It is a 10in diameter 700ft well, cemented and cased to 450ft. After the water goes through the power plant, they need to reinject the water back into the reservoir in order to maintain the resource. Fortunately, the injection wells are located within 300ft of the power plant building, and our wells are highly permeable. That means they are capable of ‘drinking’ a lot of water. Injecting this water in the right place at the right depth is the most critical component of the project, to assure long-term viability of the project. The cooling water used to supply the power plant condensers is also extremely critical. In fact, without the good cold water resource we have available the power generation project might not be viable for our low geothermal temperatures. The 1500gpm of cold water is supplied by a well 2700ft distant and 33ft uphill from the power plant. A 16in diameter insulated steel pipeline delivers the cooling water to the power plant. Because of the natural ‘drop’ of the land along this pipeline route, we are able to siphon the water out of the well and deliver it to the power plant without using a pump.

For visitors the Chena Hot Springs offers several pools for bathing, a nice restaurant, cabins to stay in, various activities. The Aurora Ice Museum features indoor ice sculptures available for viewing even in the hot summer. The complex has some greenhouses that supply fresh produce year round. There are some exports to Fairbanks restaurants.

Commentary

The Chena Hot Springs are privately owned and must be viewed as the most successful geothermal energy project in the North. Not only have the Hot Springs won many awards for energy innovation, but the Hot Springs has blended tourism activity, energy conservation so well.  It is definitely worth a visit if you are in the Fairbanks area.

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