low temp geothermal
Last week, Scott Kane and I delivered a wind turbine that is going to be installed at the Rocky Mountain Oilfield Testing Center (RMOTC). This is a federal facility that falls under the Department of Energy. All types of prototype techniques and facilities are tested here, and Scott and I had the opportunity to check out one of the latest installations. It is a low-temperature geothermal electricity generation facility.
When oil is removed from the ground, large quantities of water frequently come with it. In addition, that water can be quite warm. Nearby this facility is a well that produces 30,000 barrels per day (if my memory is good) of water that is 180-190 degrees F.
This water is not hot enough to be steam on it’s own and turn a turbine for electricity generation. However, the water is hot enough to boil a fluid with a lower boiling point, in this case this fluid is isopentane. The boiled isopentane is at a high enough temperature and pressure to turn the 250 kW turbine in this installation. The isopentane is then condensed back into a liquid through the cooling towers, and the loop continues.
The facility is operating above expectations already, and the hot water flow must be controlled so as not to overwhelm the generator. Particularly, at night, the isopentane is cooled to a lower temperature than during the day, so even more energy is available with the phase change to a gas. Not a bad problem to have, as long as you have the generator to keep up with it. These are the types of operational realities that can be learned through testing like this.
There are many sources of “low-temperature” geothermal waters like this around the world. This type of geothermal electricity generation could be a significant piece of the energy pie in the future.
Tags: geothermal