I recently read an article about a company that has a new twist on industrial geothermal power generation. Unlike standard geothermal power plants that are reliant on naturally occurring geothermal reservoirs, GreenFire Energy drills its own systems. Another benefit to this type of geothermal system is that it doesn’t involve water. Instead this technology sends supercritical carbon dioxide down into the earth to collect heat and then collects it on the other end of the closed loop.
Photo Credit: http://www.greenfireenergy.com/about-eco2g.html
This is an experimental technology, but if GreenFire can pull it off, it could revolutionize the geothermal industry. One huge limitation of current geothermal power plants is that they can only be located in certain areas around the world. These areas need to have the proper geology, a certain amount of heat, and ground water in the reservoir. With Supercritical carbon dioxide, there is a huge potential to increase geothermal power plants to much more of the earth’s surface.
Not having to use geothermal water gives this technology another advantage. Most geothermal water has a lot of dissolved minerals and salts in it. That is why it is often called brine. When you send this water through a plant and it either flashes into steam or it cools down in a heat exchanger, the dissolved minerals tend to come out of solution. This leads to scaling or fouling. All these minerals get coated on the plant equipment and hurt the plant efficiency. By just using carbon dioxide GreenFire will be able to completely avoid this headache.
I am optimistic about this technology but they are definitely going to face some challenges. The wells that this company is planning to drill are much deeper and much more costly than traditional geothermal wells. Assuming they can drill the wells and get the closed loop system completed, they will have very large up from capital costs. This will make expansion difficult. I will continue to follow this company and do a follow up post after they do their proof of concept.
If you know about any new interesting renewable technologies please let me know about them in the comments section.