Video on Geothermal Energy
As an ongoing part of our series in which we introduce the basics of renewable energy to young people and newcomers to the subject, here’s a short video I made recently on geothermal. Here I talk about the fundamentals, and present the various strengths and weaknesses of geothermal as a component of our energy mix. I hope you enjoy it.
[youtube http://www.youtube.com/watch?v=VYIKdGoQihE]
Geothermal heat, where readily and economically available, works very well to heat buildings. However, when used to generate electricity, the efficiency is not much greater than 10%. Therefore, the turbines have to be considerably larger than turbines for conventional steam generating plants and that greatly increases the capitol costs. Also, because of the low efficiency, considerably more cooling water is required to generate electricity with geothermal heat. That can be a problem in areas where water is scarce.
To keep the turbines from being excessively large, geothermal heat has been used to boil hydrocarbons, such as pentane, which in turn is used to drive turbines. That works because pentane condenses at a much higher pressure than steam and the higher pressure makes it possible to use smaller turbines which cost less.
It certainly makes sense, where it is available, to use geothermal energy to heat buildings. In fact, where readily available, it has been used for that since ancient times.
A nice video!
Geothermal energy is created far below the earth’s surface, in the form of hot molten rock or magna, being generated by the action of decaying radioactive materials such as uranium.
Traditionally, Water was used as a method of conducted the heat/energy to the turbine. However, thank to the team at the University of Technology, Sydney Australia, this may be able to be extracted using graphene heat exchangers.
This would see a huge increase in efficiency at may locations.
Chevron, (yes Chevron Oil!,) are at the forefront of developing this technology.