Reader Mike e-mails :

Here’s geothermal’s Dirty Little Secret: It’s filthy. That isn’t pure water that comes up from Mother Gaia. It’s full of sulfur and other minerals that quickly attack and destroy pipes and equipment. The physical plant requires constant maintenance and replacement. If you filter the stuff out you are left with a pile of corrosive chemicals and toxic heavy metals that qualify as an EPA supersite. Wells are abandoned and redrilled constantly as the pipes corrode.