I know I'm treading into new territory, but has anyone ran across publications, papers or possible designs to generate steam (and plenty of it) utilizing geothermal heat sources?
What little I know about geothermal energy is that scaling and corrosion are usually the biggest problems, so often there is a heat exchanger system to produce clean steam. But here are information resources:
International Geothermal Association
The world's largest geothermal operation is The Geysers, about 100 miles north of San Francisco in the Mayacamas Mountains. Calpine owns 19 plants at The Geysers, each one producing renewable "green" power.