Advanced Low-Temperature Geothermal Technology
Clean Technology 2008

Advanced Low-Temperature Geothermal Technology

D. Thomas
Trimodal Group, US

power generation, geothermal, low temperature, rankine

Trimodal has developed a revolutionary new highly efficient engine design which is our (LTPC) Engine-expander, which is a positive displacement, compounded, Organic Rankine Cycle expander operating on a binary system. The prime energy sources are non-steam temperature geothermal brines, and industrially sourced waste heat. A major benefit of this technology is that it causes no scaling which is a huge maintenance issues in both geothermal and waste heat recovery. The LTPC system can operate efficiently with temperatures as low as 150F, which is the key to opening low cost, renewable power markets globally. The LTPC engine efficiency obtained is in the area of 55% compared to 25% to 35% efficiency for a turbine using comparable steam. The secondary working fluid is a proprietary organic fluid with a very low boiling point. As an example, 2/3 of the energy of a coal fired power plant goes up the stacks and cooling towers. We can use our engine and their power output can be increased by at least 50% by splicing the LTPC array into their waste heat stream and converting this copious supply of low grade heat to electrical power. When utilized as the prime mover (engine, replacing steam turbines) coupled to the same generating and boiler infrastructure, the Trimodal system will reduce coal consumption and Carbon emissions by a comparable 50% for the same electrical output.