Closed-Loop System Using Waste Heat for Electricity

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OPEN 2012
New Haven, Connecticut
Project Term:
04/24/2013 - 12/31/2015

Critical Need:

There is a critical need to increase the efficiency of existing power generation technologies. One approach is to capture waste heat for use in separate power generation systems. Because this waste heat is unavoidable in traditional power generation, it can be considered a renewable energy source. Systems that generate energy from waste heat could dramatically increase the amount of power generated at a given location simply by making full use of the existing conditions rather than adding a new fuel source.

Project Innovation + Advantages:

Yale University is developing a system to generate electricity using low-temperature waste heat from power plants, industrial facilities, and geothermal wells. Low-temperature waste heat is a vast, mostly untapped potential energy source. Yale’s closed loop system begins with waste heat as an input. This waste heat will separate an input salt water stream into two output streams, one with high salt concentration and one with low salt concentration. In the next stage, the high and low concentration salt streams will be recombined. Mixing these streams releases energy which can then be captured. The mixed saltwater stream is then sent back to the waste heat source, allowing the process to begin again. Yale’s system for generating electricity from low-temperature waste heat could considerably increase the efficiency of power generation systems.

Potential Impact:

If successful, Yale’s closed loop system would create a low-cost energy efficient system for power generation from low-temperature waste heat.


Greater use of thermal fuels would reduce U.S. reliance on fossil fuels, strengthening America's energy security.


Thermal fuel technologies have zero net greenhouse gas emissions and can also reduce fossil fuel consumption, helping curb production of carbon dioxide emissions that contribute to global climate change.


Finding cost-effective ways to store and use thermal energy could create a profitable thermal fuels industry that spurs economic growth and creates cost savings for consumers.


ARPA-E Program Director:
Dr. Jason Rugolo
Project Contact:
Prof. Menachem Elimelech
Press and General Inquiries Email:
Project Contact Email:


Ormat Technologies, Inc.
Colorado School of Mines

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