Today, about half the energy produced by cars, factories, and power plants is wasted as heat that escapes into the atmosphere.

Engineers from Oregon State University have made a major step towards addressing one of the most common wastes of energy today by recapturing some of the heat generated by a motor and using that energy to produce power. The engineers have successfully completed a prototype machine that can be attached to the exhaust pipe of automobiles, diesel generators, factory, and utility machinery that produces waste heat. The prototype system is being perfected at the university right now.

"This could become a very important new energy source and way to improve energy efficiency," said Hailei Wang, a research associate in the School of Mechanical, Industrial and Manufacturing Engineering at OSU. "The prototype shows that these systems work as well as we expected they would."

The researcher says that over half the heat generated by industrial activities is currently wasted. Even the most efficient plants according to Wang only convert about 40% of the energy produced into electricity. Combustion engines inside vehicles are even less efficient converting only 25-40% of the energy they produce.

The system that the team in Oregon has produced is called the thermally activated cooling system. The system is able to combine a vapor compression cycle with an organic Rankine cycle, which is an existing conversion technology. Using the prototype, the team at the university was able to turn 80% of every kilowatt of waste heat into a kilowatt of cooling capability. However, the efficiency wouldn't be as high at about 15-20% efficiency if the goal was to produce electricity.

"This technology would be especially useful if there's a need to have cooling systems where heat is being wasted," Wang said. "That's one reason the research has been supported by the Department of Defense, because they see it being used to provide needed air conditioning for electronics and other purposes when they are using generators in the field."

The team is looking at the system to power air conditioning systems in a hybrid auto and recharge the batteries at the same time. German scientists have previously developed a system that is able to generate power from wasted heat that can be turned into electricity. Researchers at the ORNL have also worked on a system that captures the water that is in the exhaust from diesel engines to provide drinking water for soldiers in the field.