An international group of scientists has developed a material that can turn wasted heat into electricity with unprecedented efficiency, a discovery that may one day allow for more efficient cars and buildings. The finding was reported this week in the journal Nature.
The material is crucial to creating devices called thermoelectric generators, which are designed to create an electrical charge when a difference in temperature exists across them. When such a difference exists, electrons move from one side to the other and a voltage is created which can be captured and used as electricity.
Thermoelectric generators are commonly used in space. The Mars rover Curiosity, for example, has as its electricity source a thermoelectric generator that is powered by heat produced by the radioactive isotope plutonium-238 dioxide. When the radioactive heat arrives at just one end of the generator, electricity is generated, powering the rover for as long as the heat can be produced.
There are many situations on Earth where such generators would be useful. Cars, for example, produce hot exhaust; if that heat could be captured before it flies out the tailpipe, cars could re-use that energy and become more efficient. Similarly, many buildings—especially factories and restaurants, which are constantly spewing excess heat—could become more efficient if their heat waste was put to good use.
The problem has been that thermoelectric generators themselves have not been particularly efficient, retaining less than 10% of the energy from heat, and have been difficult to mass-produce. The new report presents a method to get around both issues by using an optimized version of lead telluride—a compound of lead and tellurium—that doubles the efficiency over previous thermoelectric uses.
There are still hurdles to overcome before we start applying this technology to reuse our heat waste. Most importantly, lead telluride is toxic, meaning that any commercial uses would have to find a different material.
