No energy conservation system is 100% effective; alas, there is always some energy that gets wasted. One common example is the automobile engine which gets quite hot. Some of the waste gets recovered by heating the car for instance.
With the completion of a functioning prototype, engineers at Oregon State University made a major step toward addressing one of the leading problems in energy use around the world today; the waste of half or more of the energy that is produced by cars, factories and power plants. New technology is being developed by the university to capture and use the low-to-medium grade waste heat which is now going out of the exhaust pipe of thousands of diesel generators, millions of automobiles and being wasted by factories and electrical utilities. These new systems, currently getting perfected at the university should be able to use much of this waste heat in either cooling or the production of electricity.
Waste heat is sometimes called secondary heat or low-grade heat can refer to heat that is produced by machines, electrical equipment and industrial processes for which no useful application may be found.
Energy is often produced by a heat engine, running on a source of high-temperature heat. According to the second law of thermodynamics, a heat engine may never have perfect efficiency. Waste heat is regarded as a waste by-product of this process.
More than half of the heat generated by industrial activities is now wasted and even very advanced electrical power plants only convert some forty percent of the energy produced into electricity. For example it is common practice to estimate in engineering that only seventy percent of the usable fuel energy is applied to the industrial engine. The internal combustion engines of automobiles are even worse — they operate around 25-40% conversion efficiency.