EVERYDAY SCIENCE

Detailed explanation-1: -True. An example of an internal combustion engine is a diesel engine. Some of the energy generated as heat by a heating system is wasted.

Detailed explanation-2: -More often than not, that heat gets thrown away, dribbling out into the atmosphere. The scale of this invisible garbage is huge: About 70 percent of all the energy produced by humanity gets chucked as waste heat.

Detailed explanation-3: -Scientists know that energy always changes from high to low quality when work is performed. During the change, some energy is lost in the form of heat, which cannot do work. The amount of energy lost as heat is often as high as 90 percent of the total energy involved.

Detailed explanation-4: -It is estimated that between 20 to 50% of industrial energy input is lost as waste heat in the form of hot exhaust gases, cooling water, and heat lost from hot equipment surfaces and heated products.

Detailed explanation-5: -A heat engine can never have perfect efficiency, according to the second law of thermodynamics, therefore a heat engine will always produce a surplus of low-temperature heat. This is commonly referred to as waste heat or “secondary heat", or “low-grade heat".