Process engineering is the engineering science of physical, chemical and biological material conversion with special attention to economy and sustainability. Petroleum to gasoline, plastics and many other products; Coal, oil, gas, wind and renewable raw materials for energy; Milk to yogurt; Hops, malt and water to beer; Potatoes and cereals to alcohol; Removal of pollutants from water, exhaust gas and soil are just a few examples of such material conversion processes.