narrower concept biological gas Concept biomass Concept calorific power Concept cold water Concept compressed air Concept cooling water Concept district heating Concept drinking water Concept environmental energy Concept fuel oil Concept gas Concept heat distribution medium Concept hot water Concept hot water Concept liquid gas Concept natural gas Concept oil Concept petroleum Concept raw(non-potable) water Concept terrestrial heat Concept water Concept water(non-potable) Concept