Preamble

In the earlier lectures we have discussed the role of energy balance on fuel saving and hence on conservation of natural resources. Energy balance is a very powerful tool to address the issues of saving natural resources.

What can be done more beyond fuel savings? Let us think.

Facts about use of natural energy resources
Fossil fuel based energy availability is associated with

a) Discharge of  in the environment and other harmful gases like  etc. 1 kg mole of carbon discharges 1 kg mole of  in the environment. In other words 1 kg carbon produces  3.7 kg .

b) Large amount of heat is carried away by the products of combustion. In metal extraction processes at high temperatures, products like liquid metal, slag, gases and coke carry a large fraction of heat. Sensible heat is the issue of concern.In this connection it is important to understand quality of heat. Quality of heat is decided by the temperature. Higher is the temperature of discharged product, higher is the quality of heat.

Sensible heat in products:  

In thermo –mechanical processing, steel is heated to . Steel is rolled at this temperature and then cooled by water. Large amounts of emissions are discharged.

In coke making coke is discharged at around  and water cooled. Large amount of sensible heat is lost and as well as emission arising from water contaminants are discharged into atmosphere. Environmental pollution is a concern.

Sensible heat in waste gas may not be possible to use since waste gases contain fine solid particles. However potential energy can be utilized.