The sorted plastic is used to produce plastic-derived fuel oil through a plastic pyrolysis process . This technology is the reverse controlled reaction to the plastic synthesis process and its principle is that the chain of plastic polymer will be broken into a number of small gaseous carbohydrate molecules by heating under anaerobic conditions, The gases are condensed into liquid by cooling. After the separation of gaseous and liquid fuel, gas is recycled for heating, liquid is further purified, and becomes renewable plastic-derived fuel oil which is a clean alternative energy source.