Synthetic Fuels by a Limited CO2Emission Process Which Uses Both Fossil and Solar Energy

Abstract

A new process combining fossil fuels and solar energy to obtain synthetic liquid fuels from coal and natural gas is investigated. The aim of the work is to develop a hybrid process for the production of liquid fuels, where fossil fuels are used as feedstock and solar energy as heat source. Gasification of coal and steam reforming of natural gas have been coupled, examined, and simulated with respect to material and energy balances. The technical feasibility of the process is discussed in two different cases: a plant located in Italy (Sicily) and one in the USA (Texas). A comparison in terms of CO2 emissions is performed among the processes presently proposed, a gas to liquid (GTL) process, a coal to liquid (CTL) process, and another hybrid configuration coupling GTL and CTL, called the modified CTL process. It is shown that the CO2 produced per unit weight of liquid fuel is the minimum among all the alternatives considered, except for the GTL one, where the value is comparable. Also, the thermal efficiency of the hybrid process is shown to be higher than those of the other cases examined, i.e., 67% more than the CTL one. The total mirrors area needed for case 1 (Italy) is 5.70 km2 and 3.37 km2 for case 2 (USA), for a production of 100 t/h of liquid fuels.