The current paper is an attempt to find a sustainable fuel strategy for passenger cars in Iran. Currently, most of Iran’s passenger cars consume gasoline, a non-renewable fossil fuel. This fuel has well-known environmental impacts, including various kinds of pollutions, as well as the threat of quick running out. These general negative characteristics of gasoline are amplified by the high consumption rate of Iran’s transportation sector, (e.g. about three times more than that of UK). The objective of this paper is firstly selecting possible Alternative fuels for Iran’s transportation sector, and then proposing the percent of cars consuming these Alternative fuels (along with gasoline). The best strategies are proposed based on environmental and economic considerations, and hence are more sustainable decisions comparing with the other strategies. The best strategies are found using partial order theory and Hasse diagram technique, which is a multi-criteria decision analysis (MCDA) tool.

Using of biomass for energy purpose in the path of sustainable energy supply and in response to increasing energy demand can be an effective solution. Biofuel reduces global warming impacts, which is today the main concern of the countries of the world by lowering greenhouse emissions and dependency of fossil fuels. Briquettes and pellets, as solid biofuels, are the most direct way of using energy from biological sources, because they only need a densification process instead of complex thermochemical and biochemical treatments. Densification process by applying pressure and temperature produces fuel briquettes and, which results in elastic and plastic deformations in biomass, increases density in biomass. Moreover energy density and durability in produced solid fuel increases. Creation of solid bridges between particle and mechanical interlocking, to density of its components, is a possible mechanism of particle bonding. Proximate and ultimate analyses can be used to measurement of intrinsic properties of particles such as ash content, volatile matter, fixed carbon, and heating value that can deeply affect on combustion process. Also, fuel briquettes and pellets are qualitatively measured with properties such as density, durability and calorific value. Combustion of solid fuels involves drying mass loss stages, devolatilization and combustion of char. The major problem of solid biofuels is the amount of ash in comparison with coal, which results in fouling and corrosion on equipment. However, different researches can focus on reducing ash problems.

In the present study, a computational fluid dynamics (CFD) method has been utilized to investigate the effects of exhaust gas recirculation (EGR) and initial charge pressure using a supercharger on the emissions and performance of a SI engine. This engine is fueled separately by gasoline and two potential Alternative fuels, hydrogen and ethanol. The results of simulation are compared to the experimental data. There is a good agreement among the results. The calculations are carried out for EGR ratios between 0% and 20% and four cases of initial pressure have been mentioned: Pin= 1, 1.2, 1.4, 1.6 bar. The effect of EGR on NOx emission of hydrogen is more than others while its effect on IMEP of hydrogen is less than others. From the viewpoints of emission and power, 10% of EGR seems to be the most desirable amount. The most noticeable effect of supercharging is on gasoline unlike hydrogen that seems to be affected the least. The comparison of results shows that hydrogen due to its high heating value and burning without producing any carbon-based compounds such as HC, CO and CO2 is an ideal Alternative fuel compared to other fuels.

The cement industry is one of the most energy and carbon-intensive industries. The energy and carbon reduction is an important issue in this industry. The present work considers the use of Alternative fuels in the cement kilns. The amounts of excess air, the location of fuel and air entrance, as well as the amount of produced gas stacks, are the main design and operational variables in the kilns. Comparative assessments of Alternative fuels (AF) are performed by the mass, energy, and exergy analysis of different regions in the kilns. The obtained results show that using Alternative fuels reduces the amounts of excess air and the exit temperature becomes closer to the ambient temperature. The Alternative fuels demonstrate lower energy and exergy loss inside the cement kiln by supplying the required energy for the clinker production. Their utilization in the current kiln reduces CO2 emissions. The results of the present work may be used for the optimal design and operation of cement kilns. This work provides an in-depth analysis of the material efficiency, main energy losses and the exergy destruction of the process.