Assessment of Hydrogen and LNG buses adoption as sustainable alternatives to diesel fuel buses in public transportation: Applications to Italian perspective

¹ Department of Mechanical and Aerospace Engineering –DIMA- Sapienza University of Rome Via Eudossiana, 18 - 00184 Roma, ITALY
² Department of Mechanical and Aerospace Engineering –DIMA- Sapienza University of Rome Via Eudossiana, 18 - 00184 Roma, ITALY
³ Department of Mechanical and Aerospace Engineering –DIMA- Sapienza University of Rome Via Eudossiana, 18 - 00184 Roma, ITALY
⁴ Department of Mechanical and Aerospace Engineering –DIMA- Sapienza University of Rome Via Eudossiana, 18 - 00184 Roma, ITALY
⁵ Department of Mechanical and Aerospace Engineering –DIMA- Sapienza University of Rome Via Eudossiana, 18 - 00184 Roma, ITALY

^* Corresponding author: michelevincenzo.migliaresecaputi@uniroma1.it

Abstract

This work deals with a technical and economical comparison between hydrogen and liquid natural gas (LNG) fueled buses with reference to the standard solution based on diesel fuel internal combustion engines. The level of service is evaluated considering the number of buses replaced and the average kilometers traveled each year for two levels. The economical comparison is made using the Total Cost of Ownership (TCO) method considering capital and operating costs. The costs of LNG and Diesel (at the pump in Italian market) are estimated with reference to the year 2020. Furthermore, an assessment of greenhouse gas emissions will be carried out starting from energy needs, adopting a “cradle to grave” approach, thus evaluating emissions from the well to the tank and from the tank to the wheel. The results show that the operating costs (0.778 €/km) of LNG solution are lower than the Diesel ones (1.072 €/km), while the hydrogen buses can become competitive in the next few .The production of hydrogen with water electrolysis considering the current electricity costs of the Italian market is expensive and involves a cost to the hydrogen pump 7,60 €/kg which makes the operating cost of the hydrogen solution is equal to about 1.420 €/km which makes this solution uncompetitive. It is also important to underline that the cost of green hydrogen production from water electrolysis strongly depends on the cost of electricity. The Life Cicle Analisis (LCA) analysis shows strong environmental benefits of the hydrogen solution in terms of CO_2eq if the hydrogen is produced by electrolysis using renewable energy sources. In the other cases, the advantage of using hydrogen is not very strong as it is associated with the use of fossil fuels that release climate-altering substances.