Life-cycle assessment of diesel, natural gas and hydrogen fuel cell bus transportation systems

Abstract

Abstract:The Sustainable Transport Energy Program (STEP) is an initiative of the Government of Western Australia, exploring hydrogen fuel cell technology as an alternative to the existing diesel and natural gas public transit infrastructure. This project includes three buses manufactured by DaimlerChrysler with Ballard fuel cell engines, operating in regular service alongside the existing natural gas and diesel bus fleets.The Life Cycle Assessment (LCA) of the Perth fuel cell bus trial determines the overall environmental footprint and energy demand by studying all phases of the complete 2 transportation system, including the hydrogen infrastructure, bus manufacturing, operation, and end-of-life disposal. LCA's of the existing diesel and natural gas transportation systems are developed in parallel.The findings show that the Perth fuel cell bus trial is competitive with the diesel and natural gas bus systems in terms of global warming potential, and eutrophication. Emissions that contribute to acidification and photochemical ozone are greater for the fuel cell buses.Scenario analysis quantifies the improvements that can be expected in future generations of fuel cell vehicles, and found a reduction of greater than 50% is achievable in the greenhouse gas, photochemical ozone creation, and primary energy demand impact categories.

Accelerating hydrogen implementation by mass production of a hydrogen bus chassis

“…The curb weight of the STEP EcoBuses is 30% greater than the conventional diesel buses on the road in Perth, and 21% greater than the CNG buses [37].…”

“…The Life Cycle Assessment (LCA) of bus transportation has shown that fuel economy is a key parameter governing the emissions profile and primary energy demand over the entire lifecycle of the vehicle [7]. Figure 3 shows the relative efficiency for various modes of transportation, based on data collected from the Public Transport Authority in Perth, Australia [8], the Sustainable Transport Energy Programme (STEP) fuel cell (FC) EcoBus trial [9], and industry expectations for a next-generation FC vehicle [10][11][12][13][14].…”

“…As discussed in Section 1, the efficiency of the vehicle is of paramount importance as fuel consumption dominates the lifecycle emissions profile [37].…”

Life Cycle GHG of NG-Based Fuel and Electric Vehicle in China

“…Comparing CNG and diesel light duty vehicles, Weiss et al [24,25] have done an LCA study showing higher efficiency and reduction of CO 2 emissions for CNG compared to gasoline. Some previous studies on comparative LCAs of heavy duty CNG and diesel vehicles were focused on transit buses [26][27][28][29]. Among them, Karman [27] found significant reductions of CO 2 emissions for vehicles in the city of Beijing, China, when switching to CNG, but stressed the importance of locale-specific data for an LCA, while Ally and Pryor [26] stated that a CNG bus can emit a little more than a diesel bus in Australia's real situation.…”

Fuels for the future

“…On the other hand, the use of H 2 in fuel cells to generate electricity or (electric) traction is relatively energy efficient if compared with the use of conventional fossil fuels (Blok 2005, Osman andRies 2007). The net effect thereof is that, with present technology, the well-to-wheel global warming potential of hydrogen produced by steam reforming of methane is roughly similar to diesel fuel, though such hydrogen does worse concerning emissions contributing to acidification and photochemical ozone (Ally and Pryor 2007). The production of hydrogen by the use of hydropower leads to much lower life cycle emissions than in the case of steam reformed methane (Koroneos et al 2004).…”