Hydrogen Fuel Cell Bus Technology State of the ... - NEXTHYLIGHTS

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Hydrogen Fuel Cell Bus Technology State of the Art Review Battery Hybrid Fuel Cell Hybrid Diesel Trolley Table 11 - Conclusions In order to be accepted as an alternative solution to diesel buses, battery buses have to: Increase battery energy density (at least by 5 or 10 times) Reduce weight Achieve far better recharging times (by 10 times) These targets are unlikely to be achieved in the next 10 years, according to the most up-to-date studies of sector 12 . For example, the maximum energy density ever achievable by battery is capped to 0.2kWh/kg by engineering constraints. In addition, it is worth noting that large automotive battery packs have still to prove outstanding safety records and that another challenge of the technology is its high capital costs. Hybrid fuel cell buses are closer to satisfying the transit agencies needs than battery buses. The technology requires very little change in the behavioural requirements of transit operators. In particular the technology offers similar performance to existing diesel fleet in terms of safety, range and refuelling time. The absence of commercial hydrogen infrastructure need not be a showstopper to the deployment of fuel cell buses, since refuelling facilities are typically purchased by transit operators as part of the decision to make a fuel cell bus deployment. The technology, however, must achieve: Substantially lower capital costs A higher availability in hybrid mode Lower fuel cost Improved fuelling logistics Hybrid diesel buses are currently the lowest cost environmental alternative to diesel buses, proving lower environmental impacts and similar economic performance (on TCO basis). The technology, however, does not offer a zero emission option. There are still improvements to be made in the cost of diesel hybrid drivetrains. Trolley buses are able to provide a low-zero carbon transportation. Due to the high cost of the overhead contact wire network (approx. €500,000 – 1,000,000 per kilometre, including substations), this technology is currently deployed only in short inner city routes. 12 See for example: Battery for Electric Cars, Challenges, Opportunities and the Outlook to 2020, Boston Consulting Group, January 2010. 58
Hydrogen Fuel Cell Bus Technology State of the Art Review 6.1 Total Cost of Ownership So far we have compared the technical performance of hybrid fuel cell buses with alternative technologies. In practice, however, transit operators compare different options through Total Cost of Ownership (TCO) models. We developed a TCO model for hybrid fuel cell buses and for three of the alternative technologies discussed above: diesel, Hybrid diesel and Trolley buses. Battery buses have not been considered due to lack of data on the actual cost of recharging facilities. The TCO model considers 9 elements: Bus financing and depreciation Overhead Contact Wire Network financing (for trolley buses) Fuel cost Taxes on Fuel Propulsion related replacement costs 13 Bus maintenance fee 14 Extra maintenance facility costs 15 Overhead Contact Wire Network maintenance (for trolley buses) CO2 price (e.g. existence of a carbon pricing system in the transport sector) The output of the model is a yearly cost per km travelled per bus (e.g. € / km / bus). We consider for all the bus technologies a discount period of 12 years, a discount rate of 3.5% 16 and an annual mileage of 70,000km (which is representative of a heavy use urban transit route). The fuel cost has been modelled using capital and maintenance cost assumptions from equipment providers, and hence is scalable with the hydrogen demand at the bus depot (larger depots use more fuel and hence reduce the effect of capital and maintenance costs). The input data for the TCO analysis are based on the information collected from interviewees as well as bus operators in the Hydrogen Bus Alliance members. The 13 The propulsion replacement cost for fuel cell buses is the cost for refurbishing the fuel cell unit at the end of its life (assumed to be at the end of the warranty). We assume this cost is 65% of the cost of an equivalent new unit between 2010 and 2015 and 40% of it by 2020 (cost reduction is foreseen to come from improved stacks’ manufacturing processes). 14 The maintenance fee for hybrid fuel cell, hybrid diesel and trolley buses includes the maintenance cost of the hybrid-electric / electric drivetrain. 15 Because hydrogen is generally treated as a hazardous chemical in most of the European regulations and standards, maintenance facilities for hydrogen-fuelled bus must be adapted (or constructed) in order to meet all the safety criteria. 16 We assume that investors (e.g. bus operators) can access public funds or financial schemes and hence benefit from low discount rates for financing bus projects. 3.5% is a typical figure within the European Union. 59
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Hydrogen Fuel Cell Bus Technology State of the ... - NEXTHYLIGHTS

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