Interest in fuel cells for road transport developed with the rise in environmental concerns around transport in the 1980s and 1990s. Most of the major vehicle manufacturers have produced prototype FCVs; in addition, new companies have emerged that specialize in the manufacture of fuel cell systems. One such company is Ballard Power Systems, which in the 1990s collaborated with DaimlerChrysler and Ford to make the world's first fuel cell bus and the demonstration NECAR (New Electric Car).
A large number of prototypes and demonstration cars have been developed in the last 20 years. Recent examples of near-production vehicles include the Honda FCX Clarity, the Toyota FCHV-adv and the Mercedes-Benz F-Cell. Altogether, these various demonstration FCVs have driven around 3 million kilometres in trials.
Several car manufacturers have announced plans to introduce a production model of a fuel cell car from 2015, but there have been previous announcements of a similar kind, with launch dates being subsequently postponed. Policy assumptions are that FCVs will not be widely available until around 2025–2030. There remain several issues to address, including the following:
The last point is crucial and raises doubts as to whether hydrogen fuel cell cars are a viable route to low-carbon transport. For example, if you started with a renewable source of energy such as biogas, this could be compressed and directly used in a CNG or CNG/electric hybrid car. To be used in an FCV, the gas would have to be processed (reformed or used to power electrolysis) into hydrogen, compressed and pumped into a tank for fuelling a car. There are energy losses at each stage and in storage. Thus although the energy efficiency in use in an FCV is better than in an ICE or hybrid car, the overall energy loss is greater.
Work out the energy losses for the following fuel supply chains from renewable fuel to powering an engine.
Take a starting index of 1.0 and assume the following:
The energy efficiency chains are as follows.
Renewable electricity (1.0) → hydrogen by electrolysis (1.0 × 65% = 0.65) → hydrogen to car (0.65 × 90% = 0.59) → fuel cell (0.59 × 45% = 0.26) → electric power to drivetrain (0.26)
Energy loss: 74%
Biogas (1.0) → electricity (1.0 × 60% = 0.60) → hydrogen by electrolysis (0.60 × 65% = 0.39) → hydrogen to car (0.39 × 90% = 0.35) → fuel cell (0.35 × 45% = 0.16) → electric power to drivetrain (0.16)
Energy loss: 84%
Biogas (1.0) → ICE vehicle (1.0 × 30% = 0.30) → power to drivetrain (0.30)
Energy loss: 70%
Biogas (1.0) → ICE hybrid vehicle (1.0 × 35% = 0.35) → power to drivetrain (0.35)
Energy loss: 65%
The long fuel conversion chains result in serious energy losses, with 70–85% of the energy being lost. This supports the case for renewable fuels to be used as directly as possible.
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