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Fuel cell hybrid taxi

Partners: Intelligent Energy, Lotus Engineering, LTI Vehicles, TRW Conekt

It may look like just another black cab, but this Hackney carriage could soon become a vital part of reducing emissions in our city centres.

Developed by a consortium including Intelligent Energy, Lotus Engineering, LTI Vehicles, TRW Conekt, the fuel cell hybrid black cab is set to make its debut in London within the next two years and has already gained international recognition for its innovative design.

‘We’ve taken a product that is core to London and really transformed it into something of the future,’ said Ashley Kells, senior programme manager for Intelligent Energy. ‘If we want zero-emissions taxis in our cities, then a battery vehicle alone won’t be able to achieve that because it can’t provide the range and refueling time and a standard hybrid can’t achieve that because it has diesel particulates.’

The solution they have come up with is cab which is powered by a hydrogen fuel cell system hybridised with lithium polymer batteries. A 100kW, 550Nm peak permanent magnet brushless motor drives the rear wheel, which is fed by a high-voltage supply from the two systems.  The cab is capable of reaching 80 mph, refuels in less than five minutes, has a range of over 250 miles on a full tank and produces no emission other than water vapour.

Intelligent Energy developed, tested and helped to integrate its proprietary fuel cell system. The design works in the same way as a conventional fuel cell systems by generating energy through reactions between hydrogen and air.

The innovation, however, is in the way the heat is managed by a patented cooling technique which injects water directly into the fuel cell stack. The heat causes most of the water to evaporate, leaving a mix of saturated air and some liquid water. This mixture is passed through a heat exchanger which reduces its temperature to 20 degrees Celsius ready to be reintroduced back into the fuel cell.

The process removes the need for an external cooling loop and humidifier. ‘What you’re left with is a fuel cell system which is zero emissions, light weight, easy to manufacturer, lower cost, smaller and because it has less parts, far more robust,’ said Kells. ‘What that means in this application is that we can use an existing vehicle to really get some benefits and make a difference in a relatively short time frame.’

Lotus Engineering has led on packaging the fuel cell hybrid electric propulsion system and designing control systems to optimise its performance. TRW Conekt conducted the safety analysis programme, including braking and steering systems, while London Taxis International (LTI) provided donor vehicles to assist with the structural modifications of the chassis. Two taxi’s have so far been constructed and have together having completed  2,000 miles on the track.

‘We’re now hoping to get some road testing done and our target is around 10,000 miles for these two vehicles,’ said Kells. ‘The next phase will be the manufacturing of around 20 vehicles. We’ve looked at LTI to do the manufacturer for this and it’s actually more simple that you would think…a diesel cab itself is constructed largely by hand so to pull the vehicle to one side and put the fuel cell in rather than the engine is a relatively straight forward task. Lotus is working with LTI to transition that build expertise.’

The black cab was first showcased at London’s City Hall in June this year. London’s deputy mayor for Policing and Chair of the London Hydrogen Partnership, Kit Malthouse, who unveiled the taxi, said: ‘The black cab is a much loved London icon, but it is also a significant source of pollution especially in the centre of the city. This prototype fuel cell black cab, which emits only water from its tailpipe, is an exciting glimpse of how hydrogen technology could soon play a vital role in cleaning up air quality for urban dwellers.’

London’s 22,000 Black cabs are estimated to be responsible for about a third of the particulate pollution in the capital, with the city’s air quality amongst the worse in Europe. Boris Johnson has this year committed to the deployment of a hydrogen refueling infrastructure, with a long-term goal for the entire London taxi fleet to be zero emissions by 2020. The consortium is planning the introduction of commercial fleets of zero emission fuel cell hybrid taxis primarily for London by 2012 and for other cities by 2014.

The group has received just under £5.5m by the Technology Strategy and together with the Greater London Authority (GLA) has put an application into the EU to receive further development funding. They have also commissioned an independent study into the advantages of a fuel cell taxi, particularly the emissions produced during production.

‘When you look at that side of things, emissions are around the third of the diesel equivalent,’ explained Kells. ‘There are some things, like the batteries, that need a little bit more energy than the diesel engine to make. But the fuel-cell itself is actually very cheap and easy to construct, and it works out at just less than 30 per cent overall impact on the environment, so that’s pretty huge.’

With an acceleration of 0-60mph fully loaded in 15.5 seconds and a range comparable to a conventional cab, it is hoped that fuel cell hybrid taxi will be a viable transport solution for London. Beyond this, the consortium claims that the powertrain technologies and expertise developed throughout the programme will be immediately transferable to other automotive applications.

Kells said: ‘London is leading this project as the showcase city for other countries. But you look at places like Shanghai and Beijing and you see that there is a real potential to export it to other countries, which could have a huge benefit to the UK economy. We think taxis are only a small part of it because the same power train can be used in any vehicle. It’s already had a great reception, and I expect it will have an even better one in 2012 when the world’s focus is on London for the Olympics.’

By developed the fuel cell black cabs and proving how clean and reliable fuel cell technology is, the Intelligent Energy-led consortium has demonstrated that the future of clean transport is viable and is not just a novelty. While the Beijing’s Olympics gave us the Bird’s Nest, the London Olympic Games may have a more lasting legacy in being the Games that provided a platform to launch clean technologies.

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