Hydrogen fuel cells: from automotive power to distributed generation

21st February 2013

Fuel cell power systems, often primarily associated with the automotive sector, actually represent a practical, highly efficient and reduced carbon emissions power source for a wide range of applications and markets. Jon Moore reports.

Beyond the transportation sector, hydrogen fuel cell power systems are being targeted at aerospace and portable electronics applications and are already making in-roads into the back-up power and distributed generation sectors. The promise of products running efficiently on hydrogen while emitting no pollution at the point of use is clearly an attractive one.

Intelligent Energy is at the forefront of fuel cell system development and implementation. In 2005 it unveiled the world's first hydrogen fuel cell motorcycle - the ENV - and more recently the Crosscage fuel cell motorcycle in collaboration with the Suzuki Motor Corporation.

Two-wheeled, powered vehicles are largely responsible for high levels of urban pollution yet have escaped public scrutiny to date. This situation is certain to change as accountability for emissions grows.

Fuel cell hybrid cars are currently under development at many of the world's leading automotive companies, combining batteries and fuel cells together in the vehicle powertrain. These are complementary technologies, often with batteries providing acceleration and enabling the use of regenerative braking and fuel cells providing cruising power while recharging the batteries.

Electric vehicles

The advantages of these hybrids over battery-only electric vehicles (BEVs) are that of range and refuelling/recharging time. BEVs have low range and need many hours of recharging, while vehicles utilising fuel cells have ranges of several hundred miles, refuelling in minutes - more akin to today's combustion engine-powered cars. In September 2009, nine of the leading motor manufacturers signed an unprecedented agreement stating their intention to commercialise fuel cell powered vehicles and expectation of for their availability to consumers by 2015. If you thought the automotive future was just battery powered, then the likes of Toyota, Honda, Daimler, Ford, GM, Nissan, Renault, Hyundai and Kia all appear to hold a different view.

Intelligent Energy is presently leading a programme to produce zero emission Black London Cabs. This programme is part-funded by the UK Government's Technology Strategy Board, with partners Lotus Engineering, LTI (London Taxis International) and TRW Conekt. The aim is to see a small fleet of the vehicles in operation in London by 2012.

The taxis will have a driving range of around 250 miles, sufficient for a full working day's operation, and able to out perform the standard vehicles in terms of acceleration. The first of these cabs will be on the test track in early 2010.

Greener Aviation

In the realm of aviation and aerospace, Intelligent Energy provided the hydrogen fuel cell system to Boeing that powered the world's first manned fuel cell aircraft in early 2008.

The Proton Exchange Membrane (PEM) fuel cell system of the Boeing-Intelligent Energy project was incorporated into the engine-bay space of a two-seat Dimona motor-glider with a 16.3metre wingspan, replacing the internal combustion engine.

The system was hybridised with lithium-ion batteries to power an electric motor coupled to a conventional propeller. The battery provided the peak power required to achieve lift-off, while the fuel cell took over entirely to power the aircraft in steady flight.

Certain characteristics of PEM fuel cell systems make them an ideal candidate as the power-train for unmanned air vehicles, they are very quiet and have low thermal and exhaust signatures. These can be important factors where stealth may be a consideration, such as in military or homeland security applications.

Electricity Production

Power distribution based on today's centralised grid structure results in poor efficiency and high emissions. Today, around 65 per cent of the fuel used by traditional coal burning power-generating plants is wasted due to a combination of inefficient energy conversion and power-line losses.

The energy sector itself is responsible for 40 per cent of global CO2 emissions, with electricity demand predicted to more than double by 2050. It is also estimated that $22 trillion of cumulative investment will be required in new plant and grid infrastructure to meet global demand for electricity by 2030 as existing electricity grids have little excess capacity.

Distributed generation (DG: on-site or close to point-of-use electricity production) is seen by many as the best means of meeting much of this increased power demand while simultaneously improving efficiency, reducing emissions, and reducing the burden on the existing grid. DG systems can also be designed to provide electricity back to the grid, reducing the need for additional central generation infrastructure.

Distributed generation

Fuel cell systems are emerging as one of the main contenders for market share in DG, serving a range of power demands from watts to megawatts. They are being targeted in particular as CHP units for residential and industrial heating and electrical needs. CHP allows the maximum utilisation of the energy content of the fuel (for example natural gas) by using both thermal and electrical outputs (heat and power).

A conventional power generation plant is approximately 35 per cent efficient - the balance is released as 'waste' heat.

CHP substantially reduces this loss by making use of the heat produced for the chosen application - industrial, commercial or residential. In this way up to about 90 per cent of the energy can be utilised.

Without a doubt, a number of factors have converged to result in the present opportunities for fuel cell technology.

As yet, however, there is no 'silver bullet' solution. Indeed, a range of practical, efficient and economic technologies will be required, as will an education process for both industry and consumers markets. Nevertheless, fuel cells are poised to play an important role in the ever-evolving energy landscape.

Jon Moore is with Intelligent Energy, Loughborough, Leicestershire, UK.




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