Hydrogen is very attractive as an alternative to fossil fuels, as it can be combined with oxygen in a fuel cell to produce electrical energy, heat and water. Unlike burning fossil fuels, there is no carbon dioxide, carbon monoxide, oxides of nitrogen or sulphur, or particulates.

If the hydrogen is electrolysed from water using electricity that has been generated using a ‘clean’ source – such as wind, wave, tidal or solar energy – then it is very environmentally-friendly.

The fuel cell concept has existed since the mid-nineteenth century but it was only in the second half of the twentieth century that fuel cell research led to units being produced commercially, albeit in small numbers. Now, with record oil prices and concerns over global warming, fuel cell development has reached a point where there are units available for a variety of applications, from automobiles to lighthouses (see panel).

Given the prevalence of automobiles, their combined fuel consumption and their contribution to global warming, it is only to be expected that a substantial amount of research is being undertaken into hydrogen fuel cells for automotive applications. Honda was the first carmaker to put a fuel cell car on the road with regular customers, delivering the Honda FCX to fleet users in the USA and Japan in 2002. The company has now unveiled a fuel cell vehicle that delivers superior environmental performance and is said to be fun to drive, known as the FCX Clarity, which is due to be available in the summer of 2008. Startup and acceleration times are claimed to be comparable to those of a similarly sized car with a 2.4-litre internal combustion engine.

Honda's engineers set out to design a car with components optimised to give an enjoyable driving experience. One result of this was the V Flow Honda FC Stack, which is a lightweight, compact, high-output fuel cell stack. Compared to the 2005 FCX stack design, the V Flow FC Stack features an entirely new cell structure that achieves a higher output of 100 kW, smaller size and lower weight, with a 50 per cent improvement in output per unit volume volume, and a 67 per cent increase in output per unit mass. Because the new stack uses a vertical flow of hydrogen and oxygen instead of the more conventional horizontal flow, water drains away more easily, power generation is more stable and the stack's size and weight are reduced. Another feature of the stack is wave-shaped flow channels that improve hydrogen and air diffusion, thereby helping to improve the electricity generation performance.

To complement the hydrogen fuel cell stack and provide additional power for acceleration, the FCX Clarity has a compact, high-efficiency lithium ion battery to store electricity from regenerative braking.

The engineers also made the fuel cell system, drive motor, hydrogen storage and other powertrain components more compact, and took advantage of the fuel cell vehicle's layout possibilities to create a revolutionary new platform with a low centre of gravity for sporty, stable driving performance. The fuel cell stack is housed in the central tunnel, the battery is under the rear seat and the hydrogen fuel tank is located between the rear wheels.

Automotive fuel cells

Daimler AG is also investing heavily in fuel cell vehicles. In November 2007 the company announced that it was taking a 50.1 per cent stake in the Automotive Fuel Cell Co-operation, a company founded specifically for developing fuel cell applications in the automotive sector. The two other companies involved are Ford Motor Company and Ballard Power Systems. Dr Thomas Weber, the member of the board of management of Daimler AG with responsibility for group research, as well as for development within Mercedes-Benz Cars, stated: “At Daimler, we have identified the future fields of activity and key technologies for zero-emission mobility, and we invest specifically in expanding our competencies in these fields. Our majority stake in Automotive Fuel Cell Co-operation is the next consequent step in this direction.”

Professor Dr Herbert Kohler, vice president with responsibility for advanced vehicle and powertrain engineering within group research as well as being the chief environmental officer of the Daimler Group, added: “With the newly founded company, we pursue the aim of strengthening our leading position in fuel cell development and going full steam ahead in our preparations for the large-scale production of fuel cell cars.”

Following successful low-temperature trials held in Sweden using a fuel cell-powered Mercedes-Benz B-Class, the company reports that it is, indeed, on target to commence small-series production of the B-Class F-Cell model in early 2010.
 
Honda and Daimler are two of the world's mainstream automotive manufacturers that are taking hydrogen power seriously, and there are plenty of others too – such as BMW, Ford, General Motors, Peugeot Citroën and Volkswagen. But hydrogen fuel cell technology is not restricted to just major manufacturers. OSCar Automotive, which is owned by RiverSimple, has initiated two collaborative projects involving industry and academia to demonstrate the viability of hydrogen fuel cell cars using currently available technology. These projects are delivering two concept cars: LIFECar, a hydrogen fuel cell sports car developed with the Morgan Car Company, Linde and QinetiQ; and Hyrban, a lightweight city car. Both projects involve research teams at Cranfield and Oxford Universities. The LIFECar prototype was unveiled at the Geneva Motor Show in March 2008 and RiverSimple's Hyrban city car is due to be revealed in the autumn of 2008.

RiverSimple says the LIFECar (lightweight integrated fuel-efficient car) summarises the company's three key design principles: whole-system design, energy efficiency and resource minimisation. Hugo Spowers, the founder of OSCar Automotive and managing partner at RiverSimple, sought to demonstrate with the LIFECar project that significant gains in fuel efficiency could be achieved with readily available technology - though the state of the art is advancing rapidly (see panel). In order for this project to take place, and with the support of the Morgan Motor Company, he formed the LIFECar consortium with Cranfield University, Linde, Oxford University and QinetiQ; together they received financial support from BERR (the UK Government's Department for Enterprise, Business and Regulatory Reform) for the project that had a budget of less than £2million (around US$3.9 million or €2.5 million).

The LIFECar combines a hydrogen fuel cell with a bank of ultracapacitors – rather than batteries – such that cruise and acceleration requirements are decoupled and resolved in a highly optimised fashion. By combining these technologies with a lightweight structure, the LIFECar is intended to achieve a combination of performance, cost-effectiveness and fuel efficiency.

Traditional and modern materials

To keep the weight down to the target of 650kg, the LIFECar’s design uses technologies that Morgan currently employs in its Aero 8, including bonded aluminium and laminated wood. For the hydrogen fuel tank, carbon fibre is wound around a drum.

Oxford University undertook the design of the electric motors, which are reported to be 92–94 per cent efficient across their operating range. Four motors are used, all mounted inboard to minimise the unsprung weight and help to improve the car's ride and handling. Drive to each wheel is via a small gearbox.

Crucial to the success of the vehicle will be the PEM (polymer electrolyte membrane) fuel cell stack, and this has been provided by QinetiQ to meet the specific needs of the LIFECar. Consisting of four 6 kW sub-stacks, the complete fuel cell achieves a quoted efficiency of 45 per cent. Furthermore, the regenerative brakes are said to enable up to 50 per cent of the kinetic energy to be converted to electricity, whereas the norm for regenerative braking is typically around 10 per cent. Cranfield University developed the management systems for the vehicle, fuel cell, ultracapacitors, motor/generators and hydraulic brakes - which are employed at low speeds.

Hydrogen fuel cells clearly offer a number of potential advantages over conventional internal combustion engines burning fossil fuels, but there remains the issue of refuelling unless onboard hydrogen generation (sometimes called hydrogen-on-demand) is employed. For the LIFECar project, Linde provided the hydrogen refuelling expertise.

Another company with experience in hydrogen refuelling is Air Products. In April 2008 Air Products commissioned a Series 100 fuelling station at the University of Birmingham’s Department of Chemical Engineering, where research projects are being carried out to ascertain the viability of hydrogen in transport applications. Engineers from the University will be comparing five hydrogen-powered vehicles with the University’s own fleet of petrol, diesel and pure electric vehicles so that they can learn more about their efficiency and performance. The researchers will determine how these vehicles need to be adapted in order to make hydrogen an attractive and cost-effective option as a future fuel. Five Microcabs have been purchased for the purposes of the research; these weigh 500 kg, have a maximum speed of 64 km/h (40 mph) and a range of approximately 160 km (100 miles).

As a direct result of this research it is hoped that the public sector will start to buy into these new technologies, providing support to companies in the supply chain that are moving from the technology demonstration phase into the early stages of commercialisation.
 
The Series 100 station has been specially designed by Air Products to meet the fuelling needs of the first hydrogen vehicles to appear on the roads. It comprises an integrated compression, hydrogen storage and dispensing system, and is optimised to fuel up to approximately six vehicles per day. The hydrogen, supplied by Green Gases, is produced by ‘green’ means, resulting in a considerable reduction in greenhouse gas emissions when compared with conventionally produced hydrogen.

As a realistic alternative to other fuels, hydrogen is certainly making progress. Nevertheless, there is still plenty of scope to improve fuel cell technology, and substantial investment is required for the infrastructure to produce and distribute hydrogen. But given the advances witnessed in the last few years, the future is looking bright and expectations are being raised.

The world’s first hydrogen fuel cell lighthouse

South Gare lighthouse is located at the mouth of the River Tees, in the North of England, near the entrance to one of the busiest ports in the UK. Although this can be an exposed and harsh environment, a team from the Centre for Process Innovation (CPI), based at Wilton on Teesside, has developed a suitable fuel cell to power the light and fog signalling system.

CPI has worked with PD Ports, which owns and operates Teesport, marine engineering company Pelangi, which maintain the lighthouse and its systems, Schunk, which manufactures fuel cell stacks, and Air Products, a producer of hydrogen and hydrogen energy applications.

The hydrogen fuel cell is housed in a cabinet attached to the lighthouse and has been powering the South Gare light, which can be seen from 25 miles out to sea, for several months.

Nigel Perry, CPI's chief executive, said: “The use of the fuel cell at South Gare is a big step forward, as we have had to develop a special unit to withstand this demanding location. Fuel cells have the potential to be an important component of our future energy supply, along with the likes of tidal/wave, wind and solar powers, nuclear and some fossil fuels, though we know these have a finite lifespan. We have proved at South Gare that fuel cells can operate in critical applications”

Andrew Ridley, conservancy operations manager for PD Ports, added: “Over a number of years PD Ports has championed the use of renewable energy sources to power its aids for navigation. These include solar, wind and wave power, and have been primarily used to operate our navigation buoys, which are subject to the unpredictable forces of the North Sea.

“The implementation of a hydrogen fuel cell to power the South Gare lighthouse demonstrates how such new and innovative energy sources can be used to power critical safety aids in a hostile environment whilst delivering both environmental and economic benefits.”

Mark Pearson, energy and process innovation manager at One NorthEast, said: “The successful development of this fuel cell is excellent. It's a world first and the knock-on effect for the energy sector as a whole could be massive.

Fuel cell stacks assembled from modules

Having already demonstrated the efficiency of its innovative FC- 42/HLC stack concept in several different applications, Schunk launched a new generation of compact and versatile modular fuel cell stacks at the 2008 Hannover Fair. The heat extraction system allows the use of ordinary tap water containing antifreeze agents, or air-cooled stacks can be supplied on request.

Schunk's standard stacks are able to match the power requirements of many applications by connecting electrically identical single units to deliver up to 1.4 kW in steps of 360 W. The ability to use the stack family in various applications assists the effort to produce large quantities at an early stage.

Besides the technological and commercial advantages of the modular stack, Schunk says that customers will appreciate the reliability of supply and the fact that fully assembled and tested stacks are delivered from a single source.