Fossils are dinosaurs
June 1st 2007

Finite sources, environmental pollution plus major security and reliability of supply issues mean use of fossil fuel as a primary source of energy is set to go the way of the dinosaur over the next few decades. Hydrogen is the future, says Linde's Michaela Dann

There is no doubt that hydrogen is the future as it can be used for powering combustion engines and or producing electricity via fuel cells.

A combustible, colourless gas, hydrogen is one of the lightest, most abundant elements in the universe. It occurs mainly in water and in most organic compounds methane, hence its huge potential as a future renewable energy source for everyday use to eliminate our dependence on fossil fuels. Hydrogen produced from water could be described as the ultimate 'green' fuel.

How is hydrogen produced? In simple terms, hydrogen can be produced from water by means of electrolytic separation, or from fossil energy carriers by means of chemical conversion processes such as 'steam reforming'.

Hydrogen fuel cells The hydrogen fuel cell has the potential to revolutionise power generation in all areas of modern society, from power stations, back-up power, power plants for buildings or portable power for items such as laptops, cell phones and portable generators. In fact, the fuel cell could power virtually any device, which today is powered by conventional batteries. There is the added benefit that fuel cells will provide power for up to three times as long as batteries before needing recharging (life span is approximately 5,000 hours although it is improving).

Commercially viable liquid hydrogen and hydrogen fuel cell technology would have a huge impact on road transport, which today is a major contributor to greenhouse gas emissions, alongside the heating of domestic homes. It has the potential to deliver all the benefits of a cleaner, safer global environment, and the technology is already well researched.

Hydrogen power is already a reality since it is estimated that over 50 million tonnes of hydrogen is produced annually. Liquid hydrogen has been used to fuel the American Apollo space shuttles since the 1960s. Hydrogen fuel cells provide the space shuttles with electricity, heat and drinking water, while several major car and bus manufacturers have prototype hydrogen fuel cell vehicles in regular use.

A single fuel cell will only produce a small amount of electricity (less than 1.16 volts) and to create a viable power pack, individual cells must be combined in a fuel cell 'stack', which may consist of several hundred cells.

There are several different types of fuel cell, but the one most commonly used in research with prototype road vehicles and forklifts is the proton or polymer exchange membrane (PEM).

A PEM fuel cell consists of a paper-thin membrane made from a solid organic compound, which functions as an electrolyte. The membrane conducts protons but not electrons. The membrane is sandwiched between an electrically negative anode catalyst and an electrically positive cathode catalyst, both of which are composed of platinum particles. This 'sandwich' is surrounded by 'flow plates', which are designed to channel hydrogen and oxygen to the anode and cathode catalysts and conduct the water and heat produced during the process away from the fuel cell.

A catalytic reaction occurs at the anode side causing hydrogen to be separated into protons and electrons. The positively charged protons then diffuse through the membrane to reach the cathode, which is bathed in oxygen. The negatively charged electrons are unable to pass through the membrane and in order to reach the cathode must flow around the membrane through an external circuit.

This flow forms an electrical current. At the cathode side of the membrane another catalytic reaction takes place as the protons and electrons reform and combine with oxygen to create water and heat, which is then dissipated or recycled.

Hydrogen highway infrastructure Some countries such as the USA and Japan are actively planning and developing the infrastructure necessary to create the hydrogen highway. It is estimated that it would only require an investment of 3.5 billion euros to build the necessary infrastructure across Europe by the year 2020.

The Austrian division of the Linde Group was involved in the opening of the first hydrogen refueling station in Perth, Australia, in 2004, and the world's largest public refuelling station opened in Berlin in November 2004 where, for the first time ever, liquid hydrogen supplied by Linde Gas is being offered alongside regular petrol and diesel services For mobile equipment applications, the Linde Group is involved in several projects with leading bus and passenger car manufacturers providing on-board liquid hydrogen tanks and systems, as well as being a cryogenic partner for several generations of research with BMW.

In fact, the first dual-fuel production car was announced this week in the UK press.

The BMW hydrogen 7 series uses climateneutral liquid hydrogen produced and supplied by Linde.

These projects demonstrate that hydrogen can function as an everyday fuel, thus paving the way for sustainable forms of transport in the future.

Research While hydrogen will no doubt be the dominant 'green' energy source of the future, there is worldwide a range of research and development programmes taking place covering the whole spectrum of alternative fuels – with both car and commercial vehicle manufacturers leading the way with hybrid fuel systems as well as hydrogen and biomass fuels.

There is no single solution and all the various 'green' energy sources and technologies will have an important part to play: There will be no 'big bang' as far as the introduction of alternative energy is concerned.

Renewable energy carriers will be developed and utilised in parallel with the current 'black' fossil fuel energy sources.

New technology will enable the blending of 'black' and 'green' sources to significantly reduce noxious emission levels and prolong the finite supply of fossil fuel sources because currently it requires 98 tonnes of prehistoric plant material to produce just four litres of petrol or diesel.

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