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Report 2 of 5:
Hydrogen
Cars/Clean Dreams - Germany
Introduction
The vast majority of transport systems in use around the world depend, either directly or indirectly, on the burning of fossil fuels which are not replaceable and will eventually run out. Burning fossil fuels is also very bad for the environment because pollution is created in the form of "greenhouse" gases and other atmospheric wastes. As the world's population grows, the increasing demand for mobility adds to these problems and it is becoming ever more important that alternatives to the damaging use of fossil fuels are found. One of the most serious pollutants resulting from the use of conventional road vehicles is the gas carbon dioxide - CO2. In fact, any process which burns organic materials, such as wood, coal, oil or gas, will result in the formation of CO2.
In order to protect the world's climate, CO2 emissions must be reduced around the world and one way to achieve this could be by using hydrogen as a replacement for fossil fuels. Hydrogen is a 'clean' fuel because it produces virtually no pollution whatsoever.
© Ludwig-Bölkow-Systemtechnik: The hydrogen bus
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Hydrogen power
Hydrogen is an element with the lightest and simplest atom of all. It is a gas under normal conditions and it is the least dense of all substances. However, it has a very high energy content in relation to its weight, its 'energy density' being three times that of petrol. It is also very abundant as it is one of the constituents of water, the other being oxygen. When it is burned in air, the only waste product is water.
There are many ways of producing hydrogen but the most promising one from an environmental point of view is by using renewable energies, such as solar, wind or water power, to generate electricity which can then be used to break down water into hydrogen and oxygen. The oxygen can be safely released into the atmosphere and the hydrogen stored for use as a fuel.
Solar energy is seen as the most likely source of hydrogen production in areas where there are high levels of sunshine on a regular basis. The amount of energy falling on the earth from the sun every day is enormous. For example, in just 70 minutes, the solar radiation reaching the earth is equivalent to the energy needs of the world for a whole year. If it proves practical to harness enough of this energy to generate hydrogen fuel, the world will be assured of an almost limitless source of energy - forever.
Hydrogen as a fuel
There are two main ways in which the use of hydrogen as a fuel is being explored. Most research over many years has concentrated on devices called Fuel Cells. However, it is also possible to burn hydrogen in an internal-combustion engine in much the same way as petrol is burned.
Fuel cells
A fuel cell is a device which makes it possible to bring hydrogen atoms into contact with oxygen from the air in such a way that electricity is produced as the two combine to make water in vapour form. The amount of electricity generated in a single cell is quite small but many cells can be stacked together to make up a power unit for any particular application. One of the types of cell best suited to driving vehicles is called the polymer electrolyte membrane cell which operates at about 80ºC and converts about 60 percent of the energy contained in the gas.
© MAN: The fuel cell
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The hydrogen bus
Several companies have come together in Germany to pool their expertise in the 'Hydrogen bus' development programme. The project, which is co-ordinated by Ludwig-Bölkow Systemtechnik and supported by the Bavarian Ministry of Transport, uses a MAN bus powered by Siemens AG fuel cells, while the hydrogen fuelling system comes from Linde AG.
The new fuel cell assembly from Siemens provides a total of 120 kW of electrical energy to power the bus. The rear wheels of the bus are driven directly by two electric motors without the need for a gearchange mechanism. The fuel cells produce direct current, so an inverter is necessary to convert it to alternating current. The inverter also provides a convenient method of controlling engine power.
The hydrogen fuel is stored in the form of compressed gas in pressurised containers built into the bus roof. There are 9 gas cylinders, together holding over 1500 litres of hydrogen fuel, enough to drive the bus for about 250 km.
Internal combustion engines
© BMW: Cross-section through the cylinder head of a bi-fuel engine: intake manifold (left); gasoline injection valve (top); hydrogen injection valve (bottom). |
The German car company, BMW, is concentrating on another approach to the use of hydrogen fuel. Since it has many years’ experience in the development and production of internal combustion engines, its development programme is based on its 750iL saloon car. Modifications to the cylinder head allow the engine to burn either petrol or hydrogen and, on the present prototypes, it is possible to change from one fuel to the other at the flick of a switch.
© BMW: Fully automated hydrogen refuelling |
The company expects the final version of the car, which will be fuelled by hydrogen alone, to have a performance very similar to the present petrol models but with the great advantage of having zero CO2 emissions. The exhaust gases will consist of air and water vapour. A number of hydrogen-fuelled 7-series BMW cars are currently in use in the district around Munich airport, providing a chauffeuring service between the airport and the city centre. An essential feature of the development programme is an automated refuelling station situated at the airport. The system is automated in order to provide maximum safety to the filling operation.
For further information, please contact:
ITDG would like to thank Ludwig-Bölkow-Systemtechnik GmbH for providing the original material on the hydrogen bus and fuel cells.
This document is an output from a project funded by the UK Department for International Development (DFID) for the benefit of developing countries. The views expressed are not necessarily those of the DFID.
Further reading available from ITDG Development Bookshop
Electric Vehicles: With Aspects on Developing Countries
M Eisenring
This publication comprises five parts. The first section deals with the history of electric vehicles, the possibilities and the limits of electric vehicles, their usage and potential market, legal regulations, conditions for electric vehicles in developing countries and solar powered vehicles. The second chapter reviews EV technology, power and energy calculations, vehicle conception, batteries, battery charging and drive systems. The focus in the third chapter is on activities and the market situation in the industrialised world and in developing countries. EV energy consumption, environmental impacts and lifecycle economics are studied in the fourth chapter. The final chapter presents future prospects of the development of electric vehicles.
£12.95 1998 PB SKAT ISBN 3908001838
From the Fryer to the Fuel Tank: The Complete Guide to Using Vegetable Oil as an Alternative
Joshua Tickell
As pollution envelops the world’s cities, temperatures on planet Earth rise, and once rich oil fields run dry, researchers scramble to find solutions to the impending transportation crisis. But the fuel of the future may be hidden places nobody thought to look. In From the Fryer to the Fuel Tank, expert Joshua Tickell unveils the problems with our fossil fuel economy and offers a surprisingly simple solution: cheap, clean-burning vegetable oil. This book provides concise, easy to understand instructions for running a Diesel engine on vegetable oil. Packed with photos, graphs and diagrams, it contains all the information you need to become independent of fossil fuels forever.
£19.95 2000 PB TEC ISBN 0970722702
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