It is all too easy for a motorist enjoying a smooth drive along a good mad to forget that the mad and the vehicles that use it are far from harmless to the environment. In November 1989 the Council of Ministers of the European Conference6 of Ministers of Transport (ECMT) adopted a Resolution incorporating a wide range of recommendations designed to curb the impact of transport on the environment. The recommendations are exacting and constitute a major challenge for the nineties.
Transportation unquestionably contributes to the greenhouse effect by producing carbon dioxide (C[O.sub.2]) - 675 million tons in 1990 in the member countries of the Organization for Economic Co-operation and Development (OECD) - methane (C[H.sub.4]), ozone precursors such as hydrocarbons (HCs) and nitrous oxide ([N.sub.2]O), as well as chlorofluorocarbons (CFCs), tropospheric ozone ([O.sub.3], from 0 to 15 km above the earth) and water vapour. These gases are emitted from fossil fuel combustion within the manufacture, operation and disposal of transport systems and from the production and processing of fossil fuels. Vehicles, especially private cars, contribute 25% of the overall C[O.sub.2] emissions in most western European countries.
Greenhouse gas emissions are not the only forms of air pollution caused by road transport. Diesel engines (mainly lorries) emit oxides of nitrogen (NOx), sulphur dioxide (S[O.sub.2]) and microscopic particles (especially of carbon) that cause visible exhaust fumes and soil buildings. Sulphur dioxide and nitric oxide react in the atmosphere with water to form sulphuric acid and nitric acid, which can turn soil and lakes acidic and eat away at building stone. They may travel long distances in the atmosphere. Gases emitted by one country often cause acid damage in another.
THE CARLESS MAJORITY
Motorvehicle production has experienced spectacular growth since the end of the Second World War, rising from about 10 million vehicles per year in 1950 to 50 million in 1990. Today there are more than 675 million vehicles worldwide (including two-wheelers). Outside the OECD countries, however, most of the world's inhabitants do not use motor transport. The countries of Africa, Asia (excluding Japan) and Latin America contain more than four-fifths of the world's population, but only one-fifth of motor-vehicle registrations. However, the number of vehicles per head has grown by 20% worldwide over the past ten years.
As Laurie Michaelis of the International Energy Agency (IEA) noted in a report presented at a seminar on Transport Policy and Global Warming organized by ECMT in 1992, "It would be technically possible, by reducing car size and performance, to reduce the energy consumption, and hence greenhouse gas emissions, of petrol cars by a factor of three. However the resulting vehicles would not achieve much market share under current market conditions. Without compromising marketable vehicle characteristics, vehicle energy efficiency is unlikely to improve by much more than 10% before 2005." In fact the commercial success of a car, based on power, speed, size, security and comfort, is usually at odds with the goals of reducing energy consumption.
In his report Laurie Michaelis makes a comparative analysis of the advantages and disadvantages of the different kinds of fuel and the environmental effects of their production and consumption. Diesel emits 15% more C[O.sub.2] than petrol. Although the image of diesel-powered vehicles as dirty, noisy and heavy is fading, their number is restricted because they cost more to buy. Liquid petroleum gases (LPG) include propane and butane. Vehicles that run on LPG have a greenhouse gas emission rate 20% less than that of petrol vehicles. The major drawback of LPG is that supplies are limited, since it constitutes only about 5% of refinery output.
Compressed natural-gas engines emit little C[O.sub.2] but a lot of methane, which makes them less enticing. …