It has been estimated that between 2000 and 2025 the world population will grow from 6 to 8.5 billion (42% increase). Most of this growth will be in developing countries, where there is huge unfulfilled demand for private cars. On this basis, the Fiat Motor Corporation has projected that over the same period the global fleet will increase from 0.7 to 1.75 billion. If this demand is to be met, it will be necessary to conserve liquid fuels for transportation and there will be a requirement for vehicles that are much more fuel-efficient than at present. Also, there will be a need to exploit non-traditional sources of fossil fuel, as discussed in Section 1.4, Chapter 1. Of course, such predictions of the increase in vehicle numbers neither take account of whether the Earth’s atmosphere can absorb the carbon dioxide, nor of the outcome of the Kyoto Protocol negotiations.
For a new technology to succeed in the marketplace, it must not only be sound and appeal to the customers, but must also be backed by major industrial muscle and finance. The Japanese have demonstrated this point well with motorcycles, cameras, and consumer electronics. Given the sizable effort that many automotive companies are now putting into electromechanical and electric drive-trains, there are good prospects that hybrid electric vehicles (HEVs) and perhaps even fuel-cell vehicles (FCVs) (see Sections 10.4 and 10.5, Chapter 10) will become commonplace throughout the world by 2020. This should make a significant contribution to energy savings in the transportation sector and will assist in the reduction of emissions of carbon dioxide and other harmful gases.
Aside from technical advances in the design of vehicles to enhance fuel efficiency, the greatest single improvement would be achieved by substituting public transport (mass transit) for private cars, particularly for travel into the city. Already in major conurbations (London, New York, Tokyo) more people travel to work by bus and rail than by private car. As public transport facilities continue to improve around the world, and as cities become even more grid-locked with traffic, it is likely that this trend will increase.
London has short-term plans to purchase 200 more buses and longer-term plans to upgrade its underground system. A congestion charge has already been imposed on motorists coming into the central business district; other UK municipalities are actively contemplating similar action. Many urban communities across the world have introduced ‘bus lanes’ to give priority to these vehicles. These lanes, in conjunction with ‘park and ride’ schemes, facilitate access to city centers. Some authorities also give priority of passage to cars with more than one occupant; this encourages ‘car pooling’, and thereby saves fuel. Finally, with the construction of safe routes, more people are returning to cycling. The Scandinavian countries and the Netherlands have set good examples in this regard. All these are moves in the right direction to remove traffic jams, make cities more accessible, and reduce both fuel consumption and urban pollution. For Europe, this is a move back towards the 1940s and 1950s when the population was only a little less than it is today, when most people went to work by public transport or by cycle, and there were comparatively few cars so that roads were less congested.
The extent to which the motorcar can be replaced by public transport in the short term is generally limited by the distribution of the population. For many, it is impossible to get to work by bus or train, and often this is through conscious choices that they have made, either in where they have bought a house or taken employment. In recent years, people have been willing to drive long distances to work rather than move home or job. Indeed, compared with having a congenial place to live and a desirable occupation, commuting by car has assumed secondary importance for many individuals. At the same time, developments in electronic communications will mean that more people can work from home, at least for part of the time, and not have to travel daily. In large cities, the choice is clear: either private cars are excluded from city centers, or admission fees are imposed at a sufficiently high rate to dissuade drivers from using their cars. Both approaches depend upon the existence of acceptable ‘park and ride’ schemes. The alternative is gridlock – when, ultimately, many commuters will give up driving in disgust or engage in political protest.
In the field of car design, we foresee a movement away from advertising peak performance to that of fuel economy. This view is based on the assumption that petroleum prices will rise significantly in real terms over the next 20 years. There is also the prospect of an increasing proportion of diesel-engined vehicles on the road, because of their greater fuel economy, and of vehicles fueled by liquefied petroleum gas (LPG), because of their cleaner exhaust (and, at present, the lower tax in some countries). The move towards diesel engines will be given a further stimulus when viable particulate traps have been perfected for cars, as well as for buses and trucks. It will be interesting to see whether the USA follows Europe in marketing diesel-engined cars and light-goods vehicles. This is only likely if petroleum prices in the USA rise nearer to European levels and, thereby, provide the incentive to make the shift. At present, the desire in the USA and elsewhere for sports utility vehicles poses a particular problem of heavy fuel consumption. Hopefully, the popularity of these vehicles will decline as petrol prices climb so that ‘gas-guzzling’ vehicles will become comparatively few in number.
As discussed above, another probable development in road transportation will be the widespread introduction of the HEV, and maybe also the battery electric vehicle (BEV) for urban use. The HEV will permit smaller and more efficient engines to be fitted without any reduction in vehicle performance. The BEV may not save much primary energy, but will effect a switch from petroleum to electricity, which can be generated from different primary fuels. It is envisaged that
by 2020 many private cars will have some form of electromechanical (HEV) or battery (BEV) drive. By that time, most family-sized cars should return at least 60-80 mi per gallon of fuel (3.5^4.7 L per 100 km). These developments will be driven not only by considerations of fuel economy, but also by local authorities choosing to follow the pattern of Southern California (see Section 10.2, Chapter 10) and introducing regulations to reduce urban pollution.
The future for FCVs is still very much open to question. There are difficult technical problems to be solved, but progress has been made by the major automotive companies who are now taking the concept of the hydrogen FCV seriously. The principal challenges remaining are those of reducing cost to an acceptable level, ensuring reliability and lifetime, deciding which fuel is to be used and whether an on-board reformer is required. If a reformer is necessary, then it has to be well integrated with the fuel cell (for good thermal management and for producing hydrogen at the required variable rate), small, and inexpensive. Should hydrogen be employed directly, then there is the question of on-board storage to be resolved, as well as the establishment of a supply infrastructure. There is also the cold-start problem and the need to eliminate impurities from the hydrogen. On the whole, we are inclined to be pessimistic about the rate of developing this technology for private cars, as a competitor to diesels and HEVs, and therefore do not expect to see a major swing to fuel-cell cars by 2020. Even so, one must recognize the dedication of many major automotive companies to the technology, and the power and influence they can bring to bear on the topic. It is possible that they may prove our pessimism to be unwarranted. If FCVs are indeed introduced in significant numbers during this period, it is more likely that they will be buses or trucks, where space to accommodate the power plant and the hydrogen store is not so restricted, and where generally longer journeys are involved.
In principle, the hybrid concept is equally applicable to railway locomotives. By having an electric hybrid locomotive, it would be possible to fit a smaller and more efficient engine that would run at constant speed and release less pollution. The problem here is that locomotives have a much longer service-life than cars so that it will take years to replace the existing stock, even after the concept has been proved in practice.
In the field of air transport, the recent trend towards quieter aircraft with lower fuel consumption will doubtless continue. There are plans to build even larger passenger aircraft than at present, with a view to reducing the operating cost per seat-kilometer. How enthusiastically the public would take to such behemoths of the skies remains to be seen.