when the first steam locomotive was made by Trevithick was only about 10 million tonnes .... internal combustion engine gave rise to the innovations which have ...
ENERGY FUTURES AND FUTURE TRANSPORT How can technological development contribute to solving the problems caused by petrol-fuelled vehicles?
PATRICK MASON Dissertation in partial fulfilment of the requirements for an MSc in Energy Studies December 1998
1
ACE 614
ENERGY FUTURES AND FUTURE TRANSPORT How can technological development contribute to solving the problems caused by petrol-fuelled vehicles?
Patrick Mason Dissertation in partial fulfilment of the requirements for an MSc in Energy Studies The University of Sheffield December 1998
CONTENTS Introduction
2
Chapter 1 A HISTORY OF TRANSPORT TECHNOLOGY AND ENERGY CONSUMPTION
4
Chapter 2 TRANSPORT AND ENERGY PROBLEMS
15
Chapter 3 TRANSPORT TECHNOLOGY
19
Chapter 4 TRANSPORT ENERGY FUTURES
30
Chapter 5 CONCLUSIONS
40
References
42
Appendix
44
2
Introduction The economic and technological developments of the past century have been vast and, for the most part, these have led to improved quality of life for a large proportion of the world’s population. The main factors which have enabled such development have been scientific advancements combined with the increased exploitation of the Earth’s resources. In the approach to the next century, there is growing concern about the sustainability of the world’s major economies and indeed, the global economy which is so dependant on non-sustainable resources. In particular, the use of the world’s fossil fuel energy resources has given additional issue for concern because of the climatic side-effects of carbon dioxide production. There has already been global recognition of this problem and a nominal response with international agreement to stabilise carbon dioxide emissions from many of the more developed countries.
A key feature of industrial and economic development is the requirement for movement of goods and people and the trading of goods and services requires a fast and economically efficient means of transport. In the last century, the world economy and in particular, western Europe, achieved great advances in economic output partly as a result of the development of the railways. During the course of this century, the railway has been succeeded by motor vehicles. The use of transport has continued to aid economic development to the point that the transport sector itself has become a major industry in itself and energy consumption in the transport sector now accounts for a third of the energy consumption in the UK. The transport sector is therefore caught in a dilemma. One the one hand it would appear to be an essential component of a functional economy and on the other hand, it is responsible for a significant proportion of the national energy demand and the environmental pollution associated with the consumption of that energy. The solution to this problem is likely to be through the application of technology. Technological development and innovation is recognised as the driving force behind economic development [Hall 1994] but it also has the potential to avoid or counteract some of the undesirable side-effects which result from economic growth.
This study will analyse the significance of developments in technology relating to the transport sector. Firstly, in chapter 1, the historical development of the transport sector in the UK and the relationship between transport activity, energy consumption and economic
3 growth will be examined. Chapter 2 will present data showing the current situation with respect to energy consumption and air pollution and a brief discussion of the associated problems will be given. An overview of the technology currently employed for road vehicles and the likely future viability of emerging technologies will be presented in chapter 3. The first three chapters will thus provide a background onto which a number of future scenarios can be projected.
The future effects that the introduction of new technologies will have on transport sector energy consumption will be explored in chapter 4. Historical data will be used to form a model for transport growth and transport energy consumption forecasts will be presented for a number of different technological scenarios. These scenarios will assume different rates of introduction of new energy efficient technology in order to show the importance of technological development to the future of transport energy consumption. In addition to a study of the possible future of transport energy consumption, some of the associated environmental and economic effects will be discussed including some of the possible beneficial effects that new technologies may have.
4
Chapter 1 A HISTORY OF TRANSPORT TECHNOLOGY AND ENERGY CONSUMPTION 1.1 ENERGY CONSUMPTION AND TRANSPORT IN THE UK, 1800 - 1933 Transport and communication are essential components in a functioning economy. In the pre-industrial world,
trade and the movement of goods was mainly by shipping and
communications and inland transport were restricted to the use of horses. The main centres of economic activity were therefore located in the major seaports. The early industrial revolution in the 18th century was characterised by large increases in the production of manufactured goods and a consequent increase in trade through international shipping. Inland transport of bulk goods was improved by the construction of inland waterways. However, without a faster, higher capacity means of moving inland goods and faster communications, the development of the industrial economy was still restricted. Then came the defining technological innovation of the nineteenth century; the railway. The railways transformed the rate of growth of the industrialised economies by not only removing the restrictions in speed and capacity in moving commodities such as coal and iron but also created a new market for such resources to build more railways. It was not until the development of the railways that the energy demand of both industry and transport really took off.
Figure 1 shows the production of coal in the UK since 1800. UK Coal production in 1804 when the first steam locomotive was made by Trevithick was only about 10 million tonnes per year [Statham 1951]. The first public railway from Darlington to Stockton opened in 1825 and rapid growth of the railway system followed. By the latter half of the 19th century UK coal production had risen to over 50 million tonnes per year and the railway network in the UK had grown to over 15,000 route-miles. By the end of the century, coal production had risen to over 200 million tonnes per year and 30,000 miles of railway were operating. The growth of the railways is illustrated in Figure 2 which shows the size of the network and the number of passenger journeys made each year since 1800. A strong correlation between the expansion of the railways, the increase in passenger journeys and national coal production (Figure 1) can be seen. The correlation is particularly striking in the period between 1840 and 1910 where the size and usage of the railways and the UK coal production all increased at a phenomenal rate. This reflects the significance of the transport system and energy supply to
5 the economic development of the last century when railways moved almost everything and coal fuelled almost everything. This railway/coal based economy reached a peak by the 1920s and figures 1 and 2 clearly show the levelling out and subsequent decline of coal production and railway use. It should not be inferred, however, that the transport sector was the main consumer of energy in this period. Since coal accounted for nearly all of the country’s primary energy supply up until the 1930s, an analysis of coal usage will give an indication of the significance of the transport sector energy consumption.
Table 1 - UK coal consumption 1913 - 1933 [Bone and Himus, 1936] millions of tonnes
Colliery Engines Gas Works Electrical Power Stations Railways Coasting Vessels Iron and Steel General Manufacture Domestic Purposes Total Home Consumption Exports Total Production
1913 18.0 16.7 4.9 13.2 1.9 31.4 47.7 40.0 173.8
1929 13.7 17.9 9.8 13.4 1.4 23.4 55.0 40.0 174.6
1933 11.6 16.7 10.3 11.7 1.2 13.1 44.3 40.0 148.9
97.7
81.8
55.6
271.5
256.4
204.5
Table 1 presents a breakdown of UK coal consumption in the first three decades of this century. It can be seen that less than 10% of this demand was used for transport (railways and waterways), roughly 50 to 60% was used in industry and 20 to 30% used for domestic purposes. Since coal was by far the dominant primary energy source in this period, an approximation of energy consumption in the industrial sector, transport sector and domestic sector and total energy consumption can be inferred from these coal consumption figures.
6
300
UK COAL PRODUCTION (million tonnes of oil equivalent)
250
200
150
100
50
2000
1990
1980
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1960
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1940
1930
1920
1910
1900
1890
1880
1870
1860
1850
1840
1830
1820
1810
1800
0
Year
Figure 1 - UK coal production since 1800 [Statham 1951 and DTI 1997]
35,000
3500
30,000
3000
25,000
2500
20,000
2000
15,000
1500
10,000
1000
5,000
500
0 1800
1820
1840
1860
1880
1900
1920
1940
1960
1980
0 2000
Year
Figure 2 - UK Railway route length and passenger journeys since 1800 [Gourvish 1980, Williams 1978 and Minby & Watson 1978]
PASSENGER-KILOMETRES TRAVELLED PER YEAR
TOTAL LENGTH OF RAILWAY ROUTE (km)
ROUTE LENGTH PASSENGER-KILOMETRES
7 1.2 ENERGY CONSUMPTION AND TRANSPORT IN THE UK, 1950 TO THE PRESENT DAY The invention of the steam railway was the technological breakthrough which gave impetus to the industrial growth and massive increase in energy consumption in the 19th century. By the turn of the century, another new technological innovation was introduced which was to change the pattern of energy consumption in the transport sector again. The petroleum fuelled internal combustion engine gave rise to the innovations which have characterised twentieth century transport: the motor car and the aeroplane. In 1885 Karl Benz built the first car powered by a single cylinder internal combustion engine. Less than two decades later, the Ford Motor Company was mass producing motor cars. By the 1920s, the motor car had begun to become a serious rival to the railway for passenger transport [Williams 1978]. The influence of this technology on UK energy consumption was as dramatic as the influence of railways a hundred years previously. The following analysis of energy consumption and transport in the UK will illustrate this.
Energy consumption is commonly divided into a number of major consumer groups, namely; manufacturing industry, transport, domestic (household) and commercial (including service industries and agriculture). Figure 3 shows total UK energy consumption and the energy consumption of each of the four main consumer groups between 1950 and 1995. The energy consumption of the transport sector is put into perspective with respect to total national energy consumption and the consumption of the other consumer sectors. Table 1 showed that in 1933, transport accounted for less than 10% of total national energy consumption. From Figure 3 it can be seen that by 1950, the transport sector’s share of the national energy demand had risen to 17%. By 1995, it’s share of the demand had risen further such that transport energy consumption accounted for 32% of the total. Energy consumption in the transport sector appears to be increasing at a faster rate than the other sectors. A more detailed analysis of the transport sector should provide some explanation of the reasons for the increase in transport sector energy consumption
8
160.00
140.00 Services & Other
UK ENERGY CONSUMPTION (Million tonnes of oil equivalent)
120.00 Domestic 100.00
80.00
Industry
60.00
40.00
20.00 Transport
1995
1993
1991
1989
1987
1985
1983
1981
1979
1977
1975
1973
1971
1969
1967
1965
1963
1961
1959
1957
1955
1950
0.00
Year
Figure 3 - Energy consumption in the four main consumer sectors and total UK energy consumption 1950 - 1995 [IEA 1996]
50.00
UK TRANSPORT SECTOR ENERGY CONSUMPTION (Million tonnes of oil equivalent)
45.00 40.00
35.00 30.00
25.00 Air
20.00 Waterways 15.00 Road 10.00 Rail
5.00
1995
1993
1991
1989
1987
1985
1983
1981
1979
1977
1975
1973
1971
1969
1967
1965
1963
1961
1959
1957
1955
1950
0.00
Year
Figure 4 - UK transport sector and sub-sector energy consumption 1950 - 1995 [IEA 1996]
9 Figure 4 shows transport sector energy consumption in the UK from 1950 to 1995. A number of developments in the transport sector can be inferred from this figure. The decline of rail transport energy consumption and the increase in road transport energy consumption between 1950 and 1970 is clear. This decline in rail energy consumption would appear to be mainly as a result of transfer of business away from railway transport to road transport which has now become by far the largest energy consuming transport sub-sector. However, the period between 1950 and 1970 also saw the replacement of steam locomotives with more energy efficient diesels which further reduced the railway’s energy demand. Perhaps the most significant point to note from this figure is that total transport sector energy consumption more than doubled between 1950 and 1995. This increase is almost entirely attributable to the increase in road transport, although an increase in air travel has also contributed to the increase. Road transport energy consumption is clearly responsible for the dramatic increase in transport sector energy consumption over this period. Indeed, energy consumption for road transport in this period increased more than five-fold such that by 1995 the total energy demand for road transport alone was double the total for all transport in 1950.
25
1,000 900
20
800 700
15
600 500
10
400 Billion passengerkilometers per year
300 Cars
5
200
Passenger-kilometres per year (billions)
Number of licenced vehicles in UK (millions)
Total Motor Vehicles
100
1995
1990
1985
1980
1975
1970
1965
1960
1955
1950
1945
1940
1935
1930
1925
1920
1915
1910
1905
0
1900
0
year
Figure 5 - Number of licensed road vehicles and number of passenger-kilometres travelled in the UK 1900 - 1995 [Williams 1978, Dept. of Transport, 1995]
10 Figure 5 shows the growth in the total number of motor vehicles in the UK and the number of passenger-kilometres travelled by road. The trend for passenger-kilometres travelled naturally correlates strongly with the increase in road transport energy consumption illustrated in Figure 4. The number of passenger-kilometres travelled in 1995 is 4.2 times the 1950 level and the number of licensed road vehicles in 1995 is 5.8 times the number in 1950. There is obviously a relationship between the number of cars and passenger-kilometres travelled. This relationship will be examined further in chapter 4 in the context of transport forecasting.
During the nineteenth century and the early twentieth century, the UK was almost entirely dependent on coal as a primary energy source. The latter half of the twentieth century has seen a decline in coal consumption in the UK with oil, natural gas and, to a lesser extent, nuclear energy making up for the overall increase in national energy consumption. Figure 6 shows the total UK primary energy supply along with the proportion of each fuel source between 1960 and 1995. It can be seen from this how the nation’s energy supply has been diversified as, in turn, oil, nuclear power and natural gas have been introduced into the energy market. This diversification has resulted from the development of new technologies which have enabled the different fuels to be economically competitive with each other.
250
Other Nuclear
Gas 150
Oil 100
50 Coal
Year
Figure 6 - UK primary energy supply and fuel source 1960 -1995 [IEA 1996]
1995
1994
1993
1992
1991
1990
1989
1988
1987
1986
1985
1984
1983
1982
1981
1980
1979
1978
1977
1976
1975
1974
1973
1972
1971
1970
1969
1968
1967
1966
1965
1964
1963
1962
1961
0 1960
UK PRIMARY ENERGY SUPPLY (million tonnes of oil equivalent)
200
11 Energy supply to the industrial, domestic and commercial sectors is mainly as electricity and natural gas and since electricity can be generated from any of the fossil fuels and from nuclear and renewable energy these sectors are not dependent on any one energy source. Indeed, for these sectors, the primary energy sources are more or less interchangeable and are able to be adapted depending on economic conditions. The transport sector, on the other hand has become almost entirely dependent on oil with 99% of the energy consumption for transport coming from petroleum [DTI 1997].
Figure 7 shows UK oil consumption between 1965 and 1995 along with the proportion of oil used for road transport. Since road transport almost exclusively uses petroleum/diesel as fuel and accounts for 80% of transport sector energy consumption, it is not unexpected that oil consumption for road transport matches the trend for transport sector energy consumption (as shown in Figure 4). However, the greater significance of this trend is not the absolute increase in oil consumption in transport, but the increased proportion of total oil consumption. Whereas other sectors have been able to diversify to other fuel sources, transport is still dependent on oil and its share of oil consumption has therefore risen to account for half of total consumption.
90
80
UK OIL CONSUMPTION (million tonnes of oil equivalent)
70
60
50
40
30
20 Oil consumed in road transport
10
1995
1994
1993
1992
1991
1990
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1981
1980
1979
1978
1977
1976
1975
1974
1973
1972
1971
1970
1969
1968
1967
1966
1965
0
Year
Figure 7 - UK oil consumption and oil consumption for road transport 1965 - 1995 [OECD, 1996]
12 1.3 WORLD ENERGY CONSUMPTION AND TRANSPORT As well as examining the details of the transport sector in the UK, a wider view of world trends in transport and energy consumption is useful to put the issues into perspective on the global scale and to put the UK situation into context. During the course of the twentieth century, world energy consumption has increased from about half a billion tonnes of oil equivalent to nearly 8 billion tonnes of oil equivalent [Smil 1994]. Over the same time, world population has increased from 1625 million to 5246 million. This represents a five fold increase in energy consumption in per capita terms. It has been shown in the case of the UK, where coal was the main energy source in the nineteenth century, that energy (coal) consumption, economic growth and the expansion of the transport sector were all interrelated. During the course of the twentieth century, the trend has continued but oil and gas have displaced coal as main energy sources and developments in transport technology have caused a shift from railways to road transport. This is also true on a global scale with a significant increase in energy consumption, and specifically, oil consumption accompanied by expansion of the transport sector in terms of infrastructure, vehicles and the associated consumption of fuel. Figure 8 shows the growth in the number of motor vehicles in the world.
800
Number of motor vehicles (millions)
700
600
500
400
300
200
100
1900
1920
1940
1960
1980
2000
Year
Figure 8 - Number of motor vehicles in the world since 1900 [Smil 1994] The profile of the graph is very similar to Figure 5 which showed the number of road vehicles in the UK. Since the motor industry is concentrated in the developed world, it is not surprising that the UK trend appears to representative of the global trend. However, the
13 patterns of economic growth in the developed world will eventually be repeated by the less-developed world and the issues of transport and energy consumption in the UK will more than likely be relevant on a global scale for a long time. Figure 9 shows world oil production since 1900 and echoes the profile of Figure 8 suggesting that motor vehicles are one of the main consumers of oil globally. In 1997, gasoline alone accounted for 28% of world oil consumption [BP 1998].
WORLD OIL PRODUCTION
Production (millions of tonnes per year)
3500
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500
0 1900
1910
1920
1930
1940
1950
1960
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year
Figure 9 - World oil production since 1900 [Ramage 1997] Figure 10 shows the mix of primary energy fuel sources accounting for world energy consumption in 1996. It can be seen that oil is the dominant primary energy source closely followed by coal and natural gas. Together, these fossil fuels contribute to over 70 % of the world’s primary energy demand. Oil alone supplies 40% of the world’s demand. WORLD ENERGY CONSUMPTION 1997
Nuclear 7%
Hydro-electric 3% Oil 40%
Coal 27%
Natural Gas 23%
Figure 10 - World energy consumption by fuel source [BP 1998]
14 1.4 SUMMARY
The main points presented in this chapter can be summarised as follows;
Industrial output, coal production and energy consumption all increased at a very high rate between 1830 and 1930.
The innovation of the railway marked the beginning of this period of rapid economic growth and the expansion of the railway system (transport sector) reflected the high growth rate.
Energy consumption in the transport sector as a proportion of total energy consumption, by the beginning of this century, is approaching 10%. This already represented a significant part of the country’s energy requirements. This overview of transport sector energy consumption since 1950 can be briefly summarised as follows;
Road vehicles have become the dominant form of transport since the development of the internal combustion engined car at the beginning of this century.
Chiefly as a result of increasing road transport, energy consumption has been increasing at a faster rate in the transport sector than the other energy consuming sectors.
The transport sector is still dependent on oil as an energy source and because there has not been diversification to other energy sources, its share of oil consumption has been rising.
15
Chapter 2 TRANSPORT AND ENERGY PROBLEMS There are many positive things to be said about the development of transport over the last century in terms of economic benefits and improved freedom of movement and quality of life for many people. However, there are a similar number of aspects to transport which are of concern because of environmental problems or potential economic problems. These problems range from local issues to global issues and action is therefore required on both a national and international basis.
2.1 LOCAL ISSUES Local problems are probably the easiest for individuals to identify with. They are the issues that most people actually experience on a day to day basis. Problems of traffic congestion, local air pollution and issues relating to road building developments. It is these issues which are likely to receive the most attention from the general public and action is therefore more inclined to be politically expedient. However, the solutions are not necessarily consistent from one location to the next. Possibly the most apparent problem to many people in urban transport is traffic congestion which has arisen from very inefficient use of the transport infrastructure. Congestion is damaging in economic terms, the cost of delays in traffic in the UK have been estimated at £15 billion [Royal Commission 1994]. However, more significantly, traffic congestion has an effect on local air pollution since inefficient use of the transport system and slow moving traffic increases the quantity of emissions per person. Vehicle emissions present a big problem in urban areas and although congestion contributes to the problem, the root cause is really shear volume of traffic in a relatively confined area. At a local level, the problematic pollutants are those which contribute to poor air quality and consequent health problems. These include nitrogen oxides (NOx), carbon monoxide (CO), volatile organic compounds (VOCs) and particulate matter (black smoke). Nitrogen oxides have been identified as causing respiratory disease, whereas particulate matter and volatile organic compounds such as benzene are known carcinogens.
The emissions of these
pollutants from road vehicles are shown in Figure 11 (a) - (d) along with figures for the estimated total emissions in the UK. This shows how significant a contribution road transport has made to the level of local pollutants.
16
3000 volatile organic compounds (thousands of tonnes)
500
1980
year
1992
0
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other sources
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other sources
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road transport
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road transport
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black smoke (particulates) (thousands of tonnes)
600
year
(a)
(b)
8000
3000 2500 nitrogen oxides (thousands of tonnes)
carbon monoxide (thousands of tonnes)
7000 6000 5000 4000
road transport
3000 2000
road transport
2000 1500 1000
other sources
500
1000 other sources
year
1986
1984
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0 1980
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0
year
(d)
(c)
Figure 11 - Total UK emissions and road transport emissions for selected pollutants [Dept. of Transport 1994]
At the local level then, there are two main needs; (i) to reduce the harmful emissions from vehicles in the local environment, and (ii) to reduce traffic congestion and improve the effectiveness of the transport system. Up to the present, the measures taken to tackle these problems have been short-term. A rather token response to emissions control in the UK has been the introduction of emissions limits on road vehicles, but with no effective means to monitor car emissions on a large scale, policing this policy is impractical. One response to traffic congestion has been to build more roads or make existing roads bigger to accommodate the volume of traffic. However, the experience in the UK has been that new
17 roads and bigger roads attract more traffic and eventually return to previous congestion levels [Royal Commission 1994].
Indeed, the problem is already recognised as being that car use is
simply too high. Without a serious change in the culture of the motor car, car use will continue to increase. Solutions to these problems must be based on moving to a more efficient system of transport in terms of moving passengers and goods with the least amount of energy use and road space.
2.2 NATIONAL ISSUES While the local problems of pollution and traffic congestion are both items affected by national policy and legislation by the central government, action is generally imposed by local government. Other important central government activities relating to transport include energy policy, trade and industry policy, environmental policy and, of course national transport policy. All of these areas must consider national as well as local issues.
Operating an efficient national transport system is, of course, an important part of maintaining a healthy economic environment. Speed and ease of transporting people and goods is an essential requirement for the functioning of industry and trade. National government has a responsibility to co-ordinate the development of transport infrastructure in accordance with its responsibility to promote the economic development of the country. Additionally, in the context of the national economy, motor vehicle manufacture and road construction are both significant industries themselves. As such, government policy on trade and industry will be likely to favour transport sector expansion rather than contraction. Unfortunately, the desirable direction of the transport sector in the context of energy policy and environmental policy is more likely to be the converse.
Energy policy in many countries has been shaped in recent decades by the events of the seventies when OPEC demonstrated its power over oil prices and made Europe and the USA very aware of their dependence on OPEC oil. Subsequently, the energy policy of the USA and many Western European countries has been to reduce dependence on OPEC by encouraging oil production in non-OPEC states and by attempting to reduce the share of national energy consumption accounted for by oil. The purpose of such action is to ensure security of the nation’s energy supply and reduce its sensitivity to changes in the oil market. Although this has been achieved to a certain extent by many oil dependent nations, in 1997, OPEC still accounted for over 40% of world oil production and has 75% of the world’s
18 proved reserves [BP 1998]. Consequently, OPEC still has the potential to wield considerable power over the global oil market.
The energy policies of oil importing countries are
therefore likely to attempt to reduce dependence on oil in order to reduce the vulnerability in the economies to oil price changes. In the UK, the energy supply has been spread between the various primary sources of coal, oil, gas and nuclear such that the nation is not totally dependent on any one. However, oil accounts for over a third of the total supply and a great proportion of oil consumption, and indeed total energy consumption is used in the transport sector. Future diversification of the energy supply away from oil is therefore obstructed by the transport sector. In many countries including the UK, a future, large scale reduction in oil consumption would require a shift in the technology used in transport.
2.3 GLOBAL ISSUES On a global scale fossil fuel consumption contributes a major proportion of ‘greenhouse gas’ pollution in the form of carbon dioxide. It has been internationally recognised and agreed that greenhouse gas emissions should be curbed as a precaution against the threat of global warming. The international agreement on climate change formulated at Kyoto in 1997 set targets for the reduction of greenhouse gas emissions including CO2. The agreement set a target to cut CO2 emissions in the UK by 20% by 2010 [DETR 1998]. In the UK, the transport sector contributes about 25% of total CO2 emissions as shown in Figure 12. Stabilisation or possible reduction in the level of CO2 emissions from motor vehicles would be welcomed as a means of fulfilling the obligations set by international agreement.
carbon dioxide emissions (millions of tonnes)
700 600 road transport
500 400 300
other sources 200 100
1992
1991
1990
1989
1988
1987
1986
1985
1984
1983
1982
1981
1980
0
year
Figure 12 - Carbon dioxide emissions in the UK [Dept. of Transport 1995]
19
Chapter 3 TRANSPORT TECHNOLOGY Previous chapters have presented the main issues relating to transport energy consumption and have focused on road transport in particular. The high energy demand of the transport sector in relation to total national energy requirement, the dependence of the transport sector on oil as an energy source and the extent to which road transport contributes towards certain pollutant emissions can all be considered as transport sector ‘problems’, in that they have undesirable effects or are a potential risk economically or environmentally. The focus of this study is the investigation into the effects that technological change may have on these ‘problem’ issues. In order to do this, an overview of current, alternative and emerging transport technologies is necessary. In each case, the energy efficiency of each technology and the associated pollutant emissions will be considered.
3.1 CURRENT TECHNOLOGY Because of its dominance in the transport sector, the examination of transport technology will start with an overview of the internal combustion engine and how it’s efficiency and economics has affected the use of energy for transport. The success of the internal combustion engine for transport applications can be credited to the number of favourable characteristics which it has. Firstly, the mechanical power which can be produced for a given volume and weight by an internal combustion engine is very high, it can be controlled relatively easily and is suited to the requirements of vehicles with sizes ranging from motorbikes to railway locomotives. Secondly, the fuel used in internal combustion engines, be it petroleum or otherwise, has a very high specific energy which means that sufficient quantities of the fuel can be carried with the vehicle to enable long range journeys to be made before refuelling. Finally, the materials from which an engine can be manufactured, (mainly steel) are abundant and inexpensive. If new technology is to improve on or replace the internal combustion engine, it must be able to compete not only in performance terms but also economic terms. Some of the technological alternatives, though technically feasible, are kept out of the market by simple economic forces. Furthermore, current transport technologies and the associated transport infrastructure is very well established and consequently there is an inertia in the market preventing significantly different technology from gaining a foothold.
20 Despite all the advantages of the internal combustion engine, it does have its weaknesses, which, in the context of this study are highly relevant. The main drawbacks are; (i) the efficiency of energy conversion is limited, and (ii) emissions are produced at the point of use. Since the internal combustion engine was developed over one hundred years, there have been continual efforts to make improvements in performance both in terms of the power density and efficiency. However, there is a limit to the efficiency with which an internal combustion engine can use the energy in the fuel to produce mechanical power output due to the thermodynamic efficiency of the process of conversion of heat energy to mechanical work. The efficiency of the internal combustion engine improves with a higher ratio of compression pressure to exhaust pressure (compression ratio). Compression ignition engines can use higher compression pressures than spark ignition engines and hence diesel engines are generally more efficient than petrol engines.
Table 2 - Typical internal combustion engine efficiency [Heywood 1988] Engine
specific fuel
Maximum
capacity
consumption
efficiency
(l)
(g/kW.h)
(%)
spark ignition / four stroke
2
274
30
indirect injection, compression ignition /
2
280
30
2.4
240
35
1.5
246
34
8.4
203
42
500
160
47
engine type
four stroke indirect injection, compression ignition / four stroke / turbocharged direct injection, compression ignition / four stroke direct injection, compression ignition / four stroke / turbocharged direct injection, compression ignition / two stroke / turbocharged
Table 2 presents the theoretical maximum thermal efficiencies of a number of different types of internal combustion engines. The most basic spark ignition engines have maximum thermal efficiencies of about 30%. Improvements in efficiency are possible by increasing the compression ratio, recovery of work from the exhaust (turbocharging) and control of the air-fuel mixture. The highest efficiencies are achieved with large compression ignition, turbocharged engines such as marine or railway diesels where the maximum efficiency can
21 be as high as 47%. In practice, engines only operate at maximum efficiency on no load and when actually delivering power, mechanical energy losses can reduce the efficiency of the engine by a further 50%. The resulting overall efficiencies are therefore limited to not much more than 25%. The very first internal combustion engines developed achieved overall efficiencies of 11 to 14% [Williams 1978]. After a century of development the overall engine efficiency of a typical car engine has been improved to only about 20%.
The internal combustion engine combined with other late nineteenth century innovations such as the mechanical clutch and pneumatic tyres were the key technologies which, when combined, eventually produced the modern motor car. After one hundred years of development, the principal features of motor car traction have not changed significantly. As previously explained, the efficiency of modern internal combustion engines is only around 20%. This means that 80% of the energy available in the fuel is lost in the process of converting it to mechanical work. In most cars, further energy loss occurs through the mechanical transmission system which may have an efficiency as low as 87%. Additionally, the power demand of vehicle accessories including air-conditioning units on present vehicles further reduces the power available for traction. As little as 15% of the original energy content of the fuel is actually converted to useful traction [Ross 1994]. Driving conditions can contribute to even more inefficiency. In urban traffic where cars are frequently accelerating and decelerating, the energy used to move the car up to speed is lost as heat with the application of the brakes. . Table 3 - fuel consumption of passenger cars [Bosch 1986] car make and model
engine
Engine
power
size
(kW)
(litres)
fuel consumption (litres / 100 km)
energy consumption (MJ / km)
@90 km/h
Urban
@90 km/h
Urban
BMW 525 e
90
2.7
6.3
11.8 traffic
2.6
5.0 traffic
Ford Escort
66
1.6
5.9
10.0
2.5
4.2
Peugeot 305 GR
55
1.6
5.6
8.9
2.4
3.7
Honda Civic GL
63
1.5
5.2
8.2
2.2
3.4
Nissan Sunny
54
1.6
5.7
7.6
2.4
3.2
Toyota Carina II GLi
74
1.8
5.5
9.2
2.3
3.9
22 The efficiency with which cars use fuel for traction is often expressed in terms of the quantity of fuel needed to travel a specific distance under specific driving conditions. The fuel consumption of a number of modern models of petrol fuelled motor car are presented in Table 3. Under urban driving conditions, the fuel consumption of these cars is in the range 7.6 to 11.8 litres per 100 kilometres. In terms of energy consumption per kilometre, this relates to 3.2 to 5.0 MJ/km. The majority of cars use a spark-ignition petrol engines since these have a power capability for their volume and weight more suited to the size of the vehicle. Lorries and buses, on the other hand, are able to accommodate larger capacity engines and use compression ignition diesel engines. In recent years, diesel engined cars have gained in popularity through their superiority in fuel economy (due to cheaper fuel) and perceived ‘greenness’ in comparison with petrol engines. However, car-sized diesel engines are only marginally more efficient in energy terms than petrol engines and the benefits of lower CO2 and hydrocarbon production are offset by higher NOx , SO2 and particulate emissions. Table 4 shows the average emissions produced from the main classes of road vehicle with both petrol engines and diesel engines.
Table 4 - emissions from road vehicles [ETSU 1996] Class of
Fuel
CO2
CO
HC
NOx
SO2
vehicle
l/100
g/km
g/km
g/km
g/km
g/km
Particulates
g/km
km
Petrol
Car
7.9
181
2.07
0.14
0.21
0.02
0.01
Diesel
Car
5.3
139
0.42
0.08
0.64
0.05
0.15
Petrol
Light goods
13.6
309
6.62
0.35
0.28
0.04
0.02
Diesel
Light goods
10.3
267
1.33
0.33
1.39
0.09
0.24
Diesel
Heavy goods
32.8
853
3.92
0.45
13.06
0.28
1.07
Diesel
Old bus
44.3
1119
16.04
5.03
15.86
0.38
1.55
Diesel
New bus
34.1
885
4.26
0.44
14.09
0.29
1.06
23 3.2 EMERGING TECHNOLOGIES
Alternative fuels Despite the efficiency restrictions of the internal combustion engine, it is still economically favourable as the means of traction provided the overall cost of the fuel is lower than the alternatives. At present, petroleum oil is the source of nearly all fuels for internal combustion engines primarily because it is the cheapest and most prolific liquid fuel. However, the internal combustion engine is capable of being adapted to use alternative fuels to petroleum. Fuels other than petrol and diesel include liquid alcohols such as methanol and ethanol and gaseous fuels such as compressed natural gas (CNG) and liquid petroleum gas (LPG). Some of these fuels can be used in existing engine designs with only slight modifications. The potential for these fuels to replace petroleum in future depends not only on their relative cost but also on the fuel storage and distribution infrastructure requirements. The quantities of pollutants produced in the exhaust gases are also an issue in assessing the relative merits of these fuels. Table 5 shows the emissions factors for alternative fuelled vehicles and the relative cost of each fuel.
Table 5 - Emissions factors and cost of alternative fuels [ETSU 1996] Fuel
Class of
CO2
CO
HC
NOx
cost index
vehicle
g/km
g/km
g/km
g/km
per km
Petrol
Car
181
2.07
0.14
0.21
1.00
Diesel
Car
139
0.42
0.08
0.64
0.95
LPG
Car
161
0.96
0.06
0.23
0.97
Natural Gas
Car
150
0.48
0.18
0.14
1.02
Methanol
Car
172
1.43
0.11
0.17
1.45
Ethanol
Car
181
0.83
0.14
0.07
1.38
In terms of environmental acceptability, the alternatives to petroleum have some advantages. Nitrogen oxide emissions in particular are lower in most cases and, although not shown in the table, all the alternative fuels have virtually no particulate emissions compared with diesel. CNG, LPG have slightly better carbon oxide (CO and CO2) emissions but in terms of reducing overall greenhouse emissions, the advantage is marginal and since the fuel
24 themselves are greenhouse gasses, this may be offset by emissions of the fuel itself. In the case of ethanol and methanol, it would appear that carbon dioxide emission are no better but it is possible to produce these fuels from sustainable biomass so that overall net CO2 production can be reduced. The gaseous fuels have the advantage of having much higher specific energy values and on a cost per joule basis, compressed natural gas and liquefied petroleum gas are considerably cheaper to produce than petrol. This cost advantage is offset by the safety and handling restrictions of high pressure liquefied gases. The different requirements for storage and distribution of gases means that a significant change in infrastructure would be needed and ultimately, LPG and CNG have no significant cost advantage. Since methanol and ethanol are liquid fuels, distribution and storage infrastructure would be much the same as for petroleum. However, the cost of production of alcohol bio-fuels is significantly higher than that for fossil fuels and the final cost may be up to 50% higher. It seems likely that alternative fuels will not make significant inroads into the road vehicle market unless there is a major change in the cost benefits of oil. More promising as a solution to energy efficiency and low emissions is electric and hybrid electric technology.
Hybrid Electric Vehicles Despite the apparent advanced state of current technologies, significant improvements in the overall operating efficiency of internal combustion engines in motor vehicles are still possible. There is an optimum speed and power output at which internal combustion engines operate at their most efficient. By only operating the engine under these optimum conditions, the overall efficiency of the system can be improved. However, to keep the engine running at a constant power output requires some additional means of absorbing and delivering power when the traction requirement is higher or lower than the engine output. This can be achieved with the use of an electrical motor/generator and an electrical energy store (battery) and such an arrangement is termed a ‘hybrid-electric’ traction system. Figure 13 shows a simplified schematic of a hybrid-electric traction system. When the required tractive power is less than the engine output power, the generated electrical energy is stored in batteries or other electrical energy storage system. When the required power exceeds the engine output, the additional power is provided from the batteries. Furthermore, it is possible to recover some of the kinetic energy of the car when braking through the use of the generator. Additionally, since the engine itself is not required to provide the full peak power for traction, it can itself be physically smaller. Hybrid-electric vehicles are capable of acceleration and speed performance just as good as conventional cars but with much improved fuel efficiency. The
25 energy source is still from the fuel used for the internal combustion engine and consequently the driving range of such vehicles is similar to that of conventional cars.
GENERATOR
ENGINE
GEARBOX
INVERTER
BATTERY
MOTOR Mechanical path Electrical path
Figure 13 - Schematic diagram of a hybrid-electric vehicle traction system
The technology for hybrid-electric vehicles is already fairly mature. High efficiency permanent magnet electrical machines with power capabilities suited for use as traction motors and for the electrical motor / generator are now well established [Mellor 1998]. Batteries suitable for the electrical energy storage requirements have been developed for some time and computer processing is now so advanced that intelligent control of a hybrid-electric drive is possible to optimise the overall efficiency of the system. In terms of fuel consumption per kilometre, current hybrid vehicle technology is capable of between 1.5 and 2.0 MJ / km. In the short term (i.e. within the next ten to twenty years) hybrid-electric vehicles are likely to become commercial competitors in the car market. This is partly because a hybrid system is more of a natural evolution of the existing technology than, for example, the all-electric vehicle and it requires no significant changes in infrastructure. It will therefore be more easily accepted by the motor industry and, more importantly, the buying customer. Indeed, hybrid-electric vehicles are already commercially available in the USA and Japan and Toyota is expected to launch the hybrid-electric ‘Prius’ in Europe in 1999 [Baggot 1997].
26 Electric Traction At the end of the nineteenth century, electric vehicle technology was actually more advanced than the internal combustion engined vehicle. Many electrically powered cars were built before the advantages of the internal combustion engine were fully exploited. An all electric vehicle traction system consists of an energy store, a traction motor (or motors) and a traction drive (to control the flow of electrical power between the energy store and the traction motors). The electrical energy source can be either an energy store such as electrochemical batteries or an electrical generation system which supplies energy from other sources such as fuel cells. The concept of the electric vehicle is clearly very attractive since there are many advantages over the internal combustion engine. Most significantly, with regards to energy consumption, electric traction systems are very highly efficient. The technology for electrical energy conversion (power electronics) and electro-mechanical energy conversion (electrical machines) are both very highly advanced. The efficiency of a state of the art electric vehicle traction system can be more than 90% [Mellor 1998] (taking the ‘fuel’ to be the input of electrical energy to the vehicle). Additionally, electric traction allows the possibility of recovering some of the kinetic energy of the vehicle through using the traction motors as generators and returning electrical energy back to the energy store. This is known as ‘regenerative braking’ and can improve the overall energy efficiency of the vehicle.
The fact that electricity for electric vehicles must be generated in power stations should be considered in the assessment of their energy efficiency, fuel source and emissions. The conversion of fossil fuel energy to electricity does reduce the overall energy efficiency of the all electric vehicle. However, even allowing for a generating and transmission efficiency of 35%, all electric vehicles may be up to 30% efficient at converting primary energy supply to useful tractive work. In terms of energy consumption per kilometre, this relates to around 2.0 MJ / km. Another great advantage of electric vehicles is the possibility of zero emissions from the vehicle itself. Given that the electricity for the vehicles is generated in power stations, the vehicle itself produces no pollutants at the point of use. Although polluting emissions may still be produced, they are more controllable at a single point of production and, importantly, away from urban centres. Electricity may be generated from a variety of primary fuel sources and the widespread use of all electric vehicles allows the possibility of fuel diversification away from oil. Furthermore, electricity generation for electric vehicles is possible from non-polluting, renewable sources.
27 Electric Vehicle Enabling Technology In order for all-electric vehicles to be competitive with conventional cars in terms of performance they must be able to deliver similar acceleration and speed capabilities and an acceptable driving range. The key enabling technologies are therefore the energy storage systems such as the batteries or alternative electrical energy sources such as fuel cells. These energy sources must have suitable energy density (energy stored per unit volume and weight) and power density (power capability per unit volume and weight).
Batteries The electrochemical battery is the most common system for electrical energy storage for electric vehicles. Energy is stored by means of a reversible chemical reaction whereby electrical charge can be input and output via an external electrical circuit. Batteries suffer a number of limitations which affect their viability as energy storage devices for road vehicles. The requirements for such a devices are, firstly, a storage capacity sufficient to provide an acceptable range for the vehicle and secondly, a suitably high power capability to provide acceptable vehicle acceleration and maximum speed. Since there is a limit on the weight and space available on a road vehicle, batteries obviously impose a limit on the available power and range of the vehicle. However, there are a number of electro-chemical battery systems that have been developed which can provide acceptable performance and range and have been implemented in currently available electric vehicles.
The most tried and tested
electro-chemical system to be used for traction purposes is the lead-acid system (Pb-PbO) which is also the system commonly used for the auxiliary electrical supply for internal combustion engined vehicles. Compared with other battery systems, lead-acid batteries are inexpensive, robust and have a reasonable lifetime. However, even the most advanced lead-acid batteries have an energy density lower than 50 kWh/kg which restricts the range of electric vehicles which use them to around 100 km [Baker 1997]. Higher performance systems include nickel-cadmium (Ni-Cd) batteries, nickel-metal hydride (Ni-MH) batteries and Lithium-ion (Li) batteries. Research and development of each of these systems has progressively improved energy and power densities. Lithium-ion battery technology has been employed in electrical vehicles such as the Nissan Altra which has a range of up to 180km [Shultz 1997].
Table 6 shows the principal characteristics of traction battery systems which are
currently available.
While these new battery technologies have enabled improved performance for all-electric
28 vehicles, they can not necessarily be seen as solutions to electric vehicle energy storage in the long term. One drawback of electrochemical batteries is their use of heavy metals which as well as being expensive, are environmentally hazardous. Perhaps the biggest drawback of battery energy storage is the rate at which they can be recharged compared with petrol fuelled cars. The rate at which energy can be transferred into electo-chemical cells is very much lower than the rate at which petrol can be pumped into a fuel tank. In order to account for this problem, electric vehicles must either be able to be situated at a charging points (e.g. parking places) at regular intervals when not required for use for a suitably long period (e.g. overnight) or replacement charged battery modules must be available for quick exchange at charging stations. Both these options would require new infrastructure to be developed on a large scale in order to make electric vehicles as convenient to use as conventional vehicles. Table 6 - Principal characteristics of electric vehicle batteries [Pellerin 1996] Specific Power
Specific Energy
Energy Density
(W/kg)
(Wh/kg)
(Wh/litre)
Lead- Acid
80
35-40
95
Nickel-Cadmium
100
42-48
100
100-120
55
120
160
120
250
Nickel-Metal-Hydride Lithium-Ion
Fuel Cells A promising technology for the long term viability of electric vehicles is the fuel cell. The fuel cell is similar in principle to batteries in that is produces electricity directly from an electro-chemical reaction. In the case of the fuel cell however, the chemical reaction is a one-way process whereby the reactants are introduced into the cell and the reaction products are exhausted. The most advanced fuel cell systems are the proton exchange membrane (PEM) fuel cell which uses hydrogen as a fuel, and the alkaline fuel cell which uses methanol as a fuel. In both cases, the overall efficiency of the conversion of fuel energy to electrical energy is considerably higher than in a hybrid-electric system and can be up to 60%. Hydrogen has the advantage of having a very high specific energy while producing no polluting gaseous emissions when burned since the only product of combustion is water. However, the infrastructure and technology for safe handling, storage and distribution of hydrogen adds to the cost. Economically, fuel cells have a number of drawbacks including the use of exotic and costly metals such as platinum and a requirement for very high purity
29 fuel since slight contamination of the materials in the electrodes can destroy the operation of the cell. Despite this, electric vehicles have been developed which use fuel cells and the long term viability of fuel cell powered vehicles would appear to be promising since they would have the advantage of the high fuel efficiency of electric vehicles but would also have the range and re-fuelling capabilities of conventional cars [Kordesch 1996].
Future Car Design The energy required to move a vehicle is governed by its mass, aerodynamic drag, tyre rolling resistance. Energy consumption is also a function of the driving conditions and the terrain (gradients) of the route. Aerodynamic drag and tyre rolling resistance represent power loss (the energy cannot be recovered) and furthermore, the faster the vehicle moves, the more of this energy is lost since aerodynamic drag is proportional to the cube of the speed. The aerodynamic design of vehicles therefore has a significant impact on overall fuel consumption. In most cases, vehicles use friction braking systems and therefore the fuel energy converted to kinetic energy in the motion of the vehicle is also lost when the vehicle is braked. Frequent acceleration and subsequent braking therefore increases fuel consumption. Since the kinetic energy is a function of the mass of the vehicle, more massive vehicles require more energy in acceleration (and therefore lose more energy in braking). Consideration of aerodynamics and weight in vehicle design is therefore important. The use of lightweight materials for vehicle construction and making vehicles physically smaller will consequently have a beneficial effect on fuel consumption. The potential for improvements in fuel efficiency through vehicle design has been demonstrated by the design of the “Hypercar” at the Rocky Mountain Institute which is predicted to improve fuel consumption to less than 0.7 MJ / km [Lovins 1998].
3.3 SUMMARY This chapter has described the main technologies currently employed for road transport and has also described some alternative technologies which are likely to become competitors in the near-term. It is clear that there is significant potential for improvement of road transport energy efficiency. The current average fuel consumption per kilometre for road vehicles is over 3 MJ / km. Hybrid-electric and electric traction is capable of improving this to less than 2 MJ / km. In the long term, it should be possible for the fuel consumption of road vehicles to be improved further to less than 1.0 MJ / km.
30
Chapter 4 TRANSPORT ENERGY FUTURES In the previous chapter, the state of the art in transport technology and some emerging technologies have been described. The future development and sustainability of transport and transport sector energy consumption is likely to depend on how these technologies are used. The analysis of historical transport technology developments and their effects has shown that in the past, technological developments have been instrumental in economic growth accompanied by expansion in transport use and associated energy consumption. The role of technology in future, however, is likely to be employed to try and reverse the trend in energy consumption and to attempt to achieve a sustainable level of transport with acceptable levels of emissions. Another effect of technological development could be a diversification in available energy sources for transport which is presently solely dependant on oil. None of these effects will occur overnight but will be apparent over the next twenty to thirty years. Having examined the historical data and investigated current developments in technology, it is now possible to explore their possible effects on energy consumption over the next thirty years.
4.1 FORECASTING TRANSPORT ENERGY DEMAND Forecasts of economic and technological development up to thirty years into the future are very prone to error since both are influenced by unpredictable human activities. However, as long as forecasts make clear their potential for error, the information provided by them can be useful. It is possible to avoid the issue of inaccuracy by attempting to encompass all reasonable eventualities. One method of doing this is by making a number of forecasts which cover the extreme cases by taking both highly pessimistic and highly optimistic views. It is helpful to also provide a forecast which is mid-way between these two extremes. A good reference which attempts to predict future energy consumption in the European Union is the European Commission’s “European Energy to 2020” [EC 1996]. This presents a number of different scenarios ranging from slowed economic growth due to world conflict (Battlefield Scenario) to enhanced economic growth due to greater international co-operation (Forum Scenario). The scenario which assumes no significant change from current economic conditions and recent trends is termed the “Conventional Wisdom” scenario. It is the conventional wisdom scenario which will be referred to for the development of models for
31 predicting transport growth. For the purposes of forecasting transport energy demand, a similar “scenario” approach will be adopted and projections will be based on the three different scenarios described here.
Scenario A The first scenario, “Scenario A”, will be the worst case example where the current trends of traffic growth and the associated pollution will continue unchecked. Scenario B The second scenario, “Scenario B”, will consider the gradual improvement of transport energy efficiency. Scenario C The third scenario, “Scenario C”, will consider a more optimistic situation in which technological breakthrough results in a much faster rate of improvement in transport energy efficiency.
Energy consumption in the transport sector can be determined from two factors, the quantity of traffic and the average energy efficiency of the vehicles. Quantity of traffic is expressed as the total distance travelled by all road vehicles in a year and is measured in vehicle-kilometres per year. The average energy efficiency of road transport is simply total road transport energy consumption divided by quantity of traffic and is expressed in megajoules per kilometre per vehicle. Each of the three scenarios will forecast the energy consumption in the transport sector based on projections of traffic growth and transport energy efficiency.
4.2 ROAD TRANSPORT GROWTH It was noted in chapter 1 that there is a link between economic growth and transport growth. Indeed, quite sophisticated models have been developed to predict growth in transport use from GDP, fuel prices and overall motoring costs [e.g. Bending and Eden 1984]. However, for the purposes of this study a more crude method of extrapolating the trends for traffic growth will be employed. Analysis of historical data can be used to derive a basic mathematical model to predict the increase in the number of vehicle-kilometres per year. The results of the models will be compared with figures from other sources in order to check their consistency with more detailed forecasts.
400
20.00
300
15.00
200
10.00
100
vehicle kilometres
5.00
GDP per capita 0 1960
GDP per capita (thousand US$ per capita)
vehicle kilometres (billions)
32
0.00 1965
1970
1975
1980
1985
1990
year
vehicle-kilometres (billions)
Figure 14 – Growth in transport use and GDP in the UK 1960-1990
350 300 250 200 150 100 50 0 0
200
400
600
800
1000
GDP (thousand US$)
Figure 15 – Correlation between transport usage and GDP in the UK 1960 - 1995 Figure 14 shows the number of vehicle-kilometres travelled and the GDP between 1960 and 1992. Figure 15 shows these two quantities plotted against each other for each year between 1960 and 1992. It can be seen that road transport use measured in vehicle-kilometres and GDP have a strong correlation and the relationship is approximately linear. Indeed, Bending and Eden [Bending and Eden 1984] have recognised that increase in car use is indeed related increase in personal incomes and therefore base their mathematical model of car use on GDP per capita. If it is assumed that other variables remain constant and that the linear relationship
33 identified remains valid then the number of vehicle-kilometres travelled per year can be modelled as;
K = a.(i ) - b
[eqn. 1]
Where i is GDP, and a and b are constants selected to fit the historical data
By curve fitting equation 1 to the historical data, the constants were found to be; a = 0.525 and b = 161.2. Since traffic growth is a function of GDP, the forecast for traffic growth is dependent on forecasts for economic growth. For each of the three scenarios, the average annual growth rate in GDP is taken to be 2.0% in accordance with the “Conventional Wisdom” scenario presented in “European Energy to 2020” [EC, 1996]. Assuming growth in GDP of 2.0% annually, the total number of vehicle-kilometres can be forecast using the expression given in eqn.1. The predicted growth in car use is shown in Figure 16 alongside the historical data. About 670 vehicle-kilometres are expected by 2020 and 855 vehicle-kilometres by 2030. This represents an average annual increase of 2.6%. This is in line with figures given by the National Road Traffic Forecasts made in 1989 [Royal Commission, 1994]
which predicted between 650 and 830 billion vehicle-kilometres by 2020.
900
vehicle-kilometres (billions)
800 700 600 500 400 300 predicted
200
historical data
100 0 1960
1970
1980
1990
2000
2010
2020
year
Figure 16 - Projected growth in road transport
2030
34
4.3 TRANSPORT ENERGY EFFICIENCY An indication of average energy consumption per vehicle-kilometre can be obtained by simply dividing the figure for total annual road transport energy consumption by the figure for annual road transport vehicle-kilometres. Table 7 presents the average road transport energy efficiency since 1960 calculated in this manner.
Table 7 - Historical trend in transport energy efficiency [Dept. of Transport 1995] Average energy consumption Year
per vehicle-kilometre (MJ / km)
1960
6.8
1970
5.6
1980
5.1
1985
4.9
1990
4.7
1995
4.3
As should be expected, the energy efficiency of road transport appears to have consistently improved since 1960 and reflects progress in the improvement of transport technology [DTI 1997].
The improvement has been quite substantial with a 60% improvement between 1960
and 1995. For 1995, the average energy consumption per vehicle-kilometre works out to be 4.3 MJ / km. A figure of 3.3 MJ / km for a current model of petrol fuelled car was given in Chapter 3. From this, it may be inferred that, on average, the energy efficiency of transport technology in current use is somewhat lower than that of the new technology. This is to be expected since improvements in transport technology will not be seen on the large scale for several years since it takes time for the old vehicle stock to be replaced by the new. . There is a limit to the practical rate of introduction of new technology. Given that the present transport fleet consists of many cars with a lifetime of at least ten years, the present technology will still have an influence on the overall efficiency of road transport for many years. The rate at which old cars are replaced by new can be inferred from statistics for annual sales of new vehicles. In the UK, between 1984 and 1994, the number of new cars each year accounts for between 9% and 11% of the total number of cars [DoT 1995]. Assuming
35 the same proportion of new vehicles entering the fleet over the next twenty years, and a steady improvement in the average fuel efficiency of new vehicles, the improvement of the overall efficiency of road transport and the resulting energy consumption can be forecast. For each of the following forecasts, it is assumed that 10% of the vehicle stock is renewed each year. The average fuel consumption of the entire stock is taken as 4.3 MJ / km and the average fuel efficiency of new vehicles is taken as 3.3 MJ / km in the base year, the base year being 1995.
4.4 FORECASTS “Scenario A” With regards to energy efficiency improvements of road transport, the worst case scenario would be that there would be no further significant improvements over the next thirty years. In this case, it is assumed that energy consumption per kilometre of new vehicles improves only marginally from 3.3 MJ / km to 3.0 MJ / km. This represents a scenario where the petroleum-fuelled internal combustion engine continues as the only significant technology and further advancements in fuel efficiency are not realised commercially. The increase in energy consumption in the road transport sector, in this case would be almost proportional to the increase in road transport use. Assuming growth in road transport as illustrated in Figure 16, energy consumption in the transport sector would almost double.
Total road transport energy consumption (Mtoe)
60 50
7
road transport energy consumption average road vehicle fuel consumption average new road vehicle fuel consumption
6 5
40
4
30
3
20
2
10
1
0 1995
2000
2005
2010
2015
2020
2025
Fuel consumption (MJ / km)
70
0 2030
year
Figure 17 - Forecast road transport energy consumption (Scenario A)
36 Figure 17 shows the forecast improvements in fuel efficiency alongside the forecast increase in energy consumption. In this scenario, the road transport energy consumption is projected to reach 50 Mtoe by 2020 and over 62 Mtoe by 2030. This represents an annual increase rate of almost 2.0%. “Scenario B” In scenario B, improvements in transport energy efficiency continue at a faster rate than in “scenario A”. The high-efficiency engine technology and hybrid-electric traction systems, as described in chapter 4, are capable of improving the average energy consumption of new cars from 3.3 MJ / km to 2.0 MJ / km. If such technology is adopted within the next ten years, it can be assumed that the average energy consumption of the road transport sector will steadily improve from the present 4.3 MJ / km to about 2.4 MJ / km by 2030. The increase in final road transport energy demand is from 35 Mtoe in 2000 to 48 Mtoe in 2030 - a 37% increase over thirty years. This increase in fact represents 1.0 % annual growth in energy consumption. These trends are shown in Figure 18.
Total road transport energy consumption (Mtoe)
60 50
7
road transport energy consumption average road vehicle fuel consumption average new road vehicle fuel consumption
6 5
40
4
30
3
20
2
10
1
0 1995
2000
2005
2010
2015
2020
2025
Fuel consumption (MJ / km)
70
0 2030
year
Figure 18 - Forecast road transport energy consumption (Scenario B)
This scenario actually reflects some of the assumptions made in the energy forecasts of the World Energy Council and the European Union. In “Energy for Tomorrow’s World” [World Energy Council, 1993],
advances in technology are predicted to include development of
advanced internal combustion engines and electric energy storage batteries for automotive
37 applications by 2010. Advanced fuel cells and hydrogen fuelled vehicles are predicted to be viable by 2025. The energy forecasts of the EU presented in “European Energy to 2020” [EC, 1996]
predict increases in energy consumption in the transport sector ranging from 0.7 %
(“battlefield” scenario) to 1.33% annual growth between 1990 and 2020. The projection presented in “scenario B” would appear to be more consistent with other economic forecasts. Scenario “C” In scenario “C” improvement in the effective energy efficiency of road transport is considered to progress at a faster rate than scenario “B”. In order for such improvements to be realised, the technologies described in chapter 4 would have to be introduced at an accelerated rate. In other words, a transport “revolution” or a significant technological “breakthrough” would be required. Energy consumption of road vehicles is predicted to improve from 3.3 MJ / km to 1.5 MJ / km by 2030. The predicted energy consumption for road transport in this scenario is presented in Figure 19. It can be seen that the improvement in energy efficiency effectively compensates for the increase in road transport usage such that by 2020, the increase in energy consumption has levelled out at 40 Mtoe. The annual growth rate between 2000 and 2030 in this case is less than 0.5%.
Total road transport energy consumption (Mtoe)
60 50
7
road transport energy consumption average road vehicle fuel consumption average new road vehicle fuel consumption
6 5
40
4
30
3
20
2
10
1
0 1995
2000
2005
2010
2015
2020
2025
Fuel consumption (MJ / km)
70
0 2030
year
Figure 19 - Forecast road transport energy consumption (Scenario C)
38 4.5 ENVIRONMENTAL IMPACT Following the production of the energy forecasts for each of the three scenarios presented, an assessment of the environmental impact of each scenario can be made. For the purposes of determining the associated carbon dioxide emissions, a simple pro-rata calculation can be made. This assumes that the primary energy supply for transport will still be obtained from fossil fuel sources even for all electric vehicles and fuel-cell powered vehicles. Table 8 shows the predicted carbon dioxide emissions from road transport up to 2030 for each of the three scenarios. It is clear from this that in all cases, fossil fuel consumption and the associated carbon dioxide production will continue to increase. Only in the best case, scenario C do emissions eventually stabilise. This is a significant point and suggests that in order to reduce overall emissions, not only must there be a change in vehicle technology but there should also be an accompanying change to non-fossil fuel energy sources. Only In scenario B and C, where electric vehicle technology is assumed to be introduced, there is potential for carbon dioxide emissions to be reduced since the energy supply in not necessarily constrained to fossil fuels and electricity may be generated from renewable sources and/or nuclear power. Similar arguments can be made for other transport related pollutants including nitrogen oxides and particulates. In the case of these pollutants however, there is an added advantage in using electric vehicles in that the pollutants are produced away from the point of use and could significantly improve urban air quality.
Table 8 - Forecast carbon dioxide emissions from road transport (million tonnes) Scenario A Scenario B Scenario C
2000 120 117 117
2010 143 133 127
2020 167 147 133
2030 207 160 133
39 4.6 ALTERNATIVE TRAFFIC GROWTH SCENARIOS As a footnote to the analysis of the effects of vehicle energy efficiency, it is worth reconsidering the alternative approach to controlling transport sector energy consumption which is to reduce the rate of growth in traffic. Previously, in section 4.2, road transport use was predicted to increase at an annual average rate of 2.6 %. If a slightly lower rate of 2% is assumed as a result of traffic reduction measures, the increase in road transport energy consumption will be at a reduced rate also. In order to compare the effects of this lower growth in road transport use, each of the forecasts made in scenarios A, B and C can be recalculated.
Table 9 – Effects of reduced traffic growth on road transport energy consumption 1995
2000
2010
2020
2030
347
400
523
673
855
Traffic growth @ 2.6% p.a. Vehicle-kilometres (billion) Road Transport
Scenario A
35.3
36.8
42.8
51.7
63.1
Energy Consumption
Scenario B
35.3
36.6
40.3
44.6
48.6
(Mtoe)
Scenario C
35.3
36.5
39.1
41.1
41.3
347
383
465
567
690
Traffic growth @ 2.0% p.a. Vehicle-kilometres (billion) Road Transport
Scenario A
35.3
35.3
38.1
43.5
50.7
Energy Consumption
Scenario B
35.3
35.4
36.0
37.7
39.3
(Mtoe)
Scenario C
35.3
35.1
34.9
34.6
34.3
Table 9 shows a summary of the forecasted road transport energy consumption for the two different traffic growth cases. It can be seen from this that the only case where road transport energy consumption can be actually reduced is that with 2.0% annual traffic growth and energy efficiency improvements in accordance with scenario C. It is clear that in order to reduce or indeed, stabilise transport sector energy consumption, a combination of energy efficiency improvements and controls on traffic growth are required.
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Chapter 5 CONCLUSIONS The main theme of this study has been to explore the effects that technological development has on energy consumption in the transport sector. It was shown in chapter 1 that, in the UK, advancement in transport technology has aided economic development and transport has grown to become one of the main energy consuming sectors. Chapter 2 explained how this increase in transport use and energy consumption has led to a number of environmental problems from urban pollution to global carbon dioxide emissions. The dependence of transport on oil was also highlighted and, although the economic effects of this are debatable, the possible future economic vulnerability resulting from reliance on a depletable energy resource was recognised. Chapter 3 covered in some detail, the state of the art in road transport technology and showed how these technologies perform with reference to pollution emissions and energy efficiency. Finally, chapter 4 presented a forecast of transport use in the UK and the associated energy consumption and illustrated the impact of energy efficiency in the transport sector. It has thus been shown that energy consumption in the transport sector and associated pollution issues are highly significant in the UK in the context of the economy and the environment. Furthermore, it has been shown that in future, these issues might be controlled by the use of new technologies.
One of the main points to be inferred from these analyses, is the importance of technology in providing the solutions to many of the problems associated with transport. If road transport continues to grow in line with the trends which have been identified, the issues of local pollution, CO2 production, energy consumption and oil dependence will become increasingly problematic. To avoid future problems, technology must continue to develop and produce vehicles with much better energy efficiencies and lower pollutant emissions. Preferably, these new vehicle technologies should be capable of using primary fuel sources other than oil. One technology capable of tackling all of these issues is the electric-vehicle. The technology already exists to make highly energy-efficient electric vehicles. However, it is unlikely that a large scale change away from the established technology will occur while electric vehicles remain limited by energy storage requirements and changes in infrastructure. The main problem in introducing new energy efficient technologies would appear to be consumer acceptance of a product radically different from conventional technology [Bauer 1996]. A
41 gradual shift towards energy efficient technologies is therefore more likely than a sudden shift. This gradual shift is likely to be an evolution from petrol fuelled vehicles to hybrid-electric vehicles to lightweight, smaller, all-electric vehicles. During the course of this evolution, the new energy efficient technologies will be adopted as and when they become commercially acceptable. It is envisaged that by 2010, electric energy storage technology will have developed sufficiently to make all-electric vehicles competitive and by 2020 hydrogen fuel cells are expected to be commercially viable for road vehicles [WEC 1993, Harrop 1995].
The last century saw a revolution in transport with the introduction of powered transport in the form of the railways. The twentieth century has seen a second transport revolution in the development of the motor-vehicle which has now become the dominant form of transport. There is no doubt that these developments have brought about huge economic benefits and improved the quality of life for many. However, the transport sector has grown to a scale such that it is now a major cause of environmental pollution and is accountable for a large proportion of the nation’s energy consumption. The next century should see another technological shift in transport but instead of creating the conditions for further expansion of the transport sector, the new technology needs to counter-act the problems that the old technology has caused. Technological development has the potential to solve the problems caused by petrol-fuelled vehicles.
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References INTRODUCTION Hall P. (1994), “Innovation, Economics and Evolution”, London, Harvester Wheatsheaf CHAPTER 1 Statham I.C.F. (1951), “Coal-mining”, London, English Universities Press Bone W.A. and Himus G.W. (1936), “Coal - its constitution and uses”, London, Longmans Green & Co. Department of Trade and Industry DTI (1997), “Digest of United Kingdom Energy Statistics 1997”, London, The Stationery Office Gourvish T.R. (1980), “Railways and the British Economy 1830-1914”, London, The Macmillan Press Williams T. I. (1978), “A History of Technology” vol. VII, Oxford, Clarendon Press Munby D.L. and Watson A.H. (1978), “Inland Transport Statistics, Great Britain 1900 - 1970” vol. 1, Oxford, Clarendon Press IEA (1996), “Energy Balances of OECD countries 1994-1995”, Paris, OECD-IEA Department of Transport DoT (1995), “Transport Statistics 1995”, London, HMSO Smil V. (1994), “Energy in World History”, Oxford, Westview Press BP (1997), “Statistical Re view of World Energy 1997”, British Petroleum Company Ramage J. (1997), “Energy- A Guidebook”, Oxford, Oxford University Press CHAPTER 2 Royal Commission on Environmental Pollution, 18th Report (1994), “Transport and the Environment”, Oxford, Oxford University Press Department of Transport DoT (1995), “Transport Statistics 1995”, London, HMSO BP (1997), “Statistical Re view of World Energy 1997”, British Petroleum Company Department of Environment, Transport and the Regions, DETR (1998), “A New Deal for Transport: Better for Everyone” Government White Paper, London, HMSO CHAPTER 3 Williams T. I. (1978), “A History of Technology” vol. VII, Oxford, Clarendon Press Heywood J.B. (1988), “Internal Combustion Engine Fundamentals”, Singapore, McGraw-Hill Book Co. Ross M. (1994), “Automobile Fuel Consumption and Emissions: Effects of Vehicle and Driving Characteristics”, Annual Review of Energy and Environment 1994, pp.75-112 Bosch (1986), “Automotive Handbook”, 2nd Edition, Milton Keynes, Delta Energy Technology Support Unit ETSU (1996), “Alternative Road Transport Fuels - A Preliminary Life-cycle study for the UK”, London, HMSO
43 Baggot N. (1997), “Is This The Answer?”, Electric & Hybrid Vehicle Technology ‘97, pp.18-25, Dorking, UK&International Press Shultz J. (1997), “Altra Ego - The New Altra EV”, Electric & Hybrid Vehicle Technology ‘97, pp.26-29, Dorking, UK&International Press Baker K. (1997), “Waiting for the Revolution”, Electric & Hybrid Vehicle Technology ‘97, pp.10-17, Dorking, UK&International Press Pellerin A. (1996), “Are You Talking Batteries?”, Electric & Hybrid Vehicle Technology ‘96, pp.68-77, Dorking, UK&International Press Kordesch K. Simader G. (1996) “Fuel Cells and Their Applications”, Weinheim, Germany, Verlagsgesellschaft mbH Lovins A. (1998), “Hypercars: The Next Industrial Revolution”, Rocky Mountain Institute, USA Mellor P.H. (1998), “Study of a Diesel Electric Hybrid Power Train Suitable For a Mid-Sized Passenger Vehicle”, Transactions of the International Conference on Combustion Engines and Hybrids, London, UK, 28-30 April 1998 Mellor P.H., Smith J., McEwan K., Hall N. (1998), “Assessment of Power-Train Technologies for the next generation of Hybrid and Electric Light-Commercial Vehicles”, Proceedings of the European Conference on Vehicle Electronic Systems, London, 16-17 June 1998, ERA Technology Ltd. report 98-0440 CHAPTER 4 European Commission (1996), “European Energy to 2020 - A Scenario Approach”, Luxembourg, Office for Official Publications of the European Communities Bending R. and Eden R. (1984), “UK Energy - structure, prospects, policy”, Cambridge, Cambridge University Press Royal Commission on Environmental Pollution, 18th Report (1994), “Transport and the Environment”, Oxford, Oxford University Press Department of Transport DoT (1995), “Transport Statistics 1995”, London, HMSO World Energy Council (1993), “Energy For Tomorrow’s World”, London, Kogan Page Department of Trade and Industry DTI (1997), “Energy Consumption in the United Kingdom”, London, The Stationery Office CHAPTER 5 Bauer M. (1996), “Transport and the Environment: Can Technology Provide The Answers?”, Energy Policy vol. 24 no. 8 pp. 685-687, Elsevier Science Ltd. Harrop G. (1995), “The Future of the Electric Vehicle - A viable market?”, Financial Times Management Report, London, Pearson Professional Ltd.
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Appendix: Forecasts of road vehicle energy consumption SCENARIO A no. of year
1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030
road vehicles
no. of cars < 1 year old
no. of vehicle-kil average fuel average fuel total road cars > 1 ometres consumption consumption vehicle year old of all road of vehicle energy vehicle stock stock 1 ometres consumption consumption vehicle year old of all road of vehicle energy vehicle stock stock 1 ometres consumption consumption vehicle year old of all road of vehicle energy vehicle stock stock
