1.1 Sources of energy

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Owen Warren
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1 1 Energy use 1

2 1.1 Sources of energy All energy is derived ultimately from the elemental matter of both the Sun and the Earth, formed in supernovae over six billion years ago. From the Sun we have both energy trapped in fossil fuels and the main contemporary renewable sources. From the elemental substance of the Earth we have uranium and geological heat. The Sun warms our planet, and provides the light required for plants to grow. Throughout past geological ages, the Sun s energy has been incorporated into plant and animal life (biomass). Through the burial and decay of biomass, the Sun s energy has been stored in coal, oil and natural gas deposits the all-important fossil fuels on which our modern civilisation depends. The only other ultimate energy source in the Earth is from the atoms of particular elements formed before the Solar System itself. These are found today in the Earth s crust 1 and mantle. The amount of energy in an atom is dependent on its size: the minimum amount of energy per unit mass is contained within the mediumsized atoms (such as carbon and oxygen), while the greatest amount is contained in small atoms (such as hydrogen) or large atoms (such as uranium). Energy can therefore be released by combining the nuclei of small atoms (fusion), or by splitting large atoms (fission). The tapping of this energy by fission or fusion of atomic nuclei is one of the most important and contentious human achievements in history. There is no shortage of energy on Earth, though a large proportion of the world s inhabitants are without access to a reliable supply of it. For them, the issue is how best to supply their needs, with the priorities being cost and availability. But for many of us, the issues are extended to include security of supply both amount and reliability and the reduction of carbon dioxide emissions. Sustainability of energy relates both to adequacy of supplies in the long-term, and the environmental effects of its use. Many people in developing nations aspire to the standard of living, mobility, agricultural productivity and industrialisation characteristic of developed countries. Fulfilling these hopes depends on the availability of abundant energy. Growth of the world s population from the present level of 7.3 billion people to a projected 9.2 billion in 2040, with most of the growth from developing nations, increases the challenge. In industrialised countries energy demand is in three major sectors: domestic and commerce; industry and agriculture; and transport. In many countries, these each account for about one-third of the energy demand, although the size of domestic demand depends very much on climate. In Australia domestic demand is relatively small, whereas in Canada, for example, it is relatively large because of the cold winters. More specifically it is possible to identify demand for particular purposes within these sectors, such as: Low temperature heat (up to 110 C) for water and space heating in homes and industry. High temperature heat (over 110 C) for industrial processes. Lighting. Motive power for factories, appliances and some public transport. Electricity for smelting metals. Mobile transport for public and private use. Figure 1. World primary energy demand EJ Energy demand and supply today The levelling-out of overall energy demand in developed countries in recent decades is primarily a result of increased energy efficiency. However, in developing countries growth in energy demand from a low starting point continually increases the pressures on resources worldwide, despite conservation initiatives see Table Year Other renewables Bioenergy Hydro Nuclear Oil Gas Coal Source: Table 2.2, IEA World Energy Outlook 2016, New Policies Scenario 1 Uranium appears to have been formed in supernovae about 6.5 billion years ago, and although not common in the Solar System, has been concentrated in the Earth s crust at an average of about 1.4 ppm. Heat from radioactive decay of this uranium drives the convection processes in the Earth s mantle, and is vital to life. 2

3 Table 1. Growing electricity demand (TWh) OECD ,040 10,372 11,388 Non-OECD 10,996 13,147 15,383 22,862 E. Europe/Eurasia Asia except China China Middle East Africa & Latin America World 20,557 23,186 25,755 34,250 Source: Table 6.1, IEA World Energy Outlook 2016, New Policies Scenario Figure 2. Primary energy import, use, export in 2015 (PJ) Net import Own use Net export Australia 5472 Canada France Germany Japan South Korea UK For some of these purposes there is a significant demand for energy in the form of electricity. Worldwide, electricity demand is increasing very rapidly, as illustrated in Table 1, and Figures 3 and 4. This is discussed further in Section US On the supply side, there are a number of primary energy sources available see Figure 1. Derived from these primary sources are several secondary energy sources or carriers. These include, for example: Electricity can be generated from many primary sources. Hydrogen mainly from natural gas. Alcohols from wood and other plant material. Oil and natural gas occur naturally, but can be manufactured from coal. At this stage, only electricity is of major importance as a secondary source, but hydrogen or methanol are expected to become significant in the future as a replacement for oil products used for transport see Chapter 7. Much energy demand can be met by more than one kind of energy supply. For instance, low temperature heat can be produced from any of the fossil fuels directly, from electricity, or harnessed from the Sun s radiant energy. Other demands such as mobile transport need to be supplied by portable and energy-dense fuels such as those derived from oil or gas, or from electricity. Both economic practicality and ethical considerations suggest that versatile, energy-dense, easily portable energy sources such as oil and its derivatives should not be used where other, more abundant fuels can be substituted. Different energy sources yield different amounts of energy per unit mass or volume, as shown in Table 2 at the end of this chapter. Primary energy resources in different countries vary enormously. There are great differences in natural endowment and this makes clear the importance of trade in energy, as indicated in Figure 2. Australia and Russia Saudi Arabia Area of colour is indicative of amount of primary energy. Russia and Saudi Arabia: 2014 figures. NB: imports and exports including 500 TJ/tonne. Source: IEA World Energy Balances 2016 Saudi Arabia export about twice as much energy as they use, Japan and South Korea import 95% and 87% of their energy respectively, apart from uranium, which increases those figures significantly. Germany imports two thirds of its energy. 1.3 Changes in energy demand and supply The uneven world distribution of energy resources means that as energy consumption rises, international trade in energy is very likely to increase. Energy-poor countries find themselves dependent on supplies from energy-rich countries as Figure 2 illustrates. Because of the fundamental importance of energy in the industrial economy, importing countries are vulnerable politically and economically. A good illustration of this vulnerability is the changing position of oil. Until the early 1970s, many countries had come to depend heavily on oil because of its relatively low cost, and world oil production tripled between 1960 and But this suddenly changed as prices rose 3

4 sharply, and with a further oil crisis in 1979 prices rose four-fold. As a result, alternatives were found and world oil consumption in 1986 was broadly the same as that in 1973, despite a substantial rise in total primary energy consumption. Forecasts in 1972 had generally predicted a doubling of oil use in ten years. The challenge of oil prices and supply in the 1970s brought about rapid changes in the production and use of other primary energy resources: Coal production and international trade in coal increased to substitute for some oil use in power generation. Nuclear power for electricity generation was adopted or examined more closely, particularly by energy-deficient countries. Most countries looked more closely at adopting measures to restrain energy consumption, and this focus continues. Renewable energy sources became significant in the supply of electricity. Japan for example, has few indigenous energy resources and little untapped hydro-electric potential. It suddenly found that supplying three-quarters of its total energy needs with oil was not sustainable in the face of escalating import costs. Even the USA, originally self-sufficient in oil, found it difficult to pay for enough imported oil to offset declining domestic production at that time. The USA was also the world s largest importer of natural gas, and security of energy supply became a major factor in its foreign policy until fracking provided substantial new domestic resources of oil and gas in the last decade. The thrust of these changes continues. Throughout the world it has been proved that it is possible to use significantly less energy per unit of economic activity. Oil use for generating electricity peaked at 22% of power produced in 1973; it now provides about 4% of electricity. The use of natural gas for electricity has increased, especially due to the inter-regional shipment of gas in its liquefied form (LNG). Wind is now the fastest-growing source of electricity. Electricity is uniquely useful for driving machinery and for lighting in both industry and homes. However, it is also used for heating and in other ways for which alternatives are readily available. It can be argued that in view of the relatively low efficiency of energy conversion to electricity (typically around 35-45%), alternatives such as natural gas should be used directly wherever possible for heating (at double the efficiency) 2. Conversely, it can be argued that uranium and coal resources are large relative to gas resources, so the most abundant primary fuel should be applied wherever possible, and that, as such, electricity use for heating (at almost 100% end use efficiency) is desirable if the electricity is produced from plentiful coal or nuclear power despite a much higher consumption of primary energy. In relation to coal, however, this argument is heavily qualified due to the one kilogram per kilowatt-hour carbon dioxide (CO 2 ) emissions. The role of electricity is increasing because it is an extremely versatile form of energy which can be generated from a wide range of fuels and can easily be reticulated to where it is in demand. In one sense the Sun is the world s most abundant energy source and the desirability of applying it more widely to direct heating as well as for generation of electricity on an increasing scale hardly needs emphasis. Meanwhile wind is increasingly harnessed for electricity. Questions concerned with the production of electricity from intermittent renewable sources are discussed in Section 2.6 In the following chapters electricity demand, use and generation are the focus of discussion. In particular the use of nuclear energy to generate electricity is discussed. The main nuclear fuel concerned is uranium, a metal which at present has virtually no other civil uses. 1.4 Future energy demand and supply Where will we obtain our future energy needs? There are a number of uncertainties: Oil production peaked in 1979 and did not return to that level until 1994, but is now abundant due to new production techniques. In addition, peak oil fears have abated. Its natural attributes mean that its optimal use remains as a transport fuel. Natural gas production, while increasing rapidly now due to its recovery from shales, is likely to approach its peak in many countries over the next couple of decades. Underground coal is costly to mine, and all coal use gives rise to concern about its effect on the climate. 2 Considering the whole sequence from production to end use, the efficiency of gas for heating is often about 40-45%. For modern highefficiency furnaces the value increases to about 70%, but overall it depends on the distance from gas sources. 4

5 Figure 3. World electricity generation - New Policies Scenario 40,000 35,000 30,000 25,000 Figure 4. World electricity generation Scenario 40,000 35,000 30,000 25,000 TWh 20,000 TWh 20,000 15,000 15,000 10,000 10,000 5,000 5, Year Year 2040 Other renewables Hydro Nuclear Fossil fuels Source: Table 6.2, IEA World Energy Outlook 2016, New Policies Scenario Inherent features of renewables mean they alone cannot satisfy all energy requirements, in the case of wind and solar due to their intermittency and low energy density. Further scope for energy conservation is limited without radical changes in lifestyle in developed countries, and is less significant in developing countries as per capita use is low. Since the oil shocks of the 1970s, many industrialised nations set out to reduce dependence on oil and develop other strategies including greater use of nuclear energy. Today the principal driver of much energy policy is not economic but environmental, with concern about global warming. As economic growth continues in most nations, and the world population grows to over nine billion by 2040, increased global energy demand is inescapable. Successive editions of the OECD International Energy Other renewables Hydro Nuclear Fossil fuels Source: Table 6.2, IEA World Energy Outlook 2016, 450 Scenario Agency s (IEA s) World Energy Outlook examine the matter, and its New Policies Scenario of the 2016 edition informs the comments here, with some reference to its more ambitious 450 Scenario, which is consistent with the goal of limiting the global increase in temperature by all means possible. The New Policies Scenario is based on national targets and intentions that have been announced. It expresses reasonable expectations going forward but is not a forecast. The 450 Scenario works back from desired decarbonisation goals and sets out some implications. Figures 3 and 4 illustrate the difference. Looking ahead a couple of decades, it is not today s industrialised countries which will dominate the scene China has already overtaken the USA as the world s largest energy consumer, and by 2040 it is expected to use nearly twice as much energy as the USA. Energy demand in India has been higher than in Russia since 2009, making it the world s third-largest energy consumer, and by 2040 it is expected to have doubled, reaching more than 90% of the USA s demand. Fossil fuels are expected to still account for 74% of primary energy consumption in 2040, compared with 81% now, and natural gas will increase its share. Offshore oil-gas worker (TRAC Oil & Gas) Global oil use to 2040 is projected to continue to increase, mostly driven by China and India, while consumption in the USA and Europe declines modestly. Natural gas use to 2040 is projected to increase by nearly 50%, mostly in the Middle East and China. Moving the product in its liquefied form (LNG) consumes a significant proportion of it. Shale gas is widely distributed, but extracting it is sometimes 5

6 problematic, and there are growing concerns over the associated release of methane. Much of the projected increase in demand for gas to 2040 comes from the power sector, though its share of electricity production drops from 40% to 38%. attractive to use on a large scale, but has the greatest contribution to greenhouse gas emissions of any fossil fuel. Carbon capture and storage (CCS) technology could boost the long-term prospects for coal, but that is unlikely to play a major role before While coal-fired power generation doubled in the 20 years to 2014, growth in coal use will slow down, with a projected 5.5% increase in demand to By 2025 India becomes the world s second largest coal user, after China. China already accounts for almost half of world coal production. Coal remains very abundant and is often available close to where it is needed most coal is used in the country in which it is produced. (Inter-regional trade in coal is expected to remain at about 19% of total coal consumed.) It is economically Table 2. Energy conversion: the heat values of various fuels Fuel Heat value Hydrogen (H 2 ) MJ/kg Methane (CH 4 ) MJ/kg Methanol (CH 3 OH) 22.7 MJ/kg 18 MJ/L Dimethyl ether (CH 3 OCH 3 ) 29 MJ/kg 19 MJ/L Petrol/gasoline 44 MJ/kg 32 MJ/L Diesel fuel 45 MJ/kg 39 MJ/L Crude oil MJ/kg MJ/L Liquefied petroleum gas (LPG) 49 MJ/kg Natural gas (UK, USA, Australia) MJ/m 3 (Canada) 37 MJ/m 3 (Russia) 34 MJ/m 3 as LNG (Australia) 55 MJ/kg Hard black coal (IEA definition) >23.9 MJ/kg Sub-bituminous coal (IEA definition) MJ/kg Lignite/brown coal (IEA definition) <17.4 MJ/kg (Australia) 9.8 MJ/kg Firewood (dry) 16 MJ/kg Natural uranium* in LWR (normal reactor) 500,000 MJ/kg in LWR with U & Pu recycle 650,000 MJ/kg in FNR 28,000,000 MJ/kg Uranium enriched to 3.5%, in LWR 3,900,000 MJ/kg *NB: natural uranium normally needs to be enriched to be used, the above figures are for it as mined. Uranium figures are based on 45,000 MWd/t burn-up of 3.5% enriched U in LWR. MJ = l0 6 Joule, GJ = 10 9 J; % carbon is by mass; mass CO 2 = mass C. MJ to 33% efficiency: x For hydrogen and methane, lower heating value is given (net of latent heat of vapourisation for water) Sources: IEA Electricity Information 2016, for coal; Australian Energy Consumption and Production, historical trends and projections, ABARE Research Report Nuclear output is expected to increase by almost 80% to 2040, slightly increasing its relative share of global electricity generation to 12% in the New Policies Scenario, thanks largely to investment in China. In the 450 Scenario it rises to 18%, which is closer to what is needed. Much of the increase in electricity generation to 2040 comes from non-hydro renewables, which are expected to increase their share of the total from 6% to 21%, mostly wind and solar PV. However, the diffuse and intermittent nature of wind and solar is likely to limit their potential. Hydro is projected to maintain a 16% share. Nearly one-fifth of the world s population does not have access to electricity supply, and a further third does not enjoy reliable supply. Almost 40% of people are without access to clean cooking facilities. There is a huge need to address these shortcomings, meet expectations and reduce poverty, whilst implementing sustainable development principles. Providing affordable power is a major part of the development solution. China and India have demonstrated that widespread access to electricity can be provided quite rapidly. Energy consumption in OECD countries is forecast to decrease by almost 4% to 2040, while that in developing countries, with accelerating urbanisation and industrialisation, is expected to grow by 51%. Overall world primary energy demand is expected to increase by 31% from 2014 to 2040, but electricity demand is expected to grow by 67% over the same period, with China and India accounting for more than half of that increase. The share of electricity in final energy consumption has doubled since the 1970s, and continues to grow from 18% in 2013 to 24% in 2040, or significantly more in the 450 Scenario. 6

7 Since the 1970s, economic factors have constrained energy demand in OECD countries, and have resulted in unprecedented increases in energy efficiency in industry and transport. The future scope for energy conservation depends on the sector involved. Where energy is a significant input to industrial processes or to transport, or an obvious cost to consumers such as with motor vehicles, major steps have already been taken to increase efficiency and hence lower costs. But where energy costs are relatively less significant, such as in commercial and residential buildings, it is likely that much scope for improvement remains. Electricity demand is growing much faster than overall energy demand. The global fleet of electric vehicles is projected to increase from 2 million in 2016 to about 150 million in Whilst impressive, this growth would result in electric vehicles comprising about 8% of all passenger vehicles in 2040, so will only have a small effect on power demand about 140 TWh/yr, except in the 450 Scenario which has higher figures and leads to demand for about 1200 TWh/yr (4% of total electricity). Energy conservation is very difficult to project. To continue to be effective, it requires a present response to future prospects of higher energy costs. It demands an attitude to energy use and lifestyle which is increasingly conservation-oriented, so that the rate of increase in overall energy consumption remains depressed after the initial easy fixes have been achieved. Despite popular acceptance of environmental ideas, there is little evidence anywhere in the world of such an attitude taking precedence over individuals desires for comfort and amenity. There is also a rapidly increasing demand for potable water in many areas with very limited water resources, particularly in North Africa and the Middle East. About 5 EJ of energy was used for water supplies in 2014, about 60% as electricity some 820 TWh, which is projected to increase to 1470 TWh in The largest part of this is projected to come from desalination, with production from seawater increasing almost nine-fold and brackish water desalination increasing five-fold. Thus in 2040 desalination accounts for more than 20% of all electricity consumed by the water sector, up from only 5% today, half of this being in the UAE. The greatest increase in desalination capacity to 2040 is in Saudi Arabia, which is likely to require an extra 100 TWh/yr (see also Section 7.4). 7

I. CITIES AND ENERGY USE

I. CITIES AND ENERGY USE A. Background Energy is the lifeblood of modern industrial society. Modern cities rely heavily on fossil fuels for the maintenance of essential services and for powering devices