Non Renewable Energy Sources

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2.1. Introduction

At present most of the energy used is generated by non-renewable sources such as coal and oil. This immediately raises the problem of what to do when they become exhausted. As it is unrealistic from the point of view of energy generation to look more than about a hundred years ahead, it is important to distinguish between sources that will last more than a hundred years and those that will not. As we shall see, oil and natural gas will almost certainly become scarce and therefore prohibitively expensive some time in the present century. Coal and nuclear will last several hundred years and so do not pose such an acute supply problem. The choice between them depends on other criteria such as pollution and climate change in the case of coal. In this chapter we consider coal, oil and natural gas; nuclear is considered in Chapter 4.

Coal is very plentiful. It made possible the industrial revolution and will remain a major source of energy for the foreseeable future. In the nineteenth century large cities like Birmingham and Manchester in the Britain and Pittsburgh in the USA grew up near the coalfields and millions of rural workers were drawn in to work in numerous factories. Raw materials were brought from faraway countries by coal-powered ships and the manufactured products exported all over the world. Huge railway networks were rapidly built and steam engines fuelled by coal transported people and freight with an ease and speed never before attained.

Coal varies in quality from anthracite that is almost pure carbon to the low-grade lignite coal. In many places the coal seams are at or near the surface, but as these become exhausted deeper and deeper mines became necessary. Originally the coal was cut by miners with pick and shovel, and still is in some countries, but in others sophisticated machinery does the work of many men. The technology is well-known and accepted, and the coal fire, merrily burning in the living room, became an essential part of the family home.

Although huge quantities of coal have been used for over a hundred years, there are still vast deposits in many countries, particularly the USA with 22% of world resources, Russia (17%), China (13%) and India (10%) (Avery 2007). It was estimated in 1996 that the coal reserves amounted to over a trillion tonnes or 760 TWy. At the present rate of world consumption, this is sufficient for well over two hundred years (see Figure 1.2). In the United Kingdom alone, it was estimated in 2005 that the reserves and resources in known mines amount to 500 million tonnes, the estimate for opencast mines is about 600 million tonnes, and for underground gas about 7 billion tonnes (MacKay 2008). This may be somewhat reduced because the rising cost of oil may make it economic to replace it by converting coal to liquid fuel. In Britain, however, coal production is declining and in 2006 coal imports were only 73% of consumption.

Nevertheless, coal has serious disadvantages. Coal mining is dangerous, dirty and unpleasant, and many miners contract debilitating diseases such as silicosis. More important for the whole population is the atmospheric pollution caused by coal burning. Until the prohibition of domestic fires, large cities suffered polluted air. In certain atmospheric conditions a deadly smog can form, stopping all transport except underground trains.

The pollution due to a coal power station depends on the quality of the coal, but in a typical case a coal power station emits each year about eleven million tonnes of carbon dioxide, a million tons of ash, half a million tonnes of gypsum, 30,000 tonnes of nitrous oxide, 16,000 tonnes of sulphur dioxide, a thousand tonnes of dust and smaller amounts of other chemicals such as calcium, potassium, titanium and arsenic. Of these the most harmful pollutant is sulphur dioxide. A study by the National Academy of Sciences shows that the sulphur dioxide released by a coal power station causes annually about 25 deaths, 60,000 cases of respiratory diseases and $12 million in property damage (Cohen 1977). To produce one gigawatt of electricity requires about 3.5 million tonnes of coal, and this contains about five tonnes of uranium. Most of the solids are trapped by filters, but a few thousand tonnes of ash escape into the atmosphere, carrying with it a corresponding fraction of the uranium. This accounts for the radioactivity emitted by coal power stations. The waste is poured into the atmosphere and damages our health, and safe disposal of the millions of tonnes of solid waste has to be arranged. The lungs of rural people are clean, those of city dwellers are grey and those of miners are black.

The emission of carbon dioxide from fossil fuel plants may be greatly reduced by pumping it into underground reservoirs such as pumped out oil wells, coal beds or deep porous rocks like sandstone that are capped by an impermeable layer of another rock. This process is known as sequestration or carbon capture (Liang-Shih Fan and Fan Xing Li 2007). It can reduce the carbon dioxide emissions into the atmosphere by up to 80% and is being studied by eight leading energy companies, and trials are under way in Japan, Norway and Canada. This is a promising development in principle, but it has still to be shown to be economically practicable. A report of the Royal Academy of Engineering gives an estimate of £30 per tonne of carbon dioxide. It would therefore be expensive to sequester the seven billion tonnes of carbon dioxide released every year, and this would increase the cost of electricity by at least one-third, possibly by 75%. Another estimate is that it may increase the cost of electricity to about 5.4 p/kWh. In addition, the generating efficiency would decline by about 10% and the capital costs would be very substantially increased. The cost is partially offset if the carbon dioxide is pumped into an oil well, as the increased pressure pushes more oil out of the well. The process, called carbon capture and storage (CCS), needs about 25 years of research and development at a cost of $20B. A proposal to build a CCS plant at Mattoon in Illinois was abandoned in December 2005 because it was estimated to cost $1.2B.

A serious problem of sequestration is the security of storage. If the carbon dioxide is stored under an impermeable layer of rock, there may still be cracks and fractures that allow some of the gas to escape. It is not possible to control or monitor any leakage that takes place. Even quite small leaks may be dangerous, and a large and sudden release can have serious consequences. Carbon dioxide is not in itself poisonous, but in large quantities it can be lethal if it displaces the air and so deprives living organisms of essential oxygen. In this way it can damage vegetation and asphyxiate animals and human beings.

The dangers of carbon dioxide have been shown by some natural releases. Thus 'in 1989 a slow release, at about 300 tons per day, was identified at Mammoth Mountain in eastern California from a geologically young dormant volcano. Levels of carbon dioxide at about 1% by volume killed about a hundred acres of forest. Although below the 10% level noxious to humans higher concentrations of up to 80% were found in enclosed spaces such as tents or cabins'.

'A more dramatic catastrophic event occurred on August 21, 1986 with the sudden release of about 1.6 million tonnes of carbon dioxide from a volcanic lake at Nyos in Cameroon. About 1700 people, mostly rural villagers as well as 3500 livestock, were asphyxiated. Most of the victims died in their sleep. The gas killed all living things within 15 miles of the lake. About four thousand people fled the area, and many of them developed respiratory problems.' It is not yet known how this happened. Some geologists think that it was due to a landslide, others think that it was due to a small volcanic eruption on the bed of the lake, while others again suggest that cool rain on one side of the lake triggered the event. 'Whatever the cause, the event resulted in a rapid mixing of the supersaturated deep water with the upper layers of the lake, where the reduced pressure allowed the stored carbon dioxide to effervese out of solution'. Pure carbon dioxide is denser than air, so it 'flowed off the mountainous flank on which Lake Nyos rests and down two adjoining valleys in a layer tens of metres deep, displacing the air and suffocating all the people and animals before it could dissipate' (Nuclear Issues 30, March 2008).

In the UK alone the coal power stations produce about 160 million tons of carbon dioxide each year. The consequences of a natural release of just 1.6 million tons in the Cameroon naturally give rise to some concern about the wisdom of sequestration in any places near human habitation.

Another method of removing some of the carbon dioxide is by using an amine scrubber. The amines combine with the carbon dioxide and the resulting liquid is then separated, the carbon dioxide going to storage and the amines are recycled. This process removes less than two-thirds of the carbon dioxide (Pearce 2008).

The total emission of carbon into the atmosphere from fossil fuel (coal, oil and gas) power stations is now about seven billion tons per year, rather more than one ton per person. The actual amount for a particular person depends on his or her lifestyle. Thus, for example, one round trip by a long haul flight emits about half a ton of carbon per person.

The carbon dioxide emitted is partially responsible for the global warming discussed in Section 7.3 and all the other chemical wastes pollute the atmosphere, the land and the sea. These disadvantages are so serious that our dependence on fossil fuels must be reduced.

After a detailed discussion Maslin (2004, p. 143) concludes that 'from the safety and environmental perspectives, the storage of carbon dioxide underground and/or in the ocean is really not feasible however helpful this would be in the short term'.

Oil has been known since ancient times, but it was only in the nineteenth century that it began to be used on a large scale. The first oil well was drilled in Pennsylvania in 1859, and thereafter production rose rapidly. Oil has a higher calorific value than coal and is more easily extracted and transported, and so during the twentieth century its use increased rapidly until it became one of the world's leading energy sources. It can be burned like coal for domestic heating and ship propulsion but is mainly used in large amounts in cars and aeroplanes that cannot be driven by coal. Thus in 2006 transport consumed about 60-70% of the oil. Huge oil tankers bring oil daily to refineries and distribution centres, whence it goes to petrol stations and airports. Our lives thus depend much more directly on a continuous flow of oil than on the availability of coal. If the oil supply is interrupted even for a few days there are immense repercussions as transport and industry come to a stop. In addition, oil is the basis of a large range of new petrochemical industries such as plastics, dyes, drugs, and paints. It can also be used for desalination of seawater in arid countries bordering the sea.

Oil wells generally last for about twenty or thirty years, and then the flow diminishes and it becomes increasingly expensive to pump it out. There comes a point when the energy spent in extracting the oil is greater that obtained by burning it, so that further extraction is uneconomic. Using sophisticated seismic and other geophysical techniques, oil companies therefore continually look for new oil fields to replace those that are becoming exhausted. Those found in recent decades in places such as Alaska and the North Sea are in much more inaccessible places than those in the Middle East, and the cost of extraction is correspondingly high.

The rate of oil production in the future can be estimated from the rate of discovery of new oilfields. The chilling fact is that the rate of discovery is falling, as more and more of the earth is explored. No new supergiant oilfields such as those in Alaska, that supply the bulk of the oil, have been found since 1975. It has been estimated that to maintain present oil production it is necessary to find new oilfields equivalent to that in the North Sea every two years. Geologists familiar with the poor rate of discovery during recent years believe this to be impossible even with the latest technology, so that oil production must soon reach its maximum and start to fall. In the USA, for example, oil production peaked in the late 1970s with the production of about 10 million barrels per day and by 2005 this had fallen to about five million barrels per day. Oil production in Venezuela peaked in 1998, in Indonesia in 1999 and in the UK also in 1999. The volume of newly-discovered reserves peaked in 2000 (Monk 2005). Worldwide, the peak is likely to be a broad one, and estimates of when this will happen vary. Thus IEA (International Energy Agency) predicts 2020-2030, BP (British Petroleum) 2015-2020 and ASPO (Association for the Study of Peak Oil and Gas) <2010 (Nuclear Issues 28, August). After the peak there will be a slow decline by about 3% per year, and as soon as the peak is passed the price will rise rapidly.

The European Community is heavily reliant on imports of oil and gas. A Report in 2001 found that 51% of oil imports come from OPEC countries and 42% of the natural gas from Russia. The oil from PEC countries was supplied by Saudi Arabia (13%), Libya (10%), Iran (9%), Iraq (7%) and Algeria (4%). Many of these sources are unreliable on the long term. The natural gas from Russia comes through a long pipeline that is politically vulnerable (Nuclear Issues 23, March 2001).

At present we are highly dependent on oil, particularly for transport. In addition, there will be increased demand from large developing countries such as China, India and Brazil.

The vital question is how long will there be enough oil, and the other fossil fuels gas and coal, to supply our needs. The current estimates are that at the present rate of use there is enough oil to last forty years, natural gas sixty years and coal 230 years. These figures are not so alarming as they appear, because they are obtained by dividing the known reserves by the annual consumption and this does not imply that after these times the reserves will be exhausted. Indeed, continuing studies reveal the surprising fact that these figures remain almost constant from decade to decade, as shown in Figures 1.1 and 1.2. The explanation is that as the existing reserves are used up the price rises and this stimulates searches for new oilfields and the development of new techniques for extracting more oil from existing ones. This produces more oil, so the price falls again. This in turn increases consumption, so that more oil is used and the price rises again. The overall result of this feedback mechanism is that the oil price remained fairly steady for some years in the range of $15 to $30 per barrel. Subsequent events have confirmed that this is over-optimistic and obviously it cannot go on forever.

In addition to these economic considerations, oil prices are subject to political decisions by the OPEC countries. This was the reason for the sharp rise in oil prices in 1973. Increased prices also occur when the demand exceeds the capacity of the refineries. At present average oil prices continue to increase: during 2004 and 2005 they rose from $35 to $55 per barrel, in 2008 they reached $120 and are predicted to rise still further.

These remarks refer to the world as a whole. The changes are more rapid in individual countries. Thus for example in Britain the oil will be exhausted in about five years and gas in about seven years. After that, without a new energy source, we will have to rely on gas imported from Libya and Russia.

Continuing dependence on oil is thus politically unwise. Most countries do not have their own oilfields, and so have to import the oil they need, putting themselves at the mercy of the oil-producing countries. Well over half the remaining proved oil reserves, amounting to between one and three trillion barrel or 130 to 320 GtC, are in the Middle East. In 1989 the percentages of oil imports from that region were 63% (Japan), 29% (Western Europe) and 11% (USA). This dependence is particularly critical because the Middle East oil reserves are expected to last about 100 to 150 years, whereas those in the rest of the world are likely to be exhausted in ten to fifteen years. Thus we will become increasingly dependent on Middle Eastern oil (Avery 2007, p. 111). By 2030 about 46% of world oil production is expected to come from the Middle East.

There are very large deposits of oil and tar sands in northern Alberta. It is however very costly to extract the oil, and it has been estimated that about two-thirds of the oil is consumed in the extraction process. There is also a large deposit of super heavy oil or tar in Venezuela. These sources of oil are heavily polluting, and if nevertheless they are developed will prolong the availability of oil, but not prevent its ultimate decline.

Thus while there is no reason to expect an imminent shortage of fossil fuels, there is a continuing need for flexible planning and the search for new sources. Despite its many advantages, it is imperative to reduce our demand for oil. It is extremely wasteful to burn it in power stations, especially because it is the only practicable source for aeroplanes, cars and the petrochemical industries. In addition, burning it in power stations produces carbon dioxide and so it contributes to global warming.

A proposal to alleviate the oil crisis has been made by the Association for the Study of Peak Oil. Their Oil Depletion Protocol 'requires the oil importing nations to reduce their imports by an agreed yearly percentage, the World Oil Depletion Rate, so as to put demand in balance with the declining world supply. At the same time the producing countries would agree to reduce their rate of production by a National Depletion rate — determined individually for each producing country as the total yet-to-produce oil divided by the yearly amount currently being extracted. The Department of Trade and Industry's figures for the UK continental shelf estimate the total remaining oil reserves at 1267 million tons with an annual production in 2005 of 85 million tons to give a depletion rate of 6.7%' (Nuclear Issues, April 2007). There will certainly be strong opposition to this proposal, but if it is accepted it will postpone the oil crisis, hopefully long enough for alternative energy sources to be developed.

Since a large fraction of the oil that is produced is used for transport, it is imperative to find new ways of driving our cars, buses, lorries and ships. Several possibilities are the subject of current research. One is to use liquid hydrogen as a fuel (see Section 3.10), another possibility is compressed air. Electricity is already used to drive trains and trolley buses, but cars require efficient ways of storing electricity. Already the Lotus company has developed the Tesla Roadster, a battery-driven car that does 135 mph, accelerates to 60 mph in four seconds and runs for 225 miles on one battery charge. However, it costs £50,000. The Indian company

Tata is working on a car driven by compressed air. The Italian company Pinifarina that works with Ferrari has built a car using hydrogen and fuel cell technology. These new developments are not yet commercially viable, but they indicate the paths that must be taken. Hopefully their costs will be reduced sufficiently by further research.

2.4. Natural Gas

Natural gas is often found not only associated with oil, but also independently. It can be used for heating and lighting, and before the advent of electricity gas was obtained from coal for this purpose. It is still widely used for domestic cooking and heating. Gas can be transported over large distances by pipeline, but in many places this is not practicable and so it is just burned at the oil wells and refineries. It can also be liquefied and transported in refrigerated tankers by ship, road and rail.

Gas can also be burned in power stations just like coal, and can also be used in many chemical industries. The large gas fields in the North Sea have made gas the cheapest form of energy at the present time, and hence stimulated what is called the 'dash for gas'. In Britain all the new power stations are gas-powered and they cost £400 per kWh to build. This is relatively cheap and convenient while it lasts, but it is predicted that the North Sea gas will be exhausted quite soon. After that, gas will have to be imported, with the same political dangers as oil.

The contribution of gas to world energy production has risen rapidly from less than 10 EJ in 1963 to about 80 EJ in 1993, accounting for about 21% of the world total. The proven reserves of gas are similar to those of oil, and the rate of consumption is only a little over one-half of that of oil. As the rate of consumption is rising rapidly it is unlikely to last longer than oil. A large gas field in Siberia is now supplying Western Europe with gas through a 5000-mile high pressure pipeline. In 1991, this supplied 20% of West European gas, including Finland (100% of total domestic supply), Austria (76%), Germany (34%), France (31%) and Italy (29%).

In the period 1992-1996 the total gas consumption in Britain increased by 45%, and this has led to price increases. The Energy Advisory Panel has estimated that the price of 17.3 pence per therm in 1990 is likely to rise to between 22.0 and 28.8 by 2005 and 25 and 37 by 2020.

The estimated natural gas reserves in 1996 amounted to 1412 trillion cubic metres, corresponding to an expected lifetime of just over sixty years. Of these reserves, 40% are in the former Soviet Union and 32% in the Middle East. For Britain, the estimated lifetime is about seven years. It is expected to peak a few years after the oil, and then rapidly decline.

In many respects, gas is now the cheapest, safest and most convenient energy source, but its lifetime is severely limited.

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