Ron Hester is an emeritus professor of chemistry at the University of York. In addition to his research work on a wide range of applications of vibrational spectroscopy, he has been actively involved in environmental chemistry and was a founder member of the Royal Society of Chemistry’s Environment Group. His current activities are mainly as an editor and as an external examiner and assessor on courses, individual promotions, and departmental/subject area evaluations both in the UK and abroad.

Roy Harrison OBE is Queen Elizabeth II Birmingham Centenary Professor of Environmental Health at the University of Birmingham. In 2004 he was appointed OBE for services to environmental science. Professor Harrison’s research interests lie in the field of environment and human health. His main specialism is in air pollution, from emissions through atmospheric chemical and physical transformations to exposure and effects on human health. Much of this work is designed to inform the development of policy.

Sustainability and Environmental Impact of Renewable Energy Sources

By R. E. Hester, R. M. Harrison

The Royal Society of Chemistry

Copyright © 2003 The Royal Society of Chemistry
All rights reserved.
ISBN: 978-0-85404-290-6

Contents

The Future of Today’s Energy Sources Bernard J. Bulkin, 1,
Sustainable Energy: Choices, Problems and Opportunities David Elliott, 19,
Renewable Energy: Technology Considerations and Electricity Integration David Infield and Paul Rowley, 49,
Landfill Gas and Related Energy Sources: Anaerobic Digesters; Biomass Energy Systems Adrian Loening, 69,
Emissions Trading Schemes: Are They a ‘Licence to Pollute’? Fiona Mullins, 89,
UK Government Policy on Renewable Energy Brian Wilson, 105,
Renewables, Sustainability and Precaution: Beyond Environmental Cost–Benefit and Risk Analysis Andrew Stirling, 113,
Subject Index, 135,

CHAPTER 1

The Future of Today’s Energy Sources

BERNARD J. BULKIN

1 The 1973 Energy Crisis

Crises inspire change. In 1973, the oil embargo associated with the Yom Kippur war led many people to look at the technologies around energy and predict that radical change would occur. There were forecasts, taken very seriously, that by 2000 oil would be nearly gone. The internal combustion engine was seen as having reached the limit of its ability to develop. Environmental concerns over air pollution were also seen as driving the rapid growth of nuclear power, and there was considerable effort being expended on commercialization of solar energy. Yet even at that time, some futurists warned that ‘energy crises’ had occurred before, and rarely had the predicted outcomes. Examples were the energy crisis associated with the lack of sites for new water wheels, and those created in many places by lack of wood through deforestation.

The main outcome of the 1973 ‘energy crisis’ was efficiency. In the United States, as shown in Figure 1, the fuel economy of the car fleet doubled between 1973 and 1980. Appliances also became much more efficient: the average new refrigerator in the United States by the late 1990s was nearly 300% more efficient than in 1973 (Figure 2). These changes, which took place relatively rapidly, have shown great staying power.

The other big outcome was a shift away from oil as a fuel, particularly for power generation. In 10 years, oil went from being 17% of US power generation to about 2.5%. The shift was technically possible (coal and nuclear were the big winners, but once this driving force was removed, nuclear growth slowed) and economically desirable.

However, the core technologies of how we generate and consume energy, and the fuels we use, did not change radically. Perhaps the biggest change on the generation side, the growth of combined cycle gas turbines, was less a technological breakthrough than the conscientious application of basic principles of thermodynamics, made possible by a combination of materials science and information technology. As far as use goes, cars are still powered by internal combustion engines (though with increased use of another old technology, diesel engines, in Europe), not by batteries or Stirling engines. Refrigerators look and function in much the same way today as they did 25 years ago.

There are lessons to learn from a look back of a quarter century. We see that radical change is possible. Doubling fuel economy of cars, tripling the efficiency of some major appliances, major changes in fuels (the UK went from 87% of its primary energy coming from coal in 1950 to 18% in 2001) do happen, and they are not fluctuations, but have long lasting effects. However, we also learn that the system has great resilience. There is a huge entrenched infrastructure which has great efficiency associated with it, and it takes major systemic shock (such as occurred in 1973) to upset it.

There are also important lessons on supply. Predicting the future supply of any fossil fuel is probably impossible. Supply over the timescales we can consider relate to margin — price minus cost — rather than to fundamentals of the geology of the planet. It is also difficult to predict either price or cost with any degree of accuracy, so the uncertainty in the difference is very great. In subsequent sections this will be illustrated with reference to developing an understanding of the current reserves of the major fuels used today, and views about the future supplies of these fuels.

2 How Fossil Fuels Have Affected Our Lives

Until the 19th century, human progress was limited by the amount of work that people could do in a day to feed themselves and their families. The economy was largely rural as a result. Beginning in the 19th century, people began to develop coal, oil and other stored energy sources to supplement solar energy. The results of plant and animal growth through solar energy, over huge areas and geologic time periods, coupled with violent geological upheaval, became available for human exploitation. Knowledge was required to develop machines capable of coupling these power inputs to human needs, and to be sure the great scientific work of the pioneers of thermodynamics and its application were critical. But what really changed the nature of how people lived on this planet was the several orders of magnitude increase of the energy sources that were available. There was, and continues to be, excess energy available to obtain more fossil fuels, to do research on how to exploit these fuels more efficiently, and to use them to drive change in cultures. Progress from that time until now has been ‘like a flash explosion compared to the steady fires of the evolutionary record for previous millions of years’.

One of the most important results of industrialization based on these energy sources is abundant food. Odum has pointed out that it is an illusion, and a conceit of industrial society, that we are better at using the sun to grow food than our predecessors. Nothing could be further from the truth. In fact, we no longer eat food made completely from solar energy: we now eat potatoes made partly of oil! The same is true in the growth of animals for both meat and dairy products. This is not just the case on the farm, but also in the factories where farm machinery is made, fertilizer is manufactured, and in the universities where farming research is done on productivity. In effect, as Odum makes quantitatively clear, our society is developed around a ‘fossil fuel subsidy’, somewhat supplemented by a nuclear energy subsidy. In this paper, one of the questions we are looking at is: how long can this continue?

3 Energy Use in the World Today: Fuels and How They Are Used

Figure 3 shows a view of the energy use in the World. It is conveniently divided into four major categories: transport, power generation, industry/domestic/agriculture, and the small amount used to convert one fuel to another (e.g. energy cost of refining of petroleum into gasoline and diesel fuel). The figure shows not only the quantities for each category of energy use, but also the fuel mix of the category.

As is well known, transport is completely dominated by oil. All other fuels combined are not sufficient to show up on a graph this size. Clearly the oil business is very dependent on demand from the transport sector, and the transport sector is very vulnerable to any disruption of supply of oil, as the entire infrastructure is built around a single fuel source.

This is not the case for the other major sectors. Power generation is very diversified, with coal, gas, nuclear, hydroelectric and oil all having significant shares. Renewables in this case are mainly wind power and a small amount of solar photovoltaic. In the case of power generation, the diversification of fuel can even occur locally; that is, a particular electric utility supplying a populous region might derive electricity from as many as four different fuels.

The energy sources for industrial/domestic and agriculture are also very diversified. Here renewable energy, which is a substantial contributor, is almost entirely burning of biomass in developing world countries. It is questionable whether this should be classified as renewable, as in many cases it results in deforestation and poor land use.

This chart and the trends that lead to the current situation are practically all one needs to know about today’s energy sources. The following are key observations:

• Transport receives a huge amount of attention in regulation and technology development, but represents less than a quarter of all energy use. Growth in the developed world is very slow in this sector. Most vehicles are in cities, and congestion is limiting growth. In the United States and parts of Western Europe there are already as many cars as licensed drivers. The potential for growth in China and India is still very great.

• Power generation is a big sector, and continues to grow strongly everywhere in the world. By contrast with transport, there seems to be nothing that will limit demand for electricity, as even the most affluent societies find new uses for electric power. As far as fuels for power generation are concerned, the last 30 years have seen significant reduction in the use of oil, and it is possible that the remaining oil could be squeezed out, certainly from all but small generators; despite widespread perception to the contrary, nuclear power continues to grow (2.8% in 2001), both through a few new plants and from higher utilization of existing plants; renewables are growing at a very rapid rate, especially wind and photovoltaics, but from a very small base and in small in crements — new capacity is generally in kilowatt additions, in contrast to big power plants in the hundreds of megawatts range; there is a continuing shift towards gas and away from coal, for environmental reasons, but the coal reserves of China are much greater than the gas reserves, and one can expect a significant amount of China’s future electric power to be coal generated.

• The largest sector, industry/domestic/agriculture, is the most diverse in every way. It is closely tied to GDP growth, so most affected by worldwide economic conditions. It is also the most distributed, and the hardest to regulate. While there is great diversity in fuel use, it is often difficult to effect change in fuels, as a particular user in a given geographic region is often tied to just one fuel. The greatest potential here is for efficiency improvements.

• Projections of how this chart will change over the coming two decades are extremely difficult and involve big assumptions. Figure 4 shows the evolution over the past 25 years, but may not be a guide to the future. For example, there are projections that are widely used showing that power generation will double from 2000 to 2020, and that the share of gas will also double (so an absolute increase in gas consumption for power of four times), while the share for nuclear power will halve. However, this assumes that no new nuclear power plants will be built during this period, and that some of the existing ones will not be relicensed to operate when their current licenses expire.

4 Nature of Oil, Coal and Gas

While we talk about the fossil fuels as if they were three substances, the reality is quite different. Each of these is found in the world with a wide variation in composition, and this variability is a big factor in determining the future of fossil fuels, both locally and globally.

In many ways, gas is the simplest. After all, methane is methane. However, as one might expect, natural gas resources have small but varying levels of C2-C4 hydrocarbons, hydrogen sulfide and, more importantly, most natural gas is found with CO2 and nitrogen. The proportion of CO2 varies widely, from less than 1 % to more than 70%. While separation of the hydrogen sulfide is straightforward and relatively inexpensive, and the higher alkanes can be separated if there is an economic use for them, or left with the methane, the carbon dioxide poses more complex problems. It greatly affects the heating value of the fuel, as does the nitrogen. Separation of the CO2 is costly, more so since there is little market for it. For giant fields with a high CO2 content, such as the Natuna field in Indonesia, after separation the CO2 must be reinjected or sequestered if it is not to have a major impact on atmospheric CO2 levels.

Oil is more complex. On the one hand, crude oils are similar in that they contain some of every possible hydrocarbon isomer from C4 up to very long chains. However, there the similarity ends. There is a very great variation in the chemical composition of crude oils found around the world. This manifests itself in very different viscosities, sulfur levels, percentages of a1kenes, aromatics, naphthenic and asphaltenic hydrocarbons, heavy metals, etc. All of this arises from variations in the conditions of formation and trapping of the oil. The lightest crude oils have viscosities similar to water or light hydrocarbons; the heaviest will not flow even at fairly elevated temperatures. The relevance of this for the future supply of oil will become clear shortly.

Coals also vary in chemical composition and structure. Again, this depends on the conditions of formation of the coals, and also on their age. Some types of coal and their chemical composition are given in Table 1.

Why is this variation in composition of the fossil fuels relevant to a discussion about their future? Because today we make use of only those that can be processed into useable fuels most cheaply. Any beginnings of depletion of the central resource being used today would bring into play new technologies for exploiting further resources. Indeed, anything that either raises price or lowers costs, independent of worries about depletion, brings new resources to market. So today, world oil reserves are 15 times greater than they were when record keeping began in 1948; world gas reserves are four times greater than they were 30 years ago, and world coal reserves have risen 75% in the last 20 years. However, for example in the case of oil, this only takes into account what is arbitrarily classified as conventional oil.

Petroleum is a broad term that includes mixtures of hydrocarbons ranging, in some cases, from gases such methane, ethane and propane, to fluid light oils, through to more viscous heavy oils, and on to shales, tar sands and bitumens. While some gas, often large quantities of gas, is almost always found associated with oil, there are also large gas fields that have smaller amounts of liquids associated with them. These liquids, usually the lighter end of the molecular weight and viscosity range, are known as Natural Gas Liquids or NGLs. Today, more than 95% of the oils that are produced are light fluid oils, that flow at room temperature or moderately higher temperatures above ambient. Some of this oil is mobilized to flow by using gas under pressure or water flooding. These liquid oils, and NGLs, are together known as conventional oil. Everything else — heavy and extra heavy oil, tar sands, shales and bitumens — that need to be mined and treated before they can be processed further, are known as unconventional oil. We see that there is a spectrum of materials found in Nature, from gas to very heavy hydrocarbons. The materials, besides varying in molecular weight distribution and viscosity, also have considerable variation in hydrocarbon type (as mentioned above, alkanes, alkenes, aromatics, etc.), sulfur content and metals.

On the higher average molecular weight side are a range of resources known as heavy oil or extra heavy oil. The amounts are huge. It is possible that Venezuelan extra heavy oil could be as much as the world’s total conventional oil reserves. More conservative estimates say that Canada and Venezuela have extra heavy oil equal to the world total for conventional oil. Figure 5 shows the amount of world reserves of conventional oil and gas (as oil equivalent) compared with three large heavy oil basins in Russia, Canada and Venezuela. While estimates vary considerably, the total unconventional oil resources are accepted to be about three times the volume of conventional oil that there was originally, before production, and about 10 times the volume of recoverable conventional oil that remains.

Technology to recover this unconventional oil continues to improve. It needs to be mined, rather than pumped, or liquefied by steam and chemically modified. There are often very high sulfur levels and high heavy metal contents that need to be removed before the oil can be processed in a refinery. All of the production is energy intensive, so the ratio of energy coming out to that going in is much lower than for conventional oil, though still higher than some alternatives that are being advocated. This is true of costs as well: while higher than conventional oil, even today they are lower than the costs of many alternatives, especially from biomass. We can expect to see steady, albeit incremental, improvement in the technology to process all unconventional oils.

5 Reserves of Fossil Fuels

Figure 6 summarizes the reserves of oil in the world, showing the geographic distribution (heavily concentrated in the Middle East) and the evolution with time over the past 20 years. While there has been some criticism of the validity of the growth of Middle Eastern reserves depicted in the figure, it seems clear that proved reserves of oil are now as high as they have ever been, despite consumption also being higher than it has ever been.

(Continues…)Excerpted from Sustainability and Environmental Impact of Renewable Energy Sources by R. E. Hester, R. M. Harrison. Copyright © 2003 The Royal Society of Chemistry. Excerpted by permission of The Royal Society of Chemistry.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.