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Chemistry for Sustainable Technologies
By Neil Winterton
The Royal Society of ChemistryCopyright © 2011 Neil Winterton
All rights reserved.
Scope of the Book
'For every human problem, there is a neat simple solution. And it is always wrong!'
H. L. Mencken
Chemistry for Sustainable Technologies: A Foundation is intended to be a different type of book. While the treatment attempts to be rigorous, it treats the chemical fundamentals quite broadly, connecting material found in a range of more specialist courses and books. Aspects of other disciplines, relevant to sustainability, are introduced, considered and explored.
The book is also designed to help the reader, particularly students of chemistry, understand the scientific method (and, as a consequence, more consciously to think as scientists) — something not formally taught in undergraduate chemistry courses. In addition to encouraging the use of these tools to get to (and to interpret) the underlying evidence behind the images and headlines we see in the media and on the internet, the book more conventionally does the following:
explains the concepts and terminology of sustainability and sustainable development and the associated complexity, inter-relatedness and uncertainty;
highlights the necessary role of science and technology in the transition towards sustainable development;
exemplifies new approaches to chemistry driven by the need for more sustainable chemical technologies; and
illustrates the central role of metrics in the critical and comparative assessment of the sustainability of technologies.
The aim is to equip the reader to:
understand the basic terminology of sustainable development and chemistry for sustainable technologies (also known as 'green' chemistry);
appreciate the non-rigorous nature of this terminology and its consequences;
place chemistry and chemical technology in a wider societal context;
recognise the importance of thermodynamic principles in judgements about what may be considered sustainable;
recognise the strengths and weaknesses of green chemistry; and
appreciate the importance of catalysis and the use of renewable feedstocks in developing sustainable chemical technologies and the challenges associated with their implementation.
The topic of sustainable development, the factors driving it and efforts being made to bring it about continue to change over time. To maintain currency, I refer to websites and weblinks that may be of use as starting points to supplement the material to be found in the academic peer-reviewed literature. The extra care needed when using such web-based material is discussed in Appendix 1.
To keep the scope of this treatment manageable but while meeting the book's prime purpose to provide a foundation to the topic of chemistry for sustainable development, there will be some matters that are not explored in the detail to satisfy every reader. In these instances, I point to accessible and peer-reviewed sources of additional information which readers could profitably explore further.
The selection of topics addressed and the examples used to illustrate them are governed, to a large extent, by the fact that this book is aimed primarily at chemists and chemical technologists. The selection I have made is different from that which those with other specialisms and interests might have made. That this is so is a reflection of the complexity and inter-relatedness of sustainable development and sustainability (Glaze called this 'hyperdisciplinarity'), something that it is important, at the outset, to recognise. The role of chemistry, and of science itself, is shown to be critically important. While absolutely necessary, however, neither is sufficient.
The main themes covered by this book include:
Sustainability and sustainable development: the impact of climate change
Science: what is it and what is its role?
Carrying capacity of the Earth; the 'master' equation and our reliance on technology; ecological footprints; can humankind survive?
The 'Gaia' principle (or Earth systems science); environmental chemistry
Waste and its minimisation; pollution and its prevention: historical and modern perspectives
Metrics, life-cycle analysis and chemical technology: the process and product chain; technological integration and industrial ecology
Importance of the Second Law of Thermodynamics: the concept of exergy
Green chemistry: principles and pitfalls; contributions from new chemistry
Central importance of catalysis
Renewable feedstocks: the transition from fossil sources; what are the constraints; biotechnology; the 'biorefinery'
Energy production: prospects and timescales
The chemist as citizen: a statement of the challenges.
The theme running through the book is chemistry's central importance both to our attempts to understand the environment and the lifeforms that populate it, as well as to our efforts to develop ways to make the demands of the human population on the planet's resources (and its associated impact) more sustainable. The technological application of chemistry requires some basic understanding of process engineering and process economics and these are introduced as part of the foundation that represents the purpose of this book. Furthermore, this foundation also encompasses the economic and social context (and associated political ramifications) of technological development, particularly relating to the challenge of climate change.
The book tries not to be polemical: it takes no position in areas of controversy, but seeks to reflect my best personal assessment of the consensus position. It is worth pointing out that a consensus view (such as prevailed when it was believed that the Earth was the centre of the solar system) can be wrong and those seeking to change this can appear to be outlandish, even dangerous, mavericks who challenge established authority. My own view on the anthropogenic (i.e. man-made) contribution to climate change has moved over the last 10 years or so, in the light of the evidence, from a point where I accepted the evidence for climate change with a lack of conviction concerning the role of anthropogenic emissions to a position now where I accept that there is a contribution to climate change arising from our emissions of greenhouse gases. While there may be a developing general acceptance that action needs to be taken to ameliorate the situation, it is less likely that there will be a consensus on what form (or forms) this action might take. However, my hope is that readers will be assisted in arriving at a rational view based on the scientific evidence as to what the current position is that may help to inform their judgements about how to proceed.
We are, in historical terms, at the beginning of the road to sustainability, so it is possible only to frame the very hard questions to which we must find answers. However, because it is possible that we are close to a point of no return (and in no position to judge whether or not how close we are), there is a sense of urgency in our search for answers to these questions. I hope that this book will enable those of the new generation who must exercise judgement to develop 'a deeper kind of prudence' and a 'capacity to worry intelligently'.CHAPTER 2
Setting the Scene
'... out of this nettle, danger, we pluck this flower, safety.'
William Shakespeare (Henry IV Part 1, Act 2, Scene 3).
2.1 THE STATE OF THE PLANET
Our immediate perceptions of the world about us are governed by what we see directly with our own eyes and the images that the media select for us to see. Both, in their different ways, are incomplete pictures. We attempt to fill in the gaps by seeking out more information and by exercising judgement based on our experience, knowledge and attitudes. This will be supplemented by additional information and insights from other sources, usually of varying reliability. However this may be done, it is true to say that many of us, while living longer and more comfortably largely as a result of improvements to our health and well-being arising from the benefits of technology, are increasingly concerned about the Earth's continuing ability to support us all. More recently, we have been exposed to more apocalyptic visions for the future of humankind relating to the consequences of the human contribution to climate change associated with increased emissions of greenhouse gases such as carbon dioxide. This has served to stimulate debate about the need for political action (and what form this should take), which has brought with it further questions about the nature of society, the economy and the environment, and their future. These components of our world are interconnected and overlapping, complex and dynamic, reflecting the diversity of the ways people have come to live with one another and with the natural world. Any approach to solving the problems of sustainable development needs to reflect on this reality. No-one has dealt with the broader aspects of this issue as well as Mike Hulme in his recent book, Why We Disagree About Climate Change.
Because of the impact that technological development has had on the environment in seeking to meet the needs of a growing population (as illustrated in Figures 2.1–2.3), there is a perhaps understandable view in some quarters that we should not look to science and technology to help map out a more sustainable future. Such a view discounts the undoubted benefits of technology. It also ignores the somewhat paradoxical fact that science and technology, increasingly, have enabled us to observe — and thereby understand — the environment and to assess the nature, extent and consequences of our impact. It is technological developments, such as rocketry and satellite construction, associated with science-driven advances in computation, communication and spectroscopy, which now allow us to see the whole planet from a space platform. We can also 'see' at different wavelengths, as the two images in Figure 2.4 from NASA's Earth Observing System satellite show: one, the reflected short-wave radiation and the other, the emitted long-wave radiation, allow climatologists, earth scientists and others to gain a more precise, global and detailed understanding of the energy received and given out by the Earth (and to do so over time).
So science and technology can, with some justification, be seen as both the source of the problem of anthropogenic environmental impact as well as the means of detecting what some of its consequences are. Can it also provide the basis for solutions to these problems? My quotation from Henry IV at the beginning of this chapter expresses my own, more hopeful view, and it is the purpose of this book to make this case — particularly from the point of view of chemistry and chemical technology.
Satellite observations also provide evidence (if such evidence was really needed) of a particular feature of our quest for sustainable development, i.e. the disparity in prosperity across the globe from the relatively well-off north (Europe, North America, Japan) and the less prosperous south. Figure 2.5 shows visible light emitted at night around the world. The contrast between North America, Europe and Japan and the countries of the southern hemisphere shows the difference in the number of population centres with public lighting infrastructure and domestic light sources that contribute to light emission. This disparity is a major factor in how acceptable, in different parts of the world, might be different policy prescriptions to address the origins of anthropogenic climate change and to bring about more sustainable development. How would car users in Europe or North America view severe restrictions on the types of cars they might be permitted to buy and on the extent to which they might use them? How acceptable to those in the developing world, seeking to reduce malnutrition, would be constraints on the use of genetically modified (GM) crops driven by the concerns of well-fed environmental activists in the developed world? It is a matter of perspective or, rather, of many perspectives.
Whatever position one takes on the role of technology, it is inescapable that the physical and chemical processes taking place in the environment are governed by the same laws that control all of chemistry. Understanding the environmental chemistry perspective, therefore, is important in addressing questions of sustainable development. I introduce environmental chemistry and the associated topic of climate change in Chapter 5.
2.2 THE 'TRILEMMA'
Seeking ways forward for society, the economy and the environment that are, at the same time, equitable, acceptable and practical is something that has been termed the 'trilemma'. Resolving the trilemma will involve reconciling the consequences of meeting the societal and developmental needs of a growing world population with the associated deleterious effects on the environment. The degree to which environmental degradation can be limited through the control of emissions is an important question addressed in Chapter 6, particularly from the perspective of thermodynamics.
The urgency expressed by some on the matter of climate change arises from their judgement of just how close we are to some point or state at which changes to the Earth's systems that support human life might become irreversible. There is a high degree of uncertainty about this: there are some who say we are at or, irretrievably, beyond this point; others say we are close to it. A few (a declining number) believe the problem is not as serious as has been made out. However, in truth, bearing in mind how limited our understanding of the complex behaviour of global climate systems actually is, it is impossible to provide scientific certainty of the quality that might allow a consensus to be arrived at and (more to the point) a way forward that might be agreed upon. This apparent absence of quantitative certainty may encourage those who are unconvinced to doubt the need for special or urgent action. Furthermore, uncertainty may encourage the simple belief that more knowledge will resolve the matter. While greater understanding is certainly needed, the degree of complexity is such that uncertainty will always remain. In these circumstances, we must rely on subjective assessments of probability — anathema to most physical scientists — to guide action under conditions of uncertainty, particularly when the time needed to reduce uncertainty sufficiently is longer than the time by which a decision needs to be made. On the other hand, scientists should be able to come to judgments about their confidence in these assessments of probabilities, underpinned by their scientific insight, knowledge and expertise.
Furthermore, it is clear that changes we are already fully aware of such as the depletion of resources, the loss of wilderness and its impact on biodiversity, constrain the options that will be considered acceptable. It is also evident that an understandable preoccupation with local problems can deflect attention from considerations of more global questions whose local impact is perhaps seen as less immediate. Indeed, it is paradoxical that action against such a threat as climate change, which is perceived by many to be invisible and intangible, may only arise when it is too late.
The nature of sustainable development is addressed in Chapter 3.
2.3 HUMAN POPULATION AND ITS GROWTH
The potentially fateful consequences of the geometric growth of a population and the mere linear growth of the resources available to sustain it were first commented on in the late 18th century by Thomas Malthus (1766–1834) when the population of the planet was ca. 0.9–1.0 billion. So, any consideration of sustainable development needs to begin with a consideration of the Earth's human population, its size and rate of growth, and what has brought this about. It is the consequence of greater understanding (and control) of the world about us that has improved average human health and longevity and allowed many of us to live lives of greater comfort and convenience brought about by technological development. A further question relates to the difficult job of estimating how many of us the Earth can reasonably sustain indefinitely. The number is believed not to be much greater than about 10 billion.
Figure 2.6 plots the growth of the population of human beings (homo sapiens), particularly since modern man emerged about 200 000 years ago and since agriculture began to be practised about 10 000 years ago. Our unique ability to control, and more directly exploit, our environment was critical in enabling a more rapid, near exponential, growth in population, leading to its current value of about six billion. It is particularly significant that about 80% of the increase in population numbers has occurred during the last 200–300 years (0.01–0.02% of man's history), i.e. since the industrial revolution, when increased mechanisation and the exploitation of power sources arising from the use of fossil energy resources amplified many-fold what unaided human labour could achieve. This period is seen as representing the beginning of a new geological period, the Anthropocene, a term first coined by the Nobel Prize winning atmospheric chemist, Paul Crutzen.
Excerpted from Chemistry for Sustainable Technologies by Neil Winterton. Copyright © 2011 Neil Winterton. Excerpted by permission of The Royal Society of Chemistry.
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Table of ContentsScope of Book; Setting the Scene; Sustainability and Sustainable Development; Science and its Importance; Measurement; Waste and Pollution; Chemistry and the Environment; Green Chemistry; Process Chemistry and Reaction Engineering; Catalysis; Renewables; Energy Production; New Chemistry; The Chemist as Citizen
What People are Saying About This
Neil Winterton developed an optional module course, covering the chemical foundations of sustainable development, out of which this book evolved. Each chapter covers a significant aspect of sustainable development, up to and including the importance of science for society. Each comes with full scientific detail and an extensive bibliography. This book clearly means business. The book will be very useful for chemistry students. Beyond that, one should hope that it inspires others involved in chemistry teaching to set up similar courses in their institutions. The global environmental problems we are facing today are not going to go away and we will need chemistry to address them. This means that chemists must be taught how their science relates to these problems and how it can provide solutions. For this, Winterton’s book is a good start.