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6.2 (a) ‘Cleaning-up’ fossil and nuclear technologies

This means mitigating some of the adverse ‘environmental’ consequences of fossil and nuclear fuel use through the introduction of new, ‘clean’ technologies that should substantially reduce pollution emissions and health hazards. These include ‘supply-side’ measures to improve the efficiency with which fossil fuels are converted into electricity in power stations; cleaner and more efficient combustion methods; the increasing use of ‘waste’ heat in combined heat-and-power scheme
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4.4.2 Geothermal energy

Geothermal energy is another renewable source that is not derived from solar radiation. As the name implies, its source is the earth's internal heat, which originates mainly from the decay of long-lived radioactive elements. The most useful geothermal resources occur where underground bodies of water called aquifers can collect this heat, especially in those areas where volcanic or tectonic activity brings the heat close to the surface. The resulting hot water, or in some cases steam, is used
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4.4.1 Tidal Energy

The energy that causes the slow but regular rise and fall of the tides around our coastlines is not the same as that which creates waves. It is caused principally by the gravitational pull of the moon on the world's oceans. The sun also plays a minor role, not through its radiant energy but in the form of its gravitational pull, which exerts a small additional effect on tidal rhythms.

The principal technology for harnessing tidal energy essentially involves building a low dam, or barrag
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4.3.2 Wave power

When winds blow over the world's oceans, they cause waves. The power in such waves, as they gradually build up over very long distances, can be very great – as anyone watching or feeling that power eventually being dissipated on a beach will know.

Various technologies for harnessing the power of waves have been developed over the past few decades, of which the ‘oscillating water column’ (OWC) is perhaps the most widely used. In an OWC, the rise and fall of the waves inside an encl
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4.3.1 Wind energy

When solar radiation enters the earth's atmosphere, because of the curvature of the earth it warms different regions of the atmosphere to differing extents – most at the equator and least at the poles. Since air tends to flow from warmer to cooler regions, this causes what we call winds, and it is these air flows that are harnessed in windmills and wind turbines to produce power.

Wind power, in the form of traditional windmills used for grinding corn or pumping water, has been in use
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4.2 Solar energy

Solar energy, it should firstly be stressed, makes an enormous but largely unrecorded contribution to our energy needs. It is the sun's radiant energy, as noted in Box 2, that maintains the Earth's surface at a temperature warm enough to support human life. But despite this enormous input of energy to our ci
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3.6 Summary

This section has described how fossil fuels provide the majority of the world's energy requirements, with bioenergy, nuclear energy and hydropower also making major contributions. The other ‘renewable’ energy sources currently supply only a small fraction of world demand, although the contribution of these ‘renewables’ seems likely to grow rapidly in coming decades, as we shall see in the following section.


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3.5 Hydroelectricity

Another energy source that has been harnessed by humanity for many centuries is the power of flowing water, which has been used for milling corn, pumping and driving machinery. During the twentieth century, its main use has been in the generation of hydroelectricity, and hydropower has grown to become one of the world's principal electricity sources. It currently provides some 2.3 per cent of world primary energy. However, the relative contribution of hydroelectric power (and of other electri
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3.1 Introduction

So what are the principal energy systems used by humanity at present, and how sustainable are they?

Until quite recently, human energy requirements were modest and our supplies came either from harnessing natural processes such as the growth of plants, which provided wood for heating and food to energise human or animal muscles, or from the power of water and wind, used to drive simple machinery.


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1.1.1 Where do we get our energy from?

The world’s current energy systems have been built around the many advantages of fossil fuels, and we now depend overwhelmingly upon them. Concerns that supplies will ‘run out’ in the short-to-medium term have probably been exaggerated, thanks to the continued discovery of new reserves and the application of increasingly advanced exploration technologies. Nevertheless it remains the case that fossil fuel reserves are ultimately finite. In the long term they will eventually become deplet
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2.2 Economic valuation: towards ecological economics

The blue whale could have supplied indefinitely a sustainable yield of 6000 individuals a year.

This is one of the earliest references to sustainability in the literature, taken from the 1971 edition of the science journal Nature (cited in Senge et al., 2006, p. 45). Here, the blue whale is given instrumental value – a means of measuring not the survival of the blue whale for its intrinsic v
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7.4 Closing thoughts

Of course, doing anything about this needs scientific evidence and understanding, but it also requires social, economic and technological changes, which can only be achieved through political will. If you want to explore some of the broader context, a good place to start would be the New Internationalist issue 357, ‘The Big Switch: Climate Change Solutions’ at New Internationalist.

Faced with the sort of predictions climatologists are making, is it sufficient for science teac
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5.6 Land and water pollution

In this section we will just take a couple of examples that show how easy it is to expose ourselves to long-term damage inadvertently. Pesticides, developed to control insects and other vermin, can increase agricultural productivity. Although pesticides were originally hailed as one of the wonders of modern technology, it was quite quickly discovered that there was a downside to their widespread use. One problem was that of bioaccumulation. Pesticides tended to be stable chemicals and
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2 Altering the environment

Later in this unit we will be considering a number of ways in which humans alter their environment.

Question 3

In what ways do you think we are altering the environment?

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Acknowledgements

The content acknowledged below is Proprietary (see terms and conditions). This content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Licence

Grateful acknowledgement is made to the following sources for permission to reproduce material in this text.

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Glossary

Glossary itemDefinition
atomthe smallest amount of a chemical element that still retains the properties of that element.
biodiversitya contraction of ‘biological diversity’, in general it describes the variety of life on Earth and specifically the total sum of the genes, species, ha
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6.4.1 The dual nature of technology

Exercise 5

List the main advantages to you of using a refrigerator in your home, then list some of the potential environmental hazards that using a fridge might entail.

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5.3 Settlement, deforestation and endangered species

Box 4: Some indicators of New Zealand's environment*

The proportion of New Zealand converted to farmland is large by world standards (52 percent compared to the world's 37 percent in 1993). Although our human population density is comparatively low (13 people for each square kilometre (km2
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3.2 The agreement to protect the ozone layer

After a decade of controversy about the possible effects of CFCs, in 1985 British scientists discovered over the Antarctic a quite unexpected ‘hole’ in the ozone layer which was the size of the USA. This helped to galvanise the international community into action (though some who took part in the negotiations claim it played little part). By 1987 the first international agreement to control substances damaging to the ozone layer, the Montreal Protocol, was established. Interestingl
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1 Introductory advice

There are two ways to approach this Introduction. The first is the more natural one: to read it straight through to get a general feel for its style and content, and to see whether you are going to find the unit and the issues it raises interesting; in short, to get an overview. There is nothing wrong with this at all.

You will find as you read through it, though, that the Introduction covers a wide range of topics. In part this is because the unit authors takes a broad vi
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