4.5 Sustainability of renewable energy sources Renewable energy sources are generally sustainable in the sense that they cannot ‘run out’ – although, as noted above, both biomass and geothermal energy need wise management if they are to be used sustainably. For all of the other renewables, almost any realistic rate of exploitation by humans would be unlikely to approach their rate of replenishment by nature, though of course the use of all renewables is subject to various practical constraints. Renewable energies are also rela
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
4.3 Indirect use of solar energy The above examples illustrate the direct harnessing of the sun's radiant energy to produce heat and electricity. But the sun's energy can also be harnessed via other forms of energy that are indirect manifestations of its power. Principally, these are bioenergy and hydropower, already discussed in Section 3 above, together with wind energy and wave power.
4.1 What are renewable energy sources? Fossil and nuclear fuels are often termed non-renewable energy sources. This is because, although the quantities in which they are available may be extremely large, they are nevertheless finite and so will in principle ‘run out’ at some time in the future. By contrast, hydropower and bioenergy (from biofuels grown sustainably) are two examples of renewable energy sources – that is, sources that are continuously replenished by natural processes. Renewable energy sourc
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.
3.2 Fossil fuels So what are the principle 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. But the nineteenth and twentieth centuries saw a massive increase in global energy us
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.
References 2.3.1 The risk society The shift from an anthropocentric concern around issues of human poverty in industrial society towards a more ecocentric concern around environmental issues in the ‘risk society’ has been expressed by the German sociologist Ulrich Beck. His 1992 book Risk Society: Towards a New Modernity suggests a shift from the safety state of industrialised society, where conflicts were manifest in struggles amongst socio-economic groups, to a society where conflicts arise from issues of uncerta Learning outcomes By the end of this unit you should be able to: describe environmental matters regarding obligation and entitlements from a ‘caring’ perspective; appreciate the significance of environmental consequentialist ethics in conversations around developing care; identify and compare formal and less formal expressions of environmental responsibility; understand ‘accountability’ in the context of environmental issues; ide Learning outcomes By the end of this unit you should be able to: practise a very basic implementation of cybernetic optimisation through the use of the Author(s): 4.3 Chain growth polymerization Chain growth polymerization is basically a three-stage process, involving initiation of active molecules, their propagation and termination of the active chain ends. Learning outcomes After working through these materials you should be able to: describe and use a general classification of models; outline and discuss the process of systems modelling, where models are used as part of a systemic approach to a range of different situations; recognise that systems models may be used in different ways as part of a process for: improving understanding of a situation; identifying problems or formulating opportunities; supporting decision 7.4.2 Reactive PVD For a simple compound, such as a metal oxide or nitride, a modification to the sputter deposition technique can be used. The plasma is formed from a reactive gas, such as nitrogen, instead of the inert argon used for conventional PVD. A side effect of the plasma excitation is that chemical bonds are broken in the source gas to release copious unpaired atoms (radicals), which are extremely reactive and form a monolayer coating of nitride on the target surface. These can then be sputtere 2.8 Good times and bad The music industry, like any other large industrial business, had good times and bad times. By 1924 the burgeoning of radio broadcasting in the United States caused a severe downturn in record and equipment sales, leading to amalgamations and bankruptcies of many of the record companies. Actually, radio broadcast studio technology proved of great importance to the record industry. The sensitive microphones and electronic amplifiers used in broadcast studios offered improved characteristics th 2.5 Review The title of this unit could have been Juggling with complexity: searching for system. This title seemed to capture something essential about the unit. Juggling is a rich metaphor and will be used explicitly in Part 3. But it also carries the idea of a skill that needs to be practised and that might seem incredibly awkward to begin with. You may find this idea helpful as you review your work in Part 1. Juggling is also a skill that, once practised, becomes second nature. This too may b 4.10 What has been learnt from the history of the telephone? Here are some points about invention and innovation that seem to have emerged from considering the case of the telephone. Invention is an ongoing process not a one-off event. It's not always possible to identify one individual as the inventor of a new technological product – even in well-known cases. Boldness and determination, allied with sufficient resources and a good support team – especially good patent lawyers †4.3 Who invented the telephone? The popular image of Bell inventing the telephone, while it has some truth, is by no means the whole story. The two most significant players in the invention of a practical working telephone were Bell and Elisha Gray. Gray was the co-owner and chief scientist of a company that manufactured telegraphic equipment. Bell's patent description had sound transmission as a minor purpose. But Gray's caveat declared that the main purpose of his device was ‘to transmit the tones of the human voi Learning outcomes On completion of this unit, you should be able to: explain invention, design, innovation and diffusion as ongoing processes with a range of factors affecting success at each stage; explain how particular products you use have a history of invention and improvement, and appreciate the role that you and your family, as consumers, have played in this history; define key concepts such as invention, design, innovation, diffusion, product champion, entrep 1.1.3 Features of diagrams As there is variety in the types of diagrams we can see and use we need to think more broadly about what diagrams are trying to represent. One distinction which follows on from the discussion above is:
Analogue representations: these diagrams look similar to the object or objects they portray. At their simplest they are photographs of real objects and at their most complicated they are colourful, fully labelled drawings of the inner workings o
