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Chapter 9, using fuels.
A large part of a person’s life depends on the use of fuels. In almost every country they use more fuels today than they did in the past. People in wealthy countries use much more fuels than people in poorer countries. To reduce these inequalities, people should increase the use of fuels in the poor countries (bad idea), or decrease the use in wealthy countries.
Fuels are energy sources -> energy is spread out when we use it. Some processes use fuels more efficiently than others. Efficiency is a measure of how much of the energy goes where we want it to.
The use of fuels can damage the environment. The global inequalities raise serious moral questions. Technical developments can not provide a complete solution.
Fuels and energy.
Fuels are useful because they are concentrated energy sources. Most energy comes from burning fossil fuels – coal, oil and natural gas. Now, they are still available, but they will eventually run out. Some comes from nuclear fuel, and in some countries they use wood or dried animal dung as a main fuel. Fuels are not our only energy sources. The earth receives a great deal of energy from the sun (solar radiation). The sun also drives the water cycle and causes wind and waves.
Fossil fuels take long to produce, and are non-renewable energy sources. Wind, water and sun are renewable energy sources.
Primary and secondary energy sources.
When fuels are burned in air, heat is released. Electricity is said to be a second energy source. It has to be generated using a primary energy source.
Energy consumption in different countries.
Energy consumption is different from country to country. It may be due to differences in climate, but this is not enough to account for the differences observed. There is also a difference between wealthy and poor people.
What are the trends in global energy use?
The worldwide demand for energy is increasing quite rapidly. The main source of this energy continues to be fossil fuels.
Current and future demand for primary energy sources.
The most of the worlds energy comes from fossil fuels or biomass (particularly wood). A little comes from hydro-schemes and nuclear fuels. Other renewable sources make a tiny contribution. Two obvious problems if energy use increases are:
• The finite supplies of fossil fuels might begin to run out; and
• The gases released when fossil fuels are burned already have a serious effect on the environment, and increasing these will make the situation worse.
Energy reserves and resources.
The main source of energy in the future will continue to be fossil fuels. 1960’s: It was feared that oil and natural gas would run out quickly (early in the 21st century).
Reducing the use of fossil fuels.
Burning fossil fuels causes environmental problems on a global scale. We have to reduce the large sectors of use, to have great impact and reduce the use of these fuels.
Energy efficiency in homes
Science and technology is helping to reduce energy consumption in homes. Improved technology is not the only, or even the most effective, way of reducing energy consumption in homes. It could also be reduced by more careful use of lights and of hot water. Still larger amounts of energy could be saved by more effectively retaining heat in homes.
Fuel-efficient transport
Technology has made some contribution towards reducing the amount of fuel used for transport. But really significant reductions in the amount of fossil fuels burned for transport cannot be achieved by science and technology alone. People have to change their habits (amount and way of travelling). The most obvious way to reduce the amount of fossil fuel used for transport is for people to reduce the amount of travelling that they do.
Changing people’s travel patterns
Many people prefer to use their cars as the way of travelling. This has important implications not only for energy consumption, but also for the quality of people’s lives. The pollution caused by vehicles also reduces the quality of life for many city dwellers much of the time. [Figure 9.19 gives a very clear view of different opinions and points of view on transport matters.]
Predicting future energy use.
The most commonest assumption that people make is: The future will be like the past. We can also say that: The future is what we (collectively) choose to make it, because we are not powerless to change things. One scenario says that until 2020 we would use a lot of fossil fuels, which will begin to decline at the time. From 2020, we will use a lot of biomass fuels, and wind and solar energy. Another scenario says, that we would use a lot of biomass and other renewable sources, because they have worries about global warning etc. The reality may turn out to be somewhere between these. All future predictions:
• Are subject to considerable uncertainty
• Are only as good as the assumptions they start from, and those built into the model.
The future is up to us.
Key terms.
The original meaning of a fuel was ‘a material for burning’. More recently the term has been extended to include nuclear fuel, which is used in nuclear power stations, though it is not literally ‘burned’. Fossil fuels are the fossilised remains of prehistoric rainforests or tiny marine animals, and have formed over millions of years. A renewable energy source is one which is being (or can be) replaced as it is used.
The scientific unit for measuring amounts of energy is the joule (J).
The Gross Domestic Product (GDP) of a country is the total value of everything the country produces in a year. The per capita GDP is obtained by dividing this by the number of people living in the country (the population). So it is a measure of average wealth.
If we want to compare amounts of energy supplied by different fuels, we have to use the same unit for all of them. Rather than using the scientific energy unit of energy, the joule, many energy planners use the kilogram of oil equivalent or tonne of oils equivalent (toe), i.e. the amount of the fuel that produces the same amount of heating as 1 kg, or 1 tonne, of oil.
The reserves of a fossil fuel are the total amount of that fuel which we believe to exist.
→ Study the figures, and the red parts in the book!

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