Chapter 23

Fossil Fuels

Energy Sources Today“Human history becomes more and more a

race between education and catastrophe”

H.G. Wells, The Outline of History (1920)

How much energy do we use?Energy is measured in joules (J).Large amounts of energy are commonly

expressed in kilojoules (kJ) or mega joules (MJ).

A kJ = 1000 J, a MJ = 1,000,000 JA petajoule (PJ) is a useful unit for

discussing national energy needs1 PJ = 1 x 1015 J

How much energy do we use?• Each person in our modern society uses on

average nearly 1000MJ per day. • This figure is one hundred times greater than

the body’s basic requirement.• The bulk of our energy is use if for transport,

heating and domestic purposes.• The national energy budget is somewhat higher.• Australia uses about 2000 PJ of energy per year,

for mining, manufacturing, commercial services, farming etc.

• Look at the picture at the bottom of page 367.

Meeting Our Energy NeedsIn ye olde days what did people used to use

to get energy??Why can’t that sustain us now??What did we now use instead??Can that sustain us??

Meeting Our Energy Needs• Fossil fuels provide nearly 90 % of the worlds

energy needs.• This include coal, oil and natural gas• There is a growing pressure to reduce our future

dependence on these fuels because– Increasing concern over the effects of gases

released into the atmosphere as a by-product of the combustion of fossil fuels.

– Fossil fuels are non-renewable and will eventually run out

– Demand for petroleum as a raw material for polymers, pains and other petrochemical products.

Meeting Our Energy NeedsCan you think of any other reasons why we

should try and limit our use of fossil fuels?What might this picture tell us?

Energy ConvertersConversions of energy of one form to another

involves ‘losses’This is usually in the form of thermal energy

Energy ConvertersThe engine in a car is an energy converter.It converts the chemical energy in petrol to

thermal energy by combustion.Petrol is mostly octane The combustion of octane is a redox

reaction2C8H18(g) + 25O2(g) → 16CO2(g) + 18H2O(g)

Turn to page 369 to see how energy is lost in a car engine

Fossil FuelsNon-renewable energy sources are those used

at a faster rate than they can be produced.Fossil fuels and uranium are fuels of this type.We will eventually run out.Sustainability is all about meeting the long

term ongoing needs of society.As well as the short-term and intermediate

needs.The concept includes the needs of the

environment as well as the economical and social well being of future generations

Fossil Fuels

Does Australia have any nuclear power plants??

Figure 23.6 Electricity production by fuel source. The size of the block represents a region’s energy use. Energy use in the world is far from equal. Source: ‘Nuclear Energy Prospects in Australia’, Nuclear Issues Briefing Paper 44, April 2005, Uranium Information Centre Ltd.

Fossil FuelsCoal, oil and natural gas formed form

primitive plants and animalsWhen we burn these we are burning the

remains of plants and animals that lived million’s of years ago.

Chemical energy in fossil fuels can be considered as trapped solar energy.

Why?

Now Its Your TurnIn groups you are going to learn about one

fossil fuel and your job is to do a PowerPoint thing like I do and summarise one fossil fuel for the class.

There is lots of info in your text book, and you can look up more if you have to.

Shayna, Charlie and Lauren – OilBen, David and Simon – CoalAndrew and Alex – Natural Gas

Fossil Fuels may cost the earthMany fossil fuels are used as raw materials

in the chemical industry.Plastics, fibres and pharmaceuticals have

all originated from fossil fuels.Can we afford to keep using fossil fuels for

transport and energy if we need this precious resource for other things?

Fossil Fuels may cost the earthWhat about the environmental cost?What happens when we burn wood and

coal?Could this contribute to the Greenhouse

effect?

What are governements doing

They are exploring possible energy sources such as:Production of biofuelsProduction of hydrogen from natural gasSolar-generated electrolysis of water to produce

hydrogen and oxygenSolar powerWind powerGeothermal powerNuclear power

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