The industrial revolution took place between the 18th-19th centuries and ever since, energy has been a vital resource that has literally fueled our progression. Energy can come from different sources and it is important to consider the consequences and benefits from using each energy source.

Fossil Fuels

Fossil fuels are substances such as coal, oil and natural gas which are derived from the remains of plants and animals. Fossil fuels still retains chemical energy which is released when it is burned. Fossil fuels provide up to 90% of the world’s energy needs. The issue of that is that not only are fossil fuels a non-renewable source of energy (it will eventually run out) but the burning of fossil fuels also has detrimental effects such as atmospheric warming.

Coal

Coal is essentially vegetation that has been decayed and is composed of large molecules; mainly carbon but also includes hydrogen, nitrogen, sulphur, etc. There are different types of coal, each is composed of a different amount of carbon and is found in different layers of the Earth. The deeper you dig for coal, the higher the carbon composition it will have due to the increase in time, pressure and temperature. The types of coal ranges from peat (60% Carbon), brown coal (70% Carbon) to black coal (80% Carbon).

Coal is converted from chemical energy to electrical energy by burning it.

$C(s)+O_{2}(g)\longrightarrow CO_{2}(g)$

Since coal is not pure carbon, burning of coal not only produces carbon dioxide but also water vapour and sulphur dioxide.

Oil/Petroleum

Mixture of hydrocarbon molecules that are in the same homologous series of alkane. Oil by itself can’t be used as fuel however the individual components, the different alkanes, are separated via fractional distillation to eventually be used as petrol, solvents, lubrication, etc.

In terms of renewability, oil/petroleum is not renewable at all and it is said that Australia’s oil reserves are soon to be completely exhausted.

Natural Gas

Natural gas is used mainly for heating and generation of electricity. It is mainly composed of methane as small amounts of other hydrocarbons such as ethane and propane. Natural gas is simply burnt in air to produce CO2, H2O as well as heat energy. Since the amount of CO2 produced per MW of electricity produced is half that of burning coal, natural gas produces less pollutants however it doesn’t change the fact that it’s still a non-renewable and harmful source of energy.

Nuclear Fuels

Nuclear Fission

Nuclear fission involves splitting heavy elements such as uranium into smaller elements while at the same time releasing energy. Essentially, a neutron is used to bombard elements such as uranium into smaller elements such as Barium and Krypton as well as more neutrons as well as energy. Energy created from nuclear fission reaction is able to generate more electricity than a few thousand tons of coal.

The formula for the above reaction is $_{ 0 }^{ 1 }{ n }+_{ 92 }^{ 235 }{ U }\longrightarrow _{ 56 }^{ 140 }{ Ba }+_{ 36 }^{ 93 }{ Kr }+3_{ 0 }^{ 1 }{ n }+energy$

Generating energy via nuclear fission also does not produce any greenhouse gas. However, the process creates nuclear waste which is highly radioactive and have long half-lives. Also, many are against nuclear fission for fear against the creation of nuclear weapons.

Nuclear Fusion

Nuclear fusion involves combining light elements such as hydrogen atoms together to form helium electrons and energy. The general formula for nuclear fusion is:

$4_{ 1 }^{ 1 }{ H }\longrightarrow _{ 2 }^{ 4 }{ He }+2_{ 1 }^{ 0 }{ e }+energy$

Nuclear fusion occurs in the sun and its product is solar energy that we receive on Earth. Controlled nuclear fusion is difficult and is not widely used because temperatures of up to 100,000,000ºC is required and it is difficult to contain substances at such a high temperature.

Biochemical Fuels

Fuels that are derived from plant/organic materials; they do not contribute to an increase in atmospheric CO2 levels.

Biogas

Biogas consists mainly of CO2 and methane gases in equal amounts that come from animal waste and plant material. A biogas generator is used to produce biogas and it’s where organic material decays in the absence of oxygen. Gases such as methane seep out of the organic matter and is stored for use as biogas. The remaining solid waste product can be used as fertiliser.

Uses for biogas include heating to power houses and farms.

Ethanol (CH3CH2OH)

Ethanol is produced through fermentation of plant material and is catalysed by enzymes from yeast in an absence of oxygen. These plant material can originate from plants such as sugarcane, corn and wheat. The fermentation process follows the equation of:

$C_{6}H_{12}O_{6}(aq)\longrightarrow 2CH_{3}CH_{2}OH(aq)+CO_{2}(g)$

The whole process of producing ethanol is as follows:

• Grain is crushed and milled
• Water is added and mixed to form slurry
• Heat to 85-105ºC as well as adding enzymes to convert starch into glucose.
• Cool the mixture to 32ºC
• Allow mixture to ferment and stop when mixture has 10-20% ethanol
• Remove Ethanol and undergo steam distillation. At this point, the ethanol content should reach up to 95% of the mixture.
• Dehydrate the mixture to get up to 99.7% pure ethanol.
• Add petrol to poison the mixture.

Ethanol is slightly polar and thus can mix with water due to its hydroxyl group. It can also be considered partially non-polar due to its hydrocarbon tail which allows it to mix with petrol which is also non-polar.

The CO2 created by the fermentation process can be captured and sold to other companies. An example might be a soft drink company may buy the CO2 for their carbonated drinks. The waste water from the distillation and dehydration steps can be used for irrigation crops.

Uses for Ethanol include being mixed with petrol to make fuel.

Biodiesel

Biodiesel is a mix of esters produced when vegetable oil and alcohol (eg. Methanol) is mixed. It is formed by the hydrolysis of triglyceride and methanol to form glycerol and biodiesel. Triglycerides from sources such as soybeans, canola oil, palm oil and animal fat can be used to produce biodiesel. Biodiesel is becoming a popular energy source because it is biodegradable, non-toxic and it produces fewer pollutants compared to other energy sources. Biodiesel is also considered carbon neutral as it does not add CO2 to the atmosphere. Rather, the CO2 required to make the alcohol required for the process recycles CO2 that is already present and thus does not require fossil fuels.

Uses:

When burnt, biodiesel releases similar energy to petrodiesel; it is capable of replacing normal diesel altogether.