Fuel Choices

Question 1

What is a fuel?

Answer 1

A fuel is a substance with stored energy that can be released relatively easily ( through a combustion reaction) for use as heat or power.

Question 2

What are the different forms of energy?

Answer 2

Potential energy (energy that is stored in chemical bonds) or kinetic energy(energy associated with movement.

Question 3

Total energy of an object?

Answer 3

The sum of its potential and kinetic energy

Question 4

What is the law of conservation of energy?

Answer 4

Energy is neither created nor destroyed, it simply changes from one form into another. When this happens the total quantity of energy remains the same.

Question 5

Second law of thermodynamics?

Answer 5

The quality of usability of energy gets worse because whenever energy is converted from one form to another, low temperature heat is also produced which is difficult to use again.

Question 6

What is a fossil fuel?

Answer 6

A fuel that has been produced over a long time by the breakdown of organic material. This process can take many thousands of years.

Question 7

Examples of fossil fuels

Answer 7

Coal crude oil and natural gas.

Question 8

Why is there a push in society to reduce our dependence on fossil fuels?

Answer 8

1. Increasing concern over the effects of gases released into the atmosphere by the combustion of fossil fuels. In particular, CO2 is believed to contribute to atmospheric warming (the greenhouse effect) and SO2 is known to cause acid rain.
2. They are a non renewable energy resource, they are used up faster than they can be produced and are limited supplies so they will not be able to meet the long term energy needs of society.

Question 9

Why can chemical energy in fossil fuels be considered trapped solar energy?

Answer 9

Fossil fuels retain the chemical energy they stored from photosynthesis while living

Question 10

Why does black coal have a higher heat value than brown coal and is a better fuel?

Answer 10

Black coal contains less water and has a higher carbon content. When coal is burnt, the energy released causes water to vaporise, reducing net amount of heat released.

Question 11

What observations indicate coal station is inefficient?

Answer 11

LOSS OF HEAT ENERGY AS STEA, IS SEEN rising from cooling tower

Question 12

What is crude oil made of?

Answer 12

Mixture of hydrocarbon molecules that are members of the homologous series of alkanes.

Question 13

Process of extracting crude oil?

Answer 13

The process of separating compounds by using their small differences in their boiling temperatures is called fractional distillation and is carried out in a fractionating tower.

Question 14

LPG constituents??

Answer 14

Propane and butane

Question 15

Disadvantage of using LPG?

Answer 15

Engine conversion required (expensive), large tanks are required, must have high pressure to see the gas in liquid form, risk of explosion is higher.

Question 16

Natural gas constituents?

Answer 16

Mainly methane with small amounts of other hydrocarbons such as ethane and propane. Used for home heating and cooking

Question 17

What is coal seam gas?

Answer 17

When natural gas is found in coal deposits where it is bonded to the surface of the coal.

Question 18

What is shale gas?

Answer 18

Where natural gas is trapped in shale rock

Question 19

Difference in coal power plant and gas fired power station?

Answer 19

steam is not used for spinning turbines in a gas fired power station. Instead hot gases from combustion expand air in a combustion turbine, spinning propeller like bladed attached generator. amount of co2 released is half that of coal fired power plants.

Question 20

Non renewable sources definition

Answer 20

Those that are used at a rate faster than they can be replaced.

Question 21

Renewable resources defintion

Answer 21

They are continually being replaced by natural processes within a relatively short period of time

Question 22

Sustainable definition

Answer 22

Sustainable is able to support energy and resources into the future without depletion. A sustainable energy future means providing for the needs of today’s society without compromising the ability of future generations to meet their own needs.

Question 23

What are biofuels?

Answer 23

Fuels derived from biological materials or biomass.

Question 24

Why can biofuels be considered to be carbon neutral?

Answer 24

As all these fuels are produced naturally, it is considered that the use of these fuels will not contribute to atmospheric carbon dioxide. In order to produce the fuels, plants have photosynthesised and removed some atmospheric carbon dioxide to produce glucose. Burning biofuels simply replaces the carbon dioxide and thus biofuels can be considered carbon neutral.

Question 25

Why are biofuels actually not carbon neutral?

Answer 25

However when sourcing plants to be used as fuels, energy is needed in growing and harvesting them. This energy production produces greenhouse gases.

Question 26

Land issues with biofuels?

Answer 26

To produce biofuels, land used can be either for fuels or crops, not both.

Question 27

Biogas composition?

Answer 27

Gaseous mixture of methane and co2. Generated when organic wastewater is digested an eraobically by the action of microorganisms

Question 28

Biodiesel

Answer 28

Manufactured from vegetable oil or animal fat, produce by a reaction between vegetable oils (esters) and an alcohol, usually methanol.

Question 29

Comparison sources

Answer 29

p: produced from crude oil
B: produced by reaction of vegetable oils from plant matter with alcohols

Question 30

Chemical structure comparison

Answer 30

P:non polar molecules with only dispersion forces between them, hence lower melting point and viscosity than biodiesel
B: Polar ester link causes stronger intermolecular forces to exist, dipole dipole, resulting in higher melting point and viscosity than petrodisel

Question 31

Flow along fuel lines

Answer 31

P:flows better at low temperatures than biodiesel as less viscous, because the molecules are smaller and non polar with weaker dispersion forces between them/
B: does not flow as well in cold climates and at low temperatures due to higher viscosity resulting from the stronger dipole dipole forces between he polar ends of the molecules

Question 32

Hygroscopic properties?

Answer 32

Biodiesel is hygroscopic so it absorbs water in storage due to polar ends of biodiesel molecules, reducing efficiency with which it burns

Question 33

Environmental impacts of petrodisel

Answer 33

Energy is used when extracting and producing these fuels. The greenhouse gases co2 and h2o are released in this process, greenhouse gases are also emitted when the fuels are combusted

Question 34

Environmental impacts of biodiesel

Answer 34

Although the production process may result in the generation of greenhouse gases, biodiesel is more carbon neutral beteecause Co2 and h2O released on combustion are converted by photosynthesis into more plant matter