C1b Topic 7 Internal Assessment: Fuels

What makes a good fuel? Energy value: e.g. kJ of heat energy released per kg; Availability: Geographical convenience, oil production levels; Storage: Health and safety issues e.g. coal very safe, natural gas more dangerous Cost: Extraction, transport, market price Toxicity and Pollution: Greenhouse effect (which produces the least or most CO2/energy released?); sulphur content of fuel (most removed before fuel used to minimise sulphur dioxide and acid rain formation); efficiency of combustion e.g. minimum carbon monoxide and soot levels Ease of use: Transferred easily

Combustion Combustion can be either complete or incomplete Complete combustion = plenty of oxygen available; carbon dioxide and water produced; blue flame Incomplete combustion = not much oxygen present; carbon monoxide (toxic), carbon (black soot), carbon dioxide and water produced; yellow flame

Word Equations – when done, convert to balanced symbol equations Methane + oxygen → Methane = CH4 Ethane + oxygen → Ethane = C2H6 Ethanol + oxygen → Ethanol = C2H5OH Butanol + limited oxygen → Butanol = C4H9OH

Alternative Fuels Most of our fuel used today comes from crude oil Examples: petrol, diesel, kerosine etc. Are these fuels renewable or non-renewable? What is meant by these terms? What are some alternative fuels that could be used?

Some Alternative Fuels Biodiesel and Bioethanol: liquid fuels made from plant material and recycled elements of the food chain. To a large extent, they are renewable and sustainable. Biodiesel is a diesel alternative. Bioethanol is a petrol additive/substitute. They are produced from crops such as cereals, oilseeds, and sugar beet. What advantages/disadvantages do biofuels have over oil?

Hydrogen: can be obtained by the electrolysis of water (so a bountiful supply!). Also, when hydrogen burns a lot of energy is released and is completely pollution-free (the only product is water). Hydrogen powered buses produce no pollution from their exhausts, but using hydrogen is not a completely pollution-free option at the moment. Explain why.

How Science Works Reliable – data can be reproduced by others (in same conditions) Accurate – precise or correct in all details Valid – data is reliable AND answers the original questions Fair Testing – controlling as many variables as possible Bias – opinion that strongly favours one side in preference to another

Think about why things might be biased People who want to make a point can sometimes present data in a biased way to suit their own purposes Example: companies may want to ‘big up’ their products (especially more expensive ones) to make a quick profit

Example: Do power lines cause cancer? Scientists desire to study the link between the presence of power lines and incidence of cancer in children Design a study that the scientists could perform. Use ideas of validity, fair testing, accuracy, and reliability when designing your study.