Fuels

• Catalytic convertors in car exhausts have helped reduce pollution. They use small quantities of precious metals, such as platinum or rhodium, and these are spread thinly over a honeycomb mesh to increase the surface area.
• A three way catalytic convertor is commonly used, since it can get rid of carbon monoxide, unburnt hydrocarbons and oxides of nitrogen.
• One reaction that occurs within a catalytic convertor is the conversion of carbon monoxide to carbon dioxide. 2CO + O2 -> 2CO2
• One reaction that occurs within a catalytic convertor is the conversion of unburnt hydrocarbons into carbon dioxide and water. C8H18 + 12.5O2 -> 8CO2 + 9H2O
• One reaction that occurs within a catalytic convertor is the conversion of nitrogen monoxide and carbon monoxide into nitrogen gas and carbon dioxide.
• There are three main issues with current fossil fuels. Firstly, they create pollution through alkane combustion. Secondly, they lead to the depletion of natural resources. Finally, they contribute to global warming and climate change.
• Biofuels are a popular alternative to fossil fuels, since they are obtained from recently deceased animal and plant matter.
• Renewable sources of energy include biofuels, sunlight, wind, waves and tides, and geothermal energy.
• Non renewable sources of energy include coal, oil and natural gas.
• Carbon neutrality is the idea that burning a fuel (i.e. combustion) produces the same amount of carbon dioxide that is absorbed when it is produced.
• An example of carbon neutrality is burning a tree for fuel whilst replanting a new one.
• Biofuels involve forming more carbon dioxide than absorbed due to harvest, transportation and processing, however they are still closer to carbon neutrality than fossil fuels.
• Ethanol is formed through fermentation of sugars, using yeasts that contain enzymes.
• The most common bioalcohol is bioethanol.
• There is a limit to the concentration of ethanol in a solution after fermentation, which then must be further extracted (which requires more energy).
• Bioethanols can be produced using bacteria instead of enzymes, and can be made from a wide range of plants and plant waste. This increases the yield of ethanol that can actually be used as fuel.
• Some advantages of fossil fuels include that no land is needed, since these fuels are obtained from underground sources. They also have a high yield and low processing and transport costs.
• Some disadvantages of fossil fuels include that their exploration and drilling are expensive, and that these processes are not carbon neutral.
• Some advantages of biodiesel and bioethanol are that there are no exploration/drilling costs and they are closer to carbon neutrality than fossil fuels.
• Some disadvantages of biodiesel and bioethanol are that lots of land is need to produce the crops, and they have a low yield. However, this yield is gradually increasing.