Alternative Fuels Flashcards
Diesel
C9 to C11
Petrol
C7 to C8 hydrocarbons
Paraffin
C12 to C16
Characteristic of replacements?
Renewable sources need to burn ŵith similar rate
Which molecule has highest and lowest energy?
Hydrogen highest, CO lowest
Brazil cars
100% ethanol from sugar cane used, 30% less CO produced, HCs levels same, ethanol unreactive in photochemical smogs
Consequence of lower oil prices
Less use of ethanol
USA
Plants exist to make ethanol, blending petrol from corn/grain
Oxyfuels
Petrol + methanol/ethanol/MTBE (methyl tertiary butyl ethane), improve combustion, less u burnt HCs, more CO to CO2 conversions
Problems
More carcinogens produced, PAN toxic to plants and cause gene mutations
Rapeseed Methyl Esther
Renewable replacement for diesel, few sooty particles, no SOx
Haly produced
22p/l compared to diesel 10p/l, no net CO2 contribution to atmosphere, CO2 released from taken in by plants
Vegetable oils and animal fats
Triglycerides, by-products of glycerol, chars, clogs-engines
Treatments
Oil with alkali (acid is released), react with methanol to form methyl ester, volatile
Britain
Sugar beet but takes 1/3 size of Wales which is unlikely, large reserves of fossil fuels
Hydrogen
Cheap production from water, good calorific value
Problems
Low density, storage, unless liquified, hydrogen used in diesel car with spark plugs, stored in stainless steel vacuum insulated tank, only 8.5 miles per gallon
LPG (liquid petroleum gas)
Less expensive than petrol, high octane rating (130), less power, storage problems, lack of filling facilities, feasible slow filling at mains pressure
Gas power problem
Require large storage tanks, compromise storage space or range
Electric vehicles
Performance same as combustion engines
Electric vehicles problems
Weight and life of batteries, range compromise
Fuel cells
Utilise liquid fuels (petrol),no pollutants from combustion, use existing supply network (not yet commercial)
