Ethanol as fuel
My new car will be flex fuel car. This means it can run on gasoline (petrol) or on alcohol (i.e. ethanol). Looking further on the two fuels I've discovered at wikipedia that:
- Ethanol has roughly two thirds the energy of gasoline on a volumetric basis. It, however, is a more efficient fuel than gasoline for two reasons. First, ethanol has a much lower adiabatic flame temperature, meaning it burns cooler. Less heat, therefore, needs to be rejected through the radiator and wasted.
- Second, ethanol has a much higher octane rating than gasoline (115). This allows engines running on ethanol to use a higher compression ratio and/or forced induction, both of which improve fuel economy.
- Automobiles optimized to run on ethanol can travel further on a gallon of fuel than equivalent cars setup for gasoline.
- There has long been widespread acknowledgement that ethanol is a cleaner-burning fuel than gasoline. Ethanol has far fewer standard regulated pollutants such as carbon monoxide and hydrocarbons, compared with plain gasoline in equivalent tests.
- Gasoline uses tetra ethyl lead, benzene and MTBE as additives to raise the octane level. Ethanol, with an octane rating of 110, doesn't need those additives.
- Ethanol appears to be less of a fire hazard than gasoline, ethanol (and methanol) dissolve in water (rather than floating on it like gasoline) so their fires can be extinguished with ordinary water hoses.
- One metric ton of sugarcane produces about 72 litres of ethanol.
- The average cost of production, including farming, transportation and distribution, is US$0.63 per US gallon (US$0.17/L); gasoline prices in the world market is about US$ 1.05 per US gallon (US$0.28/L).
- The improvement in air quality in Brazil's big cities in the 1980s, following the widespread use of ethanol as car fuel, was evident to everyone; as was the degradation that followed the partial return to gasoline in the 1990s.
- The ethanol program also led to widespread replacement of small farms and varied agriculture by vast seas of sugarcane monoculture.
- The replacement of food crops by the more lucrative sugarcane has also led to a sharp increase in food prices over the last decade.
- Since sugarcane only requires hand labor at harvest time, this shift also created a large population of destitute migrant workers who can only find temporary employment as cane cutters (at about US$3 to 5 per day) for one or two months every year.