Can cars run on alcohol? Can fuel be replaced by alcohol?

Replies

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  Ramani Aswath

  The heating value of ethyl alcohol is two thirds that of gasoline. As far as the carbon foot print (and other environmental issues) is concerned, a lot depends on how the alcohol is made.
  This article is informative:
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  Abhay rai

  Hi. i am the final year student of btech.may i appear in ies exam.?
• 

  lal

  The Internal Combustion engine should get more efficient! That would solve a huge lot of everything is what I think.
  
  I've read that, in many places a mixture of methanol and petrol is used as fuel in vehicles.
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  Don Ross

  Overall, the production and use of this alcohol doesn't warrant abandoning oil. All roads lead to oil. As stated the internal combustion engine will evolve. But the electric application is where it really is going. But more to the point of the question posed is the fact that in order to produce this alcohol, oil must be consumed. All farm raised crops depend on oil based fertilizers to grow. Never mind the fact of depleting farming soil due to climate change. The delicate economic aspect of the farming economy would also be hurt with the push to create this alcohol. Just because a technology is available doesn't mean it has a social and economical place in our world. So based on that aspect alone there should be no real discussion of a shift to a use of alcohol more than the 10% being used today.
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  Shashank Moghe

  Well, much has been discussed about this on CE and everywhere else. The low Calorific Values and the great anti-knocking properties are the basic considerations on the use of ethanol as a blend with gasoline or purely (100%, approved only in Brazil as of today) as fuel in engines. Wikipedia gives a wonderful description of this. From the documented material on Wikipedia, it appears that the corrosive properties of ethanol and the cold-start problems it poses are the only limiting factors on its use in engines. Otherwise, it can be run at par-sometimes even yielding better results with design changes-than gasoline engines.
  
  Source: Wikipedia
  
  Ethanol-based engines[#-Link-Snipped-#]
  Ethanol is most commonly used to power automobiles, though it may be used to power other vehicles, such as Farm Tractor, boats and Airplanes. Ethanol (E100) consumption in an engine is approximately 51% higher than for gasoline since the energy per unit volume of ethanol is 34% lower than for gasoline.Ethanol Fuel Cite Note Eerefaq 26Ethanol Fuel Cite Note Eiaattf 27 The higher Compression Ratio in an ethanol-only engine allow for increased Engine Power output and better fuel economy than could be obtained with lower compression ratios.Ethanol Fuel Cite Note Autogenerated6 28Ethanol Fuel Cite Note 29 In general, ethanol-only engines are tuned to give slightly better power and Torque Machine Torque output than gasoline-powered engines. In Flexible Fuel Vehicle, the lower compression ratio requires tunings that give the same output when using either gasoline or hydrated ethanol. For maximum use of ethanol's benefits, a much higher compression ratio should be used.Ethanol Fuel Cite Note 30 Current high compression neat ethanol engine designs are approximately 20 to 30% more fuel efficient than their gasoline-only counterparts.Ethanol Fuel Cite Note 31
  Ethanol contains soluble and insoluble contaminants.Ethanol Fuel Cite Note 32 These soluble contaminants, halide ions such as chloride ions, have a large effect on the Corrosivity of alcohol fuels. Halide increase corrosion in two ways; they chemically attack passivating oxide films on several metals causing pitting corrosion, and they increase the conductivity of the fuel. Increased electrical conductivity promotes electric, galvanic, and ordinary corrosion in the fuel system. Soluble contaminants, such as Aluminum Hydroxide, itself a product of corrosion by halide ions, clog the fuel system over time.
  Ethanol is Hygroscopic, meaning it absorbs water vapor directly from the atmosphere. Because absorbed water dilutes the fuel value of the ethanol (although it suppresses engine knock) and may cause phase separation of ethanol-gasoline blends, containers of ethanol fuels must be kept tightly sealed. This high Miscibility with water means that ethanol cannot be efficiently shipped through modern Pipeline Transport, like liquid hydrocarbons, over long distances.Ethanol Fuel Cite Note 33 Mechanics also have seen increased cases of damage to small engines, in particular, the carburetor, attributable to the increased water retention by ethanol in fuel.Ethanol Fuel Cite Note 34
  A 2004 Massachusetts Institute Of Technology studyEthanol Fuel Cite Note 35 and an earlier paper published by the Society of Automotive EngineersEthanol Fuel Cite Note 36 identify a method to exploit the characteristics of fuel ethanol substantially more efficiently than mixing it with gasoline. The method presents the possibility of leveraging the use of alcohol to achieve definite improvement over the cost-effectiveness of hybrid electric. The improvement consists of using dual-fuel direct-injection of pure alcohol (or the azeotrope or E85) and gasoline, in any ratio up to 100% of either, in a turbocharged, high compression-ratio, small-displacement engine having performance similar to an engine having twice the displacement. Each fuel is carried separately, with a much smaller tank for alcohol. The high-compression (for higher efficiency) engine runs on ordinary gasoline under low-power cruise conditions. Alcohol is directly injected into the cylinders (and the gasoline injection simultaneously reduced) only when necessary to suppress ‘knock’ such as when significantly accelerating. Direct cylinder injection raises the already high octane rating of ethanol up to an effective 130. The calculated over-all reduction of gasoline use and CO2 emission is 30%. The consumer cost payback time shows a 4:1 improvement over turbo-diesel and a 5:1 improvement over hybrid. The problems of water absorption into pre-mixed gasoline (causing phase separation), supply issues of multiple mix ratios and cold-weather starting are also avoided.
  Ethanol's higher Octane Rating allows an increase of an engine's compression ratio for increased Thermal Efficiency.Ethanol Fuel Cite Note Autogenerated6 28 In one study, complex engine controls and increased exhaust gas recirculation allowed a compression ratio of 19.5 with fuels ranging from neat ethanol to E50. Thermal efficiency up to approximately that for a diesel was achieved.Ethanol Fuel Cite Note 37 This would result in the Fuel Economy In Automobiles of a neat ethanol vehicle to be about the same as one burning gasoline.
  Since 1989 there have also been ethanol engines based on the diesel principle operating in Sweden.Ethanol Fuel Cite Note Scania1 38 They are used primarily in city buses, but also in distribution trucks and waste collectors. The engines, made by Scania, have a modified compression ratio, and the fuel (known as ED95) used is a mix of 93.6% ethanol and 3.6% ignition improver, and 2.8% Denaturation (Food).Ethanol Fuel Cite Note 39 The ignition improver makes it possible for the fuel to ignite in the diesel combustion cycle. It is then also possible to use the energy efficiency of the diesel principle with ethanol. These engines have been used in the United Kingdom by Reading Transport Biofuel Usage but the use of bioethanol fuel is now being phased out.
  
  Engine cold start during the winter[#-Link-Snipped-#]
  High Common Ethanol Fuel Mixtures present a problem to achieve enough Vapor Pressure for the fuel to evaporate and spark the ignition during cold weather (since ethanol tends to increase fuel Enthalpy Of VaporizationEthanol Fuel Cite Note Balabin 2007 40). When vapor pressure is below 45 Kpa starting a cold engine becomes difficult.Ethanol Fuel Cite Note 41 To avoid this problem at temperatures below 11 Celsius (52 Fahrenheit)), and to reduce ethanol higher emissions during cold weather, both the US and the European markets adopted E85 as the maximum blend to be used in their flexible fuel vehicles, and they are optimized to run at such a blend. At places with harsh cold weather, the ethanol blend in the US has a seasonal reduction to Common Ethanol Fuel Mixtures E70.2C E75 for these very cold regions, though it is still sold as E85.Ethanol Fuel Cite Note E70Green 42Ethanol Fuel Cite Note E70 43 At places where temperatures fall below −12 Celsius (10 Fahrenheit) during the winter, it is recommended to install an engine heater system, both for gasoline and E85 vehicles. Sweden has a similar seasonal reduction, but the ethanol content in the blend is reduced to Common Ethanol Fuel Mixtures E70.2C E75 during the winter months.Ethanol Fuel Cite Note E70 43Ethanol Fuel Cite Note E75 44
  Brazilian flex fuel vehicles can operate with ethanol mixtures up to Neat Alcohol Fuel, which is Hydrous ethanol (with up to 4% water), which causes vapor pressure to drop faster as compared to E85 vehicles. As a result, Brazilian flex vehicles are built with a small secondary gasoline reservoir located near the engine. During a cold start pure gasoline is injected to avoid starting problems at low temperatures. This provision is particularly necessary for users of Brazil's southern and central regions, where temperatures normally drop below 15 Celsius (59 Fahrenheit) during the winter. An improved flex engine generation was launched in 2009 that eliminates the need for the secondary gas storage tank.Ethanol Fuel Cite Note Bioenergia 45Ethanol Fuel Cite Note Gazeta 46 In March 2009 Volkswagen Do Brasil launched the Volkswagen Polo, the first Brazilian flex fuel model without an auxiliary tank for cold start.Ethanol Fuel Cite Note Flexstart1 47Ethanol Fuel Cite Note Flexstart2 48
  
  Fuel economy
  In theory, all fuel-driven vehicles have a Fuel Economy In Automobiles (measured as miles per US gallon, or liters per 100 km) that is directly proportional to the fuel's energy content.Ethanol Fuel Cite Note 55 In reality, there are many other variables that come into play that affect the performance of a particular fuel in a particular engine. Ethanol contains approx. 34% less energy per unit volume than gasoline, and therefore in theory, burning pure ethanol in a vehicle reduces miles per US gallon 34%, given the same fuel economy, compared to burning pure gasoline. Since ethanol has a higher octane rating, the engine can be made more efficient by raising its compression ratio. In fact, using a variable Turbocharger, the compression ratio can be optimized for the fuel, making fuel economy almost constant for any blend.Ethanol Fuel Cite Note Eerefaq 26Ethanol Fuel Cite Note Eiaattf 27 For E10 (10% ethanol and 90% gasoline), the effect is small (~3%) when compared to conventional gasoline,Ethanol Fuel Cite Note 56 and even smaller (1–2%) when compared to oxygenated and reformulated blends.Ethanol Fuel Cite Note 57 For E85 (85% ethanol), the effect becomes significant. E85 produces lower mileage than gasoline, and requires more frequent refueling. Actual performance may vary depending on the vehicle. Based on EPA tests for all 2006 E85 models, the average fuel economy for E85 vehicles resulted 25.56% lower than unleaded gasoline.Ethanol Fuel Cite Note Ethanol 58 The EPA-rated mileage of current United States flex-fuel vehiclesEthanol Fuel Cite Note 59 should be considered when making price comparisons, but E85 is a high performance fuel, with an octane rating of about 94–96, and should be compared to premium.Ethanol Fuel Cite Note 60 In one estimateEthanol Fuel Cite Note Bourne 61 the US Retail Price for E85 ethanol is 2.62 Us Dollar per Gallon or 3.71-dollar corrected for energy equivalency compared to a gallon of gasoline priced at 3.03-dollar. Brazilian cane ethanol (100%) is priced at 3.88-dollar against 4.91-dollar for E25 (as July 2007).
  
• 

  Ramani Aswath

  An update:
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