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Monday, April 9, 2012
Bioethanol fuel for Fuelcell cars
Bioethanol has successfully substituted Gasoline as a fuel for cars both in the form of blends with Gasoline or individually as an Anhydrous Ethanol. This successful demonstration by Brazil opens up new generation of cars called flex-fuel cars that allow usage of various blends of Ethanol and Gasoline.Bioethanol can also be used to generate Hydrogen onsite by steam reformation so that even Fuel cell cars such as Honda FCX can be felled by Bioethanol.This makes Bioethanol unique as an alternative fuel for transportation. It also facilitates onsite power generation using Fuel cell, replacing diesel engines. Substitution of Gasoline by Bioethanol has several advantages over other alternative fuels. The biggest advantage with Bioethanol is, it is renewable and it allows reduction of greenhouse gases from the atmosphere and it will be eligible for Carbon credit. It can be produced by both developing as well as developed countries using locally available agriculture produces such as cane sugar, corn, tapiaco, sorghum etc. Hydrogen generated from Bioethanol is also free from Sulfur compounds normally associated with natural gas, making it an ideal fuel for Fuel cell application in cars, as well as for power generation using SOFC (solid oxide Fuel cell) or PAFC (Phosphoric acid Fuel cell).The resulting high purity Hydrogen 99.99% can be used as fuel for all type of transportation including Fuel cell Buses, scooters and even boats. The stoichometric reaction of steam reformation in presence of catalyst can be represented by the following chemical reaction: C2H5OH + 3 H2O---------- 6H2 + 2 CO2 The Ethanol and water mixture is preheated and the vaporized mixture is fed into a catalytic reactor. The resulting Hydrogen is contaminated with carbon monoxide. This gas mixture is separated using membrane such as Palladium to get Hydrogen with less than 50ppm CO as contaminant. Such purity is acceptable by Fuel cell such as SOFC as well as PAFC.In future a small micro-reactor for on-board reformation may be possible making Fuel cell cars with onboard liquid fuel storage. Commercial reformers consumes about 0.88 lits of Bioethanol of 96% purity to generate 1 Nm3 of Hydrogen with 60% conversion. This translates to $ 5.90 per Kg of Hydrogen. Fuel cell cars offer a mileage of 240 from 1 kg Hydrogen costing only $5.90. For onsite power generation 1 kg Hydrogen generates as much as 15Kw electricity and 20Kw heat .Onsite Hydrogen generation with steam reformation also facilitates using SOFC and PAFC for high temperature power generation applications. They are ideal for CHP (combined heat and power) applications for 24x7 operations like hospitals, hotels and super markets. These fuel cells are silent in operation without any emissions except water vapor. Governments should encourage Bioethanol production and distribution for both transportation and power generation. There is a fear that Ethanol could be diverted for potable purposes illegally depriving Governments of potential reveneues.But this can be solved by denaturing Bioethanol and making it unsuitable for potable purposes. Denaturants such Pyridine has no effect on steam reformation and number of denaturants are available. Such policies will allow transition from fossil fuels to Hydrogen or Bioethanol.This is a simple and straight forward step any Government can take irrespective of the size or type of a nation. But it requires political will, determination and leadership. Developing countries need not wait for big greenhouse emitters such as US, China and India to make a decision on their Carbon emissions but start introducing Bioethanol as fuel locally.