Biodiesel and Other Alternative Fuels
Biodiesel and other alternative fuels are cleaner (no S and N), sustainable (meaning that, unlike fossile fuels which are irreversibly converted to CO2 and H2O upon combustion, these fuels can be regenerated through the photosynthetic activity of plants), and sometimes more efficient than petrol. Below I have compiled some of the biodiesel and other alternative fuels that are in use and the cities/plants where they are being produced:
I - Ethanol:
Ethanol accounts for 20% of Brazil's transportation fuel. Brazilians saw ethanol as their way of overcoming the growing burden of costly imported oil back in 1970's and 80's. It is produced through the fermentation of sugar produced from sugar cane and surplus grain. Compared to petrol (33,000kJ), ethanol provides 24,000 kJ of enery per liter. However, it is free of the polluting N and S containing compounds that make petrol so polluting.
II - Coal and Oil Residue Gasification - Methanol
When wood coal or oil residues are heated to high temperatures and treated with water vapor, Syngas (synthesis gas) is produced. This is a mixture of CO and H2 gas which when passed over zinc oxide/chromium oxide canalysts is converted to methanol. Methanol is the fuel of choice for Indy car racing because it burns cleaner and does not explode into a fireball when an accident happens. The Netherlands has the world's largest coal gasification plant in the city of Buggemun which turns 2000 tons of coal a day into syngas. Also, syngas can be converted directly to petrol by the Fischer-Tropsch process when passed over iron and cobalt or zeolite (aluminum silicate) catalysts. This is the method that the Nazis used to produce petrol in WWII when their petrol supplies were cut off. This technology is currently in use at the Bintulu Sarawak plant in Malaysia where it is producing top-grade hydrocarbons which are free of S and N compounds. Methanol is also used to produce MTBE (methyl tert-butyl ether) which is a gasoline additive that provides for cleaner burning. Such a fuel is said to be "oxygenated".
III - RME (Rapa Methyl Ester) - Biodiesel:
Rapa (also called rape) is a plant hybride of cabbage and turnip which yields a rich crop of vegetable oil called rapeseed oil. Canola oil is one variety of rapeseed oil which is low in erucic fatty acid content (considered a health hazard) and high in unsaturated fatts. When canola oil is heated with methanol in the presence of NaOH as catalyst, a reaction called transesterification occurs and RME (rape methyl ester) is produced: This can run a regular diesel engine car and is highly popular in Europe. The Italian firm Novamont, supplies RME for public transport in 17 Italian cities, taxis in Berlin and Bologna and for the Lake Como ferry in Northern Italy. In Austria, RME is sold at 100 filling stations. A chain of restaurants in Maui, Hawaii is reclaiming its waste cooking oil and using it to run its diesel power plant engines (see Pacific Biodiesel). With a little modification (See Grease Car Systems, Boston, Massachusetts), a diesel car can be run on SVO (Straight Vegetable Oil). It is worthy to note that algae can also make oil and there is continuiing research going into this at the Solar Energy Research Institute at Golden, Colorado.
IV - Hydrogen: Hydrogen delivers three times as much energy as the same volume of petrol when converted to liquid and it's sole by product when burned is water ! There are several ways to produce H2 gas.
a. Electrolysis of water (using hydroelectric power)
b. Sepration of the components of syngas.
c. Using sunlight and catalysts such as TiO2 to split water into its components.
d. Using biotechnology to engineer certain organisms (such as the common termite) or bacteria (ex. Thermoplasma acidophilum which contains the enzyme glucose dehydrogenase that extracts H2 from glucose) to convert cellulose biomass (trees, leaves, garbage) into H2 gas. Some Japanese hybrid cars use H2 to generate electricity which runs the car (when hydrogen combines with O2 it loses it's electrons which are used to genrate electricity). This is the concept behind the Fuel Cell Vehicle.
Dr. Rakesh Agrawal of Air Products, based out of San Diego, estimates that in 30-40 years, 90% of vehicles in the USA will be running on H2 or eletrcity generated by H2. The challenge is for chemical engineers to find ingenious ways of lowering the cost of production...
By Rami E. Cremesti BS, MS
July 6, 2004
Los Angeles, CA
References:
1. Molecules At An Exhibition - Portraits of Intriguing Materials In Everyday Life. by John Emsley
2. Personal research