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3.1  Introduction

    • The description “Alternative fuels” used in this section refers to sources of energy, other than petrol and standard diesel, that can be utilised to power a vehicle and which are derived from renewable or sustainable sources.

    • Alternative fuels that can be used to power a vehice fall into three main catagories: Biofuels, Hydrogen and Natural Gas.

    • Note: No fuel other than that recommended by the manufacturer should be used in a vehicle.

    • To explore this subject in greater depth please see Green Cars, Section 10 (Green Web Site Links).  

3.2  Biofuels

  • 3.2.1  Introduction

    • A biofuel is a gas, solid or liquid fuel that has been produced from a recently living organism or its metabolic by-product.

    • Biofuels used in vehicles are usually in either a liquid or gas form.

    • Sources of biofuels include sugar cane/beet, a range of vegetable oils, algae, animal fats and sewage.

    • The two main “first-generation” biofuels have been bio-ethanol and bio-diesel. These were made mainly from vegetable oils, starch and sugar.

    • More recently “second-generation” biofuels are being produced using “biomass to liquid” technology, including biomethanol, biohydrogen, HTU diesel and Fischer-Tropsch diesel. 

    • Early users of bio-ethanol have included Nickolaus Otto (for combustion engines he built in the 1860s) and Henry Ford (originally for his famous Model T car in the early 1900s).

    • In the 1890s Rudolf Diesel conceived his diesel engine to run on peanut oil. 
  • 3.2.2  Biodiesel

    • Biodiesel can be produced from any fat or oil using a process called “transesterification”.

    • Vegetable oil could be used in older indirect injection system diesel engines when operated in hotter climates.

    • Nowadays vegetable oil has to be processed into  biodiesel before it can be used in a modern diesel engine.

    • It is the most commonly used biofuel in Europe.

    • It is currently mainly manufactured from vegetable oils and has an energy content that is about 10% lower than that of petroleum diesel.

    • EN 14214 is the common international standard for biodiesel. A "B" factor is used to indicate the level of biodiesel in a fuel mixture. B40 indicating the fuel contains 40% biodiesel, etc.

    • Biodiesel can be used as B100 or blended with petroleum diesel in most modern diesel engines.

    • In 2006 Soybean and rapeseed oils accounted for about 90% of all biodiesel.

    • Other sources include, but are not limited to, sunflower, mustard, canola, palm oil, hemp, algae and jatropha.

  • 3.2.3  Ethanol

    • Ethanol is ethyl alcohol and it is the world’s most commonly used biofuel. Bio-ethanol is typically produced from crops such as sugar cane/beet, wheat and corn.  

    • Note: Ethanol can also be produced from other sources, such as petroleum and coal.

    • In 2007 countries with bio-ethanol programmes include Brazil, China, Columbia, Sweden and the USA.

    • Subject to the suitability of the engine it can be used as an alternative to, or blended with, unleaded petrol. An “E” number is used to indicate the petrol to ethanol ratio.

    • E85, for example, representing a mixture of 85 percent ethanol and 15 percent petrol.

    • Ethanol, with water content of not more than 1%, can be blended with petrol in varying ratios.

    • E10, sometimes called gasohol, can be used in the engines of most modern cars.

    • In February 2006 E20 became the standard ethanol-petrol mixture sold in Brazil.

    • In 2007 Brazil was the world’s largest producer of ethanol, which it derives from sugar cane. 

    • Cars can be made to run on E100 but problems have been  encountered starting the engine when the temperature is below 15 degrees C (59 degrees F).

    • Ethanol contains about 27% less energy than petrol (84,000 BTUs per US gallon compared to 115,000 BTUs for petrol).

    • Cars running on ethanol currently use more fuel per mile than those running on petrol. Differences of up to 15% have been reported. Check this %.

    • Fuel economy is expected to improve significantly as higher compression engines designed to run only on E100 become available. 

  • 3.2.4  Butanol

    • Butanol is an alcohol fuel and can be produced from the same crops as ethanol; mainly sugar cane/beet, wheat and corn. It can also be produced from fossil fuels.

    • Butanol contains about 4.3% less energy than petrol (110,000 BTUs per US gallon compared to 115,000 BTUs for petrol).

    • It is less corrosive than ethanol.

    • In 2006 no production vehicles were known to be approved for use with 100% butanol. Information on butanol-petrol blends/ratios, level of production, usage, etc. required.

  • 3.2.5  Methanol

    • Methanol is methyl alcohol. It is frequently referred to as wood alcohol.

    • It is currently (2007) more cost effective to derive methanol from the natural gas methane.

    • It can also be produced from light petroleum products and coal.

    • When produced from a biomass it is called biomethanol.

    • Methanol is much less flammable than petrol and this has limited its use as fuel for internal combustion engines.

    • Methanol contains about 45% less energy than petrol (63,000 BTUs per US gallon compared to 115,000 BTUs for petrol).

    • Methanol has been used as a fuel for fuel cells. See Green Cars, Section 8.7.  

    • Methanol is corrosive to certain metals, including aluminium. 

    • Pure methanol has been used in certain racing cars since the 1960s, including the American Indianapolis 500 event up to the end of the 2005 season. It has also been used in drag racers.

  • 3.2.6   Yield of Oil from Crops     

    • Note: All figures are in US gallons per acre (4,840 square yards or about 4,050 square metres).

    • Corn (18), Soybean (48), Peanuts (113), Rapeseed (127), Jatropha (202), Oil Palm (635) and Algae (10,000).

    • Algae, which has a natural oil content of more than 50%, produces over 200 times more oil per acre than soybeans.

    • One report indicated that if America relied soley upon soybean to provide all it’s current transportation and heating needs, the crop would occupy an area equal to twice the size of the country.

3.3  Hydrogen

  • 3.3.1  Vehicle Fuel

    • Hydrogen, typically stored as a liquid and used as a gas, can be used as a fuel in:

      • A slightly modified version of the petrol powered internal combustion engine.

      • A fuel cell.

  • 3.3.2  Hydrogen Data

    • Hydrogen (H2) is the most abundant element in the universe. It is designated “atomic number 1”.

    • At normal atmospheric temperatures and pressures hydrogen is a flammable gas.

    • It is a solid between absolute zero of minus 273.16 degrees C and its melting point of minus 259.34 degrees C, when it becomes a liquid.

    • It remains a liquid in the small band of 6.47 degrees C, until it rises to its boiling point of minus 252.87 degrees C. Note: Water has a boiling point of plus 100 degrees C.

    • It is usually stored as a liquid because when it is converted to gas, hydrogen expands and takes up about 840 times more space.

    • It is the lightest of the gases. About one-fifteenth the weight of air.

  • 3.3.3  Hydrogen Production  

    • On our planet hydrogen exists mainly as part of other compounds and has to be extracted from them; such as water, fossil fuels, natural gas and  coal. It is therefore a manufactured fuel.

    • In 2006 extracting hydrogen consumed about 60% more energy than the resulting hydrogen provided.

    • Two of the most common ways of producing hydrogen are by steam reforming and electrolysis.

    • Steam reforming, mainly from natural gas, is currently the most cost effective and hence the most popular method.

    • Electrolysis, which extracts hydrogen from water, is currently a much more expensive process.

    • For every one litre of petrol about four times the amount of liquid hydrogen is required to obtain the same amount of energy.

    • To store liquid hydrogen at between minus 259.34  and minus 252.87 degrees C it must be kept in a pressurised and thermally insulated container.

    • Due to the very low temperatures involved liquid hydrogen will slowly evaporate from its container.

  • 3.3.4  Cars Using Hydrogen

    • For cars using hydrogen powered fuel cells see Green Cars, Section 8.

    • BMW: BMW’s Hydrogen 7 car has an internal combustion engine that can run on petrol or hydrogen. When was it first produced?

    • The car was powered by a 350 hp (260 kW) 12-cylinder engine. 

    • Mazda: In 2004 Mazda introduced the RX-4 Hydrogen RE, rotary engined, concept car. It was designed to run on petrol or hydrogen.

    • The car has a maximum range of 341 miles (546 km) when running on petrol or 62 miles (99 km) when running on hydrogen. 

    • In March 2006 Mazda started to deliver these cars to customers.

3.4  LPG & CNG  

    • Liquid Petroleum Gas (LPG) and Compressed Natural Gas (CNG). Information under preparation.
 
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