3rd generation biofuels: aviation

Posted by Stella Kin

21 July 2010
The Engineer
EADS aircraft runs on algae biofuel

 In summary:

• One of the two AE300 engines of the EADS demonstrator Diamond Aircraft was powered by specially grown and refined algae biofuel. (The other was fuelled by normal diesel.)
• The aircraft has been certified by European aviation officials to fly with one engine powered by biofuel.
• The algae biofuel makes the aircraft 10% more efficient and fuel consumption was 1.5 litres per hour lower when compared to conventional JET-A1 fuel. 

‘Algaes have more energy content than the equivalent diesel fuel.'

•  ‘...carbon neutral’ because the CO2 that is emitted from burning the fuel is less than the amount of CO₂ the organisms absorb to grow. 

‘For one ton of raw algae material you need 1.8 tons of CO₂ to grow them’

• Exhaust gas quality measurements: algae biofuels have x8 less hydrocarbons than kerosene derived from crude oil. Nitrogen oxide and sulphur oxide emissions are also reduced.
• The major challenge is scaling up its production levels to industrial size and economy. 
• The project is supported by the German government.

Reference
theengineer.co.uk
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7 January 2009
Scientific American
Air Algae: U.S. Biofuel Flight Relies on Weeds and Pond Scum

Continental jet 516—a two-engine Boeing 737-800—completed a two hour test flight out of Houston with one engine powered by a 50-50 blend of regular petroleum-based jet fuel and a synthetic alternative made from Jatropha and algae.

The alternative jet fuel—known as synthetic paraffinated kerosenes—has as good or better qualities than Jet A refined from petroleum:

• The bio part of the blend has a lower freeze point than Jet A -- it does not freeze at high-altitude temperatures
• It delivers the same or more power to the engines, 48 megajoules per kilogram  
• It's lighter.
• The refiners, UOP, LLC, a division of Honeywell, can turn almost any plant oil into the alternative jet fuel.

"Crude oil is nothing but algae from 10 million years ago during a great algae bloom that got transported underground and today we call it crude oil," says Tim Zenk, vice president of corporate affairs at Sapphire Energy. "We take that process and speed it up by 10 million years and produce green crude."

The company hopes to produce 300 barrels of oil from algae grown in brackish ponds at its test facility by 2011 and 10,000 barrels a day in five years. It will cost "between $60 to $80 per barrel,"

But the commercial aviation industry burns nearly 240 million gallons (945 million liters) of Jet A daily and if oil prices were to approach the $150-per-barrel mark reached last year, the demand for Camelina oil might end up driving farmers to grow less wheat—a staple food crop. "If the incentives are wrong it could displace wheat," UOP's Holmgren says. "We don't want it to be priced above what the price is for food." That is why the industry is likely to use a variety of different feedstocks—Jatropha, Camelina, algae and others—to create the jet biofuel.

In the near-term, the jet biofuel is likely to be blended with the petroleum-based variety, because the biofuels lack aromatics—hydrocarbon rings—that interact with the seals in current engines, helping swell them shut.

Reference
scientificamerican.com