Fueling the Future: Aviation Fuel Alternatives

Fossil fuels are non-renewable resources because they take millions of years to form, and reserves are being depleted much faster than new ones are being made. The production and use of fossil fuels raise environmental concerns. Like most types of transport, the aviation industry depends on fossil fuels. The industry contributes 2 per cent to man-made CO2 emissions, with 80 per cent of these from flights of over 1,500 km. / 900 mi. for which there are not practical alternative transportation options.

So what if we runs out out of fossil fuel?

Humans are quiet capable of devising a way out of the problem. A global movement toward the generation of renewable energy is therefore under way to help meet increased energy needs. 

Biofuels:

Traditionally, carbon based/kerosene-like fuels have proven to be the best energy source for aircraft because of intangibles such as the ability to maintain stable temperatures. Biofuels offer many of the same benefits, and can also be used without having to change a jetliner’s propulsion system. 

Biofuels are made from living things or the waste these organisms produce. Some of these fuels come from crops or land resources that compete with food production or water use. However, Airbus encourages the development of second-generation biofuels – known as biomass – which eliminates such competition. Source options being investigated include algae, woodchip waste, camelina, halophytes such as salicornia (plants growing in salt water), waste produce and yeast. 

For example, certain types of algae sea water combined with sun and carbon can become a “biomass” plant. These offer promising options for large scale production of a fuel that is very similar to kerosene.

KLM flew the world's first commercial biofuel flight, carrying 171 passengers from Amsterdam to Paris.

Fuel cells:

A fuel cell is a device that transforms chemical energy from a fuel – such as hydrogen – into electricity through a chemical reaction with oxygen or another oxidizing agent. By applying such a “cold” combustion process, the only waste is water, heat and oxygen-depleted air – which would contribute to reductions in emissions and noise when applied aboard an airliner.

Water produced from this process also can be used by the aircraft’s water and waste systems, reducing the amount of water an aircraft would need on board. This would contribute to reduced weight, which could further decrease fuel consumption and emissions.

Airbus “Multifunctional Fuel Cell” (MFFC) system on aircraft to replace today’s gas turbine-based auxiliary power units. The system could provide an estimated 100 kW of electricity, acting as an independent source capable of providing power throughout an aircraft.

Solar power:

If solar power is a highly-promising renewable energy source for Earth-based applications, its use on aircraft has been limited because of the way such power is created and stored. While solar energy may be able to help a small aircraft fly, it is unlikely to be a practical solution for enabling larger, commercial airliners into the sky.

The technology might take a giant leap forward with future advances; but today, even if an entire aircraft was covered with the most efficient solar panels available, this still would not be enough to propel it. 

For the more immediate future, solar power could provide electricity aboard airliners once they reach cruise altitude, or possibly help with ground operations at airports.

The Zephyr, developed by BAE Systems, is the latest in a line of record-breaking solar aircraft, making a 54-hour flight in 2007, and month-long flights are envisioned by 2010.

A solar balloon is a black balloon that is filled with ordinary air. As sunlight shines on the balloon, the air inside is heated and expands causing an upward buoyancy force, much like an artificially heated hot air balloon.


references: www.airbus.com