Airline industry looks to greener fuels

A paper released by the Society of British Aerospace Companies (SBAC) today (17 April) covers research seeking practical alternatives to the current aviation fuel, kerosene. SBAC chief executive Ian Godden said the aviation industry was committed to reducing its impact on the environment by looking at new fuels that delivered an environmental benefit. "Recent test flights by Airbus and Virgin Atlantic have begun the testing process for alternative aviation fuels,” he said. Having cut fuel burn that leads to CO2 emissions by 70 per cent over the last 50 years, the industry's sustainable aviation initiative aims to cut them by 50 per cent of 2000 levels by 2020. SBAC said that road transport fuel systems had only the key requirement to provide an uninterrupted fuel supply to the engine for a small range of conditions - as a result, meeting the requirements for alternative fuels for cars was relatively straightforward. For air transport the challenge was much greater with fuels having to operate over a much wider range of conditions (from hot day take-off to the cold temperatures and pressures at altitude) and power settings whilst satisfying multiple requirements. So far, SBAC explains, the only fuel to fulfil all of these criteria at a reasonable cost is kerosene which has therefore been utilised almost exclusively by the aviation industry throughout the world for many years with aircraft engines, fuel supply and storage systems being specially designed for this fuel type. Any new fuel should be able to operate without changes to existing aircraft or the current fuel supply and storage systems. Airlines would not be able to purchase whole new fleets of aircraft to deal with new fuels - they would need to be 'drop-in' replacements for existing aviation fuel. Further challenges faced the industry in seeking alternative aviation fuels. They required a high energy content to minimise CO2 emissions, fuel burn and operating costs; needed to have a low freezing point; be stable in storage; and be compatible with aircraft materials. In addition, new fuels had to offer an environmental benefit. Proposed alternative fuels included synthetic kerosene made from coal, gas or biomass; biodiesel from crops such as rape, sunflowers, or plants such as palm or algae; and hydrogenated plant or vegetable oils. However, each of these alternatives faced practical challenges said the SBAC paper. Some offered little environmental benefit while others had many technical and logistical challenges to overcome.