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Flying is easy – recycling is difficult
| | Innovative recycling processes are to solve the extreme problems in disposing of carbon fibre reinforced plastic (CFRP).
By Peter Steinhauer
At the Peking Olympics the choice of material played an important role in a great many events. For example the frame of the racing bicycle used by the triathlon winner Jan Frodeno was made of lightweight carbon. Similarly, components used by the unfortunately not so successful German rowing eight and the arrows of the German archery team were also made of so-called carbon fibre composites (CFRP).
CFRP materials are often used when it is essential to reduce weight to the minimum. CFRP is 70 per cent lighter than steel and 30 per cent lighter than aluminium. This high-tech material is not only extremely light, it is also offers a high degree of specific strength and rigidity.
photo: Boeing
CFRP materials are used in planes
CFRP is meanwhile being used more and more in automotive construction because of its low weight. The Porsche Carrera GT with its chassis made completely from CFRP has become legendary. Since autumn 2007 BMW has offered a version of the M3 with a roof made completely of GFRP. However, components made of CFRP are only seldom used in series production vehicles. One of the reasons for this lies in the unsatisfactory disposal solutions for CFRP components found to date.
Whereas the material cycle for aluminium already functions very well, the recycling of CFRP is proving far more difficult due to its material complexity. For car manufacturers, however, recycling is of great importance. This is because the EU regulations on scrapped vehicles concluded in the year 2000 specify a recycling rate of 95 per cent to be met by car manufacturers by 2015.
The problem of CFRP material disposal is far greater in the aircraft industry. Already in the near future the aircraft industry plans to manufacture 50 per cent of aircraft components from the extremely light and stable GFRP. The production of GFRP components, however, involves creating a large volume of production waste. For many years this expensive material was simply incinerated. Thermal recycling of production waste is, however, very expensive, as GFRP waste only decomposes at high temperatures. The aircraft manufacturers have therefore been seeking an efficient recycling method for their waste for some considerable time.
Extensive landfill ban
A further problem is also becoming increasingly pressing for the aircraft industry. Experts predict that approximately 6,000 aircraft will have to be decommissioned due to their age over the next 20 years. Until now disused aircraft have simply rotted in aviation cemeteries in remote desert regions or were simply scrapped.
Both methods of disposal are a severe burden to the environment. Since 2004 most European countries have banned the disposal of CFRP waste on landfill sites. Furthermore, the European Union is planning regulations on the recycling of end-of-life aircraft along the same lines as those for scrapped vehicles. The aircraft industry, however, does not consider itself as being put under pressure by policymakers in Brussels. It also has a great interest in making the disposal of end-of-life machines more efficient and economical.
For this reason the aircraft manufacturers are presently cooperating closely with the waste management industry to develop innovative forms of CFRP recycling. In 2005 the aircraft company Airbus based in Tarbes in the south of France, together with its Suez-based subsidiary Sita, the waste disposal specialists, started work together with other partners on the pilot project “Pamela”. The name stands for “Process for Advanced Management End of Life Aircraft”. The objective of the project is to develop new standards for the ecological and economical disposal of end-of-life machines. The project includes the recycling of raw materials such as aluminium as well as carbon fibre reinforced plastics.
In 2006 American competitor Boeing joined the engine manufacturer Rolls Royce and further partners in forming the Afra - the Aircraft Fleet Recycling Association. The companies participating in the association make sure that these former kings of the air are dismantled and that up to 90 per cent of the materials used are recycled.
For the Afra companies too, the recycling of CFRP components presents a special challenge. The Afra partner companies, Milled Carbon of Birmingham, Great Britain and Karborek of Puglia, Italy, are specialists who take care of recycling the CFRP components for Afra.
CFRP Valley in Stade
In Germany the town of Stade in Lower Saxony is considered the competence centre for CFRP. The Airbus plant in Hamburg Finkenwerder is only 50 km from there. Airbus produces the vertical tail for the Airbus A.380 aircraft in Stade itself. A total of 65 companies and a research centre have been established In the vicinity of the plant in “CFRP Valley Stade”.
In Stade the CFRP recycling pioneer Hans Ahlborn has been closely involved in CFRP recycling since 1995. The particle process he developed is still in use today. The waste management company Karl Meyer, also located in Stade, and the American plant construction company Dow have founded the company CFL Valley Stade Recycling GmbH & Co. KG.
By the year 2010 the newly founded company plans to develop a large-scale industrial process to recycle CFRP scrap incurred throughout Europe and thus to find a solution to this urgent waste disposal problem. Carbon fibres with lengths of up to 50 mm are to be recovered in the plant.
An optimised pyrolysis process, which separates the carbon fibres from the surrounding resin matrix, is to make this possible. The green light for the construction of a pilot plant was given on 13 August 2008.
Europe-wide market leadership as goal
The State Government of Lower Saxony is promoting the project with a sum of 1.7 million euros. The Environment Minister of Lower Saxony Hans-Heinrich Sander emphasises the importance of the project for the region: “Through the CFRG recycling centre both Lower Saxony and CFRG Valley Stade are consolidating their leading position in Europe. It is the first location in Europe capable of implementing the value-added chain from CFRP production through to ecologically sustainable recycling.
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