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01/11/2011
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In the 'aluminium versus rivals' debate, it is the lifecycle element of its GHG footprint and how that is determined that causes the biggest sparks, as Ian Adcock reports
 "On average, every kilogram of aluminium in today's cars saves about 20Kgs of CO2 along the car's lifespan and about 18Kgs during the full lifecycle, including production, use-phase and end-of-life recycling."
Iron and its derivatives have been the principle materials underpinning the industrial revolution since the late 18th Century, and at the very core of the automotive industry since Benz built his first car and Henry Ford industrialised vehicle production.
Aluminium, on the other hand, is a veritable upstart: it only celebrated the double centenary of its discovery in 2008, while it wasn't industrialised until 1876. Little wonder, then, that prior to that aluminium was considered a precious metal more valuable than gold or platinum. However, as production increased, its value steadily dropped and, in 1893, aluminium was deemed sufficiently inexpensive for the statue of Eros in London's Piccadilly Circus to be cast from it.
Bearing this in mind, it is probably not that strange to hear Bernard Gilmont, the European Aluminium Association's building and transportation director, describe aluminium as a "very young material". Be that as it may, this upstart has certainly caused the steel industry to react vigorously, with projects such as Ultra Light Steel Auto Body (ULSAB), Ultra Light Steel Auto Closures (ULSAC) and Ultra Light Steel Auto Suspension (ULSAS), which comes as no real surprise to Gilmont. "In my personal opinion, I think, if you are a material that has been used for many, many decades and is the reference, and you see competition like aluminium arriving, it's easier to be united against a common enemy. If you see an opportunity, you want to keep it for your own business.
"When a sector is under attack and very well established on the market, you make common projects much more easily," he adds, referencing the lack of similar projects from the aluminium sector. This he partly attributes to suppliers and OEMs working independently of each other to gain market advantage. "It could be that our members are working with OEMs, but, even if we knew, we couldn't say, because we're in a very competitive world. Let's not forget that aluminium is a quite young material, so everything that comes is a new application."
Critics of aluminium are quick to criticise its greenhouse gas (GHG) credentials and point out that 1Kgs of primary steel is in the range of 5 to 15 times more environmentally friendly than aluminium – a charge that Gilmont strongly rejects. "The range is not 5 to15, but 5 to 6, and roughly 5. It's that order of magnitude. These comparisons make no sense, in that, for the automotive sector, you will never compare 1Kgs of steel to 1Kgs of aluminium. If you use aluminium to replace a steel grade or other material, you make it lighter," he argues. "You won't replace it by 1Kgs, but by 600grams or 500grams of aluminium. Comparing kilo to kilo makes no sense and even less in the automotive sector."
Gilmont goes on to explain that, if aluminium would not bring any weight-saving advantage for a defined part, then it will not be used. "Aluminium will only be used in applications where it can bring weight saving. Then you can compare 1Kgs of something else with 1Kgs of aluminium; for example, if you save half the weight of an engine block by using aluminium, rather than cast iron."
But if there is one aspect of the 'aluminium versus rivals' debate that causes disputes, it is the lifecycle element of its GHG footprint and how that is measured or determined. Rightly, Gilmont describes all vehicles as "mines on wheels", given the percentage of metallic content that can be returned to its original state for onward use. But, he argues, the mere production of a material is only part of a much larger equation. "If we compare the lifecycle of the material without talking about the use phase and fuel saving, that is only part of the story. Compared to non-metallic materials, you know that all metals are recycled and, if you look at the end of life of the vehicle, you have the material back and, if that material substitutes primary metal, then you see that aluminium and steel are very comparable. "If what you recycle is the common point of metals and you compare that to carbon fibre or reinforced composites or whatever, you'll have the [metal] material back at the end of the car's life. That makes a huge difference and that's a message we pass on to the OEMs," he says, "because, in their communications, when they talk about recycling, they just quote the energy spent to recycle the material. But they don't quote the fact that they generate material that can be used to substitute primary material, which represents a huge environmental credit. You don't recycle just because you have to; you recycle because there is a big demand to have this material back in the loop."
He goes on to argue that this isn't just a fault with automotive manufacturing, but society and legislators in general; that recycling is tomorrow's problem. "In the context of GHG, as a society we look at it in the short term and, in some sectors, very short term. Most of the time in the political debate, people just look at emissions at the beginning of the life of a product and do not care so much about what happens at the end of the life of these products.
"They see that as somebody else's problem, for another time. This is the main advantage of metallic materials; compared to others, that is often ignored.
"We consider that metals used in cars aren't something you will simply landfill at the end of the products life, but rather the material will be reused later."
Which brings us neatly around to the contentious issue – often voiced by the steel industry – that different grades of aluminium, sheet, cast or extruded, need to be separated, prior to recycling.
"What some people criticise is that today's quantity of aluminium recovered from end-of-life cars is usually directed towards castings mainly in the automotive sector." However, he maintains there is a very clear explanation for that. "If you look at what's being collected as aluminium from end-of-life cars, it corresponds to the aluminium alloy mix that was put into cars 10 to 20 years ago and at that time the majority was castings.
"The last study we made in 2005 showed that the aluminium content in new cars was still more than 70% cast alloys and those that are recycled in Europe are the smallest models, not the more luxurious models which are exported. So we end up with a mix that is, by a majority, cast alloys; so that today separating the small percentage of sheet or extrusion alloys is simply not economical."
Currently, the EAA, together with Norway's University of Trondheim, is analysing the future of aluminium castings/sheet recycling, the results of which should be available in the second quarter of 2012.
"We are building a mass flow analysis at the moment to be able to tell in which timeframe the quantity of aluminium used for sheet and profiles will be high enough, so that we would expect to have further separation in the recycling. But today that's impossible, due to the small quantity of non cast alloys.
"We expect that, over time, the percentage of non cast alloys will increase and there will be a moment in time in the coming decades – we don't know if that's one, two or three – where we'll be able to sketch various scenarios to predict when further separation becomes economically feasible."
It is, he concedes, a chicken-and-egg situation that depends on the increased take-up of aluminium sheeting in closing panels etc by mass producers such as Ford or GM, rather than niche products like the Jaguar XJ or Audi A8.
Gilmont quotes a recent report commissioned by the EAA from the Institut für Kraftfahrwesen Aachen (IKA). It concluded that, compared to a state-of-the art steel reference car, the remaining weight reduction potential of aluminium was up to 40%, using the conventional car body aluminium alloys and new high-strength alloy variants, with strength levels up to Rp0.2 of 400 MPa that are currently under investigation.
The study also assessed that the remaining weight reduction potential with intensive high-strength and ultra high-strength steel usage was limited to approximately 11%. This relatively low percentage is due to the fact that 38% of the components analysed were found to be highly relevant for global stiffness, but had low strength relevance in crash. These components are not suitable for efficient weight reduction, using steel grades with higher yield strength.
"The 40% car body weight reduction potential with aluminium is, of course, a long-term target, but, in the short term, cars could easily become 40 Kgs lighter, if they were only using innovative, proven and cost-efficient, lightweight aluminium body components, such as bonnets, wings, doors and bumpers," says Gilmont, before ending with a compelling argument for the increased use of this young metal. "On average, every kilogram of aluminium in today's cars saves about 20Kgs of CO2 along the car's lifespan," he points out, "and about 18Kgs during the full lifecycle, including production, use-phase and end-of-life recycling."
Bernard Gilmont holds a degree in Mechanical Engineering from the Ecole Polytechnique de Louvain, a degree in Energy & Oil Products Engineering from the IFP-School (Paris) and an Executive Master in Management from Solvay Business School (Brussels). After a year spent in the electricity industry and five years in the oil industry, he has been working for 11 years in the European Aluminium Association (EAA). After having started up EAA activities focused on commercial transport, he took over the management of the automotive and building activities.
Gilmont today coordinates the advocacy for aluminium in both the building and transport sectors, at the level of European institutions.
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Author
Ian Adcock
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