The case for hi-carbon

Gerd Wingefeld, R&D chief of the SGL Group, is careful to remind anybody willing to listen that the present discourse about “low-carbon” technologies is really not about carbon at all, but rather about carbon dioxide, the harmless gas so necessary for life of all kinds.

The political consensus worldwide is that CO2, emitted as a product of the combustion of petroleum fuels and, should you need a reminder, even the process of breathing, is responsible for “climate change”. Never mind that there is little genuine scientific evidence for the claim that human activities generating CO2 are responsible for even regional changes in weather, forget about a global-scale catastrophe.

Be that as it may, Wingefeld believes that a world obsessed with reducing its CO2 emissions really needs a “high-carbon” economy. He’s talking about a wonder element that’s vital for energy efficiency, weight reduction, and the effective exploitation of alternative energy sources like wind turbines and solar cells — trends the SGL Group, a leading global manufacturer of carbon-based products, has been quick to capitalise on.

The one company in the world that straddles the whole carbon-fibre value chain from precursor to part (SGL even manufactures carbon fibre structural components for the automobile sector in a joint venture with Benteler), is now fairly advanced in research into the use of carbon nanotubes to reinforce plpastics on a microscopic scale, Wingefeld told Autocar Professional. The potential that carbon-fibre-reinforced composites hold out to simultaneously reduce weight and enhance performance – at 1.6 kg/l they are the lightest, strongest, and stiffest materials available for automobile construction, Wingefeld points out – has made SGL, as the sole integrated producer, one of the hottest properties on the automotive supplier landscape. Almost a year ago to date, Volkswagen’s play for this innovative German-headquartered company, and the aggressive counteroffensive by SKion GmbH (the investment firm controlled by Quandt heiress Susanne Klatten, BMW’s largest shareholder), received a good deal of press. SKion, BMW, and VW (in that order) now own the majority of SGL shares between them.

The interest of both, the world’s leading manufacturer of luxury cars, and the second-largest carmaker withal, in SGL is no doubt to secure future supplies of carbon fibre as they increasingly incorporate composites into their material mix, but the company itself sees more immediate prospects in the automotive and supplier industries for its primary product — graphite, mostly of the synthetic variety, which it produces from petroleum coke.

Because of its amazing chemical and physical properties, graphite goes into a wide variety of products and process technologies that find eventual application in the automotive industry. For one, its resistance to high temperatures and corrosion make it the ideal material for seals and gaskets, and its self-lubrication property for dry-running vacuum pumps and bearings besides.

The proliferation of electronics in cars critically depends on graphite. According to Wingefeld, the unique combination of extreme thermal shock stability, high thermal conductivity, and low thermal expansion make it the material of choice for heating, insulating, and lining the crucibles in which wafer ingots for semiconductors are grown. Equally importantly, the low wettability of silicon on graphite prevents impurities from getting into the wafer material, he pointed out to this correspondent.

In the metal organic chemical vapour deposition (MOCVD) process used to produce light-emitting diodes, the future of automotive lighting technology, the LED wafers are “sputtered” on graphite susceptor plates coated with silicon carbide, he added.

And carbon powder milled from graphite is the highest-performance anode material available for lithium-ion batteries. Each Li-ion battery actually contains at least 10 times more graphite than it does lithium! In fact, with the Li-ion battery industry growing at up to 40 percent annually, this is one of the fastest-growing uses of graphite worldwide.

Plug-in electric vehicles like the Chevy Volt, Nissan Leaf, and Tesla Roadster all rely on lithium-ion batteries, and gasoline-electric hybrids are now making the transition from nickel-metal hydride technology. Moreover, the pure-electric vehicle market is projected to reach a volume of six million by 2020 and grow at 20 percent annually. Each of those cars will require approximately 18 kg of graphite for the battery system alone.

No wonder SGL, which commands a 40 percent market share in anode graphite together with partner Hitachi Chemicals, has “high hopes” of the electromobility sector. Wingefeld said he even foresees a “huge” potential market for Li-ion technology in India.

But it’s not just batteries that are going to drive demand for graphite in automotive propulsion systems of the future — proton exchange membrane fuel cells being developed by major OEMs for use in cars currently require up to 50 kg of graphite per vehicle!

Manfred Neumaier, MD of SGL Carbon India, which inaugurated a new facility last fortnight to manufacture graphite process equipment and specialty graphite for the above applications at Ranjangaon, sees a lot of growth potential in replacing asbestos in friction materials — where carbon offers a “real alternative” for cars, trucks, trains, and aircraft.

SGL developed the first racing application of carbon/carbon brakes for Formula One, and the first carbon-fibre-reinforced silicon carbide brake disc for roadgoing cars, which weighed half of the conventional grey iron disc. First shown at the IAA Frankfurt in 1999, it was introduced in series by Porsche in its 911 GT2 in 2001, and is now widely available in all the luxury brands of the VW group following a collaboration with Audi in 2005. Three years ago this business was converted into a joint venture with Brembo.

Neumaier said the company was in touch with Tata Motors for a couple of projects, but would not reveal whether these were for graphite or for carbon fibre. He did admit, though, that SGL India is “actively” observing the market for opportunities to trade its carbon fibre products. The company is one of the very few producers worldwide of high-tow carbon fibres (filament counts of 50,000 and above per fibre) that are the most cost-effective variety for structural components in automotive applications and industry.

Wingefeld and Neumaier both said the more immediate prospects for SGL’s speciality graphite products in Indian cars would be in seals and bearings, and the company is looking at introducing them in partnership with producers of, for example, vacuum pumps like it presently does with a major supplier of submersible pumps for industry.

Its expanded graphite product ECOPHIT, supplied as a composite with a phase-change material (PCM), forms the basis of a high-performance cold storage medium that can be used to cool truck cabins by up to 10°C for 10 hours with the engine switched off and without any external power source. Webasto markets a product using ECOPHIT and water (as the PCM) in the US under the BlueCool brand.

ECOPHIT ceiling elements have been installed in the conference room of the new office building in Ranjangaon to reduce the energy required by the air-conditioner. A similar system installed in the Deutsche Bank building in Frankfurt cut the energy required to cool the building by 50 percent by replacing the conventional air-conditioning altogether, Wingefeld said. For all those steamed up by the global warming debate, a cool idea indeed!

Eliot Lobo