Carbon Fiber Composites get a Recharge

BMW shifts the paradigm in material selection

Reducing mass is only one avenue of many that can be used to reduce carbon dioxide emissions from vehicles.  The table shows the estimated impact and penetration levels by 2025 for various approaches according to the US EPA and the California Air Resources Board.

VMR Table

Legislation around the world is pushing the automakers to comply with increasingly lower carbon dioxide emission levels.  Hence, the frantic drive toward reducing mass as one of the options to meet the legislative mandates.  Across the world each country has a different standard however, target emission levels are converging and being reduced significantly.

BMW is singlehandedly shifting the paradigm in the vehicle manufacturing world.  The announcement to use carbon fiber reinforced plastics (CFRP) for its i-series of vehicles has created a market pull for technologies related to CFRP technologies.  BMW wants to decrease mass without sacrificing safety which is why they are so focused on CFRP integrated with an aluminum sub-structure.

BMW’s strategy is built on many years of working with composites on a variety of components combined with a willingness to take on risks.  Since 1999 BMW has been developing various CFRP prototypes and niche applications.

There remain major issues with the use of CFRP that include:

  • Recyclability
  • High costs
  • Reliability
  • Lack of an extensive infrastructure for procuring the complete bill of materials
  • Repair ability
  • Lack of reliable simulation data
  • Crash and subsequent crack propagation that may lead to catastrophic failure in the field

The list goes on and on, but so does BMW.  The knowledge build-up was given a BMW management audience and a decision to go with the use of CFRP for the body-in-black was made.  There are now a number of i-programs targeted for the use of carbon composites that include the i-3, i-8 and i-12.  BMW is expected to selectively spread its increasing carbon fiber composite knowledgebase into components on its traditional vehicles as well.

BMW believes, rightfully so, that an electric vehicle platform requires a fresh approach to the vehicle’s architecture.  Hence, the LifeDrive concept was created so as to break the weight spiral and to combine lightweight and optimum crashworthiness using a clean sheet of paper.  BMW believes that this architecture is the key to stop mass compounding.  The LifeDrive approach encapsulates an aluminum structure that is responsible for crash management while at the same time off-setting the increased weight of a battery pack and providing the expected range.

The CFRP supply infrastructure is complicated and expensive as shown in the accompanying flowchart.  It is our rough estimate that BMW has spent about 1 to 1.5 billion Euros on setting up a source of carbon fiber and subsequent mat forming and part manufacturing.  This is not something that can be easily emulated by the other OEMs.  We believe BMW’s strategy is to be a market leader and set the pace.  Audi had, and still has, primarily an aluminum approach.  BMW will have a good bargaining position with legislators concerned with future rounds of carbon dioxide emission discussions having invested in a technology that other OEMs shied away from.

CFRP Value Chain

Based on the experience level and the strategic vision that BMW has committed to carbon fiber composites, this approach appears to be a clear direction for BMW.  However, we do not believe this approach will be as relevant at most of the other automotive OEMs.  On a component level, yes very much so, but on a large scale (beyond 150,000 vehicles per year), we have our doubts.