Special Report: Cars Made of Plants?

There's a quiet green revolution going on. While automakers have been talking up a future filled with biodiesel, hydrogen fuel cells and even ethanol, they've been very quietly integrating parts made from biobased materials into their present-day cars and trucks.

These environmentally friendly car parts are made from coconut, corn, flax, hemp, jute, sisal, soybeans and other plant-based materials (and occasionally from animal-based materials, like wool). They're showing up in entry-level economy cars and high-end luxury automobiles, in this country and abroad.

Considering the heavy emphasis on green cars these days, we have to wonder why automakers aren't making a big deal about their use of biobased materials. Do these components figure into the companies' strategic plans for a greener future? And exactly what benefits do we — and the automakers — receive from these earth-friendly parts and pieces?

Who's Making Plants Into Parts?

The variety of biobased automotive parts currently in production is stunning. DaimlerChrysler has been the biggest proponent of these materials, and today, up to 50 components in Mercedes-Benz A-, C-, E- and S-Class models are biobased — though not necessarily in vehicles sold in the United States.

Flax, hemp and sisal are processed into door cladding, seatback linings and package shelves (the space behind the rear seats of sedans). Coconut fiber and caoutchouc (a source of latex) are used to make seat bottoms, back cushions and head restraints. Abaca (a cousin of the banana tree) is used in under-floor body panels. And the company expects suppliers to be able to produce flexible tubing for fuel and brake systems made with castor oil soon.

Other manufacturers have been putting natural ingredients into their cars as well:

  • The BMW Group incorporates a considerable amount of renewable raw materials into its vehicles, including 10,000 tons of natural fibers in 2004. Each BMW 7 Series car boasts 24 kilograms of renewable raw materials, with flax and sisal in the interior door linings and panels, cotton in the soundproofing, wool in the upholstery and wood fiber in the seatback cushions.
  • Toyota has shown interest in using kenaf. This grass, which is related to okra, has been used to make Lexus package shelves, and it's also incorporated into the body structure of Toyota's i-foot and i-unit concept vehicles.
  • At General Motors, a kenaf and flax mixture has gone into package trays and door panel inserts for Saturn L300s and European-market Opel Vectras, while wood fiber is being used in seatbacks for the Cadillac DeVille and in the cargo area floor of the GMC Envoy and Chevrolet TrailBlazer.
  • Honda is using wood fiber in the cargo area floor for the Pilot SUV.
  • Ford mounts Goodyear tires that are made with corn on its fuel-sipping Fiestas in Europe. The sliding door inserts for the Ford Freestar are made with wood fiber.

What Are the Benefits?

Why are automakers so interested in turning plants into car parts? As it turns out, there are lots of reasons, some business-oriented, some environmentally oriented and some just plain patriotic.

For starters, many of these biobased parts replace petroleum-based components. When the parts are made here in the United States, the switch to agricultural materials reduces our country's reliance on foreign oil while also supporting American farmers. Rising and fluctuating oil prices also make biobased materials more appealing, since their prices can be more stable — and lower — than prices for the materials they replace.

From a green standpoint, the less oil we transport into this country, the less likely we are to experience an oil spill or other environmental nightmare. And if we do spill biobased materials, there's no worry, since most are biodegradable.

Biodegradability and recyclability of the finished part is another reason automakers are so keen on these materials (although not all biobased car parts are biodegradable or recyclable). While the United States hasn't issued regulations concerning end-of-life requirements for automobiles, the European Union and several Asian countries have come out with stringent guidelines. In the EU, by 2006, 80 percent of a vehicle must be reused or recycled at the end of its life; that figure increases to 85 percent by 2015. Japan is similarly strict, requiring 88 percent of a vehicle to be recovered in 2005 (recovery allows for incineration of some components), rising to 95 percent by 2015.

End-of-life isn't the only timeframe that concerns automakers these days. Most companies are looking at the environmental impact of a vehicle's entire lifecycle, from raw materials to manufacturing to a drivable vehicle to disposal.

When you consider biobased materials from a lifecycle standpoint, they've got even more appeal. Starting out in the field, as you're growing the raw materials, the plants are consuming carbon dioxide. Plus, many biobased car parts require less energy to manufacture than their more traditional counterparts. They can be easier on the manufacturing machinery, and they can be easier on factory workers. For instance, workers have experienced skin irritations and respiratory issues related to fiberglass dust; new materials that use plant fibers instead of glass fibers to reinforce molded composites don't cause these problems.

But Do They Perform?

Are automakers sacrificing anything to use biobased materials? As it turns out, biobased car parts typically work better than the parts they replace. For instance, Honda's engineering team found that the wood fiber-reinforced floor provided better dimensional stability than the other, more traditional materials being considered.

Likewise, Goodyear has found that its corn-infused tires have lower rolling resistance than traditional tires, so they provide better fuel economy. And DaimlerChrysler notes that plant fibers' ability to absorb large amounts of humidity makes them perfect for use in seat cushions, where they can increase occupant comfort.

According to BMW, it's possible to manufacture biobased composites that are as much as 40-percent lighter than equivalent injection-molded plastic parts. That's because natural fibers have high-tensile strength, durability and rigidity, plus they're easy to process and lighter in weight than glass fibers, all of which makes them excellent for reinforcing composites.

Using plant fibers in composites provides additional advantages in terms of product design flexibility, noise absorption, insulation, impact-resistance and even a reduced tendency for parts to splinter in a crash. Plus, weight reduction translates directly into better gas mileage.

Farm Groups, Suppliers and Automakers Work Together

As wonderful as these biobased materials can be, both from a philosophical and a practical perspective, developing them isn't always easy.

For some materials, smell is a factor, so research and development (R&D) has focused on eliminating the vegetable odor from interior components. In other cases, obtaining consistent quality from suppliers has been an issue. After all, different farmers are growing the raw materials in different terrain, with differing weather and different watering schedules.

In spite of the challenges, the push to develop automotive uses for biobased materials continues, and it's coming from a variety of places.

For starters, there's the government. The U.S. Agricultural Research Service (ARS) has been developing industrial and commercial uses for a wide variety of agricultural products, including waste items, like chicken feathers. Yes, chicken feathers are expected to replace plastic or fiberglass in some vehicles' dashboards, door panels, headliners and other internal molded parts soon.

Naturally, farmers have a vested interest in expanding the market for biobased materials. So it's not too surprising that they can choose to pay a small percentage of their gross sales to groups like the Soybean Checkoff and the National Corn Growers Association, which focus on researching and promoting new markets for members' crops. These groups often work with universities, many of which have R&D programs that, like the ARS, aim to create commercial and industrial uses for agricultural products.

Some of the processes these schools have developed are being embraced by suppliers to the automakers. For instance, Visteon has developed a system for making flax-based instrument panels, and Composite Products is ready to make door panels from flax. Bayer and Ashland have developed soy-resin body panels that currently are being used on John Deere tractors. These panels are dramatically lighter and more durable than the steel units they replace, and they're also more flexible and easier to paint, so we suspect it's only a matter of time before similar pieces find their way onto passenger cars and trucks.

Findlay Industries, which makes the cargo area floors for the GM and Honda SUVs and the package shelves for Saturns and Opels, also manufactures headliners for Mack Trucks that are made with a hemp, flax, kenaf and sisal mixture. These headliners are strong enough to support dome lights, speakers and curtain rails, which could make them appealing to automakers that want to incorporate overhead consoles and DVD players without attaching them to the roof steel.

Creating Global Sustainability

Interest in biobased materials goes hand in hand with automakers' relatively new goal of global sustainability. This is sustainability in a much broader sense than simply using renewable, rather than depletable, resources. The bigger-picture definition includes corporate responsibility, extending from an automaker's responsibility to its workers and customers to its responsibility for those who live near its manufacturing plants and far beyond.

For instance, DaimlerChrysler's sustainability goals include "improving the living conditions of people in poorer regions in terms of stability and prosperity, ranging from the creation of jobs to the supply of clean drinking water." As the company strives to create a "global sustainability network," it has undertaken unprecedented technology development and technology transfer initiatives involving the use of biobased materials in the Philippines, the Amazon and South Africa.

In each case, DaimlerChrysler's researchers worked with universities and other scientific institutions, as well as local governments and non-government organizations, to create programs focused on a particular plant that makes economic, social and environmental sense. A network of local farmers then cultivates that plant. Local companies process the plant's fibers. And still other local businesses turn those fibers into car parts, which are sold to DaimlerChrysler (and which can, conceivably, be sold to other automakers). And so a complete biobased automotive supply chain is created.

Why Haven't We Heard About It?

If so much good is being done with biobased materials, why aren't automakers talking about it? They certainly haven't been shy about promoting hybrid vehicles, or their efforts to develop hydrogen fuel cells, or almost anything else environmentally oriented.

Yet, when you read automakers' environmental reports — and nearly every car company produces one these days — it's darn near impossible to find a mention of biobased materials. If it does appear, it's typically buried in a section on recyclability.

Why the hush-hush?

One reason is that the use of biobased materials isn't at the top of most automakers' environmental priority lists. For example, Honda is much more focused on reducing the use of harmful materials in vehicles (such as lead in batteries and heavy metals in catalytic converters), and increasing the fuel economy of its entire fleet. So even though the company is using wood-fiber parts in the Pilot, the decision was driven more by engineering considerations than by corporate philosophy.

Similarly, GM is focusing its environmental research efforts on alternative fuels, such as E85 (a blend of 85-percent corn-based ethanol), as well as the hydrogen infrastructure needed to make fuel-cell vehicles a reality.

The notable exceptions are DaimlerChrysler and the BMW Group, both of which have identified biobased materials as a key part of their overall environmental strategy. As BMW says, "In view of the ever scarcer availability of resources, the use of natural fibers provides an exceptionally attractive solution, both ecologically and technically."

DaimlerChrysler goes a step further, identifying biobased materials as one of the two key parts of its plan to create a global sustainability network (the other is using renewable energies to replace conventional fuels). "These are two major elements of the corporate activities geared to the environmentally compatible car of the future," according to the company.

Ford also has turned the spotlight on biobased materials — though more so in years past. The Model U concept car shown at the 2003 Detroit Auto Show can trace its lineage back to what has to be the world's first environmentally oriented concept vehicle: the Soybean Car unveiled by Henry Ford in 1941.

Evidently, Henry was fascinated by soybeans back in the '30s, and he started a whole R&D lab to find commercial uses for the crop. By 1934, the lab was turning out small gearshift knobs and horn buttons made from soy extracts. A couple years later, it unveiled soy-based upholstery, followed by soy-composite body panels. To show off the latter's durability, Henry Ford gathered a group of journalists together in 1940. He swung an axe at a demonstration car's soy-composite trunk lid. When the axe bounced off, the car was unscathed, and Henry got himself plenty of publicity.

It has been 65 years since an automaker demonstrated that much showmanship with regard to biobased materials. Still, today's automobile manufacturers and their suppliers are quietly demonstrating their ingenuity and dedication to these materials.

We suspect the ripple effect of their actions and research will have far-reaching effects, touching farmers and small business owners around the world, reducing U.S. reliance on foreign oil and, by achieving a better CO2 balance over a vehicle's lifetime, maybe even reducing greenhouses gases. So, we commend them on their efforts and look forward to the day when we've got chicken feathers in our headliners and soybeans in our seats.