A Car Made Out of What?
There’s a generation of less conventional and more environmentally friendly building materials on the horizon. Sheet metal and petro-plastic beware!
Toyota’s 1/x hybrid concept, whose bioplastic exterior contains seaweed, has the same interior space as a Prius, but weighs only 926 pounds — about one-third the weight of a Prius — and aims to double its fuel efficiency.
More than a century ago, Henry Ford made a pragmatic — yet arguably visionary — decision by ditching car body panels made of wood for ones made out of sheet metal. The move increased the speed of automobile construction exponentially, and eventually led to the mass-produced car. However, metal wasn’t the only material in Ford’s arsenal of experimentation.
Ford was actually dabbling with more exotic, less factory-friendly construction materials, such as a soy-based plastic exterior that could survive the mighty swing of an ax blade. He ultimately abandoned such plant-based materials because they were too expensive.
But as a new generation of carmakers and materials researchers attempts to wring more efficiency from (and lessen the environmental impact of) the modern motor vehicle, less conventional building materials are gaining new attention.
From design-oriented projects made of bamboo and glass to Toyota’s 1/x concept, whose bioplastic exterior contains seaweed, decades of research into novel materials seem on the verge of paying off. The question is, when will these starch-infused, shape-changing marvels hit the road, and will they be cheap enough for mere mortals to afford, or will they be another novelty for the billionaire whose Lamborghini has lost its luster?
Here are some of the more promising materials automakers are experimenting with:
Corn, Seaweed & Soybeans: Bioplastics
Plastic doesn’t grow on trees — not yet, at least. Most of it, which is used in everything from water bottles to SUV dashboards, is petroleum-based. For automakers hoping to reduce their carbon footprint — whether to boost their environmental image, or to head off regulations that would penalize carbon emissions, or a combination of both — the benefits of plant-based plastics are obvious.
For example, the production of bioplastic films derived from cornstarch churns out fewer emissions than the production of those made out of petrochemicals. Plus, they are already in relatively widespread use as eco-friendly industrial packaging, which can even be designed to safely break down in landfills. In April, Frito-Lay unveiled a new Sun Chips bag that’s one-third bioplastic, and the company hopes to have a fully compostable bag by Earth Day 2010.
Challenges: But what’s an advantage for an eco-minded chipmaker is a challenge for automakers. How do you achieve the strength and durability of petroleum-based plastics while preventing the material from biodegrading during the vehicle’s life span? “With enough water and heat, this plastic can break back down into compost,” says Steve Davies, director of communications and public affairs for NatureWorks, which is working with Ford and Toyota to incorporate bioplastics into new vehicles, and whose corn-based Ingeo bioplastic is part of the new Sun Chips bag.
“You have to use special coatings to turn that tendency off, so it won’t hydrolyze back into lactic acid, or basically CO2 and water,” says Davies. For now, the relative vulnerability of bioplastics to the elements makes it a better fit inside the car, particularly in shaded areas such as the trunk. The Toyota Prius features bioplastic floor mats, and when Mazda unveiled its Premacy hydrogen model in 2007, its seat covers and instrument panel incorporated bioplastic.
Outlook: Carmakers are planning to dramatically increase the use of plant-based plastics. Mazda will begin incorporating a nonfood-based bioplastic (derived from the inedible parts of a to-be-announced crop) in some vehicles by 2013, and Toyota wants to replace 20 percent of its automobile plastics with bioplastics by 2015. Beyond the obvious environmental benefits, such as a seven- or eight-fold drop in CO2 emissions per pound of bioplastic fabric produced (compared to nylon, for example), Mazda believes that the lighter-weight materials could lead to increased fuel efficiency, and potentially better performance.
So when will carmakers be able to use bioplastics for exterior body panels or other substantial components? That depends on how quickly companies like NatureWorks will be able to boost their lightfastness and moisture resistance, and whether (or when) oil climbs back to more than $100 a barrel. When fuel goes up, the price of petroleum-based plastics rises with it, and bioplastics become even more attractive, from a financial standpoint.
Although the exact time frame is unclear, it seems inevitable that automobiles will be increasingly culled from food crops, preferably from corn husks or other agricultural waste. The process will begin from the inside out, starting with interior trim in the next handful of years, and gradually extending outward. It’s also clear that bioplastics won’t be found exclusively in eco-friendly or luxury vehicles — they’ll be as ubiquitous, and as unassuming, as the plastic already used.
The BamGoo is a single-seat electric car sheathed in bamboo. The 60-kg ecologically friendly concept car was developed by Kyoto University and can run for 50 km (30 miles) on a charge.
Bamboo, Wood & Hemp: Organic Composites
While bioplastics use plant material as one ingredient in a bubbling industrial cauldron, a handful of designers are trying to stage a comeback for the fully organic car frame. The experiments range from last year’s BamGoo, a one-seat electric car shown in Kyoto, Japan, that was made of bamboo, to the Lotus Elise Eco, which incorporates hemp in its exterior, bringing the overall vehicle weight down by 70 pounds. But the most dramatic use of plant-derived materials in a car’s construction is probably the Splinter, a 600-horsepower supercar design that is not only covered with wood, but features an oak and plywood steering column and wood-spoke wheels.
Joe Harmon, who built the Splinter as a graduate project while at North Carolina State University, wanted to show off wood’s potential to outperform traditional materials while being more sustainable. “Wood has a better strength-to-weight ratio than steel or aluminum,” Harmon says, “and when you compare it to what goes into digging aluminum out of the ground, transporting and refining it, wood takes roughly 1,000 times less energy to get the raw material in place.”
Harmon is now working with Corvid Technology to develop the woven-wood process that he created for the Splinter design. To make wood conform to complex shapes, Harmon’s process weaves it into a fabric. The wood is then impregnated with resin, allowing it to be draped, and then hardened in place. The result is what every auto engineer wants — a lightweight, fully customizable material that doesn’t sacrifice strength.
Challenges: Woven wood, and similar organic composites, share many of the advantages of carbon fiber — as well as the disadvantages. Any issues of durability can be handled with special coatings and sealants. The real problem is not necessarily the cost of producing the materials, or the fact that factories aren’t currently designed to accommodate novel materials, but that they slow down the rate of manufacture. The longer it takes to glue carbon-fiber panels in place, or to drape woven wood and allow it to set, the quicker the economics of mass-production collapse.
“Today, we make one new car on the assembly line every minute,” says Frank Field, a senior research engineer at MIT’s Materials Systems Lab. “That’s a critical time constant. If you can’t do whatever you’re doing in a minute, you’re going to have to offer me something I really have to have — and that I’m willing to pay more money for.” Since they can’t be efficiently produced in 100,000 production runs, organic composites and carbon fiber are more suited to high-priced niche products such as supercars and F1 racers.
Outlook: Harmon doesn’t expect Honda to start rolling out wood-frame Honda Civics. As a material, he sees woven wood as a more universal product, as applicable to furniture as to any vehicle. He says that with enough development, organic composites could be used in exteriors for boats as well as cars, although never in a mass-produced capacity. As for his Splinter car, which is currently a rolling chassis, Harmon hopes to get the 4-wheeled, turbocharged marketing campaign road-ready within the next couple of years.
Shape-Shifting Alloys and Polymers: Smart Materials
With all the buzz surrounding plant-based composites and plastics, it’s easy to forget an equally high-tech, and completely inorganic, class of materials about to hit the showroom floor. Shape memory (SM) alloys and polymers, collectively referred to as “smart materials,” are designed to soften when heated, and then stiffen as they cool. The potential benefits include body panels that could essentially heal themselves after an accident.
In 2008, Jan Aase, director of the Vehicle Development Research Lab in General Motors’ research and development division, saw this magic trick first-hand. After he hammered a one-inch dent into a sheet of SM alloy, Aase watched as another researcher applied a blowtorch, and the smart material popped back into shape.
Challenges: “As a demonstration, it’s incredibly impressive,” Aase says. “But the cost of the material is very high. The intricacies of stamping it still have to be worked out. In terms of reality, we’re quite far from production.” Even if the cost of smart materials comes down, the current manufacturing process — which includes multiple sheets of metal being stamped and welded together by teams of industrial robots — would be incompatible with alloys that actually unstamp themselves when heated.
The same is true for SM polymers, hard pieces of composite material that become floppy under high temperatures and rigid again when cooled. As useful as GM imagines these “morphable” polymers will be when they might be used to create components with precisely molded shapes and textures or to fill gaps between other components, the manufacturing challenges are even more daunting than for SM alloys.
Outlook: While researchers continue to experiment with the properties of smart materials, and the feasibility of using them in large components, GM is planning to introduce small applications of SM alloys in vehicles for the 2011 model year. The automaker won’t reveal what those applications will be, except to say that they’ll be in the same vein as research projects made public in 2007. That could mean features as unassuming as a remote-operated glove box, or as James Bond-worthy as “active” air dams and spoilers that automatically deploy and retract depending on speed and driving conditions.
Functionally, these initial SM alloy gadgets will be doing the same job as a standard, electric-powered actuator. But with fewer moving parts and relatively little energy required to heat and cool the tiny SM alloy springs, smart materials are about to make shape-changing cars more practical than ever. This first wave of minor applications could be only a couple of years away, and according to Aase, they won’t necessarily be restricted to luxury vehicles — the process of embedding vehicles’ SM alloy-activated devices doesn’t require large volumes of exotic materials or new manufacturing techniques.
Bottom line, there’s no timeline for when the more ambitious SM components might be available. But for GM, which has spent decades researching smart materials, the more pressing question isn’t when its cars will start reconstructing themselves after accidents, but whether the company can survive long enough to sell that snazzy, remote-activated glove box.
Based out of the Boston area, Erik Sofge is frequent contributor to Popular Mechanics and Slate.com. He specializes in everything scientific and technical.
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