March 08, 2006
Falling Carbon Fiber Costs May Be Key To High Car Fuel Efficiency

Oak Ridge National Laboratory is pursuing technological advances that will allow lightweight carbon fiber to replace most of the steel in cars.

OAK RIDGE, Tenn., March 6, 2006 Highways of tomorrow might be filled with lighter, cleaner and more fuel-efficient automobiles made in part from recycled plastics, lignin from wood pulp and cellulose.

First, however, researchers at the Department of Energy's Oak Ridge National Laboratory, working as part of a consortium with Ford, General Motors and DaimlerChrysler, must figure out how to lower the cost of carbon fiber composites. If they are successful in developing high-volume renewable sources of carbon fiber feedstocks, ORNL's Bob Norris believes they will be on the road to success.

"Whereas today the cost to purchase commercial-grade carbon fiber is between $8 and $10 per pound, the goal is to reduce that figure to between $3 and $5 per pound," said Norris, leader of ORNL's Polymer Matrix Composites Group. At that price, it would become feasible for automakers to use more than a million tons of composites - approximately 300 pounds of composites per vehicle - annually in the manufacturing of cars.

That 300 lb of composites would replace 1500 lb of steel for a net 1200 lb weight savings.

The big advantage of carbon fiber is that it is one-fifth the weight of steel yet just as strong and stiff, which makes it ideal for structural or semi-structural components in automobiles. Replacing half the ferrous metals in current automobiles could reduce a vehicle's weight by 60 percent and fuel consumption by 30 percent, according to some studies. The resulting gains in fuel efficiency, made in part because smaller engines could be used with lighter vehicles, would also reduce greenhouse gas and other emissions by 10 percent to 20 percent.

All of this would come with no sacrifice in safety, as preliminary results of computer crash simulations show that cars made from carbon fiber would be just as safe - perhaps even safer - than today's automobiles. Today's Formula 1 racers are required by mandate to be made from carbon fiber to meet safety requirements.

Combine the carbon fibers with next generation diesel electric hybrids and lithium-based batteries and the fuel savings would be even more dramatic. Doubling fuel efficiency seems plausible.

Here's a message bound to displease environmental puritans who think we should get right with the environment by making big sacrifices in our profligate and wasteful high energy lifestyles. In a recent speech at MIT Amory Lovins argued that carbon fibers could make even SUVs fuel efficient.

Even the quintessential gas-guzzling SUV could become energy-efficient if it weighed a lot less and was run by a hybrid engine or a fuel cell, according to noted author and environmentalist Amory Lovins, who spoke Monday, Feb. 27, to a packed crowd in Wong Auditorium.

Lovins is the founder and CEO of the Rocky Mountain Institute, a nonprofit organization that "fosters the efficient and restorative use of resources to make the world secure, just, prosperous and life-sustaining."

By increasing efficiency and substituting fuels such as biodiesel and natural gas saved through increased efficiency, the United States can be oil-free by 2040, said Lovins, featured speaker at the third colloquium sponsored by the Energy Research Council (ERC) and the Laboratory for Energy and the Environment (LFEE).

In a talk that shared the title "Winning the Oil Endgame" with his 29th book, Lovins presented a picture of an energy future in which more American cars will be manufactured that are competitive in the world marketplace, emissions will be drastically reduced, the economy will improve and the United States will be freed from its dependence on Middle East oil -- all with no radical shifts in government policy, taxes or regulations.

The catch? Cars, trucks and planes, which consume 70 percent of the U.S. oil supply, will virtually all have to be made of lightweight carbon composites or new ultralight steel.

Toward that end Lovins promotes the Hypercar concept.

I prefer solving problems through advances in technology to bring us even higher living standards over heeding calls for sacrifices and suffering to atone for our sins. So I'm adding acceleration of carbon fiber materials research to the list of accelerated development efforts I'd like to see in energy-related technologies. I'd also like to see lighter weight and higher energy density batteries, cheaper and higher conversion efficiency photovoltaics, cheaper and less waste generating nuclear reactor designs, and advances in building insulation technologies to make it cheaper to design extremely efficient buildings.

Share |      Randall Parker, 2006 March 08 09:22 PM  Energy Transportation


Comments
Monte Davis said at March 9, 2006 5:59 AM:

In researching the current state of play for carbon nanotubes, I've found it salutary to recall the now 40+-year history of carbon fiber, graphite whiskers and carbon-carbon composites. There were plenty of 1960s stories in Popular Science, Popular Mechanics etc. about how they'd soon be be the new aluminum or steel, and transform engineering and architecture.

By comparison to those breathless expectations, they've remained mostly niche materials for aerospace applications that can pay a big premium for high strength/weight -- and for low-volume, "glamorous" niches such as tennis rackets, golf-club shafts, bits of premium cars, etc. where arguably customers are buying the coolness factor rather than the Young's modulus. A lot of that has to do with fabrication technologies (hand-laying, autoclave curing) that remain primitive compared to metal working.

This is not at all to say they're not worth pursuing -- there has been substantial progress -- but that materials science and process engineering involove a lot of nitty-gritty details that can turn a researcher's (or science writer's) revolution into a long, slow grind.

Engineer-Poet said at March 9, 2006 7:57 AM:

One way to spur the adoption of efficiency measures is to make them pay.  This is why I've become an advocate of fuel taxes (internalizing the costs allows people to minimize the total burden, which cannot be done if there are subsidies or externalities).

Jim said at March 9, 2006 8:44 AM:

the hypercar site is pretty cool.... they'll still need steel for impact resistance. aerospace is going mostly composite, but still will require about 1/4 to 1/2 metals for joints and other tri-axially loaded components. airplanes have nil crash resistance either (aside from the sides where things like luggage mover can bump into it). lighter design obviously helps crash resistance once all cars are lighter.composites are probably quite helpful in the passenger safety cage, but generally poor in the crumple zones that will be especially needed during the transition when 1/2 the vehicles on the road are still bigger and heavy.

Brian said at March 9, 2006 8:48 AM:

Another consideration is repairability. You'll have a lot of resistance to new materials from the homespun, self taught, autobody do-it-yourselfers if the material can't be welded and doesn't blend well with bondo and the like.

Hamerhokie said at March 9, 2006 9:12 AM:

Lovins talks alot about the Hypercar in "Winning the Oil Endgame" and "Natural Capitalism." A key assumption of his premise is that manufacturing cars out of composites is cheaper in the long run, because of the cost savings in the manufacturing process itself. He points out that a big cost in introducing a new car line is in the construction of tooling, molds and dies for the bodies, costs which are substantially reduced when you go to composites. This led him to speculate that it would be easier for a composite manufacturer to go into the Hypercar biz than it would for anyone in the automotive industry, as they have way too much invested in the steel construction process.

Paul Dietz said at March 9, 2006 10:04 AM:

An amusing scenario of unintended consequences I've thought about would be if Lovins' notion (long with improvements in automated control systems) made flying hypercars feasible. Instead of saving energy, they'd expand commutes to hundreds of miles and convert most of the rural land in the US into potential suburbs.

Al said at March 9, 2006 11:00 AM:

The problem with man is that he finds it to shelf time tested methods in favor of untested ones. Steel is a very versatile and reliable material. the Industrial age heavily relied on stell. As the Chinese have discovered it is one of the "strategic" sectors in an industrializing economy. In fact, the amount consumed per capita denotes a nation's prosperity. How come that inspite of their appeal carbon fiber composites are yet to gain wide spread adotion? Other than in the aerospace industry, an industry that will readily pay for expensive components due to the high value nature of its products, other industries especially cost conscious ones have found it difficult to adopt composites.

Manufacture of the composites is an energy intensive process. It's also prohibitively expensive to join those fibers into a matrix and then form layers.

Philip Sargent said at March 9, 2006 2:17 PM:

and you can fuel it with synfuels too.

The Alliance of Synthetic Fuels in Europe (ASFE)DaimlerChrysler, Renault,
Royal Dutch Shell, Sasol Chevron and the Volkswagen group, just produced a
report http://www.carbonfree.co.uk/cf/news/wk10-0003.htm.

Though are the relatively low CO2-credentials of natural gas still as good
when an increasingly large quantity is delivered as LNG? The energy wastage
(and thus CO2 emission) is about a third higher.

By the way, although I know it's not the same thing as crash resistance per se; if it is energy absorbing you need (e.g. crumple zones rather than side-bars), then GFRP* is better than metal alloys per weight or per volume.

*Glass Fibre Reinforced Polymer i.e. fibreglass, see this wonderful talk on materials selection for sustainable/environmental goals: http://www.ifm.eng.cam.ac.uk/sustainability/seminar/documents/051019ashby.pdf


Jim said at March 10, 2006 8:23 AM:

Philip - I read your link - they used bending strengty as a proxy for impact resistance..... there's a big difference between the ability of a material to absorb energy and its bending strength. in fact these properties often move in opposite directions.

Doug said at March 10, 2006 12:22 PM:

Rather than substitute 300 pounds of composites for 1500 pounds of steel at "no" sacrifice of safety, I might be inclined to substitute 1600 pounds of composites for 1500 pounds of steel, truly at no sacrifice of safety, that is, in order to obtain the full increment in safety that the 1600 pounds of composites would provide. My point is not to talk about the strength, flexibility, and energy-absorbing ability of composites and steel, but to point out that without the federal government's chains, we'd be able to choose from among the full range of trade-offs between safety and efficiency in materials.

Philip Sargent said at March 10, 2006 4:23 PM:

..and here is one we prepared earlier:
238 miles/gallon (OK, it's a UK gallon) i.e. 1.5 litres/100km
conventional 2 cylinder diesel, no hybrid anything, just very low weight and good streamlining:

Loremo at Motor Show.


Sorry, the ref. I gave re materials design did not match the earlier statement about GFRP fracture energy. It's not new, try this URL.

Jim said at March 13, 2006 3:33 PM:

Philip - your new link doesn't support your belief about relative energy absorption either. the key concept is strain-hardening.... that is to say the opposite of necking or an upward slope to the stress-strain curve providing high strain at failure. aside from the limits to biaxial loading, the lack of strain hardening is a key limitation to fiber-reinforced polymer composites.

note that i'm NOT saying CFRP composites aren't needed because they are.... just not in the crumple zone. however, at current prices, good luck putting them anywhere on a vehicle not involved in open wheel racing - hence the importance of working to reduce carbon fiber prices.

Philip Sargent said at March 14, 2006 4:25 AM:

A bit off-topic, but to respond to that...

1. Strain hardening is the mechanism for energy absorption in ductile metals under heavy deformation.

2. Creation of a large amount of surface area in microcracks, delamination and crazing is the entirely different mechanism for energy absorption in FRP.

You can calculate fairly easily the maximum energy absorbed per unit volume of metal: it is just the area under the stress-strain curve.

The maximum energy absorbed per unit volume of FRP depends on how finely it cracks, so finer fibres and weaker interfaces absorb more energy. Harder to estimate, but easy to measure in crushing experiments.

Consideration of these two mechanisms shows that mechanism 2 can absorb rather more energy per unit volume, if the FRP is designed for it, than any metal alloy can using mechanism 1.


All explained [somewhere] in the list of references given in the previous post. A better reference for this level of discussion is an undergraduate textbook, rather than those research papers. My favourite is Ashby & Jones: Engineering materials.

In fact this isn't off topic at all.

We are talking about picking the right material for a set of requirements. One poster wanted the minimum vehicle weight for the same level of safety, another wanted the same weight and as much safety as possible (affordable). These are different problems and the optimum materials selection will probably be different. SO the answer is you just have to read this other book:
"Materials Selection in Mechanical Design, Third Edition by Michael Ashby".

The techniques of materials selection have been adopted for the UK A-Level syllabus (ages 16-18) as they are graphical and easily appreciated visually.

I can't do better than to quote an Amazon review:
"Ashby has an unsurpassed reputation in teaching engineers about materials. His approach leads the engineer from design requirements through to optimal material choices in a systematic, science-based manner.... I love this book (have given many copies as gifts!) and recommend it as a 'must-have' for material science and mechanical engineering undergraduates and their teachers, as well a cornerstone backgrounder for materials professionals in industry."

[Actually, I'm a metallurgist and I reckon I know rather a lot about strain-hardening. I used to work as a post doc for Ashby and those two books are just brilliantly clear.]

For some reason, this comment system is refusing to let me post the URLs to the Amazon pages forthese books. Sorry.

Philip Sargent said at March 14, 2006 4:27 AM:

The maximum energy absorbed per unit volume of FRP depends on how finely it cracks, so finer fibres and weaker interfaces absorb more energy. Harder to estimate, but easy to measure in crushing experiments.

Consideration of these two mechanisms shows that mechanism 2 can absorb rather more energy per unit volume, if the FRP is designed for it, than any metal alloy can using mechanism 1.


All explained [somewhere] in the list of references given in the previous post. A better reference for this level of discussion is an undergraduate textbook, rather than those research papers. My favourite is Ashby & Jones: Engineering materials.

Randall Parker said at March 14, 2006 5:58 AM:

Guys,

If your comments do not immediately show up please do NOT repost. I installed a new version of MovableType and it is deferring all comments for moderation. I can not figure out how to make that more selective (there are obvious settings for it that have no effect) and I've posted to support to get answers. So today it will be problematic. Sorry about that.

Jim said at March 14, 2006 8:28 AM:

Dr. Sargent

yes, the Ashby approach to materials selection is fantastic. I have the book on my desk now (no software).

still, I disagree that cfrp are superior to dual-phase steel for energy absorption. particularly the statement "Consideration of these two mechanisms shows that mechanism 2 can absorb rather more energy per unit volume, if the FRP is designed for it, than any metal alloy can using mechanism 1." is unsubstantiated (or if you did prove it somewhere, i missed it)

what is to prevent strain localization and cracking in frp composite, short-circuiting the highly energy absorbing creation-of-much-surface-area mechanism that you envision? in fact fracture of these types of materials is prone to the lower energy strain localization behavior. whereas dual phase steel achieves up to 25% tensile elongation due to the rate-stabilizing, strain-induced martensitic transformation.

not to mention how ridiculously cheap, energy-efficient, highly-recyclable, easily fabricated the steel is from your local mittal or whatever supplier near you.

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