Home  |   About  |   Energy  |   Politics  |   Software  |   Music

03 November 2012

Alternative materials

Part of the use modern industrial society gives to energy is to gather and synthesise disperse matter into complex materials. Due to their solid state and relative stability at room conditions, metals have always had a central role in industrial societies. The processes of mining, transport, refining and casting are vital in the modern economy and demand huge quantities of energy. And this energy demand is proportional to scarcity and dispersion of the raw material in the Earth's crust. There's an interesting post by Ugo Bardi on this matter for a deeper review.

The energy transition modern societies are undergoing today can also be (and most likely will be) a transition into a different way of using matter. A possibility that has been explorer since the 1960s is the usage of carbon fibre composites to replace metals in a variety of applications. Strong and light, they have been promising a new Industrial Revolution for a long time. But while carbon fibres dispense much of the energy consumption of mining and refining processes, they still require relevant amounts of energy in its fabrication process; barring relevant innovation on this aspect, carbon fibre won't become an everyday material.

It so happens that Nature itself fabricates materials not that different from carbon fibre reinforced polymers. Trees produce their own polymers, cellulose and lignen, that are bound together into a material that has great resistance to compression and tension: wood.

It is perhaps the colloquial look at the past to understand the future. Wood has been widely used by Man from the dawn of his existence on the planet for a multitude of applications. It is not the perfect material, but by overcoming some of its shortcomings the end result can be a product perfectly able for modern industrial requirements, with low energy consumption and with all it takes to be part of a fully sustainable economy.

TimberTower is a German company developing wind turbine towers made of pine wood. The advantages of this technology are manifold, ranging from a reduction in price, simplification of the building process and even an increase in power yield. Here's a report from a few weeks ago:
TreeHuger
Wood Could be the Future of Wind Turbine Masts
Derek Markham, 7th of September, 2012.

The new design for wind turbine masts uses timber and laminated wood panels (all from sustainable and certified timber suppliers) for the structure, covered by a plastic skin to protect the wood from weather, and the company, TimberTower, claims that their wooden masts will save 300 tons of steel for each 100 meter tall tower.

[...]

According to the company's website, one of the limitations for wind turbine masts is the bottom diameter of the steel towers, which can not be transported feasibly via highway with diameters larger than 4.2 meters, due to clearance under bridges and overpasses. Because the company's design can be transported unassembled, these limitations won't apply to their towers, and they say their towers can be completed in just 2 days.

[...]

>According to DW, that extra height could allow the turbine to generate 30 to 40% more electricity than on a standard mast, while the cost of construction would be 20 percent lower.
There's also a corporate video worth watching:



My first contact with carbon fibre composites was through cycling. Some of the European frame developers have already been working with this new material for two decades, and today it is the material of election of every other bike brand. In the full package of a modern road bike, 1 kg of carbon fibre for the frame and fork doesn't make that much of a difference in the final price. On the road, the gain in efficiency from a 1000 € alloy bike to a 1500 € carbon fibre ensemble is simply outstanding.

Days ago the Deutsche Wella published this amazing video of a company in Ghana making bike frames with bamboo that are being exported to Europe and the US. It may sound strange, but actually these frames are not very different from the first carbon fibre bike I had, with the tubes fixed to the lugs with resin. You have to jump to the Deutsche Wella website to watch this curious video.

And in Israel an entrepreneur is trying to bring to the market bicycles made entirely of cardboard. If successful, the project can result in bikes as cheap as 15 € a piece:
Business Insider
A $20 Bike Made Of Cardboard Is Headed To Market
Ori Lewis and Lianne Gross, Reuters, 17th of October, 2012

“Making a cardboard box is easy and it can be very strong and durable, but to make a bicycle was extremely difficult and I had to find the right way to fold the cardboard in several different directions. It took a year and a half, with lots of testing and failure until I got it right,” he said.

[...]

Once the shape has been formed and cut, the cardboard is treated with a secret concoction made of organic materials to give it its waterproof and fireproof qualities. In the final stage, it is coated with lacquer paint for appearance.

[...]

Once ready for production, the bicycle will include no metal parts, even the brake mechanism and the wheel and pedal bearings will be made of recycled substances, although Gafni said he could not yet reveal those details due to pending patent issues.

[...]

Gafni owns several top-of-the-range bicycles which he said are worth thousands of dollars each, but when his own creation reaches mass production, it should cost no more than about $20 (£12.50) to buy. The cost of materials used are estimated at $9 per unit.
The accompanying video is rather persuasive:



Making wheel hubs, brake springs or cables without metal is not going to be an easy task, but I won't underestimate human ingenuity. I don't expect ever to see cardboard bicycles in the Tour (neither of bamboo), but if a bike like this is possible, then an host of other applications opens, where scarce or energy intensive materials can be replaced by natural polymers.

Beyond weight, strength and longevity, carbon fibre also offers engineering possibilities that were not available before. High end bicycle manufacturers are still experimenting today, trying things like uneven frame shapes; they are now almost fully reliant on monocoque designs achieving incredible lateral stiffness but at the same time retaining some vertical forgiveness for bumpy roads. With woody materials this sort of precision is not yet at hand, so for now their market penetration should remain at the low ends, where price and overall energy consumption matters. A good example of this interplay is the music instrument industry. The weight/stiffness ratio of wood made it the perfect backbone for portable string instruments, most notably in more folkish disciplines. In 1985, rock pioneer John Entwistle abandoned the wood instruments he helped popularise to start the development of bass guitars based on synthetic polymers. A slow trend ensued that only recently got to the realm of classical instruments. Still, popular musicians will by and large continue using wood instruments, for those made with synthetic polymers remain beyond the means of most folk.

The key word in this discussion really is Sustainability. By using wood, Mankind is simply introducing a deviation to the natural carbon cycle, not so much interfering with it. But if the rate of harvest goes past the rate of natural wood production, then the process becomes unsustainable; the carbon cycle won't seize, but Society's relationship with the forest eventually could. According to the Wikipaedia, the forests of the world produce about 10 Gt of wood every year; 20 years ago about one fourth of this was already being processed by humans in some way or another.

A pine tree takes some 20 years to fully mature; for noble woods like oak this figure triples. I like to use forestry as a metaphor for the long term investment logic required to understand renewable energies like Wind or Solar. In essence forestry is subject to the same issues when facing modern day short term thinking and business decision making; such investments are difficult to square with the quarterly profits culture. It goes to show, yet again, that the energy transition is not exactly a technological challenge, rather a social one.