Mr. McGuire: I just want to say one word to you. Just one word.
Benjamin: Yes, sir.
Mr. McGuire: Are you listening?
Benjamin: Yes, I am.
Mr. McGuire: Plastics.
Benjamin: Exactly how do you mean?
Mr. McGuire: There’s a great future in plastics. Think about it. Will you think about it?
— The Graduate (1967)
A “composite” is when two or more materials are combined to create a superior and unique material. The prefix, “bio,” means the composite takes natural fibers, including wood, leaves and grasses, and blends them with a matrix (binder) made from either renewable or non-renewable sources, like lime, clay, plastics, or old tires.
Carbon fiber reinforced polymer (CFRP) is an extremely strong and light plastic with carbon fibers woven in. These are highly prized by many industries but at the moment they are very expensive to manufacture.
High-end users like Ferrari or Jaguar can absorb the added costs and pass those along to their upscale clientele. When Elon Musk’s Space X Shuttle needed a way to reduce launch vehicle weight without compromising strength or other qualities, they turned to carbon fiber polymers.
The substitution of lightweight carbon for heavier aluminum-lithium at the same strength gave Space X the ability to place a 300 ton reusable vehicle — potentially either an interplanetary spaceship or a cargo freighter — into low Earth orbit. A problem their engineers encountered, however, is that the carbon fiber polymer tended to degrade from prolonged contact with one of the shuttle’s essential cargoes — liquid oxygen.
Could a solution lie in a non-bonding, non-oxidizing form of carbon?
CFRPs have been used in high-end automobile racing since Citroën won the 1971 Rally of Morocco with carbon fiber wheels. Low weight is essential for automobile racing and carbon fiber is also ten times stronger than the steel it replaces. Racing car manufacturers went on to develop omnidirectional carbon fiber weaves that apply strength in all directions, making the cars stronger than they had been when they were pure polymer.
Building engineers were quick to adopt what they learned from Formula V. Carbon fiber polymers were soon being wrapped around steel-reinforced structures such as bridge or high-rise building columns. By enhancing the ductility of the section, they increased the resistance to collapse under hurricane, earthquake or avalanche loading.
In some countries pre-stressed concrete cylinder pipes (PCCP) account for the vast majority of water transmission mains. Due to their large diameters, failures of PCCP are usually catastrophic and affect large populations. Now carbon polymers are being retrofitted as PCCP liners that take strain off the host pipe.
As recently as 7 years ago BMW was using water cutting for parts, but today, in partnership with Airbus Helicopter and others, the carmaker has moved to carbon cutting tools — coated with ground diamond that can double feeding speeds. The carbon tools have a geometrically-defined cutting edge and are sharpened by a plasma process. For BMW and Airbus, production costs are being reduced 90 percent.
Bicycle frames of carbon polymer give the same strength as steel, aluminum, or titanium for much less weight and can be tuned to address different riding styles. Carbon fiber cellos, violas, violins, acoustic guitars and ukuleles are selected by discerning musicians for the quality and fidelity of their sound. Other commercial products already available:
- bagpipe chanters
- billiards cues
- carbon fiber posts in restoring root canal treated teeth
- carbon woven fabrics
- drum shells
- fishing rods
- guitar picks and pick guards
- helicopter rotor blades
- high reach poles for window cleaning
- laptop shells
- passenger train cars and furnishings
- suitcases and briefcases
- tent poles
- thermoplastic films for moisture and corrosion barriers
- tripod legs
- violin bows
- walking sticks
Even though the unique properties of carbon make it a superior choice for these applications, up to now the high cost has been a challenge. What if that barrier could be breached by recycling and blending carbon — from agricultural, municipal and industrial wastes that might otherwise return to the atmosphere or ocean — and plastics, like polystyrene, that are poisoning soils, waterways and the ocean with a non-degradable toxin?
Combining biochar at rates of 5, 15, 25, and 40 percent by weight with wood and plastic to make alternative composites to traditional wood-polypropylene binders, scientists found:
- All biochar rates increased flexural strength by 20 percent or more
- Tensile strength was highest with 5 percent biochar
- Tensile elasticity was highest with 25 and 40 percent biochar
- Water absorption and swell decreased
- Biochar additions showed improved thermal properties.
Wood plastic composites (WPCs) have annual growth rates of 22 percent in Northern America and 51 percent in Europe. Often polyethylene, polypropylene and polyvinyl chloride use wood flour or fiber as fillers, and more recently, resin impregnated paper waste from particleboard and fiberboard manufacture. The advantages of using bio-based components in these plastics is that wood and paper are non-abrasive, low in cost, widely available, low density and weight, flexible and recyclable.
Decking for outdoor applications represents the largest market for WPCs. In Europe, the WPC market, outside automobiles, is 120,000 tons, with more than half going to decking. Now manufacturers are shifting product lines to include siding, roofing, windows, door frames, and outdoor furniture. Some are already incorporating nanoscale reinforcing fillers like nanoclay and carbon nanotube into the composite material.
An extrusion technology called “waxy technology” recycles and transforms more than 12 different types of post-consumer plastics and packaging materials into long lasting, termite-resistant plastic lumbers, potentially sparing many forests from the axe. An ideal product for building, construction and furniture making, extruded lumber costs 32 percent less than pressure-treated timber, avoids arsenic and other eco-toxins, and last more than 40 years without replacement even in sunny, windswept, and coastal areas or in underwater applications. Applying cascade carbon thinking to this scenario could supply both process heat and a low cost, high value filler material, and sequester ever more carbon.
Any carbon that does not go back to the atmosphere and does not go back to the oceans can take a break from the carbon cycle. It doesn’t have to burn to become CO2. It does not have to digest or decay to become CH4. It doesn’t have to kill coral reefs or warm the Earth. It can just chill. It can be a building or a bicycle, it doesn’t matter. Just chill a few centuries while we get our act back together.
Impregnated paper waste is a major challenge for recycling due to the large amounts produced, potential toxicity and low biodegradability. Just a medium sized paper impregnating factory can produce 400 tons per year. One option is oriented strand board, but that just kicks some of those problems down the road. A better option would be pyrolysis.
Until recently, all carbon fiber came from a chemical called acrylonitrile, made from petroleum, ammonia, and oxygen. The process for making acrylonitrile produced potentially explosive heat and made toxic wastes, including hydrogen cyanide gas. In 2017, a team of researchers at the National Renewable Energy Laboratory developed a process for producing acrylonitrile from corn stalks and wheat straw that doesn’t make heat and has no toxic byproducts.
The MAI Carbon Cluster — an initiative from the German Federal Ministry of Education and Research — has been looking at high volume production processes that could cut the cost of carbon fiber by as much as 90 percent and raise recycling rates to more than 80 percent. The effort, which has seen Audi and BMW working together despite initial reservations, now involves a total of 114 partners including Airbus, BASF, Eurocopter, SGL and Voith.
During a workshop at the Ecovillage Training Center in Tennessee in 2017, we made cascaded concrete with various biochar concentrations. We made composites by melting soy-foam packing peanuts and the kinds of styrofoam clamshell containers they use at take-out in restaurants (and typically wind up in landfills, rivers or the ocean). We made chardobe brick and compressed CINVA ram brick. We made grout for a tile bench. These exercises were only scratching the surface of the potential, but they showed what lies ahead.
By melting extruded polystyrene foam packing peanuts and clamshell containers — (C8H8)n — in an acetone bath — (CH3)2CO — and adding powdered biochar (C) until it stiffened, a char-tile is produced that is light, structural, fracture-resistant, and can be molded to any shape. It could be kitchen tiles, surfboards, iphones, tennis rackets, boats or biodomes.
The potential for these kinds of innovations is huge. The global automotive industry produced about 63 million passenger vehicles and 21 million commercial vehicles in 2012. By 2020 production could grow to 100 million vehicles per year, with China accounting for about 18 to 20 percent of the total.
The typical passenger vehicle curb weight ranges between 3,000 and 4,000 lb (1,364 and 1,818 kg). The weight of sport utility and crossover utility vehicles (SUVs and CUVs) is usually 500 to 1,000 lb (227 to 454 kg) more.
Some quick math tells us that each year more than 150 million tons of new cars and trucks hit the roads around the world, including 120 million tons of steel and 10 million tons of aluminum. Composites make up less than one percent by weight, and CFRP currently only about 9000 tons, a minuscule 0.05 percent of the total global automotive materials.
Every 100 lb (45 kg) reduction in weight cuts the fuel need by roughly 2 to 3 percent. Designers have discovered, however, that weight reduction in one area sets up further weight reduction in other components and systems — resulting in a virtuous spiral of weight reduction. Composite bodies weigh 50 to 70 percent less (250 lb/113 kg) than steel, and that allows engineers to downsize chassis members, body panels and exterior accessories, structural and cosmetic interiors, suspension, drivetrain, exhaust and engine bay pieces, brake systems, fuel systems, wheels and other components.
As weight becomes an increasing concern for fuel mileage, as the impact of new carbon emissions regulation hits the steel and aluminum industries, and as the potential for automobiles to go from carbon producing to carbon removing is better understood, some big changes and opportunities lie directly ahead.
Old automakers that find themselves asleep at the wheel may find the marketplace is a cruel master — the penalty for not staying current increases each design cycle, and design cycles are getting shorter — moving from about nine years to six or less.
It is projected that by 2025, the auto industry (including race car teams and aftermarket accessory vendors) will consume about 25 percent of the global carbon fiber production capacity. Airlines may consume another 25 percent. Although CFRP is a growth industry, there are drawbacks. Metals are readily repaired, reused and recycled and there is a huge global marketplace in all those areas. The same cannot yet be said of CFRP. To avoid material wastes, landfill expenses and exposure to fines in some regions, the industry is going to have to get a better grasp of carbon cascades.
The market addressable by recycled carbon fiber (rCF) is 55,000 MT/yr with 50,000 MT/yr of CF scrap available to fill this. That 5000 ton gap represents an immediate opportunity, but more important is the long term — designing recycling into the whole process. Lux Research cites present CF capacity of 120,000 tons/yr versus projected near-term demand of 225,000 tons/yr, as rail cars, bridges and buildings increase their CFRP content. The CF industry must grow rapidly and rCF should play a major role in meeting demand.
A new CFRP rail bogie frame is being made using 80 percent compression molded rCF and 20 percent virgin fiber (vCF). These carbon rail cars reduce weight over their steel counterparts by 75 percent, cutting wheel-to-rail loads by 40 percent.
According to an industry insider’s report,
For vehicles priced less than $120,000 with production volumes greater than 20,000 units per year, the inclusion of recycled carbon fibers will be critical to meeting the economic performance required to make money from automobile sales. Further, the energy it takes to reclaim carbon fibers is small compared to that required during virgin fiber production. Added to a reduced need for petroleum-based feedstocks, recycled carbon fiber adds an extra green dimension to CFRP solutions.
Consider this hypothetical scenario: Luxury automobile manufacturer X, which sells 100,000 vehicles annually in the North American market, can raise its average fuel economy from today’s 29 mpg to 40 mpg by 2025, a 33 percent improvement. But it still fails to meet the 55 mpg target. The current fine assessed to the manufacturer is $55 per 1 mpg under the standard, multiplied by the manufacturer’s total production for the U.S. domestic market. In this scenario, manufacturer X would be fined approximately $82.5 million. Similar incentives exist in Europe, but they are even more onerous. In the U.K., failure to meet emissions standards results in a fine of €95 ($123 USD) per gram of CO2 per kilometer over the limit per vehicle. For flagship Jaguar Land Rover Ltd. (Whitley, Coventry, U.K.) sedans or Aston Martin (Gaydon, Warwickshire, U.K.) sports cars, this represents as much as an additional $20,000 or more per vehicle.
Retired or scrap carbon fiber for reuse in manufacturing is a first stage cascade — easily accomplished by a combination of compression molding and thermoplastic films that provide shape and cohesion to the rCF content. A second stage could be separation of the carbon content in an exothermic process — burning or dissolving away the non-carbon portion and leaving behind cascade carbon that can be put to new uses. A third cascade might be capturing the heat from that second stage and transforming it into process steam, electricity, or commercial heating and cooling. The fresh carbon supplied by these processes offers scores of possibilities.
Carbon, arranged into chains and rings by photosynthesizing plants, then rearranged to weave into fabrics, fibers and filaments, will soon surround us in our buildings, modes of transportation, and much, much more. Much better there than the atmosphere or oceans.
Thanks for reading! If you liked this story, please consider sharing it around. Our open banjo case for your spare change is at Patreon or Paypal. This post is from Carbon Cascades: Redesigning Human Ecologies to Reverse Climate Change by Albert Bates and Kathleen Draper, coming from Chelsea Green Publishers later this year (the book is free to our sponsors).