Over the course of the last century, the exponential expansion of industry has seen the production of materials like steel, aluminum, cement and plastics skyrocket. It is estimated that the amount of these so-called energy-intensive materials produced every single year comes to 10 times the total weight of every living person on Earth, and accounts for a fifth of the world's carbon emissions.
How to go about cutting these emissions poses a difficult and complicated problem — one that we can't solve just by improving the efficiency of material production alone. With this in mind, a team of engineers from the Department of Engineering at the University of Cambridge has assembled a thoroughly researched guide to reducing our dependence on materials production — and you can access it online for free.
The book, which was made available online on Wednesday, is titled Sustainable Materials With Both Eyes Open, and is billed as a six-part manifesto for drastically reducing the world's carbon emissions.
According to Julian Allwood, who led the research team and specializes in low carbon materials research, the challenge presented to us by the increasing demand for energy-intensive materials isn't reducing the rate of energy consumption in the manufacturing process, but the rate of consumption of the goods themselves.
"Energy intensive industry is already highly motivated to reduce its energy consumption because energy purchasing is about one third of its costs," explains Allwood in a press release. "Overall, it doesn't have many further efficiency options left, and we also have to face the fact that demand for these materials is growing, and likely to double if unchecked." He continues:
We wanted to consider whether we could cut emissions by reducing the amount of stuff produced in the first place. Every aspect of our lives today depends on materials like steel and aluminum. If we want a sustainable future, we need to reduce the impact of producing them, and our biggest option for achieving this is to reduce our thirst for new material.
These conclusions, and others drawn by Allwood and his colleagues, are presented in the research team's 350-page book, the final product of a three-year period spent working with industry and manufacturers to suss out realistic ways to curb humanity's ever-increasing demand for energy-intensive materials.
I'll be honest, I've yet to look through the entire thing, but I can attest that the chapters on diverting manufacturing scrap and doing away with built-in product obsolescence (and, equally important, perceived product obsolescence) — chapters 14 and 16, respectively, in Part III of the book — were both excellent.
The book is free to read online, and definitely worth checking out, even if you can't spare the time to pore over all 350 pages in their entirety. And for those looking for a distilled version of the book's most salient points, the authors have created what they describe as a six part "Material Manifesto," which you'll find below.
1. Use less metal by design
The study argues that we could make big savings by optimising the design of metal components. The materials used by industry are often designed in a regular shape to make production easier and more efficient. But this means that they often use more material than they have to. For example, the metal "I" beams used in most steel frame buildings are produced to standardised specifications, rather than for specific tasks.
The researchers calculate that if we can optimise the beam designs to suit their use, we could make weight savings of up to 30% - with a similar reduction in the emissions caused by production. Similar techniques could be applied to the production of components for cars, the "rebar" used to reinforce concrete, and steel cans for food storage. One simple tweak would be to change regulations. "Pretty much everything in a building is over-designed out of fear for safety," Allwood says. "All national building regulations in the UK are written with a minimum level of steel. If we instead gave firms a target level, we would be able to stop people over-specifying without compromising safety."
2. Reduce yield losses
At least 25% of liquid steel and 40% of liquid aluminium never makes it into products. Instead, it is cut off as scrap in manufacturing. One extreme example is the aluminium wing skin used for aeroplanes – 90% of the metal produced in this process ends up as "swarf", or aluminium scrap.
The researchers found that this is often the result of habit, rather than necessity. Simply designing more components with tessellating or near-tessellating shapes would make a big difference. Clothing manufacturers have, for example, actually derived the algorithms needed to make sure that rolls of fabric are used to maximum effect. Manufacturers could do the same thing with the metal they receive. The team calculated that reducing yield losses through this and other techniques would cut CO2 emissions by about 16% in the steel industry, and 7% in the aluminium industry.
3. Divert manufacturing scrap
Scrap metal is usually sent for recycling, which means melting it (an energy-intensive process). In fact, it could just be used elsewhere. For example, most steel scrap comes from "blanking skeletons" – the remains of sheets of steel after shapes have been cut out of them. About 60 megatons of steel are scrapped on this basis every year. The study says that we could effectively reduce scrap steel by half if these skeletons instead went to the manufacturers of smaller components, who can use what's left.
Alumnium swarf cannot be cut in the same way, but it can be compressed and welded at room temperature. The researchers have been developing a technique to create new components by swarf-extrusion – squeezing aluminium through a die, and creating solid-bonded swarf that can be re-used.
4. Re-use old components before recycling at all
Old components are often recycled when they could instead be re-used directly. Car dismantlers are an example of good practice, breaking up damaged or old vehicles and re-using the components. But steel in construction remains the biggest potential asset and although the beams from dismantled buildings are usually recycled, they could often instead be used again straight away. "When you take a building down, the steel girder is totally reusable," Allwood says. "All you need to do is unbolt it and clean it – because steel doesn't degrade in use. Re-use means we can avoid all the energy of melting, casting and re-rolling old steel."
5. Extend the lives of products
Most demand for products in developed economies isn't to expand the overall stock, but to replace existing items. Fridges are a good example – we still need them but in the UK we destroy, every year, 33% more fridges than we make cars. The researchers advocate modifying products rather than replacing them wholesale, and urging manufacturers to develop adaptable designs that would help this process. This requires a change in thinking and an end to planned obsolescence.
Is this an economically convincing argument? Allwood reckons so: "If we can purchase a standard new fridge for around £200, expecting it to last 10 years but guaranteed for only three, we're unlikely to agree to pay £2,000 for a fridge with a 100 year guarantee. However, we might agree to pay £40 a year indefinitely for a fridge that would always be maintained and upgraded to the latest standards. And if that's the case, we can offer the supplier double their income over a much longer period, compared with a single purchase with no commitment."
6. Reduce final demand
The fall-back option that no policy-maker would ever condone, except in times of war. Yet it remains the case that we could be living with less stuff overall. In the UK, for example, we each spend 225 hours per year in the car. We have 28 million licensed cars with, on average, four seats in each. There are 60 million people. So each car seat is, on average, in use for 2% of the year. We could reduce our overall stock to 7 million cars with ease.
This is, of course, scuppered by the convenience factor of having a car when we need it. But the researchers looked into recent studies of happiness and well-being and found that there is little reason to believe that we would be less happy than we are now if we took measures such as this. Indeed, with only 7 million cars in the UK, we would all be £1,000 a year better off on average and our journeys would be a good deal quicker and less stressful. We may not want to make these changes to our convenient lifestyles, but that is not to say that we couldn't do it if we needed to.