̽��ֱ�� of Cambridge - steel

Cement recycling method could help solve one of the world’s biggest climate challenges

sc604 — Wed, 22 May 2024 14:47:38 +0000

Researchers from the ̽��ֱ�� of Cambridge have developed a method to produce very low-emission concrete at scale – an innovation that could be transformative for the transition to net zero.

Using lasers to ‘heat and beat’ 3D-printed steel could help reduce costs

sc604 — Mon, 30 Oct 2023 09:01:39 +0000

̽��ֱ��method, developed by a research team led by the ̽��ֱ�� of Cambridge, allows structural modifications to be ‘programmed’ into metal alloys during 3D printing, fine-tuning their properties without the ‘heating and beating’ process that’s been in use for thousands of years.

̽��ֱ��new 3D printing method combines the best qualities of both worlds: the complex shapes that 3D printing makes possible, and the ability to engineer the structure and properties of metals that traditional methods allow. ̽��ֱ��results are reported in the journal Nature Communications.

3D printing has several advantages over other manufacturing methods. For example, it’s far easier to produce intricate shapes using 3D printing, and it uses far less material than traditional metal manufacturing methods, making it a more efficient process. However, it also has significant drawbacks.

“There’s a lot of promise around 3D printing, but it’s still not in wide use in industry, mostly because of high production costs,” said Dr Matteo Seita from Cambridge’s Department of Engineering, who led the research. “One of the main drivers of these costs is the amount of tweaking that materials need after production.”

Since the Bronze Age, metal parts have been made through a process of heating and beating. This approach, where the material is hardened with a hammer and softened by fire, allows the maker to form the metal into the desired shape and at the same time impart physical properties such as flexibility or strength.

“ ̽��ֱ��reason why heating and beating is so effective is because it changes the internal structure of the material, allowing control over its properties,” said Seita. “That’s why it’s still in use after thousands of years.”

One of the major downsides of current 3D printing techniques is an inability to control the internal structure in the same way, which is why so much post-production alteration is required. “We’re trying to come up with ways to restore some of that structural engineering capability without the need for heating and beating, which would in turn help reduce costs,” said Seita. “If you can control the properties you want in metals, you can leverage the greener aspects of 3D printing.”

Working with colleagues in Singapore, Switzerland, Finland and Australia, Seita developed a new ‘recipe’ for 3D-printed metal that allows a high degree of control over the internal structure of the material as it is being melted by a laser.

By controlling the way that the material solidifies after melting, and the amount of heat that is generated during the process, the researchers can programme the properties of the end material. Normally, metals are designed to be strong and tough, so that they are safe to use in structural applications. 3D-printed metals are inherently strong, but also brittle.

̽��ֱ��strategy the researchers developed gives full control over both strength and toughness, by triggering a controlled reconfiguration of the microstructure when the 3D-printed metal part is placed in a furnace at relatively low temperature. Their method uses conventional laser-based 3D printing technologies, but with a small tweak to the process.

“We found that the laser can be used as a ‘microscopic hammer’ to harden the metal during 3D printing,” said Seita. “However, melting the metal a second time with the same laser relaxes the metal’s structure, allowing the structural reconfiguration to take place when the part is placed in the furnace.”

Their 3D printed steel, which was designed theoretically and validated experimentally, was made with alternating regions of strong and tough material, making its performance comparable to steel that’s been made through heating and beating.

“We think this method could help reduce the costs of metal 3D printing, which could in turn improve the sustainability of the metal manufacturing industry,” said Seita. “In the near future, we also hope to be able to bypass the low-temperature treatment in the furnace, further reducing the number of steps required before using 3D printed parts in engineering applications.”

̽��ֱ��team included researchers from Nanyang Technological ̽��ֱ��, the Agency for Science, Technology and Research (A*STAR), the Paul Scherrer Institute, VTT Technical Research Centre of Finland, and the Australian Nuclear Science & Technology Organisation. Matteo Seita is a Fellow of St John’s College, Cambridge.

Reference:
Shubo Gao et al. ‘Additive manufacturing of alloys with programmable microstructure and properties.’ Nature Communications (2023). DOI: 10.1038/s41467-023-42326-y

Researchers have developed a new method for 3D printing metal that could help reduce costs and make more efficient use of resources.

This method could help reduce the costs of metal 3D printing, which could in turn improve the sustainability of the metal manufacturing industry

Matteo Seita

Jude E. Fronda

Retrieval of a stainless steel part made by 3D printing

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UK steel can survive if it transforms itself, say researchers

sc604 — Fri, 15 Apr 2016 08:38:33 +0000

̽��ֱ��report, by Professor Julian Allwood, argues that in order to survive, the UK steel industry needs to refocus itself on steel recycling and on producing products for end users. He argues that instead of viewing Tata Steel’s UK exit as a catastrophe, it can instead be viewed as an opportunity.

Allwood’s report, A bright future for UK steel: A strategy for innovation and leadership through up-cycling and integration, uses evidence gathered from over six years of applied research by 15 researchers, funded by the UK’s Engineering and Physical Sciences Research Council (EPSRC) and industrial partners spanning the global steel supply chain. It is published online today (15 April).

“Tata Steel is pulling out of the UK, for good reason, and there are few if any willing buyers,” said Allwood, from Cambridge’s Department of Engineering. “Despite the sale of the Scunthorpe plant announced earlier this week, the UK steel industry is in grave jeopardy, and it appears that UK taxpayers must either subsidise a purchase, or accept closure and job losses.

“However, we believe that there is a third option, which would allow a transformation of the UK’s steel industry.”

Instead of producing new steel, one option for the UK steel industry is to refocus itself toward recycling steel rather than producing it from scratch. ̽��ֱ��global market for steel recycling is projected to grow at least three-fold in the next 30 years, but despite the fact that more than 90% of steel is recycled, the processes by which recycling happens are out of date. ̽��ֱ��quality of recycled steel is generally low, due to poor control of its composition.

Because of this, old steel is generally ‘down-cycled’ to the lowest value steel application – reinforcing bar. According to Allwood, the UK’s strengths in materials innovation could be applied to instead ‘up-cycle’ old steel to today’s high-tech compositions.

According to Allwood, today’s global steel industry has more capacity for making steel from iron ore than it will ever need again. On average, products made with steel last 35-40 years, and around 90% of all old steel is collected. It is likely that, despite the current downturn, global demand for steel will continue to grow, but all future growth can be met by recycling our existing stock of steel. “We will never need more capacity for making steel from iron ore than we have today,” said Allwood.

Apart from the issue of recycling, today’s UK steel industry focuses on products such as plates, bars and coils of strip, all of which have low profit margins. “ ̽��ֱ��steel industry fails to capture the value and innovation potential from making final components,” said Allwood. “As a result, more than a quarter of all steel is cut off during fabrication and never enters a product, and most products use at least a third more steel than actually required. ̽��ֱ��makers of liquid steel could instead connect directly to final customer requirements.”

These two opportunities create the scope for a transformation of the steel industry in the UK, says the report. In response to Tata Steel’s decision, UK taxpayers will have to bear costs. If the existing operations are to be sold, taxpayers must subsidise the purchase without the guarantee of a long term national gain. If the plants are closed, the loss of tax income and payment of benefits will cost taxpayers £300m-£800m per year, depending on knock-on job losses.

Allwood’s strategy requires taxpayers to invest in a transformation, for example through the provision of a long term loan. This would allow UK to innovate more than any other large player, with the potential of leadership in a global market that is certain to triple in size.

He singles out the example of the Danish government’s Wind Power Programme, initiated in 1976, which provided a range of subsidies and support for Denmark’s nascent wind industry, allowing it to establish a world-leading position in a growing market. Allwood believes a similar initiative by the UK government could mirror this success and transform the steel industry. “Rapid action now to initiate working groups on the materials technologies, business model innovations, financing and management of the proposed transformation could convert this vision to a plan for action before the decision for plant closure or subsidised sale is finalised,” he said. “This is worth taking a real shot on.”

A new report from the ̽��ֱ�� of Cambridge claims that British steel could be saved, if the industry is willing to transform itself.

We will never need more capacity for making steel from iron ore than we have today.

Julian Allwood

Public domain

Blast furnace #5, Port Talbot Steelworks

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Steel’s inner strength

lw355 — Mon, 09 Jun 2014 08:55:36 +0000

For thousands of years, steel has been used to make or do just about whatever we ask of it, from ancient suits of armour to modern skyscrapers. It has been mass produced since the mid-19th century, and global production of this most ubiquitous of materials currently stands at more than 1.4 billion metric tonnes per year.

Although all steel consists primarily of iron and carbon, it has an almost infinite variety of properties, depending on the type or amount of other elements added to the mix, or the temperature at which the steel is produced. This complexity makes steel extremely versatile, but also very difficult to understand and to design from the atomic level.

Professor Harry Bhadeshia of the Department of Materials Science and Metallurgy has spent the past three decades researching the nature of steel to develop new alloys for a range of applications. One of these alloys, super bainite, has been licensed to Tata Steel and is currently being manufactured in the UK by the company for use as super-strong armour for military vehicles, as well as for other applications.

Bainite is a microstructure that forms when austenite, a high-temperature phase of steel, is cooled to temperatures between 250 and 500°C. ̽��ֱ��structure of austenite transforms as it cools, when slender crystals of iron incorporate themselves into the structure, and carbon compounds known as carbides form. ̽��ֱ��resulting bainite structure is very hard, but the carbides make it brittle and prone to cracking.

Working in collaboration with Professor Peter Brown of the Ministry of Defence (MoD), Bhadeshia and Dr Francisca Caballero in the Department of Materials Science and Metallurgy set out to refine and enhance the properties of bainite, originally for use in gun barrels.

Using precise modelling, they determined that there is no lower limit to the temperature at which bainite can be produced. By heat-treating it at temperatures around 200°C – closer to those that are normally used for baking cakes rather than for manufacturing steel – for 10 or more days, a new form results: super bainite. In addition, by adding elements such as silicon and molybdenum, carbides and harmful impurity phases are prevented from forming in the steel, reducing the likelihood of cracks.

Super bainite is strong – very strong. With a tensile strength of some 2.5 gigapascals, just one square metre can support a weight equivalent to the weight of 2.5 billion apples. It has a higher density of interfaces than any other type of metal, and is the world’s first bulk nanostructured metal.

̽��ֱ��strength of super bainite derives not only from the lack of carbides, but also from the tiny size of the iron crystals within its structure. Most types of steel are made up of very fine crystals: the smaller and finer the crystals, the stronger the resulting steel will be. ̽��ֱ��crystals in super bainite are between 20 and 40 nanometres thick, comparable to the width of carbon nanotubes. In comparison, the crystals in conventional bainite are between 200 and 500 nanometres thick.

“ ̽��ֱ��size of these crystals means that the steel is very difficult to deform, resulting in a more perfect structure,” said Bhadeshia. “And because of the very slow cooking process, which is actually quite simple, we can make the steel in very large quantities at low cost.”

̽��ֱ��cooking time resulted in a product with highly desirable characteristics, but the long wait meant that super bainite was only suitable for certain commercial applications. Supported by funding from the Engineering and Physical Sciences Research Council and the MoD, Dr Carlos Mateo (also from Cambridge), Brown and Bhadeshia set out to accelerate the process. Through the use of kinetic and thermodynamic modelling, they found that by tailoring the composition of super bainite and heat-treating it at slightly higher temperatures, up to 250°C, it could be manufactured in a matter of hours rather than days, without any significant loss in performance.

In 2011, super bainite was licensed to Tata Steel, one of the world’s largest steel producers. Tata is now manufacturing the material at its facility at Port Talbot in South Wales, which is the first time that high-carbon steel has been manufactured on a large scale in the UK for 20 years. It is currently available commercially for civil applications such as automated teller machines for dispensing money, and as super-strong armour for use on military vehicles, under the name Pavise™.

Brown and his colleagues at the MoD’s Defence Science and Technology Laboratory at Porton Down determined that, counter-intuitively, perforations bored into super bainite made it even more capable of protecting vehicles from projectiles.

“ ̽��ֱ��ability of perforated super bainite steel to resist projectiles is at least twice that of conventional monolithic rolled homogeneous armour,” said Brown. “By introducing perforations into the steel, we create a large number of edges, which interrupt the path of incoming projectiles.”

Super bainite’s enormous strength makes it ideal for these types of applications, where strength and toughness are paramount. In addition to defence applications, there are spin-off high-carbon alloys for which the demand in Europe is up to 400,000 tonnes each year, for items such as springs, bearing cages and hand tools, where hard and thin sheets of steel are required. About 80% of these high-carbon steels that are being manufactured in Wales are now exported to markets worldwide.

“In addition to its superior ballistic properties, Pavise™ is manufactured in a far simpler way than other commercially available ballistic armour, and its performance comes from its unique properties,” said Kevin Edgar, Head of Marketing, Engineering Sectors at Tata Steel. “Other armours have long lead times owing to complex production routes, whereas we can produce this product alongside regular production runs, which means we can react more quickly to what the end users require and work with them – this flexibility gives us a real advantage.”

̽��ֱ��researchers in Bhadeshia’s group are now working with their partners in industry to address super bainite’s main weakness which, ironically, is its strength. “As it is so strong, super bainite cannot be welded, so it cannot be made into very large structures where pieces need to be joined together,” he said. “We are again working with MoD to further refine the structure so that it can be welded, without losing the characteristics that make it such a unique and high-performing material.”

A long-term collaboration between the ̽��ֱ�� and industry has resulted in a super-strong form of steel, which is now being manufactured in the UK for use as stronger and cheaper armour for front-line military vehicles.

By introducing perforations into the steel, we create a large number of edges, which interrupt the path of incoming projectiles

Peter Brown, MoD

Tata Steel

Perforations in super bainite make the material even better at protecting armoured vehicles from projectiles

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Better building through design

sc604 — Wed, 04 Jun 2014 08:16:01 +0000

̽��ֱ��construction industry, which uses half of the 1.5 billion tonnes of steel produced each year, could drastically reduce its carbon footprint by optimising the design of new buildings. Smart design could slash the sector’s carbon emissions by around 50%, without any impact on safety. If buildings are also maintained for their full design life and not replaced early, the sector's emissions could in total be cut by around 80% - the target set in the UK's 2008 Climate Change Act.

New research from the ̽��ֱ�� of Cambridge has found that the amount of steel used by the construction industry, and the resulting carbon emissions, could be significantly lowered by optimising the design of new buildings in order to use less material.

At present, in order to keep labour costs down, the construction industry regularly uses double the material required by safety codes. Analysis of more than 10,000 structural steel beams in 23 buildings from across the UK found that on average, the beams were only carrying half the load they were designed for. ̽��ֱ��results are published in the June 4th issue of the journal Proceedings of the Royal Society A.

Over one-quarter of the steel produced each year is used in the construction of buildings. Demand for steel is increasing rapidly, especially in the developing world, and is expected to double in the coming decades.

̽��ֱ��iron and steel industry contributes nearly 10% of total global carbon emissions, which climate change experts recommend be halved by 2050. Coupled with skyrocketing demand from the developing world, drastic action is required if a reduction in the sector’s carbon footprint is to be achieved.

One option to achieve this reduction is by designing and building more efficiently, delivering the same performance from buildings but with less steel, but this is not common practice at present.

“Structural engineers do not usually design optimised structures because it would take too much time; instead they use repetition to decrease the cost of construction,” said Dr Julian Allwood of the Department of Engineering, who led the research, which was funded by the UK’s Engineering and Physical Science Research Council (EPSRC). “This leads to the specification of larger steel components than are required.”

̽��ֱ��researchers found that building designs are exceeding Eurocode Safety Standards by a factor of two and so are unnecessarily using double the amount of steel and concrete needed. “As materials are cheap and structural design time is expensive, it is currently cheaper to complete a design by using safe but considerably over-specified materials,” said Dr Allwood.

Additionally, many buildings are being designed to last for 100 years but on average are replaced after just 40.

By designing for minimum material rather than minimum cost, steel use in buildings could be drastically reduced, leading to an equivalent reduction in carbon emissions, at relatively low cost. ̽��ֱ��net result of avoiding over-design and early replacement is that the UK could provide the same amount of built space with just 20% of the materials - and therefore 20% of the carbon emissions - used at present.

“We need to see a more sensible use of materials in the construction sector if we are to meet carbon reduction targets, regardless of the energy mix used in manufacturing the materials,” said Dr Allwood, who is also Director of the UK INDEMAND Centre, which aims to enable delivery of significant reductions in the use of both energy and energy-intensive materials in the industries that supply the UK’s physical needs.

̽��ֱ��construction industry could slash its carbon emissions by as much as 50% by optimising the design of new buildings, which currently use double the amount of steel and concrete required by safety codes.

We need to see a more sensible use of materials in the construction sector if we are to meet carbon reduction targets

Julian Allwood

Andreas Levers via Flickr

Construction

Yes

Licence type:

Attribution-Noncommerical

Six steps to a better material world

ns480 — Wed, 30 Nov 2011 15:58:59 +0000

A six-part manifesto for drastically reducing a fifth of the world’s carbon emissions, caused by the production of materials like aluminium and steel, has been released online.

̽��ֱ��list is at the core of a new study by a team of eight researchers, who spent three years working with industry and manufacturers to find out how our demand for vital materials such as metals, concrete and paper can be made more sustainable in the future.

Their findings are being published as a book, Sustainable Materials With Both Eyes Open, which can be read for free online at: https://www.uselessgroup.org/publications/book/chapters. In an effort to communicate their ideas as widely as possible, the group has also broken new musical territory by releasing an album of songs about them.

Samples from the 12-track recording “With both eyes open”, which purports to be “the first album written for the 300 million people worldwide who convert metal ores into finished buildings, vehicles and goods”, can be found on the website as well, and the album is now available from Amazon. There Are No Silver Bullets by ̽��ֱ�� of Cambridge

At heart, the research has a deeply serious message. Most of what we use on a day-to-day basis depends on producing energy intensive materials – metals, ceramics and polymers. At the start of the 20^th century, global production of these materials was virtually nothing. Now we make 10 times our own bodyweight of steel, aluminium, cement, plastics and paper every year, for every person alive, and it costs us a fifth of all the world’s energy to do so.

This brings with it a number of problems, such as associated land stress and demand for water. ̽��ֱ��most pressing issue, however, is that materials production involves burning fossil fuels and putting CO2 into the atmosphere.

̽��ֱ��team of eight researchers, all from the Department of Engineering at the ̽��ֱ�� of Cambridge, set out to find ways to make materials production more sustainable in a way that will have a real impact on the Intergovernmental Panel on Climate Change’s target to reduce greenhouse gas emissions to 50-85% of 1990 levels by 2050.

This is easier said than done: “Energy intensive industry is already highly motivated to reduce its energy consumption because energy purchasing is about one third of its costs,” Dr Julian Allwood, who led the research team and specialises in low carbon materials research, says. “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.”

“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 aluminium. 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.”

̽��ֱ��book identifies a raft of options for reducing our demand for materials production, most of which have received very little attention. Although the study looks individually at cement, plastic and paper, at its heart is a list of six steps which could make huge changes to the carbon footprints of the aluminium and steel industries. In summary these are as follows:

Use less metal by design. ̽��ֱ��researchers argue that we use more material than we need in areas such as construction, car manufacturing, and the production of food cans.
Reduce yield losses. Some industries waste a large fraction of the material they originally receive due to “off-cuts”. ̽��ֱ��book suggests several ways of refining processes to limit this effect.
Divert manufacturing scrap. Does scrap metal really need to be scrapped? ̽��ֱ��researchers argue that in many cases it could be given to other companies or remoulded at room temperatures instead.
Re-use old components rather than recycle them. Car dismantlers are already doing this, but other industries could be doing it more, with re-use of steel in construction looking particularly attractive.
Extend the lives of products. Goodbye, in-built obsolescence – we could and should be refining products to extend their life-cycles.
Reduce final demand. Could we make a difference individually by using less stuff? ̽��ֱ��answer is unquestionably yes – but whether we are prepared to is a different matter. ̽��ֱ��researchers found no evidence that we would be any less happy if we did, however.

Overall, the impact of making all or a number of these changes could be huge. By optimising steel beams for buildings, for example, the researchers reckon we could cut the emissions caused by producing these beams by about 30%. Similarly, taking a series of measures to reduce yield losses would lead to an estimated 16% reduction of CO2 emissions in the steel industry, and 7% in the aluminium industry.

Allwood and his team are now focusing not just on releasing their findings, but on encouraging manufacturers and other companies to develop real-life case-studies that show these changes can be made to the way our materials are produced. For example, the researchers are already working with a supermarket chain on the construction of a new outlet made entirely from old materials (point 5).

“ ̽��ֱ��aim now is to get this connected to policy,” he adds. My job is really to try to trigger demonstrations of how these ideas could work. I think that everyone has a fear of something that has never been tried before. If we can provide examples that people can copy, then it greatly reduces the barrier that stops governments and companies from implementing these ideas and helping them to spread.”

Every year we make 10 times our own bodyweight of steel, aluminium, cement, plastics and paper, for every person alive, using a fifth of all the world’s energy supply to do so. Now researchers are releasing a manifesto to change that and help cut carbon emissions. And they’ve also released an album of songs to go with it.

Every aspect of our lives today depends on materials like steel and aluminium. If we want a sustainable future, we need to reduce the impact of producing them.

Julian Allwood

Joost J Baker Ijmuiden from Flickr

Scrap-metal

Material Manifesto - Six things we could do to make the future of materials use more sustainable

1. Use less metal by design

̽��ֱ��study argues that we could make big savings by optimising the design of metal components. ̽��ֱ��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.

̽��ֱ��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.

̽��ֱ��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. ̽��ֱ��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. ̽��ֱ��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. ̽��ֱ��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. ̽��ֱ��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

̽��ֱ��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.

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