Industry, society and Earth itself is facing a climate emergency. As countries around the world scramble to adopt cleaner sources of energy and shrink their carbon footprints, industry is being urged to decarbonise manufacturing processes. It might seem like a task of Herculean proportions but, here, Samir Jaber, technical writer at materials and suppliers database Matmatch, explains five approaches manufacturers can take to reduce carbon emissions.

Today, the issue of climate change is treated as an economic challenge as much as an environmental problem or existential threat. In fact, the World Economic Forum set "Stakeholders for a Cohesive and Sustainable World" as the theme for its 2020 annual meeting in Davos, Switzerland.

As such, we are seeing more businesses act to become greener, especially in industry. For example, in 2019, the Russian metals group En+ called on the London Metal Exchange — the world's largest industrial metals market — to introduce new disclosure rules on carbon dioxide (CO2) emissions. These rules would force aluminium producers on the exchange to reveal the carbon footprint of their metals.

Nevertheless, the industrial sector remains one of the biggest causers of carbon emissions worldwide; especially in the ways that it produces materials. According to the World Steel Association, the steel industry generates as much as nine per cent of direct emissions from fossil fuels.

However, it is possible for manufacturers to lower the carbon emissions of their operations and the environmental impact of products through their entire lifecycle. This can be achieved through a mix of design considerations, new manufacturing techniques and material sourcing strategies. Here are five ways manufacturers can minimise their carbon emissions.

1. Eco-design engineering
Manufacturers can lower their CO2 emissions by considering and actively minimising the environmental impact of a product across its entire lifecycle, from material extraction and supply to end of life. This is commonly known as ‘eco-design', but many manufacturers and engineers may know it as the ISO/TR 14062 standard for environmental management in product design.

Design engineers can follow the principle of eco-design by considering factors such as the amount of energy and materials consumed in production, or how the product and its manufacturing by-products may impact biodiversity. Then, engineers and manufacturers can investigate alternative processes, systems or materials to minimise the impact.

Even for manufacturers in the materials industry, these considerations can lead to substantial changes in processes and industries that were previously carbon intensive. A prime example here is aluminium supplier Rusal.

On average, approximately 11.5 tons of CO2 per ton of aluminium are produced due to processes such as smelting. However, Rusal publicly set its sights on achieving carbon-free aluminium by 2021, which led to the company developing its ALLOW range of low-carbon aluminium alloys.

These materials each have a carbon footprint that is typically under four metric tons per ton of aluminium, owing in part to hydropower used to power certain processes. This makes ALLOW one of the lowest carbon aluminium products available; which is why Matmatch is proud to feature this product range on our materials search engine.

This not only shows the impact of considering environmental factors when planning the design or manufacturing of products, it also shows the impact that can be made by substituting materials. A manufacturer sourcing aluminium alloys from Rusal, rather than from standard suppliers, could potentially reduce the carbon footprints of its products by approximately seven tons of CO2 per ton of aluminium.

2. Material substitution
Just as switching to a lower carbon version of the same material can reduce carbon footprints, so too can finding alternative materials for conventional designs. An example is the rise of bamboo toothbrushes as a substitute for plastics. This design alteration made the product biodegradable and offset CO2 emissions due to the raw material's ability to absorb carbon.

However, any design engineer knows that it's not as simple as choosing a different material for a product and using that instead. The key to successful material substitution is to choose a new material with similar properties to the original; whether that applies to mechanical properties like tensile strength, or chemical and thermal properties.

Historically, this has been the key challenge for design engineers. However, the rise of online material databases like Matmatch make such material comparisons a far more streamlined process.

This is fortunate for many industries, such as packaging, where environmental issues have driven the need for a shift in materials. Concerns over plastic pollution have led to many consumers demanding more environmentally friendly alternatives. This has, in turn, driven a rise in biopolymers and biodegradable polymers, which are designed to replace traditional, petroleum-based plastics — as used in packaging for products such as beverage bottles and ready meals.

Materials substitution covers more than just a like-for-like swapping of input materials. In a paper published in 2017, the United Nations' Technology Executive Committee (TEC) outlined several material substitution possibilities for manufacturers to improve the eco-efficiency of materials. These possibilities included substituting the input material, designing with fewer input materials and lightweight designs.

The latter idea is comparable to the concept of lightweighting in the automotive industry, where lighter designs are preferred to improve a vehicle's fuel economy. Generally, less energy is required to produce lighter materials and this, in turn, reduces the carbon footprint of production.

However, there is sometimes a perception that lighter materials being less dense are to be lacking in the mechanical properties necessary to make them suitable for certain applications. This is not strictly true. One area of ongoing research is into lightweight materials with structures that reinforce their mechanical strength. For example, the UK's University of Exeter is researching the use of honeycomb structures in lightweight materials, primarily for aerospace applications.

Design engineers and manufacturers must also consider the abundance of substitute materials. As the TEC observes in its paper, "The substitution potential…depends on the properties of the material and the availability of sufficient amounts of alternative material. For example, more than 200 kg steel and 380 kg cement are produced each year worldwide per capita. No other material is currently available that could replace them in such quantities (IPCC 2014)."

3. Remanufacturing plans
With materials such as steel where abundance is a concern, manufacturers can reduce the carbon emissions in the production chain by remanufacturing. This involves the reclamation of used durable materials, such as steels, and products that can be reused in future manufacturing processes. This practice is relatively common in the automotive industry, where parts such as engines, steering systems and transmissions are often remanufactured.

In fact, one of the earliest examples of remanufacturing comes from the automotive sector. Following the Great Depression, Henry Ford responded to the lull in new car sales by remanufacturing car engines in the 1930s. This was because sustainability is something of a bonus; the main benefits are cost and time savings for manufacturers and customers alike.

Today, similar remanufacturing initiatives are run by several industrial manufacturers. For example, SKF Bearings, one of the world's biggest manufacturers of industrial bearings, offers a bearing remanufacturing service to prolong the service life of its products. This reduces the need for new bearings to be manufactured for existing systems.

As an example of how this can save on the need for new material processing, GKN Automotive states that its driveshaft remanufacturing service allows the company to "save at least 1,600 tons of steel per year by re-using 80 per cent of the steel from cores collected."

If we consider this alongside the 1.85 tons of CO2 produced per ton of steel, as reported by the World Steel Association, that is at least 2960 tons of CO2 emissions avoided by remanufacturing.

4. Additive manufacturing
Remanufacturing is just one alternative manufacturing technique that can reduce carbon footprints. Another is additive manufacturing (AM), which has grown in popularity in recent years — and it's easy to see why. AM wastes less product, uses less energy and is highly versatile.

Traditional manufacturing techniques, such as moulding and forming, are subtractive processes whereby products are made from larger blocks of material. This means that waste is inherent to the process, and not all of these material offcuts can be recycled or reused. AM simply uses the amount of material that is required and no more, which reduces waste and the carbon intensity of designs.

If design engineers were to have any reservations around AM, it would be that the technique has been limited in the types of materials readily available. This is because AM requires materials in specific forms, such as powders. Fortunately, at Matmatch we have seen a boom in the types of materials for AM, with various metal alloys, steels, resins and biopolymers now available.

With this technique, design engineers can also experiment with new types of structures and designs that were previously impossible, or impractical, with subtractive manufacturing. For example, a lattice design can be used to strengthen certain aspects of a product's design, while using less material and also being lighter. This ties in with the TEC's aforementioned suggestion of material substitution as a way to design with fewer input materials.

5. Reduce yield losses
AM's ability to reduce material excess and waste is similar to the final approach that manufacturers can take to reduce CO2 emissions, which is to reduce yield losses. A manufacturing plant manager that's familiar with the concept of overall equipment effectiveness (OEE) will likely know of the six big losses: equipment failure, planned stops, idling, reduced speed, production defects and reduced yield.

Each of these losses not only impacts performance and productivity, but also the amount of energy used and the carbon footprint, accordingly. There are many options for manufacturers to address these losses, ranging from implementing data-driven maintenance strategies to introducing automation to production lines. However, these often require investing in technology or systems.

In contrast, less investment is demanded by how production defects and rejects are handled. That is according to a 2018 research paper by Rong Li of Syracuse University in New York, US, which explored this exact topic. According to Li, "a manufacturer may choose to (1) scrap all not quite perfect products (NQPPs) at a cost and carry the high‐end products only, or (2) sell some or all NQPPs to a value‐conscious low‐end market and carry both high‐end products and low‐end products".

Li concluded that selling these NQPPs to low-end markets might deliver the maximum profit to manufacturers, stating that "the profit increase could be up to 33 per cent or even higher if the manufacturer switches to the scrapping strategy". However, this does not account for environmental regulations governing CO2 emissions and how these impact costs.

For example, the EU's Emissions Trading System (ETS) assigns costs and credits to the carbon output of European businesses. The carbon cost of scrapping and manufacturing new products might change the equation for manufacturers. Instead of either scrapping or selling NQPPs, at Matmatch, we recommend the third option: remanufacturing and reusing NQPPs.

A greener world
Future generations looking back on our carbon age will, of course, see a time of environmental hardship — but also a time of hope. The techniques and technologies do exist that can help manufacturers and design engineers to minimise their impact on the environment.

For design engineers, it is a matter of ensuring that the use of designs and materials are planned with their environmental impact in mind. This means identifying and verifying the accuracy of information about a material's carbon footprint — and, to this end, using a reliable source of materials data is vital.

Transitioning away from the practices established by decades of industrial development might be a Herculean task, but it is one that industry can take small steps towards accomplishing. Only time will tell how effectively low carbon manufacturing proves in combatting the climate crisis.