The materials transition: Ensuring we build with low-carbon materials
Everything is made from something. How do we minimize the emissions associated with the materials we use every day?
Published: March 13, 2024
By Tony Potter and Olivier Maronneaud
Highlights
The materials transition comprises the decarbonization of materials production, the reduction and reuse of waste through the creation of a circular economy, and the substitution of materials to use those with the lowest carbon intensity.
The consumption of materials will continue to grow alongside population and GDP. Choosing the right mix of low-carbon materials will be key to the energy transition.
Plastics are versatile materials with low energy intensity — and a bad rap. They are essential to the energy transition as construction materials for wind and solar power and for lightweighting in the transportation industry. They also have the potential to substitute products that have higher energy intensity such as metals.
Plastic waste is, however, a significant challenge, and future legislation to control plastic pollution is highly likely.
The circular economy accounts for a small fraction of plastics supply, principally via mechanical recycling. Although the production of recycled pellets will more than double in the next 10 years, the underlying demand growth for polymers is such that virgin resin demand will continue to grow. We are nowhere near reaching “peak polymer.” The bottleneck is the development of capacity to collect, clean and sort waste; these plants are small compared with a world-scale virgin polymer plant.
What is the materials transition?
The path to net-zero will require all parts of the economy to decarbonize, key elements of which are the building blocks we use for construction, manufactured goods, automotive production, packaging and even the textiles for the clothes we wear. Whether steel, aluminum, concrete, glass, paper or plastic, industries must invest in new technologies to reduce the greenhouse gas emissions produced in their manufacture. Material waste must be eliminated, and reuse must be promoted by creating a circular economy. Where the material performance envelope allows, products should be designed and manufactured using materials with the lowest carbon intensity possible. Collectively, the materials transition is the combination of reducing GHG intensity when producing materials, decreasing waste and creating a more circular economy, and substituting materials with those with the lowest carbon intensity.
Plastics are indispensable
The chemical industry now finds itself in a world that frowns on its main product: carbon. Thermoplastic polymers and resins are sequestered carbon. Although plastics are an indispensable part of virtually every aspect of life, much of their utility is generally overlooked, including the following:
Their role in keeping food fresh, therefore reducing waste in agricultural supply chains
Their role in lightweighting in the transportation industry for improved fuel efficiency
Their use as essential components of wind turbines and solar panels to decarbonize power generation
Their use in clothing in the form of polyester, nylon and acrylic fibers
The COVID-19 pandemic highlighted the essential role of plastics in the healthcare industry, but generally plastics are losing the public relations war. Plastics have lower energy intensity than just about every competing material, but the problem is not plastic in itself; it is what we do with it. The world has a litter problem, with inadequate systems to collect and process waste, which has led to a very visible plastic pollution problem.
Circular carbon economy is in its infancy
The circular plastics economy is still “under construction.” A mechanical recycling industry is developing, but recycled plastic pellets still account for a small part of polymer demand. The most recycled polymer is PET bottle resin. (Polyethylene terephthalate (PET) is a type of clear, durable and versatile plastic.) A PET bottle is easily recognized and separated from the rest of the household waste by the consumer, with producers sponsoring bottle-collection schemes and incentives, such as using schools as collection points. Approximately 11% of PET is reused in bottle manufacture; a further 30% is downcycled to (chemically identical) polyester fiber use.
The recycle rate of other polymers is significantly lower. Recycled polyethylene (PE) accounts for about 7% of total demand. S&P Global Commodity Insights forecasts that the volume of recycled PE will more than double over the next 10 years, but this will still account for less than 10% of supply, given the underlying demand growth. There are regional variations: Europe has the highest recycle rates, whereas in some emerging economies, the recycle rate is still close to zero. High-density PE has more use in durable applications and has a higher recycle rate than low-density and linear low-density PE, which are used more in film applications. Applying a similar analysis across the full suite of commodity thermoplastics, we do not forecast “peak polymer,” or a peak in virgin polymer demand, between now and 2050.
Other recycling technologies are also in development. “Advanced” or “chemical” recycling involves turning waste plastic into a hydrocarbon feedstock such as pyrolysis oil, suitable for feedback back into a chemical plant. These technologies can handle a wider slate of polymers as feedstock, requiring less sorting. The first units in operation have a capacity of 30,000-50,000 metric tons per year; units with 300,000-500,000 metric tons of capacity are expected to be developed over the next 10 years. For comparison, a world-scale steam cracker will process up to 5 million metric tons of naphtha per year. Advanced recycling is still not at a scale to impact the petrochemical industry feedstock balance.
Whatever the recycle technology, a major bottleneck in scaling plastics circularity is the collection, cleaning and sorting of mixed waste streams. New virgin polymer capacity is built in increments of as much as 1 million metric tons when a new chemical complex is built. In contrast, polymer waste is collected 1 kilogram at a time by the curbside. The waste supply chain must be developed so that its own carbon footprint does not negate the benefit of recycling.
The availability of right-quality recycled resin has constrained brand owners and resulted in recycled polymer prices exceeding those of virgin resin. An S&P Global analysis of 16 major brand owners with a combined plastic consumption of about 12 million metric tons — approximately 10% of the global packaging industry — indicates approximately 11% recycled polymer content currently in their packaging. They have pledged to increase recycled content and reduce overall plastic consumption (or at least virgin plastic consumption), with targets in the 25%-50% range by 2030. This suggests that, among them, they will consume about 4 million metric tons of recycled polymer by 2030. Resin producers’ pledges suggest over 10 million metric tons of circular plastic will be part of their companies’ total portfolio by 2030. This amount will still be a small part of total thermoplastic demand, which is roughly 350 million metric tons.
Beyond packaging, plastics use continues to grow and is essential to the greening of society. Renewable power depends on epoxy resins for wind turbines and on PE films for solar panels. Electric vehicles will need less nylon resin in high-temperature applications under the hood but more polypropylene in the body design for lightweighting. Overall, the global demand for materials will continue to grow alongside population and wealth, exacerbating the decarbonization challenge. Along the way, governments are likely to enact legislation to control plastic pollution, yet the options to substitute plastics invariably involve more energy-intensive materials. The wider materials transition will not be possible without plastics as part of the solution.
Looking forward: Scale and technologies
Accelerating the materials transition requires the scaling of circularity and the development of new technologies. Chemical recycling processes need larger-scale and more robust catalyst systems to remove additives and contaminants. However, these requirements are moot if the supply chains to collect plastic waste are not sufficiently developed — and in a manner sufficiently low carbon that there is indeed a net emission savings from the circular economy.
Plastics could substitute higher energy-intensive materials in many applications. But other industries are also decarbonizing, with steel in particular investing heavily in hydrogen. Fundamental research to expand the performance envelope of plastics to replace other materials, such as concrete or steel, is currently aspirational, but countries dependent on fossil fuel sales are incentivized to develop new high-performance plastics and applications as alternate ways to monetize their hydrocarbons.
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