The Mechanics of Ceramics: How the Industry Can Decarbonize


Although the world’s industries have tried to transition to more sustainable methods, the annual global extraction of materials has tripled over the last 50 years. In Europe’s ceramics industry has halved its energy consumption over the last 25 years thanks to new manufacturing technology. 

According to the European Commission, the ceramics sector in Europe provides over 338,000 jobs and is worth €27.8 billion to the EU economy. Although it is faced with high energy prices and reliance on raw materials from non-EU producers, the SMEs that make up the industry can react quickly to both changing demands and new opportunities.  

Professor Ian M Reaney, the Dyson Chair in Ceramics at the University of Sheffield’s Department of Materials Science and Engineering was recently in Modena to discuss the challenges faced in the ceramics industry, the new technologies that can potentially drastically cut emissions, and his own motivations for helping the industry innovate.

As an expert in ceramics, what do you see as the main challenges in your research?

It’s manyfold. Most ceramics are made using heavy methane burners, and therefore you have significant carbon emissions associated with the traditional ceramics industry, tiles, pottery and so forth. There are also challenges to create materials for sustainable applications, such as batteries, fuel cells, capacitors for electric vehicles to enhance performance and so forth. Those materials need to be improved so that we can help make the world [become] more efficient in its use of energy.


You delivered a keynote at the 9th International MSSM conference where you discussed the sustainability of the manufacturing of ceramics. What are your thoughts on this?

Professor Ian M Reaney, Dyson Chair in Ceramics at the University of Sheffield’s Department of Materials Science and Engineering

One aspect is the volume production of ceramics – this area of Italy is very famous for the production of high-volume traditional ceramics. These factories have been around for sometimes hundreds of years. They, broadly speaking, use the same manufacturing methods since the last 30 to 40 years. They burn methane, which is obviously more expensive than it used to be, but the worst aspect is that it’s a huge CO2 emitter. The temperatures are very high, so there are a lot of gas burnt. You sinter or densify these ceramics at about 1100°C to 1200°C.

So to create sustainable manufacturing processes is an important goal that we really need to address and achieve in the next few years.


What are the alternatives?

Currently in terms of the volume production of ceramics – pottery, bricks, roof tiles, decorative tiles – there are very few alternatives that can be dropped in immediately.

Furnaces are enormous. They cost millions, and they’re designed to run for 30 to 40 years. It’s very high in capital equipment expense. The problem is moving away from that is expensive, the technologies are not so clear at the moment.

There are two competitive technologies. One would be to retrofit the systems to burn hydrogen or mixtures of CH4/hydrogen, but the technology is in its infancy. The other is to create electric furnaces, but these electric furnaces will be brand new furnaces that would replace the ones in the factory. So, your capital equipment expense is extremely high. That has to be factored into any kind of longterm planning for a company if they wish to go down the path of electrification.


And so, the challenge for sustainability is to decrease the unnecessary heat.

In terms of sustainability, there’s a couple of things. There is a lot of waste associated with ceramic production. Ceramics are fragile, mistakes are made in production, and defects form. The first thing is to minimise the waste. The second is to reuse the waste that is made. And also, in reusing waste or adding things to the process, you have the possibility of decreasing the densification temperature [the temperature that helps fuse small particles into a dense bulk]. But that’s quite difficult in a traditional process and you may only achieve a few tens of degrees. That’s beneficial and we sure should do it. But that isn’t reducing massively the embodied carbon within the product. It is decreasing it and improving it, but it’s not a silver bullet.


How are these waste products currently managed?

Managed well, we [can] recycle a significant amount in-house in a ceramic factory. All pre-fired [ceramics] would get recycled, and partial recycling of the fired waste would occur. But then you have something called industrial symbiosis, where you can reuse that waste in other technologies. Cement/concrete is one that is very popular because cement contains particulates, and those particulates can be chunks of fired waste from other manufacturing routes from ceramics.

Unfortunately, if you go to any ceramics factory, you will see either the waste stored adjacent to the factory or in the worst case sent to landfill. Finding the means of achieving industrial symbiosis is a big challenge and one that they’re addressing. But it’s going to take a while.


What role does water have in these processes?

Water is in everything. You use water as part of the glazing process. You usually do something called a waterfall of a particulate slurry, and the base of that slurry is water. Water gets emitted from the clay itself because it’s a hydrated mineral. Water is pretty much in all the processes.

I would say the most obvious place you see water would be during the spray-drying process, which gives this granulation, and also in the application of the glaze and something called the engobe, which is a name for a pre-glaze layer.


One project highlighted at MSSM is the EU-funded iWAYS project, which aims to enhance sustainable industries by introducing technologies capable of recovering water and energy from industrial exhaust gases. How could iWAYS tech benefit the ceramic industry in your opinion?

The iWAYS project’s main goals is energy recovery through heat pipe exchange systems primarily, and water recovery. So, one could imagine that you could recover water from processes and reuse that in a granulation and throughout the process of ceramic manufacturing.

Energy recovery systems that iWAYS and previous projects have developed are also important. The heat exchange systems based on heat pipe technology can span a range of temperatures, which is unusually large. So, it can do low temperature, low grade heat and high grade heat equally well. It can give you significant energy recovery and it can put heat back into production and decrease the energy in total being used by the manufacturing process.

I think it has two aspects. I think the main one is likely to be the energy recovery, but you also have to manage the water and make sure you recycle and reuse it.


In your opinion what is the single best action to decarbonise the ceramic industry?

It needs a holistic response. You need to look at the resource efficiency, which is to reuse as much waste as possible. You need to look at reduced carbon, raw materials, and the eradication of limestone, for example, from formulations.

You need to look at the energy recovery with perhaps heat pipe technology to address things that aren’t currently utilised. Redirection of hot air is used routinely, but the heat pipe systems are much more advanced than that.

The other one is to encourage governments to decarbonise the grid. But we can’t wait until those mega projects of hydrogen and electrification are complete. We need to start with resource and energy efficiency concepts that are discussed in iWAYS, for example. We need to start with that immediately, if it’s not already ongoing, because you can make headway in this area quite substantially by doing small amounts of improvements in decarbonisation through resource efficiency. It will be the dominant (carbon mitigation) strategy for at least ten more years before the mega projects of hydrogen and electrification start to have an effect.


How have you seen the industry evolve in Europe?

That depends where you are in Europe, because a great deal of the ceramics industry is now outsourced to the Far East. I think there’s been an evolution in thinking that we want to keep the jobs here and keep control of the embodied carbon rather than just stopping production and allowing high embodied carbon products to be imported from other countries.

I think there’s an emerging thought pattern of sustainability coming out of the companies now. It’s in part driven by government initiatives, but also driven in part by realising there’s a market for sustainable products. At the end of the day, people want to make money.

If you look at the three pillars of sustainability, it’s economy, society and environment. You need to have all those three. Economy is part of sustainability. What’s the point in having a perfectly sustainable net zero product that nobody buys? There’s an acceptance that this is a viable way forward as a business model. I can see things changing, whereas before it was going towards super low-cost production or maintaining some high-quality materials at very high value with no thought of the high embodied carbon. Most companies now have a whole line of sustainable products with better green credentials, and they have to show those green credentials as well. Those products have to be demonstrably greener.


Do you think companies are becoming more aware of these sustainability issues in the ceramics industry?

It’s the carrot and the stick. There is a ‘stick’ from government; we can’t keep on burning fossil fuels, so there are imposed carbon allowances and things like that. And then you have the ‘carrot’ – things like the European Green Deal, and we have similar things happening in the United Kingdom. These things work in tandem – an encouragement approach from investment and a stick approach from legislation.