We know from structures like Herstmonceaux Castle that clay bricks will endure for hundreds of years. We want to confidently think the same of our natural environment and quality of life for future generations. For Michelmersh and the wider construction industry, this means committing to decarbonising our operations to help meet the UK’s net zero target by 2050. That’s why we’re proud to share the successes of our green-hydrogen-fired brick feasibility project—HyBrick™.
If you haven’t heard of Michelmersh or the HyBrick™ project before, this blog post will explain everything you need to know. If you’ve already been following our journey, we’ll reveal the results and what’s next for sustainable construction materials.
What is the HyBrick project?
We had a simple but ambitious goal for the HyBrick™ project—to prove that we could use hydrogen instead of natural gas to fire clay bricks and retain the same technical properties.
Firing is the hardening process that follows drying, before which clay bricks are still in their ‘wet’, mouldable form.
Our aim was to reduce the carbon emissions associated with our clay brick firing process by 60 per cent or more. This was also the reason we chose to use green hydrogen, which producers extract from water, instead of fossil fuels, via electrolysis.
We wanted to test this novel firing method with our best-selling product, the Freshfield Lane First Quality Multi. As a result, the technical properties the HyBrick had to meet included:
- * Compressive strength of more than 27N/mm2
* Water absorption of no more than 12 per cent - * An F2: frost-resistant rating (suitable for all conditions)
- * Thermal conductivity of 0.51W/m.K
We received funding from the UK government’s Industrial Fuel Switching competition (IFSc) for the HyBrick™ project. We also worked with industry specialists and expert partners to make HyBrick™ a reality and share our study findings. Our thanks go out to Hydrogen Sussex, Limpsfield Combustion, Net Zero Associates, the University of Brighton, Greater South East Net Zero Hub, FT Pipeline Systems, Geopura, and Safety Monitors.
Why is the HyBrick project important for net zero goals?
The UK’s net zero carbon emissions goal is the most pressing focus for the construction industry’s sustainability efforts. That’s because the construction industry is responsible for around 37 per cent of global carbon emissions. That figure captures the entire construction supply chain, from raw material extraction to on-site activity to the energy needed to heat and cool the built environment. It also includes construction product manufacturing.
Reaching net zero by 2050 is vital if we want to prevent irreparable harm to the planet and people. This urgency has prompted hydrogen feasibility studies by manufacturers across steel, concrete, and glass. Michelmersh has joined their ranks to be the first clay brick manufacturer to conduct a green hydrogen feasibility study for one of its key processes, which we called HyBrick™.
Clay brick sustainability
Clay bricks are one of the more sustainable construction materials when you consider they can last for hundreds of years. They already produce zero operational carbon, meaning they require no maintenance after application and release no carbon during their lifespan. Where we can improve clay bricks is their embodied carbon. This includes the carbon emissions associated with raw material extraction, manufacturing, transportation and application.
We’ve already been able to reduce the carbon intensity (per tonne of product) of our operations by more than 24 per cent since 2016. That’s thanks to initiatives like:
- * Making production processes more energy-efficient
- * Phasing in electric forklifts, HGVs, and cars
- * Switching to renewable electricity, including on-site sources
- * Swapping to bio-based plastic packaging for our products
- * Innovating in product development, such as product sizing, dematerialisation, or using recycled content
One of our remaining and most significant hurdles is the emissions from natural gas for the clay brick firing process. Firing is one of the most energy-intensive processes involved in clay brick manufacturing, requiring temperatures of over 1000°C. That’s why it was our focus for the HyBrick project. If we can reduce the carbon emissions associated with drying and firing using natural gas, we can prove the potential of clay brick for helping to decarbonise construction.
How we made HyBrick
Before the firing stage, we used all the same materials and processes we would normally to produce the First Quality Multi. Then, we created our ‘control’ bricks, firing just under 20 cycles to determine our baseline carbon emissions and product specifications using the hydrogen-ready burner.
After this, we started the process of making HyBrick™ itself:
Retrofitting the kiln
To meet the right conditions for hydrogen firing, we retrofitted a small independent kiln that we use at Freshfield Lane for special-shaped bricks. Hydrogen has a higher flame temperature, burns faster than natural gas, and needs more air for combustion. So, we needed to ensure that the kiln could withstand those differences with higher levels of moisture, exert more control over the firing curve, and draw more oxygen in to create airflow. This involved replacing burners, manufacturing a skid to reduce the hydrogen pressure, and other modifications to allow engineers to precisely measure and control the firing curve.
If you haven’t encountered the firing curve before, imagine a line graph with time on one axis and temperature on the other. The firing curve line starts at zero for both factors, then curves upwards as the temperature increases in the kiln to vitrify the clay bricks, which makes them stronger and less porous. Then, the temperature slowly decreases, and the line curves down again. Different firing curves produce different brick characteristics. So, it’s a key recipe and differentiator between clay brick manufacturing processes, technologies, materials, and products.
Implementing new health and safety measures
Hydrogen is a promising alternative to natural gas for the clay brick firing process. Under the right combustion conditions, the only byproduct is water, compared to natural gas which produces carbon dioxide in the combustion process. But, hydrogen also carries a higher risk of accidental ignition because it has a wider flammability range than natural gas.
This leads to greater health and safety measures when working with hydrogen. As we were the first clay brick manufacturer to conduct this kind of hydrogen-firing study on an industrial brick manufacturing site, there was little support for us. We used a retrofitted kiln in a non-enclosed space, which would have allowed any hydrogen leaks to dissipate into the air, avoiding dangerous build-up. And our steel skid manufacturer, FT Pipeline Systems, designed and installed multiple fail-safe devices into the skid to shut down the hydrogen flow if there was a leak. Nevertheless, we invested in numerous Hazard and Operability (HAZOP) studies, leak and flame detectors and an ultrasonic warning system. This final element would instantly alert people across the whole Michelmersh site if the detectors sensed a hydrogen leak or flame outside the kiln.
We detected no leaks during the three firings, but the equipment and training we’d invested in gave us confidence that safety was ensured throughout the study.
Firing the bricks
The main change to our firing methodology using hydrogen instead of natural gas involved adjusting the firing curve. As we’ve already mentioned, this is often a differentiator between clay brick manufacturing processes. But, alongside our engineers also had to adapt ours to account for the combustion differences between the two gases.
With the funding we received from the Industrial Fuel Competition, we were able to run three firing trials using 100 per cent green hydrogen as the fuel source. For future trials, we could focus on making the process even more fuel efficient by optimising the firing curve further and experimenting with the drying process. Other variables we could test include the configuration of bricks inside the kiln to improve airflow and adding more oxygen to the kiln.
The results of the HyBrick project
Our original target was a 60 per cent reduction in carbon emissions associated with the firing process. The results of the first HyBrick™ project indicated that we had exceeded that—achieving an 81 to 84 per cent reduction in carbon emissions over the three trial burns. What’s more, with further trials and process optimisation, we believe we could increase this figure. With on-site hydrogen production, we could achieve an even higher percentage. All while meeting the high technical standards of our natural-gas-fired First Quality Multi brick.
What’s next for HyBrick and sustainable construction materials?
The results demonstrate promise for using green hydrogen to fire clay bricks and reducing carbon emissions in the construction supply chain. But, before we commit to this alternative fuel source, we want to explore more opportunities for decarbonisation. Biogas, syngas, recovering recycled heat, and electrified kilns are all potential options. They may also be faster to rollout than green hydrogen, which is currently hard to produce at the scale needed to meet demand.
With all that said, hydrogen feasibility studies for clay bricks are continuing in the UK. A consortium of ceramics manufacturers, including Michelmersh and led by Ceramics UK, has had funding from Phase 2 of the IFSc to run more hydrogen feasibility trials by 2025. This highlights the importance of government funding for these projects, particularly for sectors like ceramics. The UK steel sector, for example, has fewer, larger manufacturers with annual turnover in excess of £1 billion. Whereas ceramics manufacturing is fragmented across hundreds of companies without the same level of investment power individually. We hope that the results of the HyBrick™ project will inspire other ceramics manufacturers to apply for and call for more decarbonisation funding. If you’re curious to see how HyBrick™ looks and performs, you can do so at Energy Revolution: The Adani Green Energy Gallery at the London Science Museum for the next 10 years. In partnership with Unknown Works and Lyons & Anoot, the HyBrick™ bench is now a tangible representation of clay brick’s role in more sustainable construction.
