Europe looks to the future. And when it comes to energy, the future is green. That is why Europe is accelerating its transition to clean energy.
Hydrogen is a key player in building a climate-neutral future. But hydrogen is not always sustainable. Producing it without relying on fossil fuels is a major challenge. That’s where the H2STEEL project steps in, exploring innovative ways to produce clean hydrogen while supporting the decarbonisation of the steel industry.
One exciting result from our research involves using biochar. This is a carbon-rich material made by heating organic waste. This waste can be sewage sludge (the muddy leftover of wastewater treatment) or agricultural residues (unused plant parts and other biomass). Despite biochar’s humble beginnings, the material can become a powerful catalyst for hydrogen production. A catalyst speeds up a reaction. Biochar can be a catalyst in methane pyrolysis, a process where methane (CH4) changes into hydrogen and solid carbon. Methane pyrolysis does not release carbon dioxide (CO2) into the atmosphere.
Why Methane Pyrolysis?
Hydrogen can come from different processes and sources. In fact, hydrogen is colour-coded based on how it is produced. There is green hydrogen, black hydrogen, grey hydrogen, and so on. But most traditional hydrogen production emits large amounts of CO2. Methane pyrolysis offers a clean alternative. Methane is the main component of natural gas and biogas. The hydrogen that results from pyrolysis is called turquoise hydrogen and has no direct greenhouse gas emissions if renewable electricity is used to produce it.
But the process is inefficient and expensive without catalysts. That is where the biochar comes in.
Giving New Life to Waste
In our research, we explored how different types of biochar performed as catalysts for methane pyrolysis. We discovered that not all biochars are equal. Their performance depends on how they’re made and treated.
Our team tested different samples and treatments. Chemical leaching was used to remove impurities from biochar, obtaining a carbon-richer material known as biocoal. Milling was also employed to make smaller particles of catalyst, while activation allowed to create pores and increase the surface area. Each of these steps can improve the biochar’s ability to break down methane and produce hydrogen efficiently.
What Makes a Good Catalyst?
We found out that several key properties determine how effective a biochar catalyst is:
- Surface area: the reaction happens at the surface of the biochar. Generally, when more surface area is exposed, a catalytic reaction becomes faster, but other factors influence the reaction speed in the case of methane pyrolysis.
- Pore structure: abundant pores help store the solid carbon product. This leads to longer catalytic activity. Pores also increase surface area.
- Size: biochar has variable size, and small particles have the best performance. The low size of the particles improved heat and mass transfer.
- Impurities: if the residue the biochar was made from had impurities, these will show up in the biochar as well. Removing ash and metals from biochar led to the formation of a biocoal with higher poteitnal.
By using these processes, we transform a material commonly seen as waste into a high-efficiency and low-cost catalyst.
From Lab to Industry: Selecting the Best Candidates
Our goal wasn’t just to identify the best-performing materials in the lab. We want to use them in industrial settings. That is why we analysed industrial feasibility and energy costs. Treatments like surface activation improve performance but can be expensive. Others, like leaching and milling, offer a good balance between performance and affordability.
Based on our evaluations we selected four biochars for further testing in a proof-of-concept reactor. Two came from sewage sludge and two from agricultural digestate. We chose each one because they show great performance in breaking down methane, are cost-effective and scalable. This means they can work in an industrial setting, provide an economic benefit, and be produced in high enough quantities for real-world use.
Understanding the Chemistry to Simulate a Real Reactor
To help design a full-scale reactor, we needed to understand how fast and effectively these biochars work. To do that, we conducted detailed kinetic tests, measuring the velocity of methane breakdown at different temperatures and catalytic conditions.
Using all this data, we created a simulation of a counter-current moving bed reactor. This is simply a system where methane and the solid biochar catalyst flow in opposite directions to maximize efficiency. The model helped us:
- predict how long the catalyst and methane need to stay in the reactor
- understand the effects of temperature and particle size on performance
- optimize the design for future industrial-scale use
What’s Next? Scaling Up for Real Impact
We showed we can use waste-based carbon materials to enable clean hydrogen production. This represents a major step forward in clean hydrogen production. By transforming everyday waste into valuable catalysts, we are not only supporting green energy but also promoting a circular economy, one of the core priorities of the EU.
The next phase of the project involves producing these biochar catalysts in larger quantities. Then, we can proceed to test them in our proof-of-concept reactor. This will allow us to confirm their performance in real-world conditions and move closer to scaling up the technology.
Why This Matters
The work from H2STEEL shows how innovative materials and smart engineering can help solve some of the toughest challenges in energy and climate. By turning waste into a useful material for clean hydrogen production, we’re helping to pave the way towards:
- Lower emissions in metallurgic industry
- Sustainable use of biomass and waste
- Affordable hydrogen production
As we continue this journey, we will be sharing updates and results from the next stages of testing. Stay tuned to learn how biochar might power a greener future.
AuthorS: Enrico Sartoretti, Piercosimo Vedele, Samir Bensaid Politecnico di Torino