A New Recipe For Greener Cement, Made With Ammonia And Hydrogen

Imperial researchers are part of a 12-partner European project testing whether cement plants can run on ammonia and hydrogen fuel, partly recovered from wastewater, and whether the switch would genuinely cut emissions.

Cement is like the glue holding together our homes, roads and bridges. But producing it costs us around 7% of global carbon dioxide (CO₂) emissions, partly because the process needs extreme heat, which has long come from burning fossil fuels.

A new project called HARMONI aims to change that. Funded by the European Union with almost €8 million shared between 12 partners across Europe, it will explore whether cement plants can swap fossil fuels for a blend of ammonia and hydrogen, and help balance the electricity grid at the same time.

As a core project partner, Imperial researchers based in the Department of Civil and Environmental Engineering will assess whether the approach delivers genuine environmental, economic and social benefits.

Heat is the heart of the problem
In industries such as cement, steel, glass and ceramics, between 70%-92% of energy use goes on high-temperature heat.

One promising alternative fuel is green ammonia. It contains no carbon, so burning it releases no CO₂. Most ammonia today is made using fossil fuels, but green ammonia is now produced using renewable energy sources such as wind and solar power.

Ammonia is also easy to store and move. A global shipping network already exists. The catch is that it is hard to burn. It ignites poorly, its flames travel slowly, and it can also release nitrogen oxides (NOx), which are harmful air pollutants.

HARMONI’s answer is to recover ammonia from wastewater (either from the plant itself or from nearby treatment plants), top it up with green ammonia from external suppliers, and split some of it into hydrogen on site, a process known as ‘cracking’. Hydrogen helps the fuel burn better, and the blend delivers the very high temperatures that cement-making needs.

The system will also adjust its fuel mix as renewable power supply rises and falls. That would let a cement plant take in spare wind and solar energy when it is plentiful, acting as an ‘intelligent energy hub’ for the electricity grid.

Professor Evina Katsou, Chair in Water Engineering, Department of Civil and Environmental Engineering, said: “A fix that only moves the problem somewhere else is not good enough. In HARMONI, our job is to check, across the whole life cycle, whether this approach really cuts emissions without creating new problems, using trialled scientific methods and data-driven evidence.”

Project partners will first test the key technologies separately, in laboratories and small-scale experimental set-ups. They will then bring them together in a digital twin, a virtual copy, of a real cement plant in Alicante, Spain.

Putting the green promise to the test
Professor Katsou leads Imperial’s contribution alongside Dr Elham Mousania, Dr Daniel Dias and Dr Elena Koumaki. They will build models that follow cement from raw materials to the factory gate, tracking the energy and water used along the way. This approach, known as life cycle assessment, shows where the benefits lie, where trade-offs appear and which stages need attention.

Working with Norwegian project coordinator SINTEF, the researchers will also estimate what the new approach would cost and examine its social impact, including worker safety and local job creation. They will also review what could stand in the way of adoption, such as the approvals needed to change fuels and the rules for connecting to the grid, and turn their findings into recommendations for policymakers.

These results will feed into the digital twin, which is being built by project partner IDENER. Professor Katsou’s group will also help design its operator interface, so it works for the people using it. The team is also creating tools and training for the people who will use the technology.

Dr Mousania, Research Associate in the Department of Civil and Environmental Engineering, said: “Our interactive tool will let other cement plants explore the approach for themselves, so owners can judge whether it would work on their site before they invest. Alongside this, we are designing a training programme with plant managers, operations staff and technology developers.”

The training will be available online, so staff can learn at their own pace, through the Erasmus+ Skills4EII Hub, part of the EU skills alliance for energy-intensive industries.

By the end of the project in August 2029, they hope to tell industry and policymakers with confidence whether switching cement production to ammonia and hydrogen really pays off, for the environment and for the people who run the plants. The findings could also help other heavy industries, such as steel, glass and ceramics.