Turning waste into fuel could help cut cement’s carbon footprint

Waste that would otherwise end up in landfill could help low-carbon cement production by reducing the industry’s reliance on fossil fuels, according to Australian researchers.

Adelaide University PhD candidate Geethmi Thisakya, along with her supervisory team, Dr Navodana Rodrigo, Dr Chamitha Wijewickrama and Professor George Zillante, has systematically reviewed global research on using refuse-derived fuel (RDF) in cement manufacturing, examining its potential to support cleaner industrial production and more sustainable waste management.

Cement is essential for buildings, roads and infrastructure but is also responsible for an estimated 8% of global carbon dioxide emissions.

The industry relies heavily on coal and other fossil fuels to generate the extreme heat needed to produce cement. At the same time, large quantities of combustible waste, including materials that cannot be recycled, are sent to landfill.

Refuse-derived fuel is made by processing suitable waste into a fuel that can replace some conventional fossil fuels. Using it alongside traditional fuels in cement kilns is known as co-processing.

The researchers reviewed 211 scholarly articles published between 1991 and July 2025 and examined 48 in detail, including seven regulatory documents.

Their findings, published in the International Journal of Building Pathology and Adaptation, show growing global interest in RDF as a way to address two environmental challenges at once: reducing waste sent to landfill and lowering dependence on fossil fuels in cement production.

Geethmi Thisakya, a PhD candidate in the School of Civil Engineering and Construction, said the research highlighted the opportunity to connect waste management with industrial decarbonisation.

“Previous research has highlighted the potential of refuse-derived fuel to turn suitable waste materials into a useful resource rather than sending them to landfill,” Thisakya said.

“However, our review shows that realising this potential requires more than simply replacing coal with waste. We need consistent fuel quality, clear regulations and stronger evidence about the environmental and economic impacts.”

The study also uncovered widespread confusion between refuse-derived fuel and solid recovered fuel (SRF), a more highly standardised form of waste-derived fuel.

While both can be used in cement manufacturing, inconsistent terminology and varying quality standards make it difficult to compare research findings, interpret regulatory requirements and ensure reliable fuel quality.

The research team further emphasised that clearer standards would be essential for expanding the responsible use of waste-derived fuels.

“Cement manufacturers need confidence that alternative fuels will perform consistently, meet environmental requirements and support safe, reliable production,” Thisakya said.

“Developing stronger quality assurance systems and clearer regulatory frameworks will help industry make informed decisions about using waste-derived fuels.”

The review identifies several priorities for future research, including improving fuel classification, strengthening quality control, comparing regulations across countries and conducting more detailed assessments of environmental, economic and social impacts.

The researchers say more work is also needed to understand how RDF performs under different industrial and geographical conditions.

While recycling and reuse should remain priorities, RDF may provide an alternative for combustible materials that cannot be practically recycled, according to the researchers.

‘Refuse-derived fuel in cement manufacturing: a systemic review of research trends, gaps and future research directions’ is published in the International Journal of Building Pathology and Adaptation. DOI: 10.1108/IJBPA-08-2025-0200