Coal phaseout undermines co-benefits of fly ash as a clinker substitute

Public summary

* Fly ash replacing clinker turns waste into remarkable environmental and economic benefits.

* Coal phaseout erodes symbiotic benefits and boosts cement’s decarbonization costs.

* Existing low-carbon techniques cannot fully fill CO2 shortfalls from insufficient fly ash.

* Early cross-industry joint optimization is key to containing soaring decarbonization risks.

Abstract

Replacing clinker with fly ash is a critical CO2 mitigation pathway for cement clinker plants (CCPs), yet this potential may be adversely affected by the phaseout of coal-fired power plants (CFPPs). Here, we draw upon a high-resolution infrastructure-level database encompassing approximately 4,460 CFPP units and 1,540 CCP production lines in China. Through industrial symbiosis simulations and cost-benefit analyses, we evaluate the mitigation performance and adaptation costs of CCPs under various future CFPP retirement and flexible dispatch pathways. Our findings indicate that CCPs could reduce CO2 emissions by 141 Mt and generate 8.2 billion Chinese Yuan (CNY) in economic benefits through clinker substitution with fly ash. However, under the 1.5°C warming target by 2050, the coal power phaseout would undermine these benefits by more than 80%. While deploying adaptation measures could offset 57 Mt of CO2 losses, these measures incur an additional 5 billion CNY in costs for CCPs, potentially turning net economic benefits into an estimated loss of 17 billion CNY. Developing systematic and collaborative decarbonization strategies for highly connected sectors is essential for mitigating transition risks and improving decision-making effectiveness.