Waste-heat power (steam Rankine): Impact and additionality

Displacing coal power without burning anything new

WHR power displaces grid or captive coal power without new fuel, typically avoiding 0.5-0.7 t CO2 per MWh where grids are coal-heavy. It does not cut the host's process emissions and can make a fossil plant cheaper to keep running.

Direct Scope 1 and Scope 2 abatement

WHR adds no new combustion, so its abatement is the grid or captive power it replaces. The CNBM 13 MW unit reports 51,419 t CO₂ avoided a year from 79.29 GWh, about 0.65 t per MWh (calculated). In India, CSE (2026) finds WHR at about 80-90% of cement plants, generating 30-35 kWh per tonne of clinker and meeting up to 25-30% of a plant's electricity, and estimates that fitting WHR at the remaining plants would save a further 1.37-1.60 Mt CO₂ a year. Triveni Turbines put adoption at about 70% of Indian kilns and above 80% in China in 2021 (company view); the figures differ in base (plants versus kilns) and year. UltraTech alone runs 444 MW. DOE estimated US technical potential at 8,840 MW across 2,946 sites, against 938 MW installed. NITI Aayog's 2026 roadmap counts WHR with renewables as a lever worth 6-10% of cement emission cuts.^134151617

Water and air synergy

A steam cycle needs make-up water and, if wet-cooled, evaporative cooling, a real constraint at water-stressed Indian cement sites; air-cooled condensers cut water use at some cost in output. Cooling kiln gas in the boiler reduces the water sprayed in conditioning towers and drops dust in the boiler hoppers. DOE notes that WHP adds no new emissions. Thermal discharge falls because less heat leaves the stack.¹²

Avoided lock-in

WHR does not raise clinker or gas output, but it lowers a host's power cost and can tilt a decision to keep an old kiln or gas plant running. In a combined-cycle plant the steam cycle is what makes gas power competitive, so it strengthens gas lock-in. In cement the risk is smaller because clinker kilns will exist for decades even under net-zero roadmaps, and process change (more preheater stages, more alternative fuel, lower clinker ratio) shrinks the waste heat over time. Investors should model a declining heat supply rather than assume today's level.¹³

Sources

1. Waste Heat to Power, CHP Technology Fact Sheet Series (DOE/EE-2347) US Department of Energy, 2021
2. Manual on Waste Heat Recovery in Indian Cement Industry Confederation of Indian Industry, Sohrabji Godrej Green Business Centre, 2009
3. 2050 Net Zero Roadmap one year on, action progress case study: CNBM, using new WHR power generation technology Global Cement and Concrete Association, 2022
4. UltraTech becomes first Indian company with 2 GW green power capacity Construction World, 2026
5. Cementing the Transition: the role of energy efficiency in decarbonising India's cement sector Centre for Science and Environment, 2026
6. Demand for WHRS has slowly picked up across the country, says Arun Mote, Triveni Turbines (interview; company view) EPC World, 2021
7. Roadmap for Cement Sector Decarbonisation NITI Aayog, 2026