Indian researchers propose plasma and nuclear power to green cement industry

Cement manufacturing is responsible for roughly 8% of global greenhouse gas emissions, making it a significant contributor to climate change. A new global action plan by two Indian researchers aims to change that by replacing fossil fuels with plasma powered by nuclear energy.

N. Bhanumathidas and N. Kalidas, founding directors of the Visakhapatnam-based Institute for Solid Waste Research and Ecological Balance (INSWAREB), have proposed using thermal plasma torches – superheated ionised gases reaching 3,000°C to 10,000°C – to produce clinker, the key ingredient in cement, without burning coal or other fossil fuels.

Traditional cement production relies on coal combustion and high-purity limestone inside rotary kilns. This process generates extreme heat and releases large amounts of carbon dioxide, sulphur, and fly ash. The proposed plasma route would eliminate direct combustion emissions, but it requires massive amounts of electricity. To meet this demand, the researchers suggest pairing industrial plasma plants with Small Modular Reactors (SMRs), which offer clean, stable, and long-term energy.

Operational statistics cited by the researchers illustrate the efficiency gains. A conventional rotary kiln consumes over 0.25 tons of coal per ton of clinker. A plasma route requires 0.72 tons of coal-equivalent to meet a 1.2-megawatt demand. However, a nuclear power route would use just 36 grams of radioactive material for the same 1.2-megawatt need. Put another way, 1 kg of radioactive material matches 20,000 kg of coal, and nuclear plants have lifespans exceeding 60 years, compared to 20 years for coal-based thermal plants.

INSWAREB has also conceived an Engineered Granulated Cementitious Slag (EGCS), a binder produced exclusively through plasma technology. The intense thermal energy melts and fuses industrial waste – such as India’s 2.86 billion tons of pond ash occupying over 26,000 hectares – into a homogeneous mineral glass. When ground with dry alkali activators, this material creates a high-strength cement with a blemishless microstructure and long service life.

Addressing the high capital cost of SMR-Plasma plants, the researchers suggest tapping carbon funds and new financial pathways opened by the global consensus to triple nuclear capacity. They have posted their global call on ResearchGate and addressed a mail to the Principal Scientific Advisor, Government of India, urging a National Plasma Policy, Kalidas told The Hindu.

This approach establishes a circular economic model that clears hazardous fly ash ponds, utilises low-purity limestone, and eliminates direct combustion emissions.

Kalidas noted that pilot-scale initiatives are already gaining momentum internationally. Heidelberg Materials in Sweden successfully operated a continuous plasma kiln pilot using carbon dioxide, and the University of Florida installed high-temperature plasma arc reactors to produce clinker at pilot scale.

The researchers highlight the broader context: despite over three decades of effort by the UNFCCC and COPs, the global circularity rate stands at just 6.9%. Over 93% of all materials used in production activities are virgin resources stripped from the Earth. The proposal aims to address this global issue to some extent.

The plan is not yet implemented on a commercial scale, but it offers a potential pathway for the cement industry to significantly reduce its carbon footprint while utilising waste materials.