ULTRA-SUPERCRITICAL THERMAL POWER PLANTS
ULTRA-SUPERCRITICAL THERMAL POWER PLANTS
Why in News?
The foundation stone was laid on September 20, 2026 for a 3,200 MW Ultra-Supercritical Thermal Power Plant at Chapar in Assam’s Dhubri district, being developed by Adani Power at an estimated cost of ₹48,000 crore.
The project is expected to become the largest power plant in Northeast India, with commissioning planned in phases from December 2030.
Chapar Ultra-Supercritical Thermal Power Project
Scale and Configuration
• Investment: ₹48,000 crore.
• Total capacity: 3,200 MW.
• Configuration: Four units of 800 MW each.
• Developer: Adani Power Limited.
• Commissioning: Planned in phases from December 2030.
• Employment: Expected to generate up to 20,000 jobs during construction and around 5,000 jobs after becoming operational.
Wider Power Investment in Assam
The Chapar plant forms part of a proposed ₹63,000-crore power investment in Assam.
This wider investment includes two pumped-storage plants worth ₹15,000 crore, with a combined capacity of 2,700 MW.
The thermal power project is also expected to create opportunities for local contractors, suppliers, transport operators and service providers, thereby supporting the wider local economic ecosystem.
What is Ultra-Supercritical Technology?
Ultra-supercritical (USC) technology is an advanced coal-based thermal power technology that operates at very high steam temperatures and pressures to achieve greater thermal efficiency. In a conventional thermal power plant, coal is burned to generate heat, which converts water into steam; this high-pressure steam drives a turbine connected to a generator to produce electricity. USC plants use higher steam temperatures and pressures to convert the thermal energy of fuel into electricity more efficiently.
How does Ultra-Supercritical Technology Work?
The basic principle of USC technology is that higher steam temperature and pressure increase thermal efficiency, which reduces fuel consumption per unit of electricity and can consequently reduce associated emissions. In a conventional subcritical plant, water undergoes boiling, involving both liquid water and steam. When operating conditions cross the critical point of water, the distinction between liquid and steam disappears and the working fluid behaves as a single phase. Further increases in temperature and pressure enable ultra-supercritical operation, allowing the plant to extract more useful energy from the same quantity of fuel.
Thermal power technologies can therefore be understood as a progression from subcritical to supercritical to ultra-supercritical systems. Subcritical plants operate below the critical point of water and generally have lower efficiency, while supercritical plants operate above the critical point and achieve higher efficiency. Ultra-supercritical plants use still higher steam temperatures and pressures, with steam temperatures generally exceeding 600°C, allowing greater efficiency and lower fuel consumption than conventional thermal technologies.
Why is Ultra-Supercritical Technology Important?
The principal advantage of USC technology is higher efficiency, as greater thermal efficiency allows more electricity to be generated from the same quantity of fuel. This also reduces the amount of coal required to generate a given amount of electricity and can lower associated CO₂, SOx and NOx emissions compared with less efficient thermal technologies. However, USC remains a coal-based thermal technology, so higher efficiency reduces fuel consumption and emissions per unit of electricity but does not eliminate the environmental concerns associated with coal-based power generation.
The progression in efficiency can be understood as: subcritical plants achieve around 38% efficiency, supercritical plants around 41–42%, and Advanced Ultra-Supercritical (AUSC) technology around 46%.
Why do USC Plants Require Advanced Materials?
The operation of USC plants at very high temperatures and pressures places considerable demands on plant components. Therefore, they require advanced materials capable of withstanding severe operating conditions, particularly in steam generators, steam turbines and high-temperature piping. The development of materials that can maintain their performance under such conditions is consequently an important technological challenge in improving thermal power efficiency.
India’s Advanced Ultra-Supercritical (AUSC) Effort
India has pursued Advanced Ultra-Supercritical (AUSC) technology to improve the efficiency of domestic thermal power generation and reduce its carbon footprint.
While USC refers broadly to ultra-supercritical technology, AUSC represents a further technological advancement aimed at achieving higher efficiency and reducing coal consumption and associated emissions.
India’s indigenous AUSC technology development involved Bharat Heavy Electricals Limited (BHEL), the Indira Gandhi Centre for Atomic Research (IGCAR) and NTPC, with funding support from the Ministry of Heavy Industries, BHEL, IGCAR, Department of Science & Technology and NTPC. The project had a total outlay of approximately ₹900 crore, of which MHI contributed around ₹470 crore.
The AUSC technology was estimated to reduce coal consumption and CO₂ emissions by about 11% compared with supercritical plants. The R&D phase has been completed successfully, while the subsequent phase envisages the development of a world’s first 800 MW AUSC Technology Demonstration Plant under the aegis of the Ministry of Power and NTPC
