The concept of supercritical technology was introduced as a national plan in the Integrated Energy Policy report of 2006 issued by the Planning Commission. It noted that the average fuel conversion efficiency of Indian power plants is just about 30.5 per cent, though the new 500 MW plants have efficiency of 36 per cent. State-of-the-art supercritical boilers can reach an efficiency level of 46 per cent depending on plant location.
Under Indian conditions an efficiency level of 38-40 per cent should be attainable. This alone can reduce coal requirement by 111 million tonnes.
Consequently, India’s leading utilities and suppliers aligned themselves with this goal which led to the birth of several JVs manufacturing supercritical equipment to improve the efficiency of coal power plants in the country.
Ultra-supercritical technology is the new paradigm that the Indian power sector is aiming to touch. India’s power generation over the next few decades will continue to depend heavily on coal. The latest figure for total installed capacity of power generation in India is 273 GW. Out of this, installed capacity for coal stands at a colossal 165 GW!
Coal fires most of the power plants across the world despite being a finite source and its reserves are expected to last just over a century at current rates of production. Hence, there are already views that recommend a more efficient use of the resource.
What is within our capability is to minimise the carbon footprint of coal-fired plants. This is wherethe more fuel-efficient ultra-supercritical technology can contribute. Even in the US, coal still accounts for over 40 per cent of total electricity generation.
Innovation and improvement
Ultra-supercritical technology uses steam with very high temperatures, up to 620°C, and pressure, up to 300 bar, resulting in a much higher efficiency than conventional coal fired plants. A unit burns much less coal, thereby generating less emission per megawatt of power output.
With constant innovation and technological advancement, the focus of power equipment manufacturers remains on developing power equipment using newer alloys and tube materials that can withstand even higher pressures and temperatures to raise efficiency to 50 per cent.
These supercritical and ultra-supercritical technologies also hold the key to India’s power woes as the nation looks to augment its power production with tighter control over pollution levels. Despite the focus on renewable energy, thermal power plants will continue to dominate India’s landscape.
The 12th Five Year Plan witnessed the introduction of supercritical technology through the development of Ultra Mega Power Projects (UMPPs) with a capacity of 4,000 MW each.
So far, four ultra mega power projects (UMPPs) of 4,000 MW each have been commissioned in Sasan (Madhya Pradesh), Mundra (Gujarat), Krishnapatnam (Andhra Pradesh) and Tilaiya (Jharkhand). Reliance Power has pulled out of Tilaiya. Twelve more supercritical UMPPs are being planned for Chhattisgarh, Gujarat, Tamil Nadu, Andhra Pradesh, Odisha, Maharashtra and Karnataka.
The government is also looking to upgrade existing large power plants to larger UMPPs with greater capacity, cleaner and better technology, and investment in R&D for the development of advanced ultra-supercritical technology.
In line with India’s mega plans for thermal energy and requirement for cleaner power generation technology, Alstom Bharat Forge Power Private Limited (ABFPPL), a joint venture between Alstom and Bharat Forge, has started production at a new state-of-the-art manufacturing facility for supercritical and ultra-supercritical turbines and generators in Gujarat.
It is evident that ultra-supercritical technology, where efficiencies greater than 45 per cent can be achieved, is the next big change as coal-fired power plants enter a key stage of evolution.
Power generation companies are likely to make this technological switch to drive up output and plant load factor, curb variable costs and cut down discharge of pollutants in the atmosphere.
At the same time, the rigorous research and development by power equipment makers is bound to make turbines and generators more robust and efficient with temperatures of over 700°C within the realm of possibility.
Efficiency savings will not only reduce operating costs and make better use of fossil fuels, they will reduce the overall liability for emissions.
The writer is country president of Alstom India & South Asia