Experts at the third session of the International Conference on “Coal-Based Power” organised by Delhi-based non-profit Centre for Science and Environment (CSE) presented various technologies that could be used to make coal use more efficient.
Lesley Sloss, Principal Environmental Consultant, IEA clean Coal Centre, said that future growth hinged critically on the power sector in emerging economies, especially India, Southeast Asia and China. Almost three-quarters of India’s energy demand was being met by fossil fuels, a share that had increased since 2000 notably because of a rapid rise in coal consumption.
This was leading to high levels of air pollution in human habitations. To deal with pollution, new technologies were needed. But mobilising Rs 7 lakh crore per year in energy supply investment was a constant challenge for Indian policy and regulation. Despite this, encouraging early signs were visible, Sloss said.
She mentioned High Efficiency, Low Emissions (HELE) technologies, and said that these could help save 2.25 Gigatonne (Gt) of carbon dioxide annually if all of the world’s coal-fired power plants (with an average reported operating efficiency of 33 per cent) were upgraded or replaced with state-of-the-art HELE units operating at an efficiency of 45 per cent.
In India, 72,000 MWe is required to meet projected demand for 2040. Carbon dioxide emissions range from 858 Metrictonne (Mt) in 2020 to 1,444 Mt in 2040. Under the 50-year plant retirement scenario, no new HELE capacity is required to meet projected demand in 2020. For 2040, new HELE capacity of 119,600 MWe is required to meet projected demand at an estimated cost of US$350.9 billion.
Sandeep Tandon, Project manager of the United Nations Industrial Development Organization (UNIDO) talked about interest in gasification and work done in India. He talked about Integrated Gasification Combined Cycle (IGCC) and related experiments that are subsequently going on.
In his view, Indian coal has high ash content (35 to 45 per cent). It also has low sulphur content. Several gasifiers like slurry feed and dry feed, available in other parts of the world, are not suitable for Indian coal, he said. But gasifiers like fluidized bed and moving bed suit Indian coal.
He emphasised over the need of more coal testing and suggested policy changes like more stringent emissions standards for power plants, tax credits or other incentives for using IGCC, soft loans and building IGCC plants. He also emphasised about local technology ownership.
Jayendra Acharya, Deputy General Manager from JSW, talked about the Circulating Fluidised Bed Combustion (CFBC) technology. It was invented by Fritz Winkler of Germany and promoted by Douglas Elliott in the 1960s.
The advantage of CFBC technology is the combustion efficiency which generally is in the range of 97.5 per cent to 99.5 per cent.
Heru Dewanto, Director, PT Cirebon electric Power and PT Indika energy Tbk, Indonesia said that boilers were becoming more and more efficient. He talked about Super Critical technology and said that the country was moving from sub critical to ultra critical. However, there were some challenges like local requirement of technology as Indonesian law asks for 38 per cent local technology.
Naushaad Haripersad, Manager from Clean Coal Technologies, ESKOM in South Africa, talked about Super Critical Technology. In his view, the term “super-critical” refers to the critical transition point of water to steam at pressures over 22 mega Pascal (MPa). Super-critical units typically refer to main steam conditions of 24 to 30 MPa and 538 to 600 degrees Celsius (ºC), with a single reheat stage at 566 to 600ºC.
The super-critical boiler is a once-through design which (with sliding pressure) means that heating, evaporating, and superheating of the incoming feed water are completed within a single pass through the evaporator tubes and therefore does not require the use of a steam drum to separate and re-circulate water during normal operation.
This technology provides improved cycle efficiency and hence improved environmental performance. He highlighted its benefits like increased gross efficiencies in terms of reduction in coal consumption of approximately 5 per cent and also reduction in emissions in the order of 5 per cent.
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