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India Cleans Up

World Coal,


India’s growing economy requires increasing amounts of energy to fuel the country’s rapid development. Energy security has therefore become a core focus for the Government. Although India is poorly endowed with oil and natural gas, it has large reserves of coal. This has resulted in increasing dependence on energy imports, raising concerns over security of supply. In recent years, the Government has made efforts to diversify the country’s energy mix. However, these have been hampered by the limited hydrocarbon reserves, environmental concerns associated with additional hydro projects and reservations about nuclear power. Realistically, coal remains the country’s only abundant energy source and most estimates suggest that there are sufficient reserves to last for over a century.

Despite its poor quality, the economic and strategic benefits of coal over other forms of energy look set to ensure a continuing central role in the Indian economy for many years to come. Notwithstanding ongoing efforts at diversification, the amount consumed will rise significantly during the coming decades. Increasingly, clean coal technologies (CCTs) will have an important role to play in this developing story.

The power sector

India is desperately short of electricity and the ever-growing demand continues to outpace increases made in generating capacity. Blackouts remain a common occurrence in many cities and around 40% of India’s more rural residences still lack electricity. As rural electrification spreads, demand will rise further and even more capacity will be required. Although flagged up as a high priority in several recent five-year national plans, many planned additions to the generation sector have been delayed, and frequent coal shortages do no help. However, in an effort to address the growing electricity requirements and tackle current shortages, new coal-fired power plants are being built and planned.

At the moment, nearly all coal-fired plants rely on conventional pulverised coal combustion (PCC) technology, using subcritical steam conditions.

Recently, emphasis on the use of CCTs has increased. Currently, the main thrust in the power sector remains the deployment of PCC technologies, but using much higher (supercritical) steam conditions, as opposed to the more conventional subcritical.

Supercritical PCC power generation

Supercritical technology offers significant efficiency gains over conventional subcritical PCC, reducing coal consumption and lowering emissions. In many parts of the world, supercritical technology is already well established. Within India, despite various delays and setbacks in recent years, there is also an ongoing programme to introduce supercritical PCC technology.

As part of its drive to increase generating capacity, the Ministry of Power, the Central Electricity Authority (CEA) and the Power Finance Corp. have been working together to develop a number of ultra mega power projects (UMPPs), each of up to 4 GW, on the basis that economies of scale can produce cheaper power. These are being developed via a tariff-based competitive bidding process and will adopt supercritical PCC technology. Eventually, UMPPs are expected to add more than 30 GW of capacity to the Indian power sector.

There are also a number of more modest projects being developed.

The increasing adoption of supercritical technology will eventually help push up the overall generating efficiency of the Indian power fleet. Although this has been rising slowly, the overall average is low due to a combination of poor (and declining) coal quality, high ambient temperatures, and a pressing need to keep outdated, inefficient plants online.

Fluidised bed combustion

Not all Indian power plants rely on PCC systems: fluidised bed combustion (FBC) is increasingly being deployed. Indian coals can be difficult to burn effectively in some types of combustion equipment. FBC systems are renowned for their fuel flexibility and are particularly well suited to accommodating such difficult fuels. The simplest system is bubbling FBC (BFBC), which can tolerate a wide variety of fuels and fuel blends. The other is circulating FBC (CFBC). Alongside high fuel flexibility, this can offer important benefits, such as compact boiler design, high combustion efficiency and relatively low emissions. Recent years have seen the growing use of the technology in India, including the repowering of some conventional combustion plants.

IGCC technology

Since the 1980s, the main focus of IGCC development in India has been work undertaken by Bharat Heavy Electricals Ltd (BHEL). Over more than two decades, BHEL carried out a multiphase development programme, from which it was concluded that the most appropriate IGCC technology within an Indian context should be based on air-blown pressurised fluidised bed gasification (PFBG). This is considered to be the most suitable form in terms of process efficiency, economics and environmental impact. The system is expected to produce electricity more cheaply than plants based on alternative gasifier designs.

Reducing environmental impact

Coal-fired power plants are responsible for a high proportion of the country’s SO2 emissions. The low sulphur content of most Indian coals means that this is not generally considered a major issue. However, the large increase in the use of indigenous coal for power generation and industry has meant that SO2 emissions almost doubled between 1985 and 2005. To date, abatement measures have been limited to the provision of stacks of sufficient height to ensure adequate local dispersion. However, for new larger plants, the Government now recommends allocation of space should flue gas desulphurisation become a requirement in the future.

Controlling CO2 emissions

To date, apart from more general measures, Indian efforts to control CO2 emissions have been focused largely on boosting the performance of existing power plants and installing newer, larger, more efficient units. However, the main drivers have been the need to increase electricity output and reduce coal consumption, rather than to tackle CO2 emissions per se.

Until recently, there appeared to be little Government support for the application of technologies aimed directly at CO2 control or capture. However, there has been a growing realisation that these systems could eventually have a part to play and Indian decision makers have begun to acknowledge their potential importance.

At the moment, no carbon capture projects are being developed and none appear to be planned, at least in the near term. But there are growing commercial links between major Indian equipment suppliers and overseas technology developers, and Indian researchers are involved in a number of important ongoing international collaborative R&D programmes.

Author: Dr Stephen Mills, IEA Clean Coal Centre, UK

This is a condensed version of a regional report that appeared in the January issue of World Coal. Subscribers can access this issue here. If you are not a subscriber and would like to receive World Coal's monthly blend of regional reports, technical insight and industry comment, you can subscribe here.

Read the article online at: https://www.worldcoal.com/special-reports/25012011/india_invests_in_clean_coal_technology/


 

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