Feel the heat: India’s environmental dilemma

22 February 2013

India’s power sector is so heavily dependent on thermal generation, especially coal-fired power stations, that it is having a huge impact on the environment. NTPC’s Arup Roy Choudhury speaks to Laura Walkinshaw about how the world’s next superpower is looking at a supercritical solution to the problem of burning coal more efficiently and cleanly.

Strong economic growth in recent years has undoubtedly put India in the running for superpower status. A thriving communications industry, coupled with IT centres in Bangalore and Hyderabad, have helped it overtake Japan as the world's third-largest economy in purchasing power terms, and enabled its growing middle class to enjoy the fruits of their labour with air-conditioning, fridges and televisions.

But 2012 has proved to be a testing time for India. Economic growth has slowed from 8-9% in previous years to a GPD of 5.3%, while severe blackouts in July - which affected more than 700 million people and forced industries to grind to a halt - have highlighted the need for a reliable power supply.

An ever-increasing demand for electricity has led to India's installed capacity being heavily dependent on its thermal power generation, 57% of which comes from coal-fired plants, contributing about 70% of total power generation.

Despite being one of the world's lowest consumers of electricity per capita, India already has one of world's largest carbon footprints and is currently the third-most-dependent nation on coal for power generation.

And with India's coal supply predicted to run out in four decades, coupled with rising costs in fuel and bottlenecks in the supply chain, energy suppliers are being forced to look at ways to make thermal power generation more efficient and environmentally sound.

Lowering India's emissions

The first step towards lowering India's greenhouse gas emissions was taken in 1995 when India's largest power producer NTPC established the Centre for Power Efficiency and Environmental Protection (CenPEEP) in collaboration with USAID. The mandate was to reduce greenhouse gas emissions per unit of electricity generated by improving the overall performance of coal-fired power plants.

At the start of USAID's Greenhouse Gas Pollution Prevention Programme (GEP), which ran until 2011, India's power generation capacity - 70% of which used coal for fuel - had an average efficiency of less than 30%, according to USAID.

According to NTPC's annual report, the creation of CenPEEP and other energy-efficient measures has led to the avoidance of over 30 million tons of cumulative CO2 since the inception of CenPEEP activities.

Overcoming power challenges

State-run NTPC, which was ranked the largest independent power producer and energy trader globally in 2012 in Platts' Top 250 Global Energy Companies ranking, recorded the highest growth in its history last year, and boasts a 27.4% share in India's total power generation.

In order to continue on the road to development, chairman and managing director Arup Roy Choudhury says there are challenges NTPC and the power sector as a whole must overcome - including insufficient fuel supply, poor financial health of state utilities, inadequate tariff revisions, lack of distribution reforms, and delays in land acquisition and environmental clearances.

"NTPC plans to overcome these challenges through various measures," Choudhury says. "It has introduced bulk tendering of 660MW-800MW supercritical units to step up capacity. This has helped in enhancing the equipment manufacturing capacity in the country through the induction of leading global manufacturers, which are setting up facilities in India through joint ventures."

"Despite being one of the world’s lowest consumers of electricity per capita, India already has one of world’s largest carbon footprints."

Another way in which NTPC is keeping ahead of the game is by directly importing coal, saving at least 15% of costs, as well as increasing the blending ratio and optimising the cost of generation.

To add an installed capacity target of 14,038MW by 2017, Choudhury says the company will focus on supercritical technology at its coal-fired plants. "The bulk of the new capacity will come through supercritical units, leading to greater efficiencies and reducing the negative impact on the environment, thus promoting sustainable growth," he says.

A supercritical solution

Supercritical units - which operate at higher temperatures and pressures, achieving higher efficiency and CO2 reductions than traditional systems - first came to the forefront in India in December 2011 when private thermal power producer Adani Power installed the country's first supercritical unit in the Kutch district of Gujarat.

NTPC soon followed with the commissioning of its first 660MW supercritical unit at Sipat in Chhattisgarh last year. The company has since commissioned another two supercritical units at the plant, with Doosan Koran supplying the boilers and the turbines being sourced from Power Machines, Russia.

When USAID's GEP programme ended, it recommended that supercritical power plants were the best low-cost option for reducing greenhouse gas emissions, and Choudhury says it is important to adopt this advanced technology.

"As carbon consciousness becomes more prominent, technologies for gaining efficiency and reducing emissions from coal-fired plants become more important," he adds. "That is one reason why supercritical and ultra-supercritical boiler technologies are re-emerging as new materials and designs help drive higher efficiency levels and ease of operation."

While conventional units of 500MW in a power plant achieve efficiency levels of 35-38% depending on the grid and operational restraints, supercritical units of 600MW can obtain 38-40% efficiency, typically reducing CO2 emissions by around 6%.

"Supercritical units are predominantly based on the once-through technology and are better amenable to varying load conditions, and have a quicker response time," Choudhury adds.

Increased power plant efficiency

Through its activities with CenPEEP, NTPC has introduced technology such as the SMART 24/7 fleet-wide monitoring system, which connects all units at NTPC generating stations, and allows the company to monitor the efficiency of 65 subsystems at its plants. Rather than waiting for operators to detect a problem, which can take time, office operators have the ability to remedy the situation - fast.

NTPC is also using state-of-the-art pollution control systems to control air and water pollution, while closed-cycle cooling systems have been installed at various projects and have proved to be very effective in cutting down thermal pollution, according to the company.

In addition, ambient air-quality monitoring systems have also been installed and networked to provide online access to the central pollution control board. Electrostatic precipitators with 99.99% efficiency are being utilised, along with flue gas conditioning (FGC) systems set up at older plants to help bring suspended particular matter emissions below statutory limits.

Non-fossil fuel alternatives and future plans

While coal will remain the main fuel for power generation in India for the foreseeable future, NTPC is looking to non-fossil sources to meet demand. Work has already begun on three hydroelectricity projects with total capacity of 1,491MW, while a roadmap for the development of 1,000MW through renewable energy sources is under development.

The company is also playing a key role in the implementation of the first phase of Jawaharlal Nehru National Solar Mission, an initiative by the Government of India to promote ecologically sustainable growth and address energy security challenges.

As for increasing the efficiency of coal-fired power plants and continuing to lower emissions, NTPC intends to adopt supercritical and ultracritical technology in all future projects. This includes its 3,300MW Barh project in Bihar, which is expected to be operational from next year.

"Achieving even higher efficiencies through higher temperature and pressure is currently limited by the availability of suitable materials that can withstand those parameters," Choudhury says. "Worldwide research is currently concentrating on this aspect of developing materials that can allow us to go for even higher parameters of temperature and pressure."

NTPC’s SMART 24/7 fleet-wide monitoring system.

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