Company officials admitted that they had juxtaposed the emission data for 2005-06 with the generation data of 2007-08 to arrive at such a conclusion.
During those two financial years, the country's largest thermal power producer increased its generation capacity by nearly 6 per cent to around 200 billion units per annum, almost all from fossil fuels (gas and coal). "When we use generation and emission figures of the same year, we no more remain at the second position," said a senior official of the company.
This was in response to a report by Washington-based Centre for Global Development, which said NTPC was the world's third-largest polluting power producer.
The report drew instant criticism from the NTPC management, which accused CGD of using wrong data and also questioned its methodology.
In response to a questionnaire sent by Business Standard, CGD, a non-profit organisation, said its own calculation for energy intensity revealed that the Indian power company could not claim to be the second most efficient power producer in the world.
"NTPC's pairing of power production (figures) from 2007-08 with emissions data from 2005-06 resulted in an artificially low carbon intensity,"
according to a statement by CGD.
While calculating the energy intensity value, NTPC had used the latest (2007-08) figures for its total power generation of about 200 billion units and compared it with the carbon-dioxide emission figures from 2005-06 of about 182 million tonne.
This led the company to arrive at an energy intensity of about 820 gram per kilowatt hour.
In 2006-07, NTPC's power plants had ejected a total of about 186 million tonne of carbon to produce about 188.67 billion units of power.
These numbers suggest that its energy intensity is about 890 gram per kilowatt hour and means that the company stands at seventh position in terms of energy efficiency.
Some experts have questioned CGD's methodology. "The report focuses on the current emission levels only, without getting into the cumulative emissions of the last 100 years or so, and therefore presents a very biased picture," The Energy and Resources Institute Director Leena Srivastava said.
NTPC's internal calculation also has two exemptions which ruled out many of the world's efficiently-run plants: It considered only companies which have a generation of above 125 billion units and those which have above 50 per cent usage of fossil fuels in their fuel mix.
As a result, a large number of carbon-efficient power generators in Japan and Europe have got excluded.
