CNG not that green: pollution board

CNG is not without environmental drawbacks says a new Central Pollution Control Board study. The study says burning CNG has the highest rates of potentially hazardous carbonyl emissions. These conclusions have attracted criticism from many, including environmentalists. Chetan Chauhan reports. Emission notes

Updated on: Jan 6, 2011, 07:43:31 IST

Hindustan Times | By Chetan Chauhan, New Delhi

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CNG is not without environmental drawbacks says a new Central Pollution Control Board study. The study says burning CNG has the highest rates of potentially hazardous carbonyl emissions. These conclusions have attracted criticism from many, including environmentalists.

The study also made a case for regulating CNG and other fuels for methane emissions. Methane, a greenhouse gas, is a key contributor to climate change. Among the study's finds were that retrofitted CNG car engines emit 30% more methane than original CNG engines. Almost all CNG car engines in India are retrofitted.

CNG or compressed natural gas, has been touted as the greenest of the fossil fuels. There is little doubt that in terms of carbon emissions and well-known pollutants like sulphur dioxide, CNG is more environmentally friendly than oil or coal.

But the CPCB study argues that when it comes to carbonyl emissions, CNG is worse than a "dirty" fuel like Bharat Stage II diesel.

Carbonyls are a class of chemicals that range from harmless acetic acid (vinegar) to suffocating formaldehyde. Some of them have been shown to be linked to cancer after prolonged exposure.

Critics have questioned the study's conclusions on carbonyl emissions.

"There are a lot of scientific discrepancies in the study," said Anumita Roy Chowdhury, associate director, Centre for Science and Environment, an NGO instrumental in getting the government to introduce CNG public transport in Delhi in late 1990s.

Chowdhury, in a letter to the CPCB, asked why certain highly toxic carbonyl compounds, like butadiene, were ignored by the study.

The CPCB said the study represented the first attempt to generate data on carbonyl compounds.

"A comprehensive study on carbonyl compounds can be done," PCB chairperson SP Gautam said.

Another criticism of the study, was that only non-efficient retrofitted CNG vehicles, not done by auto manufacturers, were tested despite company-fitted CNG vehicles being available.

In India, except one company, most car makers sell CNG retrofitted vehicles. A CNG engine is about 20-30% more efficient than a retrofitted CNG kit.

"I can't understand why only one greenhouse gas methane was checked and others like carbon dioxide, whose concentration in emissions is higher, was left out," Roy Chowdhury said.

Emission notes

ABOUT THE AUTHOR
Chetan Chauhan
Chetan Chauhan is the National Affairs Editor looking into all aspects of news and features from across India. A Chevening scholar with over three decades of experience in reporting and news management, Chetan has extensively covered all important aspects of the social sector, political economy, environment and climate change nationally and internationally. He did a journalism course at the Reuters Institute of Journalism in Oxford and Digital Media training at Nanyang Technological University in Singapore. He started as a reporter with The Statesman in 1996 and joined the Hindustan Times in 2000 in the metro bureau covering environment, crime and Delhi politics. He covered hot local news, from the Jessica Lal murder case to the rebellion of Delhi Congress MLAs against then Chief Minister Sheila Dikshit, to the replacement of toxic vehicle fuel with cleaner compressed natural gas (CNG) in the national capital. Some of his stories on air pollution became part of the Supreme Court’s landmark MC Mehta versus Government of India case in the National Capital Region (NCR), forcing the government to take corrective measures. As part of the national political bureau since 2004, he covered important central sectors such as environment, education, social justice, labour, rural development, water resources, renewable energy, agriculture, broadcasting and the Planning Commission for more than a decade producing several exclusive and investigative breaking stories. His specialisation is the environment, having covered at least a dozen United Nations global conferences on climate change, biodiversity and wildlife including climate summits in Paris, Copenhagen and Bali. He also covered India’s two five-year plans ---11th and 12th and reported on drafting and execution of right based laws such as Right to Education, Right to Information and rural job guarantee law, MG-NREGA, now being introduced in new format as VG-RAM-G Act. He has in-depth knowledge of social sector issues. He was one of the first to report on tigers vanishing from Sariska and Panna wildlife reserves in 2004 and 2008, respectively, leading to the setting up of the National Tiger Conservation Authority (NTCA) and the introduction of stringent penal provisions for poaching. He has written extensively on the rising human-animal conflict in India and the degradation of India’s biodiversity hotspots because of mining and other activities. Since 2004, Chetan has covered Parliament comprehensively and participated in training on the nuanced coverage of Parliament proceedings. He has travelled extensively across India to cover national and provincial elections since 1998, especially in the Hindi heartland states, considered India’s road to power. He writes a regular column for Hindustan Times, Ecostani, on important national politics, economy, Himalayan ecology and environmental issues. His other responsibilities include providing inputs for edits and edit page articles for the publication, apart from managing news flow from across India.Read More

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