Fuel for Thought in China

Since late last year, many of the country's largest cities have often been blanketed by nasty smog. The poor air quality has spurred debate over the most effective ways to cut pollution.

One of the bigger questions is how to better control emissions from the more than 240 million vehicles on China's roads.

Auto emissions in Beijing, Shanghai and the Pearl River Delta region contribute up to 34% of PM2.5 pollution, research by Michael Walsh, former head of the International Council on Clean Transportation showed. (PM2.5 refers to fine particulate matter of 2.5 microns in diameter or less that is easily absorbed into the lungs and can cause breathing problems, among other health issues.)

Along with existing policies to control car use, there have been public calls for the government to improve fuel quality by reducing sulfur and manganese content in gas and diesel.

Different fuel standards are applied in different regions of the country. In May, the capital adopted on the strictest, the Beijing V standard, which mirrors Europe's Euro V. The standard caps sulfur content at less than 10 parts per million (ppm), whereas the National IV regime in place in cities like Shanghai has a 50 ppm limit. Some regions using even lower standards.

The State Council, China's cabinet, plans to apply the Beijing standard to the entire nation, calling it National V. A special committee has been formed to work on the draft of the new standard.

In February, the cabinet said that National IV standard would be adopted nationwide by 2014, and National V would come into effect in 2017.

Obstinate octane

However, no consensus has been reached on the National V standard, and refiners, auto manufacturers and government agencies are debating key issues.

Disagreements have arisen on the extent of cuts to sulfur and manganese levels, and how to share the inevitable cost increases.

A committee under the General Administration of Quality Supervision, Inspection and Quarantine held a meeting in December with representatives from refining companies, auto manufacturers and environmental protection organizations to discuss a draft of the National V standard.

The hope was to finalize the standard this year, but debates over abandoning a manganese additive used at refineries and lowering octane ratings were intense.

Pollution from vehicles mainly comes from sulfur and manganese in fuel. Reducing sulfur in crude oil requires a hydrogenation process, while removing manganese would mean stopping the use of MMT, which is used as a lead-free, octane-enhancing additive in gas.

Reducing the levels of both would sacrifice octane content in fuel and lead to lower octane ratings.