BEIJING, Nov. 15 (Xinhua) -- A total of 1,105 small coal-fired boilers had been converted to natural gas by Thursday, when Beijing started its annual heating season, marking the completion of a nine-year campaign in China's capital to have all 14mw boilers use clean energy.

"Starting from 1998, we have earmarked 2.5 billion yuan (about 328.95 million U.S. dollars) and upgraded about 16,000 14mw boilers," said Du Shaozhong, deputy head of the Beijing Municipal Bureau of Environmental Protection.

Also since 1998, some 44,000 hotel boilers and restaurant stoves have shifted to clean energy, which is defined as natural gas or electricity.

Together, these projects could save 6 million tons of coal, reducing annual emissions of sulphur dioxide and soot by 48,000 and 26,000 tons, respectively.

According to Du, the 14mw boilers are mostly in downtown Beijing, and their emissions affected the city's air quality and residents' health.

In 1998, Beijing had 106 days, or 79 percent of the days during the four-month heating season, where airborne sulphur dioxide exceeded the national standard of 0.15 milligrams per cubic meter.In 2006, the number of days dropped to 27.

After 1998, policies were drafted to promote clean energy. For example, work units utilizing geothermal heat were eligible for a subsidy of 35 yuan to 50 yuan (4.6 to 6.6 U.S. dollars) per square meter.

A project was launched in 2001 to replace household stoves in bungalows with electric radiators. By the end of 2006, around 15,000 out of 21,000 inner-city households had bid farewell to their smoky stoves.

As a result of such efforts, the proportion of clean energy in Beijing's energy consumption rose from 45.4 percent in 2000 to 59.9 percent in 2006.

Beijing's air quality on Thursday, the first day of the heating season, was recorded as degree one -- the best. Seen from the top of the 221-meter Central TV Tower, most large chimneys in Beijing were puffing out white vapor, rather than black smoke.

But Du noticed that smoke from two chimneys in the west was gray. "We need an inspection to ensure the use of clean energy," he said.

Up to Thursday, Beijing reported 221 days in 2007 where the air quality was degree one or two, accounting for 69.3 percent of the total. The goal of "Blue Sky" (to have 67 percent of days where air quality is at degree one or two) seems within reach.

Yet Du said it was too early to be optimistic. "China is the world's No. 1 coal consumer, followed by the United States," he said. "In China, coal makes up 75 percent of total energy consumption, compared with 20 percent in the United States. The figure is down to 40.1 per cent in Beijing."

In Beijing, coal is mainly used in industrial facilities and large heating boilers.

Beijing faces tremendous pressure to improve its air quality ahead of the 2008 Olympic Games. Numerous measures have been undertaken, including boosting public transportation with a new North-South subway line and slashing public transport fares. The city aims to open two additional new subway lines before the Olympics.

Also, the leading steel manufacturer Shougang Group, a heavy polluter, began relocating its facilities to north China's Hebei Province in 2005. All current Beijing-based steel operations are to move to Hebei by 2010, with only the headquarters, research and development facilities, sales departments and the logistics center remaining in the capital.