The capital of Northeast China's Heilongjiang Province has achieved preliminary success in promoting the use of environment-friendly fuels in its vehicles, China Daily reported Thursday.

The number of vehicles powered by liquefied petroleum gas (LPG) has increased sharply to 5,000 in the past few years.

Nearly 30,000 tons of petrol and 30 million yuan (US$3.6 million) can be saved annually from the move, according to the Harbin Municipal Development and Reform Commission.

LPG is a by-product from the refining of crude oil. Bottled LPG had served as the main cooking fuel of urban residents in Harbin since the early 1990s.

But urban residents began to turn to piped gas in 1995 when the Harbin-Yi'an gas line was established to supply coal gas to the city.

Apart from a small number of suburban residents, bottled LPG is a thing of the past for most people in Harbin.

The declining use of LPG has prompted the city's officials to devise new ways to make better use of it.

"Harbin is among the first batch of cities to consider using LPG to power vehicles," said Ci Yuqin, an official from the Municipal Double-Fuel Vehicle Promotion Office.

The city was included as one of the 16 key cities to promote gas-powered vehicles in the country.

Thirty-four per cent of the 5,000 vehicles are buses and more than 60 per cent are taxis.

"Buses and taxis are the main contributors to Harbin's air pollution. We will not curtail pollution unless more environment-friendly fuels are used," said Ci.

There are now 20 LPG stations in the city, with each district having two or three stations.

Harbin Refinery of the China National Petroleum Corp has the capacity to produce 50,000 tons of LPG annually, making the city's further development of vehicle-use LPG possible.

LPG has a price advantage over petrol, the price of which rose recently.

"Promoting the use of LPG is not only good for the environment but also could ease the pressure on petrol supplies," said Tian Ru, from the municipal Development and Reform Commission.

The 5,000 vehicles are able to run on LPG or petrol. Ci said this means "their emissions are still very high."

Harbin has now introduced two LPG-only engines from China FAW Group Corporation for experimental purposes and plans to buy more if they prove to be successful.

It also planned to make the city's 100 diesel-powered buses, which may fall into disrepair in the near future, able to run on LPG.

"Although the cost of LPG-only motors is higher, it is worthwhile to use them in the long run," said Ci.

Many metropolises in China have realized the importance of clean fuel.

Guangzhou has vowed to change all of its buses to LPG by the end of next year.

Ci predicted liquefied natural gas (LNG) might be the solution to both the energy shortage and pollution.