Expo 2010 Shanghai will be able to offset 60 to 70 percent of its carbon emissions due to the adoption of various green technologies and initiatives, organizers said over the weekend.

As efforts to try to offset the carbon footprint of the largest World Expo in history will continue after its six-month duration, the event can expect to become carbon neutral in four to five years, said Huang Jianzhi, deputy director of the Bureau of Shanghai World Expo Coordination.

Efforts include energy conservation and industrial upgrading within the city, promotion of green technologies showcased at the Expo, voluntary reduction of carbon emissions by both individuals and enterprises, and the planting of trees, said Sun Jian, deputy director of the Shanghai Environmental Protection Bureau.

Authorities said earlier that the Expo, which is expecting some 70 million visitors from China and abroad, is expected to produce nine million tons of carbon emissions, with more than 80 percent to blame on transportation.

To reduce emissions from such a large number of visitors, Shanghai and the US Environmental Defense Fund (EDF) have jointly launched a green-commuting project to encourage people to choose greener means of transportation, such as walking or public transportation, to get to the Expo Garden.

Organizers also worked with the Green Commuting Fund (GCF) under the China Association for NGO Cooperation to introduce the world's first low-carbon transportation card in Shanghai in April.

The card, intended to promote the use of public transportation, costs 40 yuan ($5.90), with half the amount being allocated to green projects. Card buyers can also check which projects their money has gone to by typing in the card number at the official website, cleanair.net.cn.

According to Zhang Jianyu, an environmental expert at GCF, nearly 20,000 cards have been sold in less than a month when they were only targeted at enterprises in Shanghai. They will be sold to the general public from the end of this month through four different channels - the We Are the World Pavilion at the Expo Garden, the Shanghai Dazhong Transport Company, the budget hotel operator, Home Inn, and the online shop yihaodian.com.

"It is vitally important for the general public to participate in the carbon reduction initiatives if we want to achieve a low-carbon Expo. So far, we have been greatly motivated by the strong interest and passion among the public," said Zhang.

A Voluntary Emission Reduction (VER) action was launched in April at the Shanghai Environment and Energy Exchange to offset carbon emissions of the Expo. Individuals and enterprises can purchase and donate VER products for any Expo pavilion to help offset emissions.

To set an example in hosting a green Expo, organizers have gone to great lengths to bring in world-class green technologies.

The country's largest solar power generator system, with a total capacity of 4.6 megawatts, has been installed in the Expo Garden, while energy-saving LED lights have been installed throughout the venue.

Clean-energy-powered automobiles are used for the internal transportation system.