Shanghai Daily news

Workers yesterday install an 85-ton shield for the construction of the Xizang Road S. Tunnel across Huangpu River, which is being built to help traffic flow for the Shanghai World Expo in 2010.

Shanghai is setting the benchmark for a clean and green city - with a little help from the sun.

Solar energy will be used to provide the illumination for a new tunnel across the Huangpu River, which will be in operation by 2010.

The tunnel light system will be the first of its kind on China's mainland, project engineers said yesterday.

The Xizang Road S. Tunnel is being built to streamline traffic flow for the World Expo in 2010.

Located in the center of the 5.28-square-kilometer Expo site between the Nanpu and Lupu bridges, the tunnel will span 2.67 kilometers and link Xizang Road S. in Puxi with Pudong Road S. on the river's eastern bank.

"The purpose of using solar energy is energy conservation ... and to advocate energy conservation for the world fair," said Pan Guoqing, an engineer of Shanghai No.2 Municipal Engineering Company, the project contractor.

In a preliminary plan, about 250 square meters of solar-reception membranes, or panels, will be paved atop the two tunnel entrances to absorb the sun's energy and transfer it into power for interior illumination.

Major construction on the tunnel will start in the middle of this year, but full details of the solar project haven't been decided, engineers said. The overall cost of the tunnel project is not known.

However, it is estimated that the single solar facility for the tunnel, which may generate power capacity of 40 kilowatts per hour, will cost four million yuan (US$500,000), the engineers said.

Solar power may account for less than 10 percent of the tunnel's power consumption, with the rest coming from conventional electricity supplies, they added.

Under normal conditions, the solar power facility will have a shelf life of about 25 years.

The Shanghai government is covering all operation expenses for the tunnel, including the solar power section.

The tunnel will incorporate two tubes and four lanes.

City officials expect 70,000 people to cross the Huangpu River every hour during the six months of World Expo.

Li Jianjun, a professor of energy technology of the Shanghai Academy of Sciences, said: "Though solar power accounts for a small amount of power in the tunnel, it sets a good example to promote clean energy."

He said Shanghai has an advantageous geographical location with regard to its average hours of sunlight.

He also said solar power has been extensively used in Western countries in urban construction. During the 2000 Sydney Olympics, for example, solar energy was extensively used for stadium and residential facilities.