No 1: Car sharing

Beijing and Guangzhou have introduced a balloting system for car licenses to prevent rapid increase in car population.

But the move has been criticized by some experts as "not that wise" to ease traffic congestion. Instead, they suggest offering more efficient public transportation and borrowing innovative means from other countries.

At the Guangzhou International Award for Urban Innovation recently, Michael Glotz-Richter, a senior project manager of Sustainable Mobility for the City of Bremen, Germany, presented the city's car-sharing project.

Under the creative system introduced since 2002, car-sharing members are issued a PIN and they can book a vehicle at any time of the day by phone, smartphone app or through the Internet. It costs 2 euros ($2.6) per hour and 20 euros a day.

"It costs me around 70 percent less each month by joining the project compared to having my own car because it makes me take public transport or ride a bicycle more often if the place I will go is not that far away," says Glotz-Richter. "And I do not have to pay for car maintenance."

Fuel and insurance costs are included in the rates.

Users can collect a car and return it to any of the 48 stations throughout the city where there are exclusively reserved parking spots. The city plans to build another 40 stations by the end of 2013, according to Glotz-Richter.

Glotz-Richter says the project is so effective that among the current 8,000 users, 70 percent who owned a car in their household in the past have given up using their private cars.

No 2: Rainfall collection

Australia's Melbourne showcased a project called the Darling Street Stormwater Harvesting.

The project collects rainfall into a tank built underground and irrigates neighboring parks and trees along the streets with the treated stored water.

The project provides an alternative water source for irrigation, according to Ralf Pfleiderer, a water-sensitive urban design coordinator.

"Melbourne rains a lot in winter but is very dry in summer so the project can help store water in winter and offset the water shortage in summer," he says.

From 2000 to 2010, the city saw much less rainfall than usual and a lot of trees suffered from the drought, prompting the city to initiate the project in 2009 and began operation in 2011.

The cost of reusing the rainwater is up to 75 percent less than using tap water and the project also brings other benefits such as reduced demand on the city's water storage for irrigation, improved water supply to parks and gardens, and reduced flow of run-off into waterways, according to Pfleiderer.

It is also a good means to mitigate floods, he says. "We can empty the tank as quickly as possible before heavy rains come."

The capacity of the current tank is 450 cubic meters and the city plans to build another tank with a capacity of 5,000 cubic meters under a park and a third one with the capacity of 2,500 cubic meters under a building.

"Similar rainfall storage projects could be introduced to cities such as Beijing, which has water shortage," says Pfleiderer.

As a city with a population of more than 20 million, Beijing is using every means it could to offset water shortage. They include excessive exploitation of groundwater and water transfer from neighboring provinces.

No 3: Garbage reduction

Vancouver, a city in Canada, launched the Greenest City Initiative in 2009 with the aim of becoming the greenest city in the world by 2020. Garbage sorting is part of the program.

"The holes we dig for burying garbage are getting full, so a big debate in Vancouver now is whether to burn or continue to bury garbage. We take a very innovative approach that is to encourage citizens to make zero waste, which means you cannot waste any more," says Kerry Jang, deputy mayor of Vancouver.

Elaborating on the initiative, Jang says the government encourages residents to separate garbage into three types namely food, plastics and paper.

In his city, waste paper and plastics are recycled and food waste is used as fertilizer.

"Residents are against garbage burning because it will pollute the air so we must burn very little and we are adopting technologies to efficiently reduce toxins during the burning process," he says. "But our ultimate goal is garbage reduction."

- Chen Xin