Like many places in the world, Hong Kong does not have strong wind speeds, so wind turbines have not been widely installed there. But now engineers at the University of Hong Kong and a private renewable energy company have developed a new micro wind turbine that can generate electricity even if wind speeds are as low as two meters per second. Lucien Gambarota, the main inventor of the technology, says the small turbines are ideal for crowded cities such as Hong Kong because they can be installed on rooftops and balconies. Their design is simple: plastic gearwheels, each about 25 centimeters in diameter, are linked to one another and turn, moved by the wind. Groups of gearwheels can be arranged in an array of shapes and sizes, ranging from about two up to thousands of square meters, depending on how much energy is needed and how much space is available. The energy generated by the turbines is stored in a battery, which then powers electrical appliances. The wind turbine is easy to install and comparatively cheap. At the moment, a set of 20 gearwheels costs about $25. Gambarota says the price will go down once the turbines are being mass-produced, making them a good option for consumers who want to cut down on their energy costs. The technology can also help power bigger buildings. Administrators at Hong Kong's Sea School, a secondary school offering basic seaman training, will install the new micro wind-turbines on its roof in April.