Secretary for the Environment Edward Yau Tang-wah watches as cookware powered by bicycles, solar-panelled golf carts and a car made of flattened aluminium cans vie for top prizes at a green invention competition at the Science and Technology Parks yesterday. The third annual Hong Kong Technology and Renewable Energy Events buzzed with creative vigour as more than 420 teams of students, businessmen, professionals and civil servants showcased ideas aimed at fuelling daily appliances with solar, wind and kinetic power. 'The lack of space in Hong Kong makes it difficult for us to develop renewable energy,' Mr Yau said. More than 1,000 schoolchildren took part in the event, which also featured designs aimed at improving rural life, such as a bicycle-powered thermal heater and a self-lighting scooter for navigating through farmland at night.