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Katherine Forestier

THE AVERAGE HONG KONG household uses 800 litres of water a day and as that water tumbles down high-rise drain pipes it builds enormous kinetic energy - a fact that charged  a group of students in Form Three at St Paul's Co-Educational College to come up with a bright idea.

They recognised the waste's potential by devising a watermill-like turbine to be fitted near the bottom of pipes in order to convert the rush of used tap water into electricity.

Looking rather like a child's giant marble run, water makes the wheel spin with the rotational force brought to the dynamo and creates electricity - 4.5 volts when water falls from a first floor and using a 4 ohm resistor - according to the students' experiments. They said that over six hours it could create enough energy to power one standard air conditioner.

The device, the students added, cost just $200 and could reap that back in energy savings in just 20 days.

Before switching to the drain idea, their first plan had been to see how energy could be captured from tickets rushing through MTR ticketing machines.

'We started thinking from our daily activities,' said Rosy Yang Yung-yung, 14, of their innovation. Now they are even thinking of patenting the invention.

Parco Lo Ka-shun, 15, said they weren't able to patent their device until they were 18 but were hoping to persuade the school to do it for them. 'People said it was innovative and applicable so we think it's worth patenting,' he said.

Although the current version is just a rough model made out of piping and plastic, Rosy said an improved version made out of aluminium could be commercially viable. 'It could easily be installed in people's homes.'

Parco explained that as tap water rushed down the pipe the electricity generated would be stored in a battery for later use.

Albert Wong Hogan, 15, worked out that it could generate enough electricity to save an average housing block nearly $4,000 a year.

'A building with 30 floors and about eight families to a floor would save $3,680 a year,' he said.

The students' invention was the final idea presented last Saturday to the Student Science Conference hosted by their school and including students from 10  other schools in the mainland, Taiwan, Singapore and Australia. The theme of the five-day event, co-organised by the University of Hong Kong and based at the Kadoorie Agricultural Research Centre on the slopes of Kwun Yam Sham in the New Territories, was conservation and sustainable development.

The projects were students' own contributions to meeting the many  challenges facing the planet, from recycling initiatives in schools to how Australia could better recycle its scarce water resources.

A team from the Anglo-Chinese School in Singapore shared their bright idea for re-using the tonnes of crab shell discarded by restaurants. When mixed with mud it was found to be an effective breeding ground for a purple anaerobic bacteria that removes lead from water.

The students of the Convent of the Holy Infant Jesus, Singapore, meanwhile, addressed waste management - the city state has limited landfill space that will run out by 2045. And nor could it keep building incinerators. The answer, they suggested, lay  with the community reducing the amount of waste it created.

However, one student in the audience noted the dilemma that poses to industrial economies. If demand were reduced, and hence output, there would be a negative knock-on effect for the economy.

Students from Nankai High School in Tianjin, who spoke in English as fluently as their peers in Singapore, had better news. Despite high levels of faecal coliforms and e-coli in the Haihe River, the city's tap water had none and met national standards.

Professor Allan Cheung Shi-chung, associate dean of HKU's Faculty of Science, praised students for the high standard of scientific research and knowledge they displayed, despite their young ages. 'Many topics already exceed secondary school level,' he said. 'Many would have been our students' term projects.'

He had advice on how they could improve their work. They should read more literature in order to ensure their topic was really original. 'There is no second place for any scientific study. If you are not the first there is no value,' he told them. And in creating their presentations they should not include so much written detail. 'We are here to listen to you, not to read,' he said.

In addition to presenting their research findings, students got to do fieldwork, planting trees and making bird boxes at the Kadoorie centre and visiting the Swire Institute of Marine Science, a sewage treatment plant and Castle Peak Power Station.

St Paul's principal Dr Anissa Chan Wong Lai-kuen said the aim of the conference was to enable students to understand the basic principles of environmental science and how science, technology and research could support it.

'This could not be a more timely or important topic. We can no longer ignore the signals from the planet,' she said.

The conference was also part of the college's aim to broaden students' perspectives through exchanges with schools in other countries. 'I hope in future years we can host more events like this that involve different countries and different fields,' Dr Chan said.

Professor Kwok Sun, HKU's new dean of science, said the university had got involved because it wanted to promote greater integration with secondary schools and philosophically it liked the international exchange of the Student Science Conference.

He fuelled students up at the opening of the event. 'For us to pretend we can dump year after year billions of tonnes of greenhouse gasses without consequences is to bury our heads in the sands,' he told them. While living in Canada for 20 years he had seen the affect first hand, in the retreat of glaciers, he added.

The faculty plans to develop environmental science as an interdisciplinary area. Environmental issues embraced everything from biological sciences, chemical processes and geology to sociology and economics. 'The solutions for the environment are very much economic problems: the price you need to pay in terms of economic development. It's obviously not a pure scientific problem,' Professor Kwok said.

It sat well with the broader approach for both four-year degree programmes and the liberal studies element of the new senior secondary curriculum.

The students gained more than greater environmental knowledge. 'It was the friendships fostered,' said Chong Yong, of the Anglo-Chinese School. 'We have made a lot of international ties. I can imagine more co-operation between schools.'

Rosie Yang echoed this. 'I believe science is something that can cross regional borders and bring people from all over the world together,' she said.

Wang Shasha, 17, of Tianjin's Nankai High School, said: 'Our friendship is based on saving the environment, sharing the same goal. That should last for life.

'It's one world. We must make efforts as a whole. The environment is not owned by us: by China or Australia.'

During the week these 75 students did much to display their green awareness.

However, St Paul's showed how far schools have to go before creating genuinely eco-friendly environments. As delegates presented their research in its cavernous hall, no one was measuring the vast amount of energy being wasted as air conditioners belted out cold air through wide open windows and doors.



Bright ideas in the pipeline