7 December 2010

Smart, sustainable cities powered by hydrogen produced on rooftops

Sustainable hydrogen power from our rooftops that is safe, affordable and green.

RESEARCH towards smart, sustainable cities has taken a significant leap forward at NUS Engineering. Picture this: Residents being able to make use of power produced by hydrogen fuel cells, with the hydrogen produced on their rooftops at a fraction of the cost they are paying for electricity. This may be possible in the near future. Explained Dr Ernest Chua Kian Jon, Department of Mechanical Engineering, Principal Investigator for the research project at the Faculty of Engineering: “Rooftops can be equipped with photovoltaic (PV) panels which make use of sunlight to produce enough electricity for electrolyzing water, separating the hydrogen and oxygen. The hydrogen is then stored into fuel cells which in turn generate power for home consumption by residents in the block.” What’s exciting is that Dr Chua and his team are developing a “hybrid” process to “split” water, combining both photocatalysis and

electrolysis and ultimately, making the entire process more cost effective. Obtaining hydrogen from water through electrolysis has been a common method for a long time. The major setback of

a high amount of energy needed for the process has however, remained unresolved.

“Using our hybrid method of combing electrolysis with photocatalysis, we are able to reduce energy consumption for the process by up to 80 per cent, producing the same amount of hydrogen from water,” Dr Chua explained. The secret, says Dr Chua, is the components of suitable photocatalyst, the redox medium of iron (Fe2+ and Fe3+ iron pairs) and the incorporation of solar thermal heat into the photo-reaction. With this “secret recipe’ and the harnessing of both sunlight and solar

The secret is in the combination of chemicals used as photo catalysts.

Dr Ernest Chua Kian Jon was inspired by what he has learnt about photo catalysts to produce hydrogen from water at the Osaka University while on a Hitachi Fellowship.

heat, only a low electrical voltage of about 10V to14V is required for electrolysis to take place. This amount of electricity can be drawn from several small PV panels. Photocatalysis is not a new discovery of course. However, previously, the method is effective when only exposed to UV light. Another significant finding from Dr Chua’s research is that now, any light source (visible or non visible) is sufficient to kick start the process. Dr Chua, who has just returned from a Hitachi Fellowship in August this year, had worked with Japanese researchers on the use of photocatalysts to obtain hydrogen from water. Very much inspired, Dr Chua returned to NUS to work on combining photocatalysis with electrolysis in the production of hydrogen. His team now comprises Dr Ho Ghim Wei, Department of Electrical and Computer Engineering who is able to offer her expertise on electrolysis; and Engineering Science Programme (ESP) students HU Peiguang, Liu Haohui, Goh Tian and Yuan Ye. The ESP team has earlier, emerged one of the finalist teams at the ‘Cleantech Open’ competition 2010, with their concept of producing hydrogen from rooftops of HDB estates. By using renewable resources such as water and sunlight, their method provides an inexpensive and clean way to produce hydrogen that can be used to provide electricity for buildings. “This system can be implemented easily in HDB apartments, converting them into energy-generating buildings. It will also provide extra shielding from sunlight on rooftops, resulting in reducing the cost of air-conditioning for the buildings,” said Dr Chua. “It can also be applied onto vehicles powered by hydrogen. The setback for such cars is the need for them to renew their hydrogen supply constantly. With the adaptation of our method, such cars will be able to enjoy self-renewal of hydrogen without having to stop constantly for refueling,” said Dr Chua. This project is, therefore, key to the significant trimming of carbon footprint for a mega-city in the building and transportation sectors. The team is now working towards developing a prototype of a rooftop system for the entire process of obtaining hydrogen from water which can be used to generate electricity via fuel cells for home consumption by residents.