Rain can be used as an effective tool in the creation of renewable energy, according to researchers in Hong Kong.

A City University of Hong Kong (CityU) research team has developed a generator that uses a field-effect transistor-style structure to produce electricity from rain droplets.

The design connects an aluminium electrode with an indium tin oxide electrode layered with PTFE, a material with a “quasi-permanent” electric charge. When rain hits this surface, it bridges the two electrodes and creates a closed-loop circuit, helping to release any stored charges.

Professor Wang Zuankai, from CityU’s Department of Mechanical Engineering, said: “Our research shows that a drop of 100 micro-litres [1 micro-litre = one-millionth litre] of water released from a height of 15 cm can generate a voltage of over 140V, and the power generated can light up 100 small LED lights.”

The research is a potentially ground-breaking achievement in the science community’s efforts to tackle the energy crisis.

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In its current form, the generator can only produce a small burst of energy. The researchers will now look at how to produce a continuous generation of power over a sustained period – something the team believes is possible.

Professor Wang thinks that, in the future, the technology could be installed onto different surfaces where a liquid contacts with a surface, such as the hull of a boat or even smart umbrellas and water bottles.