OREANDA-NEWS. January 27, 2015. Alice Ho Miu Ling Nethersole Hospital in Tai Po plans to use landfill gas to generate electricity in an attempt to go greener.

It is the first hospital to trial the alternative energy supply. It will cost HKD13 million for installation and the system is still being designed. It is expected to be ready for use in July next year.

A generator will be used for a combined heat and power system. While it produces electricity, waste heat at a temperature of 500 degrees Celsius from the generator's exhaust will go to a boiler to produce steam. Waste heat from generator cooling will also be used in a heat exchanger for hot-water supply.

Unlike a conventional generating system, which only converts 40 per cent of the power it creates to electricity, the new cogeneration system uses another 40 per cent of generated power for thermal-energy supply, and releases the remaining 20 per cent as waste energy.

The methane - which will come from the Ta Kwu Ling landfill in the northeastern New Territories - provides a cheaper alternative fuel. Each unit of methane costs about 0.1 cents, in contrast to 0.15 cents per unit of gas.

The hospital expects to spend about HKD 5 million on purchasing methane from Towngas, the only local gas supplier.

"The new system will save the hospital around HKD 2 million annually on fuel, which is 7 per cent of the energy expenditure," said Yuen Pak-leung, senior manager of engineering for the Hospital Authority.

The more efficient use of power would reduce the carbon emitted annually by the hospital by 2,000 tonnes, or 12 per cent.

"Methane has similar ingredients and heating value to natural gas. No exhaust fumes will be emitted from the combustion," Yuen said.

A tiny piece of vacant land next to the waste-collection point will house the new generator, which will also provide electricity for two sets of non-essential air-conditioning chillers. They will be connected to hospital wards, offices and corridors.

The generator has a dual-mode design to handle emergencies. "If there is any problem with the methane, the machine can be switched to electricity mode," Yuen said.

Nethersole Hospital is located close to a 19km pipeline that transports methane from the landfill site to the Towngas production site in Tai Po, which burns the landfill methane to produce gas.

An extension of a 600-metre pipeline will be built at the junction of Ting Kok Road and Chung Nga Road to bring the methane to the hospital.

The price of methane is subject to change during the guaranteed 10-year supply period from Towngas. However, Yuen said methane was expected to remain cheaper than gas despite the potential rise.

The hospital's pilot scheme will be reviewed after it has run for two years.