How A*Star uses heat to stay cool, save electricity

How A*Star uses heat to stay cool, save electricity
The system taps waste heat to produce hot water, which is then channelled to an absorption chiller and used in a thermochemical reaction to produce cool water.

Heat is often released into the environment as an untapped by-product during industrial processes, such as the generation of electricity.

Scientists here, however, have found a way to harness such energy, called waste heat, to cool buildings. The technology, known as the Combined Heat and Power (CHP) system, will reduce the amount of waste heat released into the atmosphere.

It is also expected to help building owners cut their electricity bills, as less electricity is needed from the grid to power air-conditioners.

By making use of waste heat, the system is also expected to be at least 16 per cent more energy efficient, according to Singapore's Agency for Science, Technology and Research (A*Star).

In a commercial building, air-conditioning comprises up to half the amount of total energy used.

Unveiled yesterday, the technology was jointly developed by A*Star's Experimental Power Grid Centre and Japanese tech giant Hitachi, after three years of research.

The CHP system works by tapping 440 deg C waste heat from a diesel generator to produce hot water of about 90 deg C. Channelled to an absorption chiller, the hot water is used in a thermochemical reaction to produce cool water.

The cooled water, at about 7 deg C, then circulates throughout the building and helps lower room temperatures, making it comfortable for occupants.

The CHP system is still in a pilot stage and is now being test-bedded at the A*Star facility on Jurong Island.

The project received partial funding of $900,000 from the A*Star-Ministry of National Development Green Building Joint Grant Call.

A*Star's Associate Professor Ashwin Khambadkone noted that although a diesel generator - considered a source of pollution - is used to generate waste heat in the pilot, there is still a "nett reduction in carbon footprint" compared to conventional air-conditioning systems.

This was derived based on initial emission calculations conducted by the scientists, he said.

More tests will be conducted to find out more about the project's energy efficiency before it is rolled out commercially.

Mr Kunizo Sakai, president and chief executive of Hitachi's Infrastructure Systems Company, said the CHP system will be commercialised next year, based on results of the pilot.

Commenting on the CHP system, he said: "(This will) provide solutions of increasing energy-efficiency and reduce carbon dioxide emissions with lower cost for buildings and factories, primarily in Asia."

This article was first published on Aug 27, 2014.
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