New plant mixes food waste, used water to produce energy

PUB's biogas facility is test-bed to see if process can be done elsewhere

SINGAPORE is exploring a new way to turn unused calories into energy, and may one day be able to convert the thousands of tonnes of food dumped here each day into valuable energy sources.

When organic material in food waste and sludge from used water react with bacteria, this produces biogas for electricity generation. And a new 2,000 sq m demonstration plant at the Ulu Pandan Water Reclamation Plant will be the first in Singapore to make use of this reaction when it begins operations in September.

The co-digestion facility was launched by national water agency PUB and technology company Anaergia yesterday, the second day of the Singapore International Water Week Technology and Innovation Summit.

The PUB demonstration plant can treat up to 40 tonnes of combined food waste and used water sludge. A drop in the ocean compared with the amount of such waste produced here, but the facility will be a test-bed to see if similar processes can be rolled out elsewhere.

The country's four water reclamation plants, including the one in Ulu Pandan, are already producing biogas from sludge, which supplies up to one quarter of each plant's electricity needs. By combining used water sludge with food waste, the amount of biogas produced can be doubled due to the higher calorific value in food waste, PUB said.

Said Anaergia chairman and chief executive Andrew Benedek: "The idea is to take waste from a waste water plant and turn that into energy, and extend it further by adding food waste, and doing so efficiently, so you can turn a waste water plant into a sustainable plant, energy-wise."

The plant will run for a year and a half before the authorities decide if the technology can be used at the future Tuas Water Reclamation Plant and the National Environment Agency's (NEA) Integrated Waste Management Facility, which are located together, when the facility is ready in 2024.

PUB's chief technology officer, Mr Harry Seah, noted that if the effort was successful, Anaergia's patented technology could supply at least 50 per cent of the future plant's electricity demand.

The hope is that the plant could eventually achieve energy self-sufficiency, using only as much energy as the treatment process itself generates.

The technology harnesses anaerobic digestion, a biological process that breaks down organic materials without oxygen, to produce biogas.

Food accounts for one-tenth of all waste produced here. About 788,600 tonnes of food was thrown away last year, slightly less than the 796,000 tonnes in 2013, but still much more than the 606,100 tonnes in 2009. Only 13 per cent of last year's food waste was recycled.

Minister for the Environment and Water Resources Vivian Balakrishnan noted at the summit opening on Tuesday that as Singapore lacks a significant agricultural sector and as a lot of energy is wasted in food incineration, the best way forward was to recover the energy from food and use it to recycle used water.

"This project is significant, because it... potentially increases the yield of water from our recycling plants."

A version of this article appeared in the print edition of The Straits Times on June 18, 2015, with the headline 'New plant mixes food waste, used water to produce energy'. Subscribe