Waste oil conversion prevents smooth ride for biodiesel plans

PUBLISHED : Monday, 19 September, 2011, 12:00am
UPDATED : Monday, 19 September, 2011, 12:00am


Waste cooking oil, or 'gutter oil', is commonly used in Hong Kong restaurants and fast food chains. And there is a huge demand for it.

It is often collected from restaurants, reprocessed again into cooking oil and resold on the mainland and in Hong Kong.

'[I estimate] more than 80 per cent of Hong Kong's used cooking oil taken by collectors is sold to the mainland for reprocessing into cooking oil,' said Teddy Choi Wai-hung, executive director of Champway Technology, which operates a biodiesel plant in Tuen Mun's Eco Park.

He claims the export of such oil from Hong Kong is not illegal and there is little visual difference between recycled and fresh oil, so the black market is thriving, as reported in a South China Morning Post article on July 18.

Waste cooking oil costs about HK$4,500 per tonne, but can be resold at prices similar to fresh cooking oil, from HK$10,000 to HK$20,000 per tonne, Choi says.

A TV news report said one in 10 of China's restaurants use gutter oil. Illegally recycled oil may contain dangerous substances, such as aflaxtoxin, which can cause cancer, the China Daily newspaper said.

There have also been reports of acrolein, which has harmed animals in experiments, being found in repeatedly heated cooking oil. Its toxic effects on humans have yet to be determined. Yet food safety is of paramount concern to consumers; the government must clamp down on illegal trading of used cooking oil.

Choi said the government should run a licensing system for collectors of used cooking oil, and restaurants selling oil to such authorised dealers should have their waste-water treatment surcharge reduced.

Used cooking oil can be converted to biodiesel, which has similar chemical properties to diesel, according to Champway. Biodiesel is a green and renewable energy source which can be a substitute for diesel-run lorries and buses. It is more eco-friendly than diesel, too. Biodiesel-fuelled cars produce 70-75 per cent less carbon dioxide gas.

Using waste oil to make biodiesel would help keep the city clean, and stop gutter oil being recycled for human consumption.