“We want to collect more kitchen waste to promote the development of the technique,” he said. “In a densely populated city like Shanghai, a huge amount of kitchen waste can be better utilised to pursue a greener local economy.”

Separated kitchen leftovers, also known as wet waste in mainland China, can be turned into resources such as compost or oil and methane gas for industrial use.

Shi told the Post that Shenergy, which supplies more than 10 billion cubic metres of natural gas, or 95 per cent of the city’s total, has a gargantuan natural gas infrastructure network to support the development of the new technique.

“With centralised efforts to tackle the wet waste [in Shanghai], storage and logistics costs are manageable and make the technique commercially viable,” he added. “We have confidence in producing green methanol at a cost lower than international standards.”

In March, Hong Kong and China Gas (Towngas), one of the largest natural gas distributors in mainland China, signed a strategic cooperation framework with Shenergy to jointly promote the development of green energy businesses, which includes exploring markets for green methanol and hydrogen.

Shenenergy, owned by the Shanghai municipal government, produces electricity that accounts for a third of the city’s total.

Shanghai, the mainland’s commercial and financial hub, spearheaded moves to scientifically dispose of food waste in 2011, with the aim of making better use of resources and reducing pollution.

Traditional disposal methods such as burying or incineration are less effective when wet waste is included. The former causes secondary pollution from leachate – contaminated liquid – and methane in landfills, while burning rubbish creates toxins.

In July 2019, Shanghai took the lead among Chinese cities in launching a compulsory waste sorting system, under which household waste must be sorted into four categories: wet rubbish (leftover food), dry rubbish, recyclable waste and hazardous waste.

Shanghai’s efforts to improve the way it tackles waste came amid President Xi Jinping’s repeated calls for the country to manage its waste more effectively.

In March 2017, Beijing set out plans for a standardised system and regulations for rubbish sorting by 2020, with a target for 46 major cities, including Shanghai, to recycle 35 per cent of their waste by then.

The third phase of a waste-processing plant under construction at Chengtou’s site in Laogang, on the city’s east coast, will be able to handle 2,000 tonnes of food waste per day.

Shanghai generates about 7,000 tonnes of wet waste each day.