The South East New Territory's gas utilization facility, situated in Tseung Kwan O, Hong Kong Special Administrative Region, China. /CGTN
Solid waste in China's Hong Kong Special Administrative Region (HKSAR) goes to three active landfills.
The South East New Territories (SENT) Landfill is one such landfill that takes construction waste, a category of solid waste. As landfill waste decomposes, greenhouse gases like carbon dioxide and methane are released into the atmosphere.
At SENT, such gases are collected and converted into synthetic natural gas. The waste-to-energy initiative, located in the Tseung Kwan O district, was launched in 2017 by Towngas, the city's sole gas supplier.
After synthetic gas is produced, it gets transported through a 12-kilometer underground pipeline to the offtake station in Tseng Lan Shue, where it is integrated into the gas supply network.
The facility can produce as much as 8,000 cubic meters of synthetic natural gas per hour, which is equivalent to the size of about 4 million bricks.
Towngas also utilizes gas from two other landfills, one that's still actively receiving waste, while the other isn't. SENT is its latest gas utilization facility.
"This is quite a project that can save the emissions of carbon dioxide," said Isaac Yeung, head of corporate affairs at Towngas. "This plant (SENT) already reduced carbon dioxide emissions by 12,243 tonnes in 2020 – equivalent to 552,000 tree seedlings."
According to Towngas, synthetic natural gas from landfills contributes to about 1 percent of its fuel mix for gas production in the HKSAR. The rest is made up of natural gas (61 percent) and Naphtha (38 percent), a type of fossil fuel.
The company has also been operating a hydro-treated vegetable oil (HVO) initiative in east China's Jiangsu Province, where inedible bio-grease feedstock, like used cooking oil, is converted into advanced biofuel, which can cut nearly 90 percent of greenhouse gas emissions compared to traditional fossil diesel.
The plant produced around 88,000 tonnes of HVO last year for Europe, which saved about 259,000 tonnes of carbon emissions, in Zhangjiagang City, Jiangsu Province, east China. /CGTN
Having conducted tests with local vehicles, Towngas hopes to achieve that in the HKSAR as well.
Latest government data from last year showed the HKSAR's greenhouse gas emissions in 2018 hit 40.6 million tonnes, a 0.5-percent rise from 2017. Of that amount, waste management contributed to 7.4 percent, while electricity was a major contributor at 65.6 percent.
However, Yeung estimated that Towngas, as a whole, including consumption from its customers, contributed to less than 1 percent of that, a success he attributed to adopting a low-carbon footprint initiative early on.
He added that Towngas is confident in achieving its target of a 30-percent reduction in carbon intensity of gas production, compared to 2005, within the next two years.
This comes as the government has set a goal for the HKSAR to achieve carbon neutrality by 2050.
Authorities recently released an updated blueprint on waste, which aims to reduce waste and cut out all landfills by 2035. It is timely, as the current landfills, which were expected to have reached their full capacity in 2020, have been expanded but will only last till 2030.
The South East New Territories Landfill, where waste, deposited during the day, gets buried under soil at night. /CGTN
Per official data, municipal solid waste disposed at landfills have increased from 3.3 million tonnes to 4.04 million tonnes from 2010 to 2019. The per capita disposal rate also increased to 1.47 kilograms per day for the same period.
The government has already initiated another option – a $4-billion incinerator that's expected to be completed by around 2025 and can reduce about 440,000 tonnes of greenhouse gas emissions per year. But, it may not be enough.
Carlos Lo, director of the Center for Business Sustainability at the Chinese University of Hong Kong Business School, said it might be hard for the HKSAR to solve its waste problem on its own, because land is limited and expensive, and with industrial production not well developed, it's difficult to have a full recycling industry chain.
"We should consider the waste and energy issues from a regional perspective, so that we can have a regional solution," said Lo, who added that there are already quite a few incinerators in the Greater Bay Area. "Instead of building a new one, we may consider to just use the incineration there – help to burn our waste, instead of us to build one, because they already exist."
Lo also said, to achieve a greener economy, a bigger responsibility lies with producers more than consumers. The expert explained that it's because consumers are always in a passive position of choosing given options, whereas producers have a stronger capacity, with research and money, to improve their products to be greener.