In Hong Kong, rubbish is deposited in landfill sites, which give off landfill gas as the waste matter and other organic components decompose. This gas, made up of methane, carbon dioxide and small amounts of non-methane hydrocarbons, in turn needs to be flared off both polluting the environment and contributing to global warming. To minimise the wastage of this renewable energy, Towngas commenced the harnessing of landfill gas with uiltisation projects at the landfill site at Shuen Wan in 1999, followed by the very much larger Northeast New Territories site in 2007 and Tseung Kwan O South East New Territories site in 2017.
Shuen Wan Landfill Project
We were the first organisation in Hong Kong to utilise landfill gas for commercial purposes. In 1999, we invested over HK$10 million to build Hong Kong's first landfill gas utilisation plant at the Shuen Wan Landfill. The landfill gas is treated on site then transmitted through 1.3km of underground pipelines to our Tai Po production plant for use in the gas production process.
Northeast New Territories (NENT) Landfill Project
In 2007, we began collecting landfill gas from the Northeast New Territories (NENT) Landfill. Landfill gas Treatment Units (TUs) have been installed at the NENT site to remove carbon dioxide, hydrogen sulphide and non-methane hydrocarbons from the raw landfill gas. The treated gas is then transferred through a 19-km long pipeline to our Tai Po Production Plant, where it is used as a heating fuel for gas production.
The NENT landfill gas utilisation project is one of the largest examples of "green" energy recovery and reuse in the world. It not only provides a new source of renewable energy, reducing the use of fossil fuels in our town gas production, it also significantly reduces the emission of greenhouse gases, thus helping to improve air quality in Hong Kong. According to our estimates, the project cuts the emission of carbon dioxide by 135,000 tonnes and reduces the consumption of naphtha by 43,000 tonnes, annually.
Tseung Kwan O South East New Territories (SENT) Landfill Gas Utilisation Project
The Tseung Kwan O South East New Territories (SENT) Landfill Gas Utilisation Project was commissioned in 2017. The landfill gas collected is converted into synthetic natural gas in a treatment facility at the landfill site, then transmitted to the offtake station in Tseng Lan Shue through a 12 km pipeline and finally integrated into the gas supply network. As one of the largest energy conservation and emission reduction environmental projects in Hong Kong, this waste-to-energy project is expected to reduce the emission of carbon dioxide by 56,000 tonnes per year, equivalent to the absorption of 2.4 million tree seedlings per year.
Our specially designed landfill gas treatment facility is the largest of its kind in Asia while the ejector designs at the off-take station is world’s number one. The installation of landfill gas compressors and desulfurisers, the adoption of low-temperature purifiers (-25⁰c) and Pressure Swing Absorption transformers, and the application of the most advanced technology together contribute to a production capacity of 8,000 cubic metres of synthetic natural gas per hour.