Since 2007, DSD has joined the Inter-departmental Working Group on Climate Change set up by the Environment Bureau for formulating polices and measures in adapting climate change to reduce greenhouse gas emissions and combat climate change. In support of “Hong Kong's Climate Action Plan 2030+” (Action Plan) published by the Government in 2017 that encourages extensive use of renewable energy, DSD has actively implemented energy-saving initiatives and adopted hydropower, solar power and biogas to generate energy.

To address global warming, DSD maintains close connection with other cities and regions and join the Connecting Delta Cities, a subsidiary of the international organisation C40 Cities Climate Leadership Group, and represents the HKSAR Government to exchange flood prevention techniques with other delta cities. DSD is also a member of the Hong Kong/Guangdong Joint Liaison Group on Combating Climate Change.

Newly Implemented Measures for Saving Energy and Harnessing Renewable Energy

In 2017-18, we continued to optimise the operation of our sewage treatment works and sewage pumping stations, as well as replace aging equipment with more energy efficient ones to save energy. Concurrently, we promoted wider use of renewable energy. The measures in place include:

• Replacing conventional fluorescent lamps with light emitting diode (LED) lamps;
• Optimising operation procedures and replacing equipment with more energy efficient ones at sewage treatment works and sewage pumping stations; and
• Installing photovoltaic solar panels.

During the year, the above measures saved about 2.1 million kilowatt-hours of electricity (equivalent to carbon reduction of about 1,470 tonnes¹).

Electric Vehicle

Powered by batteries, the operation of electric vehicles (EV) does not involve gasoline combustion or produce emissions, which helps improve street-level air quality in Hong Kong. As at end March 2018, there were 31 EVs in our fleet. In 2017-18, there were totally 46 medium EV chargers installed in our sewage treatment works and sewage pumping stations across Hong Kong to make charging more convenient and readily available.

Hydro-turbine System at Stonecutters Island Sewage Treatment Works (SCISTW)

Installation of Photovoltaic Solar Panels in Sewage Treatment Facilities

Converting Biogas to Energy

Sludge collected from secondary sewage treatment produces biogas during anaerobic digestion process. Biogas is a form of renewable energy which contains 65% methane (the remaining components mainly being carbon dioxide). DSD has installed combined heat and power (CHP) generators and gas-turbines that run on biogas to generate electricity and thermal energy for in-house use. As of 2017-18, a total of five CHP generators, with a combined capacity of 3.6 megawatt, have been installed at Shatin STW, Tai Po STW and Shek Wu Hui STW, while two gas-turbines with a total capacity of 280 kilowatts have also been in place in Shatin STW and Yuen Long STW. During the year, the total energy generated by biogas in our STWs was equivalent to about 27 million kilowatt-hours.

To maximise the use of biogas generated during the sludge treatment process, we plan to install additional CHP generation and gas-turbine systems at our sewage treatment facilities such as Shatin STW, Tai Po STW and Yuen Long STW. On completion of these installations, the total power generation capacity will reach 5.4 megawatt.

Study on Food Waste/Sewage Sludge Anaerobic Co-digestion

We are conducting a six-year Food Waste/Sewage Sludge Anaerobic Co-digestion Trial jointly with the Environmental Protection Department (EPD) in Tai Po STW. Pre-treated food waste, collected by EPD, will undergo anaerobic co-digestion with the sludge in Tai Po STW for biogas production and to provide renewable energy for the use of our facilities. Currently, the engineering works of the trial are at the construction stage and the anticipated completion date is early 2019.

Carbon Audit

To reduce greenhouse gas emissions effectively from daily operations, we actively conduct carbon audits at our plants to identify major sources of emissions. During the year, carbon audits were carried out at Sai Kung STW, Sham Tseng STW, Stonecutters Island STW, Tai Po STW, Shatin STW, Shek Wu Hui STW, Siu Ho Wan STW and Stanley STW. With appropriate measures like reducing energy consumption of machinery, enhancing operation efficiency and using renewable energy, we have successfully lowered greenhouse gas emissions.

In the future, DSD will continue to conduct carbon audits in more STWs and adopt appropriate carbon reduction measures to provide quality stormwater drainage and sewage treatment services for the public in the most environmentally friendly manner.