City

Hong Kong

Population

7 million

Project start date

2006

Annual C02 reduction

2,100 tons

Annual financial savings

HK$2.4 million (US$ 300,000)

Initial investments

HK$7 million (US$ 900,000)

Project status

Completed

Contacts

Mr. Eddie Pak
Senior Electrical and Mechanical Engineer
Shatin Sewage Treatment Works
1 Shui Chong Street, Shatin, Hong Kong
Email: eddiekmpak@dsd.gov.hk

Water

Hong Kong

Installation of Combined Heat and Power Generation System to Recover Energy in Biogas

What is it?

In 2007, Hong Kong began using a 330 kW Combined Heat and Power Generation System (CHP) at the city’s Shek Wu Hui Sewage Treatment Works (SWH STW).

This system utilizes the biogas generated by the sewage treatment process as combustion fuel for generating electricity and thermal energy. The system generated about 3 million kWh equivalent electrical power in 2007. This resulted in savings of HK$2.4 million in recurrent costs for electricity and avoided about 2100 tCO2 in emissions.

How does it work?

The electricity generated by the CHP supplies power for the facilities within the sewage treatment works, while the recovered thermal energy supplies heat for the sludge digestion process via recirculation water.

Key results

Biogas offers substantial reductions in greenhouse gas emissions and its use in this CHP system has avoided around 2100 tCO2 in emissions.

Next steps

With the successful experience, more CHPs are going to be installed in other sewage treatment works in Hong Kong. Additional biogas generators of about 600kW are planned to be installed at Tai Po STW and SWH STW in 2008 and 2009 respectively. This will make better use of the biogas generated by sewage treatment processes, and improve the efficiency of electricity and heat generation. Moreover, these new biogas CHP installations will contribute towards reduction of greenhouse gas emissions in Hong Kong.