Waste-to-Energy: Eco-co-combustion of Municipal Solid Waste With Cement Production

By Green Island International (BVI) Ltd.
In collaboration with
The Hong Kong University of Science and Technology

Funded by
Innovation and Technology Fund
under the University-Industry Collaboration Programme

Background: Waste Management In Hong Kong

• Increasing amount of waste generation, on average 3% growth per year over the past few years. In 2006, 9,279 tonnes per day (tpd) of municipal solid waste was disposed at landfills (Source: Monitoring of Solid Waste in Hong Kong 2006, Environmental Protection Department), which is equivalent (in volume) to about 100 double-deck buses.
• Space of the three strategic landfills will be exhausted in 5 to 8 years.
• Recycling solves only part of the waste problems, end-solution for the non-recyclables/ non-recoverables is needed. The mission of HK Environmental Protection Department (EPD) is to move from the strategy of waste disposal (i.e. landfills) to waste minimization and recovery pertaining to both the material and energy content.

The project aims at developing the process and equipment design for an integrated waste management system. Its uniqueness is a synergy with cement manufacturing, utilizing its flue gas neutralizing capability to conduct thermal treatment of non-recyclable fraction of waste in a sustainable, safe, and pollution-free way.

Two advantages of the Waste-to-Resources recovery strategy:

1. Waste-to-Materials Recovery

Reuse of residual ash resulted from the treatment process as clinker input for cement manufacturing.


2. Waste-to-Energy Recovery

Recovery of energy generated from exothermic destruction of waste as an alternative energy input for cement manufacturing, thereby reducing consumption of non-renewable fossil fuels (e.g. coal).

Integrated Waste Management System

Unlike the conventional incinerator characterized by mass burning as well as conventional practice of waste management, Eco-co-combustion aligned with a material recovery and recycling facility at the front-end to separate out the recyclables from the input waste. This ensures that the waste with recycling value can be sorted out before final treatment by Eco-co-combustion.

The following picture compares the life cycle of waste under the scenarios of landfill and Eco-co-combustion.

The Pilot Plant Study - Introduction

• The study involved a demonstration facility to be built within GIC in Tap Shek Kok, Tuen Mun, consisting of a material recovery and recycling facility and a Eco-co-combustion facility for thermal treatment of waste.
   
• As required by Section 14 of the Air Pollution Control Ordinance, GIC submitted its license application to the Environmental Protection Department (EPD) on 30 October 2002. EPD granted the license on 25 November 2003, allowing the operation of the pilot plant in Tap Shek Kok. EPD’s website contains the details regarding the license.

The Pilot Plant Study – FAQ's

• How long will be the operation of the Pilot Plant?

According to EPD's license conditions, the Pilot Plant can only be operated for a cumulative duration of 16 weeks maximum over the licensing period of two years (effective from 25 November 2003). This involves a number of testing modes, plant shutdown and adjustments will take place between different modes. So, the duration of the Pilot Plant operation is calculated in terms of the cumulative days of actual operation.

• What will be the scale of the Pilot Plant?

According to EPD's license conditions, the Pilot Plant can treat not more than 24 tonnes of municipal solid waste per day. This is a small scale compared to Hong Kong’s daily disposal of more than 9,000 tonnes of municipal solid waste.

•  How to monitor the environmental performance of the Pilot Plant?

During the Pilot Plant operation, independent monitoring on emission performance will be employed. The Hong Kong Productivity Council is the Independent Consultant ("the Independent Consultant") and is responsible for the monitoring of the ambient air quality in terms of total suspended particulates, respirable suspended particulates, sulphur dioxide, nitrogen dioxide, heavy metals and dioxins. The Independent Consultant will also monitor the on-site emission of particulate matter, heavy metals and dioxins.  According to the EPD's license conditions, the data of the on-site and continuous parameters have to be made continuously and instantly available to EPD for its surveillance. The Independent Consultant is using the laboratory of the Hong Kong Baptist University for sample analysis.

• Any adverse impacts on human health?

EPD's license requires the Pilot Plant to fully comply with the emission limits which are in line with the most stringent international standards, including heavy metals and dioxins.

•  Will the Pilot Plant stand forever?

The Pilot Plant is a temporary facility for verification purpose only. The key objective is to collect the data for further evaluation of the technical feasibility of the Eco-co-combustion process.

 

The Pilot Plant Study

• Construction & Commissioning

The plant was installed by February 2005, and was commissioned in April and July/August 2005 in order to demonstrate its performance to EPD according to the licensing conditions. Continuous operation of the pilot plant was started in early October 2005 and completed in December 2005. No more than 24 tonnes of municipal solid waste was treated every day for a cumulative period of 11 weeks.

• Air Quality Monitoring

Two off-site stations had been established in Butterfly Estate and Lung Kwu Tan Village for baseline monitoring of ambient air quality. The monitoring had commenced in December 2004 and was continued throughout the pilot plant study until one month after the project finished. 

 

The off-site baseline monitoring results are now available. Please click here.

• Approval from EPD

Subsequent to the successful load commissioning trials, the Environmental Protection Department had agreed to the use of the pilot plant for a limited period during which the company analysed recovery and recycling as well as the disposal of non-recyclable materials. The operating scale, including both duration and volume of waste being handled remained the same as originally planned.

• Renewal of License

As the original Specified Process (SP) license expired before the completion of the pilot project, an application for renewal of the license was submitted to the Environmental Protection Department so as to complete the plant testing of the technology. There was no increase in either the 16-week cumulative operating time of the pilot plant or the volume of waste being handled (not more than 24 tonnes per day).

 

Note: The SP license was renewed effective from 25^th November 2005 and expired on the 24^th November 2007 under the same terms and conditions of operation as before. As the project is completed, there will be no further renewal.

• Status of Pilot Plant Operation

The pilot plant project has completed its research objective and the pilot plant operation was closed down on 17^th December 2005.

• Decommissioning of the Pilot Plant

The decommissioning of the pilot plant is a Designated Project (DP) as it is included in the category of projects which requires an Environmental Permit (EP) for decommissioning under the Environmental Impact Assessment Ordinance (EIAO Cap.499).

The decommissioning process for the pilot plant was started with the preparation and submission of a Project Profile (PP) to the Environmental Protection Department (EPD) in accordance with the guidelines under the EIAO. Following review and public consultation on the PP, the EPD has issued an Environmental Impact Assessment Study Brief (EIA-SB). An EIA report conforming to the requirements of the EIA-SB was prepared for submission to EPD to obtain an EP for decommissioning of the pilot plant.

As part of the EP application process, a Contamination Assessment Plan (CAP) has to be approved by the EPD. Accordingly, a CAP was prepared and submitted to EPD for review and comments. The CAP was approved by the EPD on 29 January 2008 and Site Investigation (SI) work was carried out in compliance with the regulatory requirements.

After completion of the SI work, a Contamination Assessment Report (CAR) was compiled and presented to EPD and approval was received on 27 May 2008.

A demolition permit from the Buildings Department (BD) is also required for the decommissioning of the pilot plant. A Demolition Plan was prepared in co-operation with the building consultant and an application for approval of the Demolition Plan was submitted to the BD on 20 January 2009. The Demolition Plan was approved by the BD on 13 March 2009.

Work was continued on the EIA in co-operation with the environmental consultant and after a series of studies and evaluation the EIA report was submitted to the EPD on 20 March 2009. Following further amendments as required by the EPD and consultation, advice was received from the EPD on 4 May 2009 that the EIA report is suitable for public inspection. The EIA report was made available for public inspection from 15 May 2009 to 13 June 2009.

After the public inspection period, the EIA report for the demolition of the pilot plant at Tap Shek Kok was approved by EPD on 23 June 2009.

The EP for the demolition project was issued by EPD on 24 June 2009.

Both the approved EIA report and EP issued is placed on the EIA Ordinance Website (http://www.epd.gov.hk/eia).

• Current Status of the Pilot Plant

Subsequent to the approval of the EIA report and issue of the EP, preliminary activities for the decommissioning of the pilot plant were started.

Tenders were called for the demolition works from potential contractors on the list of Registered Specialist Contractors (Demolition Works) maintained by the BD. The tender was awarded on 24 July 2009.

The demolition procedure as prescribed by the BD was followed with submission of a Site Supervision Plan with supporting documents followed by an application on 11 August 2009 for consent to the carrying out of the demolition works .

Precautionary measures as required by the BD including erection of hoarding and barriers on the demolition site were carried out.

 

Consent to the commencement and carrying out of the works was given by the BD on 8 September 2009.

 

The decommissioning of the pilot plant commenced on 15 September 2009 and the demolition works were conducted in compliance with regulatory guidelines and the terms and conditions including the mitigation measures prescribed in the EIA Report and EP.

 

Practical completion of the demolition works was reached on 7 December 2009 according to schedule.