Giving Waste a Second Life

From Waste to Energy

By Jintian  NI and Xiaoxiao ZHANG

In Hong Kong, the amount of municipal solid waste (MSW) keeps climbing. The food waste, accounting for a significant proportion of the city’s overall waste, has not been reduced at source. It not only brings great hidden dangers to the environment, but also increases the waste disposal problem in Hong Kong landfills, which needs to be solved urgently.

MSW disposal in 2021 averaged over 10,000 tons per day, an increase of 5.1% over 2020, according to the Hong Kong government. In Hong Kong, about 30% of the daily MSW is food waste, the largest share.

Chu Lee Man, a life sciences professor at the Chinese University of Hong Kong, said that the main reasons why waste disposal problems, especially for food waste, are getting worse is because there is delayed implementation of waste separation measures, a lack of funds for specific problems in the context of only a blueprint plan, and imperfect laws, resulting in little disciplinary action and low public participation.

Food waste transfer vehicle at work in the Central and Western District, Hong Kong Island.

In the Legislative Council’s Food Waste and Yard Waste Plan, the government aims to reduce the amount of food waste discarded in landfills by about 40% by 2022, from 3,600 to 2,160 tons per day.

However, data from the Environmental Protection Department shows that more than 3,000 tons of food waste were dumped in landfills every day in 2021, increasing by 5.6% over 2020. Only 3% of the food waste is recycled, while the rest of the organic matter decomposes and releases the greenhouse gas methane, leaving a harmful impact on the environment.

Educational animation on turning waste into energy at the Organic Resources Recovery Centre O·PARK.

Waste-to-energy (WTE) is the process of converting energy in waste into heat or electricity through various technologies. According to the Energy Efficiency Office of Electrical and Mechanical Services Department (EMSD), the main types of WTE technologies include “landfill gas utilisation, anaerobic digestion and thermal treatment with energy recovery.” MSW, especially the organic part of it, can be a valuable energy source after being processed. Converting waste to energy is not only an effective way to dispose waste and prevent food waste from harming the environment, but processed energy can also be used again by human beings.

Compost sample made from food waste at O·PARK.

As the total amount of waste generated in Hong Kong continues to rise, landfills are already overburdened. At the same time, discarded waste has also had a negative impact on the air, water, and other natural elements.

Professor Chu said garbage collection and recycling is much more efficient than reducing at the source. “The government has already invested in this industry, trying to ‘turn waste into treasure,’”he said.

In 2009, the Hong Kong government confirmed funding for the construction of a sludge incinerator in Tuen Mun. Since then, T·PARK, a waste-to-energy incinerator plant for sludge, was officially opened in 2016. Subsequently, WTE plants for other types of waste, including O·PARK, I·PARK, and Y·PARK, have been set up and put into operation one after another.

In December 2014, the Hong Kong government officially launched the design and construction of O·PARK1, which was put into operation in Siu Oyster Bay, North Lantau, in 2018.

In order to spread knowledge to the general public, O·PARK also offers tours and public education. According to the O·PARK tour guide, O·PARK’s concept of turning food waste into energy has gained not only the support of many Hong Kongers, but also the help of many industrial and commercial organisations.

“Now O·PARK is capable of processing 200 metric tons of source-separated food waste per day, reducing the burden on landfills,” O·PARK said. Now over 200 organisations have responded to O·PARK’s call to sort food waste at the source, collect, and transport it to O·PARK1 for the next step of WTE conversion.

The model of O·PARK, which has been operating since 2018.

O·PARK staff wear respirators to prevent inhalation of toxic gas, while the transfer vehicle dumps the waste. 

During the tour, the guide would show visitors how this organic resource recovery centre adopts the WTE strategy by using anaerobic decomposition technology to turn kitchen garbage into biogas, a kind of renewable energy, which can then generate electricity. Meanwhile, the residue generated in the process can be turned into useful materials for landscaping and agricultural production.

A guide shows visitors photos of the bunker, where food waste is first stored.

Tiffany Tse, an official from the Environmental Protection Department, said that the government has always attached great importance to promoting the source reduction and recycling of food waste.

“The Government will continue to develop O·PARKs and optimise the use of sewage treatment works for carrying out food waste and sewage sludge anaerobic co-digestion to enhance the overall food waste treatment capability in Hong Kong, ” she added.

Although O·PARK has alleviated the food waste disposal problem to a certain extent and slightly reduced the proportion of food waste in landfills, it can hardly help Hong Kong solve the overall waste disposal problem fundamentally. According to the Environmental Protection Department, the total amount of MSW at landfills in Hong Kong continues to climb, affecting environmental hygiene and health safety.

To further handle waste disposal in the city, the Hong Kong government has stuck to adopting the WTE strategy and building Integrated Waste Management Facilities (IWMF). The aim is to significantly reduce the volume of mixed municipal solid waste at landfills and recover valuable resources through the WTE strategy. Since this can help reduce the waste disposed of in landfills, the WTE strategy can extend the use period for Hong Kong’s landfills now that the IWMF Phase 1 (I·PARK 1) is under construction.

The Secretary for the Environment and Ecology Tse Chin-wuen said in a press release that the amount of MSW that needs to be disposed daily in two New Territories landfills is expected to be reduced by approximately 3,000 tonnes in 2025 thanks to the I·PARK1. After IPARK2 is put into use, landfills in the North East New Territories will no longer be required to receive MSW. He added that the government would also strongly support this initiative, and I·PARK3 is in the future waste treatment plan.

3,600 tons of waste is equivalent to 300 double-decker buses.

Candy Lam, the guide interpreter of I·PARK, is responsible for the management of the I·PARK Information Center. She believes that the primary reason why solving the waste management problem in Hong Kong is difficult is because the residents are not fully aware of the seriousness of the issue.

The Hong Kong Solid Waste Monitoring Report 2021 shows that the per capita of household food waste disposal has reached 0.32 kg per day. Lam also pointed out that reducing food waste generation at source is also necessary to solve Hong Kong’s waste disposal problem.

“First of all, I also think I am not environmentally friendly enough. For example, in Japan, waste classification projects are done very well, but in Hong Kong, this aspect of public awareness will be lacking,” she said.

In fact, waste classification bins have been implemented in Hong Kong. Still, many residents do not know exactly which type of waste belongs to which kind of bins, while the government has not taken strict punitive measures for waste separation. Therefore, the containers are not used to their fullest extent.

Recycling bins for paper, plastic bottles and metals at the Yau Tsim Mong District, Kowloon.

Finally, Lam mentioned that primary school students are now exposed to this kind of education, and schools are also starting to let children understand the basics of waste classification through some general knowledge courses and social practice so that they can understand the current situation and tricky crux of waste disposal. In response, I·PARK Consulting Center has also set up activities and cartoons suitable for children’s education to help kids learn more efficiently.

It is worth mentioning the Big Waster mascot in Hong Kong, which was introduced in 2013 together with the “Food Wise Hong Kong” campaign to encourage the public to reduce food waste at source. The Big Waster is everywhere in O·PARK, and many parents bring their children to visit the Big Waster during holidays since its cute image makes a deep impression on children. During the tour, O·PARK prepared various interactive games and animations, which allowed visitors to understand the whole process of WTE for food waste and let visitors visualise the environmental hazards of food waste.

Children take photos with O·PARK’s Big Waster.

Speaking on this, Lam expressed her confidence in the future development of garbage disposal in Hong Kong. The situation will improve as long as the citizens are well educated and the government is willing to continue investing in waste treatment facilities like I·PARK and O·PARK.

Sludge samples on display in T·PARK.

Sludge, as part of the special waste, is a semi-solid residue left over from the sewage treatment process and has a very high potential as an environmental hazard. According to the Hong Kong Environmental Protection Department, about 2.8 million cubic metres of sewage are generated per day and the facilities need to treat about 1,200 tonnes of sludge daily in Hong Kong.

As the sewage treatment system is being updated and iterated, the amount of sludge output is also increasing and is expected to increase to 2,000 tonnes per day by 2030.

Y·PARK filled with wood, located just next to T·PARK.

With such a large amount of sludge, disposal only in landfills may not be a good way to deal with it. Therefore, in 2009, the Hong Kong government decided to apply the WTE strategy to sludge and fund the construction of a plant dedicated to the conversion of sludge into energy — T·PARK. T·PARK has four incinerators and can treat up to 2,000 metric tons of sludge daily through a high-tech thermal treatment process. According to the guide during the T·PARK tour, the heat energy is reused and electricity is generated to power the facility —just the same power strategy as I·PARK — with enough energy left over to power 4,000 homes. After incineration, the sludge is converted into ash and residue, which is reduced in volume by 90%.

“This not only significantly reduces the waste volume and load on the landfill but also reduces greenhouse gas emissions by up to 237,000 metric tons per year,” the T·PARK tour guide said.

Wastewater treatment system, sewage will be treated and recycled for various non-drinking purposes in the plant area.

In addition, the Hong Kong government continues to develop WTE technologies with the establishment of Y·PARK after 2018, designed to promote the recycling of garden waste and its conversion into valuable energy and materials. Abiding by the same WTE strategy, Y·PARK helps to reduce disposed gardening landfills and carbon emissions. In this way, this facility can contribute to achieving zero waste in landfill and promote carbon neutrality in the long run, responding to national calls for such efforts.

Pros and cons are both clear for the current WTE strategy in Hong Kong. The advantages are that it can not only reduce the burden on landfills, but also promote energy recycling and consequently protect the environment.

At the same time, however, the efficiency of the strategy needs to be further confirmed. As Professor Chu said, the current energy output is far from offsetting the government’s initial investment, and the technical solutions are not mature enough for mass production. Lam also mentioned that the lack of relevant legal system and the awareness among the population is fatal to the implementation of government policies. It still seems uncertain whether the WTE strategy will provide a bright future for solving Hong Kong’s waste problem.

Extra Credits

Advisor    Sam Colombie
Editorial Director    Hailey Yip
Multimedia Director    Madeleine Mak
Multimedia Producer   Wulfric Zhang
Copy Editor     Hugo Novales
Fact Checker    Larissa Gao
Photographer    Safiullah Ahmadzai