Many people don't like the idea of building an incinerator in Hong Kong, but in the medium term there appears to be no alternative. This is because landfills, which the territory relied on in earlier decades to dispose of municipal solid waste (MSW), are now almost full. In the long term, though, we need to focus on eliminating waste at the source.

Already 13 landfills have been filled and closed. The remaining three strategic landfills will reach capacity by 2019. The Southeast New Territories landfill, which takes 4,800 tons of MSW a day, will be full around 2015; the Northeast New Territories landfill, 2,500 tons a day, around 2017; and the West New Territories landfill, 6,100 tons a day, around 2019.

Hong Kong depends on landfill disposal far more than comparable economies in the region. South Korea stores 19 percent of its MSW in landfills, Taiwan 2 percent, and Singapore 1 percent, while Japan doesn't use landfills. In stark contrast, Hong Kong dumps a whopping 52 percent of its MSW in landfills.

The Hong Kong SAR is the fourth most densely populated territory in the world, with over 6,600 people per square kilometer in mid-2012, behind only Macao, Monaco and Singapore. There isn't room left for any more landfills, especially if we want to retain important features like country parks, which comprise roughly 40 percent of Hong Kong's land area and which attracted 12 million visitors in 2012.

The Environment Bureau's current plan, as outlined in its Blueprint for Sustainable Use of Resources 2013-2022, prescribes a range of urgent actions to reduce, re-use and recycle waste. These are designed to reduce the proportion of MSW going into landfills from 52 to 22 percent, while increasing the proportion of recycled waste from 48 to 55 percent as the new incinerator burns the remaining 23 percent.

There are worries about potential air pollution caused by an incineration plant. Hong Kong operated four waste incinerators - in Lai Chi Kok, Kennedy Town, Mui Wo and Kwai Chung - from the early 1970s to the 1990s. Their aim, like now, was to reduce landfill MSW disposal. They were closed as a result of the 1989 government White Paper on Pollution in Hong Kong. Decommissioning was prolonged by the discovery of toxins at the sites.

The government, therefore, has to ensure that the technology used is more advanced and will result in less pollution. It has chosen to build a moving grate incinerator. This will not only remove most of the waste, it will generate energy.

Incineration reduces, but does not completely eliminate, solid waste. The solid mass is typically shrunk by over 80 percent and the volume cut by 95 percent. The remainder is usually put in landfill. Moving-grate incinerators are more efficient than the static burners they replaced, ensuring more complete combustion. They also require less frequent maintenance than older models.

Critics of this technology say it is less advanced than plasma arc gasification, which uses a plasma torch powered by an electric arc to ionize gas and catalyze organic matter into synthetic gas and harmless slag. This is the most efficient way of producing carbon monoxide and hydrogen for electricity generation. The much higher temperature converts inorganic constituents to non-hazardous slag, unlike incineration.

Several plasma arc facilities have started work reducing landfills, but the scale at present is limited. One plant now under construction, for example, will be installed on the US's latest-generation aircraft carrier, which is more the equivalent of a small town than a giant metropolis such as Hong Kong.

Under Secretary for the Environment Christine Loh says that while it may be desirable in some ways, plasma arc gasification cannot cope with the 3,000 tons of MSW a day forecast in Hong Kong's blueprint, which is why European countries are adopting moving-grate incineration instead.

She cites the example of Copenhagen, which is building an incineration plant in the city center, topped off with a ski slope. When this is finished in 2017, it will produce heat for 160,000 households and electricity for 62,500 residences. Denmark has long been a model of combined heat and power electricity generation, as well as of good design and concern for the environment.

Adopting state-of-the-art waste-to-energy incineration is an advance on the old policy of relying almost entirely on landfill. But it is no substitute in the long term for eliminating solid waste at source by reducing, re-using and recycling.

As Head of Global Relations in the OECD's Investment Division up to 2010, the author wrote and published major policy reviews for the governments of China, India, Indonesia and the Russian Federation. The article is the second in a series of articles exploring policies to address Hong Kong's waste management challenges.

(HK Edition 12/12/2013 page1)