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An incinerator isn’t our only choice

Submitted by admin on Jan 31st 2013, 12:00am

Comment›Insight & Opinion

Tom Yam

Tom Yam says while there’s no question that Hong Kong needs a waste treatment plant, an incinerator based on fading technology that’s also highly polluting isn’t our only choice

Most of us would agree that reducing waste at source, recycling and reuse is the best long-term approach to Hong Kong’s waste disposal. But let’s face it, given the 18,000 tonnes we generate daily, there’s no way that the “three Rs” can prevent our garbage from filling up all three landfills by 2019.

The landfills will have to be extended. And thermal decomposition technology will need to be employed as well. The critical questions are: what is the technology, and where should this technology be located?

It’s important to note that thermal decomposition technology is not limited to incineration. It encompasses newer, more advanced technologies that need a little more vision to consider. Unfortunately, the Environmental Protection Department has only applied tunnel vision to the problem so far.

Since 2007, it has been fixated on building a colossal incinerator costing HK$15 billion that uses old technology to burn 3,000 tonnes of waste a day. Worse, the department proposes to build this bonfire in the pristine natural environment of Shek Kwu Chau, off south Lantau.

The way the department has been pushing this mega incinerator, you’d think there was no alternative. But there is. A more flexible and creative strategy is to build a small-scale, state-of-the-art plasma gasification plant that can be integrated with the existing waste-disposal facilities at one of the current landfill locations. If this plant proves successful, its capacity can be gradually expanded.

Phasing it in will minimise the risks of deploying this advanced technology: we can see whether it disposes of our waste efficiently. If the pilot plasma gasification plant performs well, build more at other landfill sites. Adopting cutting-edge technology while managing potential risks would be the approach of a “world city”, rather than putting all our eggs in one basket with a mass-burn incinerator based on sunset technology.

The core technology of the moving-grate incinerator beloved of the Environmental Protection Department has not changed in 50 years. It burns waste at 800 degrees Celsius, releasing combustion gases into the atmosphere. Almost a third of the waste remains hazardous ash that needs to be transported to landfills for disposal. Incremental improvements to this technology over the years have mainly involved pollution-control devices to manage – but not eliminate – toxic emissions.

In the United States, the number of incinerators using moving-grate technology has fallen from 186 in 1990 to 87 in 2010, due to their health risks and high costs, along with the increase in waste reduction and recycling. No new incinerators have been built in the US since 2010. Last year, the New York City government specifically excluded moving-grate technology in its request for bids to build a new waste-to-energy treatment plant.

In Japan, the number of moving-grate incinerators was cut by 25 per cent between 1998 and 2005, when it stood at 1,320. Plasma gasification technology has been introduced at two locations. In Europe, wide-ranging waste reduction and recycling have actually led to an over-supply of incinerator capacity.

It is only in developing countries like China that moving-grate incinerators are being constructed in significant numbers. Manufacturers using this technology recognise that it is coming to the end of its life cycle. They are pushing to squeeze profits from it before it becomes obsolete.

Although moving-grate technology incinerates waste into ash, the gasification process converts waste into synthesis gas and slag – a type of solid waste – with recovery of energy and valuable metals. Gasification is completely different from incineration; burning does not occur in a plasma gasification unit.

Plasma gasification employs extreme temperatures (4,000 to 8,000 degrees) in the absence or near-absence of oxygen, with organic and other materials broken up into chemical elements that are then either collected (in the case of valuable metals), vitrified to produce an inert glass-like slag, or reformed into synthesis gas that can be used as an industrial feedstock or converted to energy.

About 100 commercial plasma gasification waste-processing facilities have been constructed worldwide since 1994. Most of these plants are used to vitrify incinerator ash. Others are used to process medical waste, hazardous waste and other difficult types of waste. Two in Japan are treating municipal solid waste, with more being planned. One in Ottawa, Canada, is being built. British Airways recently reached a deal to build plasma gasification facilities that can convert waste into aviation fuel. Four in the US, two in Britain, four in Canada, one in India and one in China are reportedly being planned .

An examination of scientific and technical literature, media reports and other sources found no health or safety problems, and few environmental problems, with plasma arc disposal systems. Also, no environmental or health and safety problems have been reported among the eight plants treating materials including asbestos, tannery waste, aluminium dross, catalytic converters, medical waste and munitions.

If plasma gasification is the best solution, the obvious question is: Why aren’t there more waste-disposal plants using this technology? The answer is simple: The capital cost is still very high. However, as with any new technology, the cost will inevitably drop as it is used in more plants and adopted by more users.

The choice that Hong Kong faces is clear: will it use a sunset, pollutant- emitting technology for a plant built in a pristine environment, or will it judiciously integrate step by step an advanced technology in existing landfills that is being adopted worldwide with much less environmental and health impact?

Is the Environmental Protection Department smart enough to understand the difference?

Tom Yam is a Hong Kong-based management consultant. He holds a doctorate in electrical engineering and an MBA from the Wharton School of the University of Pennsylvania


Waste disposal




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