Reply To: Alternatives to waste incineration


Science column by me for South China Morning Post (Sunday Morning Post), appears today, also posted to this site: 'Science fiction' waste solution a real option


Plasma arc incineration is a forward-looking and realistic alternative to landfills, and won't generate the toxic emissions associated with burning waste

Is this true? Can Hong Kong find no better way of dealing with waste than shipping it to a beautiful coastal area and setting fire to it? There's actually a range of alternatives, ranging from straightforward to one that seems verging on science fiction.

Plasma processes are much hotter, perhaps well over 4,000 degrees Celsius. These temperatures, coupled with intense ultraviolet light, blast molecules apart; organic chemicals disintegrate to simple components. The resulting gas mixture called syngas (synthetic gas), is mainly carbon monoxide and hydrogen. Other material forms something like lava, which can be solidified into glass-like material with metals and other toxins so effectively "locked" within that Japanese incinerators treat fly ash with plasma arc torches.

The syngas can be burned to generate electricity, rather as incinerators may be used for "waste-to-energy". But in another marked contrast to incineration, the syngas has other possible uses. One company, Solena Fuels, is working with airlines and a shipping company to develop projects that transform syngas into jet fuel and ship fuel from waste. Advanced Plasma Power, which specialises in plasma arc treatment of municipal waste, is exploring ways to synthesise natural gas.

Here in Hong Kong, the Environmental Protection Department has fielded an array of objections to plasma arc treatment.