Reuse and recycling can only be done so far. Buzzy new expression in the waste management industry is "zero waste," which means it does not produce waste at all. Even after reusing and recycling, there is always something left. Many environmentalists see turning waste into usable energy (Waste-to-Energy, or W.T.E.) as a practical step towards true zero waste. Others see W.T.E. nothing more than a Ponzi scheme, because energy needs provide incentives to produce more waste.
There is no consensus, but a South African case study by urban planning scholar Trynos Gumbo at Coincidence illustrate one way W.T.E. actually works in real life.
eThekwini Municipality is one of the largest urban areas in South Africa, including Durban and its surroundings. As is typical in developing countries, many streams of solid waste consist of organic waste. By comparison, rich countries end up with more metal and glass. However, the organic waste in eThekwini is often disposed of improperly, creating aesthetic and health hazards. Garbage is left to rot, releasing methane that changes the climate. The municipality reasoned that if the gas would be released, they might also use it.
The theory is that gas made by decomposition of organic matter in landfill can be captured and burned for electricity generation. (Some W.T.E schemes burn garbage directly as an energy source, even though it produces more by-products). Because eThekwini is fast learning, not all landfills are conducive to this process. The first landfill that is tried does not produce enough gas. The second continues to fill with water and fine sand, clogging the extraction pipe. The third landfill, however, produces a lot of gas, and can continue to do so even after the landfill is closed as projected in 2022. A buffer zone around the site helps maintain habitat for wildlife.
W.T.E. Newer sites in much larger landfill also go down to rocky beginnings – initially most of the gas is burned rather than extracted. Finally the site produces enough electricity to reduce capacity near nearby fossil fuel plants. The factory helped alleviate a number of local problems; the air becomes cleaner, improper disposal decreases, and the factory employs local workers.
But there are some problems. Technology is expensive, making it difficult to improve. There is still no answer to what happens when the overall level of waste begins to decline. Gumbo also made questionable claims that there was no carbon waste at all.
There are many large landfills that exist, rot and produce methane. For now, as Gumbo said, W.T.E. can use gas to be produced in any event. W.T.E. may work best as a transition technology until full renewable energy takes over.
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By: Trynos Gumbo
Consilience, No. 12 (2014), p. 46-62