Tuesday 30 July 2019

Plastic and landfill

A snippet:
Modern landfills are constructed to deal with any leachate from the disposal of plastics. Fees charged at the tip are designed to ensure that the landfill covers its costs. When those fees are set properly, all of the costs of waste disposal are incorporated into the price each of us pays for a council rubbish bag or for a trip to the dump – including the cost of the land purchased for the tip.

Contrary to the usual stories of shortages of land for landfill, fairly simple back-of-the-envelope calculations show it would take thousands and thousands of years before lack of land for landfill became anything close to a problem. The more relevant problem is ensuring that tips are properly constructed – land is a small part of the overall cost of a new site. And at the end of their useful lives, landfills do not have to be a blight. Hamilton’s superb gardens, for example, are built over its old rubbish dump.

Rather than using the waste disposal levy to encourage waste minimisation, we might instead use it to help councils deal with legacy issues from ancient landfills built to inadequate standards with insufficient provision for whole-of-life contingencies, and to improve the filtration of storm-water outflows to keep litter from flowing out to the sea.
But there may now be an even better solution that has some rather serious backing:
One startup wants to eliminate the pollution by essentially vaporizing garbage to turn it into clean energy and fuel. The company, called Sierra Energy, just raised a $33 million Series A investment round led by Breakthrough Energy Ventures, the Bill Gates-led fund that also includes investors like Marc Benioff, Richard Branson, and Jeff Bezos.

The company isn’t aiming to replace recycling or composting, but to handle the millions of tons of waste that currently goes to landfills. “We take what’s leftover,” says CEO Mike Hart. The technology can process nearly anything, including medical waste and hazardous waste. “It allows you to recycle the entire waste stream,” he says. “The way we do that is by bringing the temperature of waste up to 4,000 degrees Fahrenheit, twice the temperature at the core of a volcano. At that temperature, everything breaks down molecularly.”

The technology, called FastOx, uses a modified blast furnace, the same basic equipment typically used to make steel. By injecting pure oxygen into the furnace, the new process starts a chemical reaction with carbon in the waste, heating up the furnace. “This doesn’t require external energy,” Hart says. “It’s just a chemical reaction of carbon and oxygen.” The process also adds steam to regulate the temperature, which sustains itself as the system keeps feeding in more trash. Any metal inside the garbage melts and can later be reused.
Another nice feature of landfills: if this kind of tech pans out, you can pop one of these units next to the old dump and you've a great source of feedstock for it. Garbage goes in, energy comes out. Read the whole thing over at Fast Company.

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