Incineration of plastic waste: is it a good idea?

What to do with the endless stream of plastic waste if we don’t want it clinging to tree branches, swimming in the oceans, and stuffing the stomachs of seabirds and whales?

According to a report released by the World Economic Forum, plastic production is expected to double over the next 20 years. At the same time, about 30% of plastic is recycled in Europe, only 9% in the USA, and in most developing countries they recycle the smallest part of it or do not recycle at all.

In January 2019, a consortium of petrochemical and consumer products companies called the Alliance to Fight Plastic Waste committed to spending $1,5 billion to tackle the problem over five years. Their goal is to support alternative materials and delivery systems, promote recycling programs, and – more controversially – promote technologies that convert plastic into fuel or energy.

Plants that burn plastic and other waste can produce enough heat and steam to power local systems. The European Union, which restricts landfilling of organic waste, is already incinerating nearly 42% of its waste; The US burns 12,5%. According to the World Energy Council, a US-accredited network representing a range of energy sources and technologies, the waste-to-energy project sector is likely to experience strong growth in the coming years, especially in the Asia-Pacific region. There are already about 300 recycling facilities in China, with several hundred more under development.

“As countries like China close their doors to importing waste from other countries, and as overburdened processing industries fail to deal with the plastic pollution crisis, incineration will increasingly be promoted as an easy alternative,” says Greenpeace spokesman John Hochevar.

But is it a good idea?

The idea of ​​burning plastic waste to create energy sounds reasonable: after all, plastic is made from hydrocarbons, like oil, and is denser than coal. But the expansion of waste incineration may be hindered by some nuances.

Let’s start with the fact that the location of waste-to-energy enterprises is difficult: no one wants to live next to a plant, near which there will be a huge garbage dump and hundreds of garbage trucks a day. Typically, these factories are located near low-income communities. In the US, only one new incinerator has been built since 1997.

Large factories generate enough electricity to power tens of thousands of homes. But research has shown that recycling plastic waste saves more energy by reducing the need to extract fossil fuels to produce new plastic.

Finally, waste-to-energy plants can release toxic pollutants such as dioxins, acid gases, and heavy metals, albeit at low levels. Modern factories use filters to trap these substances, but as the World Energy Council states in a 2017 report: “These technologies are useful if incinerators are working properly and emissions are controlled.” Some experts are concerned that countries that lack environmental laws or do not enforce strict measures may try to save money on emissions control.

Finally, burning waste releases greenhouse gases. In 2016, US incinerators produced 12 million tons of carbon dioxide, more than half of which came from burning plastic.

Is there a safer way to incinerate waste?

Another way to convert waste into energy is gasification, a process in which plastic is melted at very high temperatures in the almost complete absence of oxygen (which means that toxins such as dioxins and furans are not formed). But gasification is currently uncompetitive due to low natural gas prices.

A more attractive technology is pyrolysis, in which plastic is shredded and melted at lower temperatures than gasification and using even less oxygen. Heat breaks down plastic polymers into smaller hydrocarbons that can be processed into diesel fuel and even other petrochemicals, including new plastics.

There are currently seven relatively small pyrolysis plants operating in the US, some of which are still in the demonstration phase, and the technology is expanding globally with facilities opening in Europe, China, India, Indonesia and the Philippines. The American Council on Chemistry estimates that 600 pyrolysis plants can be opened in the US, processing 30 tons of plastic per day, for a total of about 6,5 million tons per year – just under one-fifth of the 34,5 million tons of plastic waste that is now produced by the country.

Pyrolysis technology can handle films, bags and multi-layer materials that most mechanical processing technologies cannot handle. In addition, it produces no harmful pollutants other than a small amount of carbon dioxide.

On the other hand, critics describe pyrolysis as an expensive and immature technology. It is currently still cheaper to produce diesel from fossil fuels than from plastic waste.

But is it renewable energy?

Is plastic fuel a renewable resource? In the European Union, only biogenic household waste is considered renewable. In the US, 16 states consider municipal solid waste, including plastic, to be a renewable energy source. But plastic is not renewable in the same sense as wood, paper or cotton. Plastic doesn’t grow from sunlight: we make it from fossil fuels extracted from the earth, and every step in the process can lead to pollution.

“When you extract fossil fuels from the earth, make plastics out of them, and then burn those plastics for energy, it becomes clear that this is not a circle, but a line,” says Rob Opsomer of the Ellen MacArthur Foundation, who promotes the circular economy. product use. He adds: “Pyrolysis can be considered part of the circular economy if its outputs are used as raw materials for new high-quality materials, including durable plastics.”

Proponents of a circular society are concerned that any approach to converting plastic waste into energy does little to reduce the demand for new plastic products, much less climate change mitigation. “To focus on these approaches is to digress from the real solutions,” says Claire Arkin, a member of the Global Alliance for Waste Incineration Alternatives, which offers solutions on how to use less plastic, reuse it, and recycle more.

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