Science – Getting rid of waste

There are four main pathways for dealing with plastic waste: landfill, composting, incineration and recycling. Landfill alienates land and water. Composting, while useful, may contribute to microplastics. Incineration or waste-to-energy (WTE) has major issues, which I’ll outline below. Recycling is achieved via a global strategy called The Circular Economy (CE).

The CE strategy has been led by two global companies, Dow Chemical, which is the largest manufacturer of plastics in the world and UniLever, which owns 400 consumer product brands. A core strategy of the CE involves the cyclic reuse of plastic waste as a valued resource and feedstock for new or replacement products, rather than as rubbish to be incinerated. The CE strategy is based on reducing the range of plastic types to include only those types that can be recycled (types 1,2 and 5 in Aotearoa). The number of major global companies now invested in the CE has increased to 550. In Aotearoa, many larger companies such as the Warehouse Group and Noel Leeming are committed to operating in a more sustainable fashion. Consumers, in selecting their suppliers, have the power to encourage many more companies to pursue recycling strategies.

The capital cost of a WTE process for a city the size of Auckland (generating about five million tonnes of waste per annum) can be estimated to be about $1 billion. Such a WTE process must operate at high levels of waste supply for 25 years for the capital cost to be paid off. As the CE has a target of 100 per cent recyclability within five years. This means that the taxpayers of Auckland would bear the burden of clearing this major capital debt for 20 years beyond the end of the useful life of the WTE plant. This is reflected in the case of a WTE in Sweden, which must import plastics waste from the UK in order to fill its own plastic waste shortfall, and hence to make its WTE plant fiscally viable. That plastic waste shortfall is growing because Sweden, like the EU generally, is trending towards recycling.

WTE plants in the USA have been reported to contribute 200 million tons of carbon dioxide to the existing greenhouse gas atmospheric burden each year. The global WTE emissions are likely to be about one billion tons of carbon dioxide. Further, incineration of some plastics, including polyvinyl chloride and others, yield carcinogenic gases, dioxins and furans, which are very diffusive and hence are a serious threat to human health. Total elimination of the carcinogenic dioxins and furans in the interest of community health, requires elevated furnace temperatures that are expensive to achieve, and which increase the level of carbon dioxide emissions. Tokyo is an example of a wealthy city that continues to ignore the climate emergency, after initially accepting the risks of carcinogenic emissions before upgrading to elevated temperature incineration. These same challenges and the associated long-term rates burden would apply to a WTE process large enough to incinerate the waste generated by the population of Auckland.