How Earth’s plastic pollution problem could look by 2040



Rich Carey/Shutterstock

Costas Velis, University of Leeds and Ed Cook, University of Leeds

During a visit to a bookstore a few weeks ago, we couldn’t help but stare at a display unit featuring no fewer than ten books telling you how to rid plastics from your daily life. We’re bombarded by information on the topic of marine litter and plastic pollution, but how much do we really know about the problem?

Think about other planetary challenges, like climate change or ozone layer depletion. Mature areas of research have developed around them, allowing scientists to identify where the gases that cause these problems come from, and how much reaches the atmosphere each year.

But when it comes to plastic pollution, we know close to nothing about how and where plastic waste is generated, managed, treated and disposed of, especially in low and middle income countries. As a result, we’re struggling to limit the amount of litter accumulating in the environment.

Our research published in Science involved a herculean effort to spot, track and model the current and future flows of plastics into the world’s land and waterbodies. We found that plastic entering the marine environment is set to double by 2040 and, unless the world acts, more than 1.3 billion tonnes of plastic waste will be dumped on land and in waterbodies.

By identifying the ways in which this litter is produced and distributed, we’ve also discovered how best to reduce the plastic deluge. In the process, we found the unsung heroes on the frontline fighting the pollution crisis who could be the world’s best hope of stemming the tide.

Discarded face masks on a rocky beach.
Single-use plastic consumption has increased during the pandemic.
Fevziie/Shutterstock

The world’s plastic problem in numbers

We developed a model called Plastic-to-Ocean (P₂O) which combines years of accumulated knowledge on global flows of plastic. It compares our current production, use and management of waste with what is projected in the future.

Do you burn your waste in the garden or in the street? Do you drop it into the river? If you answered no to both of these questions then you are possibly one of the 5.5 billion people whose waste gets collected. If you were among the remaining two billion, what would you do with your uncollected waste? Would you make use of a nearby stream, cliff edge, or perhaps squirrel the odd bag in the woods after dusk?

More often than not, uncollected plastic waste is simply set on fire as a cost-free and effective method of disposal. Our model suggests that cumulatively, more than 2.2 billion tonnes of plastic will be open burned by 2040, far more than the 850 million tonnes that’s anticipated to be dumped on land and the 480 million tonnes in rivers and seas.

Having tracked the sources of plastic items through the supply chain and their fate in the environment, we explored what might help reduce aquatic pollution. We found that the single most effective intervention is to provide a service for the two billion people who currently don’t have their waste collected.

A graph showing how different measures could reduce the flow of plastic into the ocean.

Breaking the Plastic Wave, Author provided

But, of the nine interventions we tested, none solved the problem on their own. Only an integrated approach that in addition to increasing collection coverage includes interventions such as reducing demand for single-use and unrecyclable plastic and improving the business case for mechanical recycling, could be successful. For the countries suffering most from plastic pollution, this knowledge could offer a way forward.

But even in our best-case scenario, in which the world takes the kind of concerted and immediate action proposed in our study, approximately 710 million tonnes of plastic waste will be released into the environment by 2040. That may sound a lot, but it would mean an 80% reduction in the levels of plastic pollution compared to what will happen with no action over the next two decades.




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Could waste pickers save the day?

Our work also cast light on the contributions of 11 million waste pickers in low and middle-income countries. These informal workers collect waste items, including plastics, for recycling, to secure a livelihood for day-to-day survival. The model estimates that they may be responsible for 58% of all plastic waste collected for recycling worldwide – more than the combined formal collection services achieve throughout all the high-income countries put together.

Without this informal waste collection sector, the mass of plastic entering rivers and the ocean would be considerably greater. Their efforts should be integrated into municipal waste management plans, not only to recognise their tremendous contribution but to improve the appalling safety standards that they currently endure.

A man in India peddles a bicycle cart to collect rubbish.
An additional 500,000 people will need to be reached by waste collection services each day until 2040.
EPA-EFE/JAIPAL SINGH

Establishing a comprehensive baseline estimate of sources, stocks and flows of plastic pollution, and then projecting into the future, has been an immense task. When it comes to solid waste, the availability, accuracy and international compatibility of data is notoriously insufficient.

Plastic items occur throughout the world in tens of thousands of shapes, sizes, polymer types and additive combinations. There are also considerable differences in cultural attitudes towards the way waste is managed, how plastic products are consumed, and the types of infrastructure and equipment used to manage it when it becomes waste.

Our modelling effort was a delicate and tedious exercise of simplifying and generalising this complexity. To understand how reliable, accurate, and precise our findings are likely to be, think of the first models that estimated how sensitive the climate is to human influence back in the 1970s.

Hopefully, the strong evidence base we have presented today will inform a global strategy and strong local preventive action. The plastic pollution challenge can be substantially controlled within a generation’s time. So, is anyone ready to act?The Conversation

Costas Velis, Lecturer in Resource Efficiency Systems, University of Leeds and Ed Cook, Research Fellow in Circular Economy Systems, University of Leeds

This article is republished from The Conversation under a Creative Commons license. Read the original article.

New Zealand wants to build a 100% renewable electricity grid, but massive infrastructure is not the best option



Juergen_Wallstabe/Shutterstock

Janet Stephenson, University of Otago

A proposed multibillion-dollar project to build a pumped hydro storage plant could make New Zealand’s electricity grid 100% renewable, but expensive new infrastructure may not be the best way to achieve this.

New Zealand’s electricity generation is already around 80% renewable, with just over half of that provided by hydro power. The government is now putting NZ$30 million towards investigating pumped hydro storage, which uses cheap electricity to pump river or lake water into an artificial reservoir so that it can be released to generate electricity when needed, especially during dry years when hydro lakes are low.

The response to the announcement was mostly enthusiastic – not least because of the potential for local jobs. But whether it is the best solution needs careful evaluation.

There are many realisable changes to electricity demand, and New Zealand should consider other, potentially cheaper options that deliver more efficient use of electricity.




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Promise of a purely renewable grid

Electricity is mooted to play a major role in achieving New Zealand’s target of net zero carbon emissions by 2050. To support the government’s plan to accelerate the electrification of the transport and industrial heating sectors, generation will need to grow by around 70% by 2050, all from renewable sources.

Worldwide, pumped hydro energy storage is seen as a promising option to support cheap and secure 100% renewable electricity grids.

New Zealand’s analysis will mainly focus on one particular lake, Lake Onslow. If it stacks up, it would be the biggest infrastructure project since the “think big” era of the 1980s. But at an estimated NZ$4 billion, the cost would also be massive and the project would likely face opposition on ecological grounds.

Such a scheme would be a step towards the government’s target of 100% renewable electricity generation by 2035 and fit with the overall goal of New Zealand achieving net zero carbon emissions by 2050. It would also solve the problem conventional hydropower plants face during dry years, when water storage runs low and fossil-fuelled power stations have to kick in to fill the gap.

But the possible closure of the Tiwai Point aluminium smelter would free up around 13% of renewable electricity supply for flexible use. This alone raises the question whether a pumped storage development on this scale is necessary.




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Changing supply and demand

Getting to 100% renewables and achieving a 70% increase in supply in the next 30 years will mainly come from new wind and solar generation (both now the cheapest options for electricity generation) as well as some new geothermal. Major new hydro dams are unlikely because of their significant environmental impacts.

As a result, electricity supplies will become increasingly variable, dependent on the vagaries of sun, wind and river flows. This creates a growing challenge for matching supply with demand, especially if hydro lakes are low.

Last year, the Interim Climate Change Commission concluded New Zealand could get to 93% renewable generation by 2035 under current market conditions. But it warned the final few per cent would require significant overbuilding of renewable generation that would rarely be used.

It suggested the most cost-effective solution would be to retain some fossil-fuelled generation as a backup for the few occasions when demand overshoots supply. At the same time it recommended a detailed investigation into pumped storage as a potential solution for dry years.

A hydropower lake in New Zealand
New Zealand already has more than 100 conventional hydropower stations supplying renewable electricity.
Dmitry Pichugin/Shutterstock

Electricity demand — the collective consumption of all businesses, organisations and households — is also changing.

Households and businesses are switching to electric vehicles. Farm irrigation is becoming widespread and creates new demand peaks in rural areas. Heat pumps are increasingly used for both heating and cooling. These all create new patterns of demand.

And households aren’t just consuming power. More and more people are installing solar generation and feeding surplus back into the grid or storage batteries. Local community energy initiatives are starting to emerge.

New markets are developing where businesses can be paid to temporarily reduce their demand at times when supply is not keeping up. It is only a matter of time before such demand response mechanisms become commonplace for households, too. In the near future, housing collectives could become virtual power plants, and electric vehicles could feed into the grid when supply is stressed.

Cheaper options with added health benefits

So with more reliance on sun, wind and water, electricity supply will become more variable. At the same time, patterns of demand will become more complex, but will have more potential to be adjusted quickly to match supply, on time scales of minutes, hours or days.

The big problem lies with winter peaks when demand is at its highest, and dry years when supply is at its lowest – especially when these coincide. At these times the potential mismatch between demand and supply can last for weeks.

The current solutions being mooted are to increase the security of supply, either with fossil-powered generation or pumped hydro storage. But there are options on the demand side New Zealand should consider.

New Zealand houses are typically cold because they are poorly insulated and waste a lot of heat. Despite relatively new insulation standards for new houses and subsidies for retrofitting older houses, our standards fall well below most developed countries.




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We can take inspiration from Europe where new buildings and retrofits are required to meet near-zero energy building standards. By investing in upgrading the national housing stock to something closer to European standards, we could achieve a significant drop in peak demand as well as additional benefits of lower household heating costs and better health.

Efficient lighting is another under-explored solution, with recent research suggesting a gradual uptake of energy-efficient lighting could reduce the winter evening peak demand (6pm to 8pm) by at least 9% by 2029, with the bonus of lower power bills for households.

Such solutions to the supply-demand mismatch could be much cheaper than a single think-big project, and they come with added benefits for health. Alongside the NZ$30 million being put into investigating pumped hydro storage, I suggest it is time to develop a business case for demand-side solutions.The Conversation

Janet Stephenson, Associate Professor and Director, Centre for Sustainability, University of Otago

This article is republished from The Conversation under a Creative Commons license. Read the original article.