recycling

vaporizing-plastics-recycles-them-into-nothing-but-gas

Vaporizing plastics recycles them into nothing but gas

chemistry, plastics, recycling, Science, Sustainability / /

Breakdown —

Polypropylene and polyethylene can be broken down simultaneously.

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A man stands next to piles of compressed plastic bottles.

Our planet is choking on plastics. Some of the worst offenders, which can take decades to degrade in landfills, are polypropylene—which is used for things such as food packaging and bumpers—and polyethylene, found in plastic bags, bottles, toys, and even mulch.

Polypropylene and polyethylene can be recycled, but the process can be difficult and often produces large quantities of the greenhouse gas methane. They are both polyolefins, which are the products of polymerizing ethylene and propylene, raw materials that are mainly derived from fossil fuels. The bonds of polyolefins are also notoriously hard to break.

Now, researchers at the University of California, Berkeley have come up with a method of recycling these polymers that uses catalysts that easily break their bonds, converting them into propylene and isobutylene, which are gasses at room temperature. Those gasses can then be recycled into new plastics.

“Because polypropylene and polyethylene are among the most difficult and expensive plastics to separate from each other in a mixed waste stream, it is crucial that [a recycling] process apply to both polyolefins,” the research team said in a study recently published in Science.

Breaking it down

The recycling process the team used is known as isomerizing ethenolysis, which relies on a catalyst to break down olefin polymer chains into their small molecules. Polyethylene and polypropylene bonds are highly resistant to chemical reactions because both of these polyolefins have long chains of single carbon-carbon bonds. Most polymers have at least one carbon-carbon double bond, which is much easier to break.

While isomerizing ethenolysis had been tried by the same researchers before, the previous catalysts were expensive metals that did not remain pure long enough to convert all of the plastic into gas. Using sodium on alumina followed by tungsten oxide on silica proved much more economical and effective, even though the high temperatures required for the reaction added a bit to the cost

In both plastics, exposure to sodium on alumina broke each polymer chain into shorter polymer chains and created breakable carbon-carbon double bonds at the ends. The chains continued to break over and over. Both then underwent a second process known as olefin metathesis. They were exposed to a stream of ethylene gas flowing into a reaction chamber while being introduced to tungsten oxide on silica, which resulted in the breakage of the carbon-carbon bonds.

The reaction breaks all the carbon-carbon bonds in polyethylene and polypropylene, with the carbon atoms released during the breaking of these bonds ending up attached to molecules of ethylene.“The ethylene is critical to this reaction, as it is a co-reactant,” researcher R.J. Conk, one of the authors of the study, told Ars Technica. “The broken links then react with ethylene, which removes the links from the chain. Without ethylene, the reaction cannot occur.”

The entire chain is catalyzed until polyethylene is fully converted to propylene, and polypropylene is converted to a mixture of propylene and isobutylene.

This method has high selectivity—meaning it produces a large amount of the desired product. That means propylene derived from polyethylene, and both propylene and isobutylene derived from polypropylene. Both of these chemicals are in high demand, since propylene is an important raw material for the chemical industry, while isobutylene is a frequently used monomer in many different polymers, including synthetic rubber and a gasoline additive.

Mixing it up

Because plastics are often mixed at recycling centers, the researchers wanted to see what would happen if polypropylene and polyethylene underwent isomerizing ethenolysis together. The reaction was successful, converting the mixture into propylene and isobutylene, with slightly more propylene than isobutylene.

Mixtures also typically include contaminants in the form of additional plastics. So the team also wanted to see whether the reaction would still work if there were contaminants. So they experimented with plastic objects that would otherwise be thrown away, including a centrifuge and a bread bag, both of which contained traces of other polymers besides polypropylene and polyethylene. The reaction yielded only slightly less propylene and isobutylene than it did with unadulterated versions of the polyolefins.

Another test involved introducing different plastics, such as PET and PVC, to polypropylene and polyethylene to see if that would make a difference. These did lower the yield significantly. If this approach is going to be successful, then all but the slightest traces of contaminants will have to be removed from polypropylene and polyethylene products before they are recycled.

While this recycling method sounds like it could prevent tons upon tons of waste, it will need to be scaled up enormously for this to happen. When the research team increased the scale of the experiment, it produced the same yield, which looks promising for the future. Still, we’ll need to build considerable infrastructure before this could make a dent in our plastic waste.

“We hope that the work described…will lead to practical methods for…[producing] new polymers,” the researchers said in the same study. “By doing so, the demand for production of these essential commodity chemicals starting from fossil carbon sources and the associated greenhouse gas emissions could be greatly reduced.”

Science, 2024. DOI: 10.1126/science.adq731

Vaporizing plastics recycles them into nothing but gas Read More »

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These household brands want to redefine what counts as “recyclable”

plastics, Policy, recycling, syndication / /
These household brands want to redefine what counts as “recyclable”

Olga Pankova/Moment via Getty Images

This story was originally published by ProPublica, a Pulitzer Prize-winning investigative newsroom. Sign up for The Big Story newsletter to receive stories like this one in your inbox.

Most of the products in the typical kitchen use plastics that are virtually impossible to recycle.

The film that acts as a lid on Dole Sunshine fruit bowls, the rings securing jars of McCormick dried herbs, the straws attached to Juicy Juice boxes, the bags that hold Cheez-Its and Cheerios—they’re all destined for the dumpster.

Now a trade group representing those brands and hundreds more is pressuring regulators to make plastic appear more environmentally friendly, a proposal experts say could worsen a crisis that is flooding the planet and our bodies with the toxic material.

The Consumer Brands Association believes companies should be able to stamp “recyclable” on products that are technically “capable” of being recycled, even if they’re all but guaranteed to end up in a landfill. As ProPublica previously reported, the group argued for a looser definition of “recyclable” in written comments to the Federal Trade Commission as the agency revises the Green Guides—guidelines for advertising products with sustainable attributes.

The association’s board of directors includes officials from some of the world’s richest companies, such as PepsiCo, Procter & Gamble, Coca-Cola, Land O’Lakes, Keurig Dr Pepper, Hormel Foods Corporation, Molson Coors Beverage Company, Campbell Soup, Kellanova, Mondelez International, Conagra Brands, J.M. Smucker, and Clorox.

Some of the companies own brands that project health, wellness, and sustainability. That includes General Mills, owner of Annie’s macaroni and cheese; The Honest Co., whose soaps and baby wipes line the shelves at Whole Foods; and Colgate-Palmolive, which owns the natural deodorant Tom’s of Maine.

ProPublica contacted the 51 companies on the association’s board of directors to ask if they agreed with the trade group’s definition of “recyclable.” Most did not respond. None said they disagreed with the definition. Nine companies referred ProPublica back to the association.

“The makers of America’s household brands are committed to creating a more circular economy which is why the industry has set sustainability goals and invested in consumer education tools” with “detailed recycling instructions,” Joseph Aquilina, the association’s vice president and deputy general counsel, wrote in an email.

The Green Guides are meant to increase consumer trust in sustainable products. Though these guidelines are not laws, they serve as a national reference for companies and other government agencies for how to define terms like “compostable,” “nontoxic” and “recyclable.” The Federal Trade Commission is revising the guides for the first time since 2012.

Most of the plastic we encounter is functionally not recyclable. It’s too expensive or technically difficult to deal with the health risks posed by the dyes and flame retardants found in many products. Collecting, sorting, storing and shipping the plastic for reprocessing often costs much more than plowing it into a landfill. Though some newer technologies have pushed the boundaries of what’s possible, these plastic-recycling techniques are inefficient and exist in such limited quantities that experts say they can’t be relied upon. The reality is: Only 5 percent of Americans’ discarded plastic gets recycled. And while soda bottles and milk jugs can be turned into new products, other common forms of plastic, like flimsy candy wrappers and chip bags, are destined for trash heaps and oceans, where they can linger for centuries without breaking down.

The current Green Guides allow companies to label products and packaging as “recyclable” if at least 60 percent of Americans have access to facilities that will take the material. As written, the guidelines don’t specify whether it’s enough for the facilities to simply collect and sort the items or if there needs to be a reasonable expectation that the material will be made into something new.

These household brands want to redefine what counts as “recyclable” Read More »

from-recycling-to-food:-can-we-eat-plastic-munching-microbes?

From recycling to food: Can we eat plastic-munching microbes?

food supply, microbes, plastic, recycling, Science, syndication / /

breaking it down —

Researchers are trying to turn plastic-eating bacteria into food source for humans.

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From recycling to food: Can we eat plastic-munching microbes?

Olga Pankova/Moment via Getty Images

In 2019, an agency within the US Department of Defense released a call for research projects to help the military deal with the copious amount of plastic waste generated when troops are sent to work in remote locations or disaster zones. The agency wanted a system that could convert food wrappers and water bottles, among other things, into usable products, such as fuel and rations. The system needed to be small enough to fit in a Humvee and capable of running on little energy. It also needed to harness the power of plastic-eating microbes.

“When we started this project four years ago, the ideas were there. And in theory, it made sense,” said Stephen Techtmann, a microbiologist at Michigan Technological University, who leads one of the three research groups receiving funding. Nevertheless, he said, in the beginning, the effort “felt a lot more science-fiction than really something that would work.”

That uncertainty was key. The Defense Advanced Research Projects Agency, or DARPA, supports high-risk, high-reward projects. This means there’s a good chance that any individual effort will end in failure. But when a project does succeed, it has the potential to be a true scientific breakthrough. “Our goal is to go from disbelief, like, ‘You’re kidding me. You want to do what?’ to ‘You know, that might be actually feasible,’” said Leonard Tender, a program manager at DARPA who is overseeing the plastic waste projects.

The problems with plastic production and disposal are well-known. According to the United Nations Environment Program, the world creates about 440 million tons of plastic waste per year. Much of it ends up in landfills or in the ocean, where microplastics, plastic pellets, and plastic bags pose a threat to wildlife. Many governments and experts agree that solving the problem will require reducing production, and some countries and US states have additionally introduced policies to encourage recycling.

For years, scientists have also been experimenting with various species of plastic-eating bacteria. But DARPA is taking a slightly different approach in seeking a compact and mobile solution that uses plastic to create something else entirely: food for humans.

The goal, Techtmann hastens to add, is not to feed people plastic. Rather, the hope is that the plastic-devouring microbes in his system will themselves prove fit for human consumption. While Techtmann believes most of the project will be ready in a year or two, it’s this food step that could take longer. His team is currently doing toxicity testing, and then they will submit their results to the Food and Drug Administration for review. Even if all that goes smoothly, an additional challenge awaits. There’s an ick factor, said Techtmann, “that I think would have to be overcome.”

The military isn’t the only entity working to turn microbes into nutrition. From Korea to Finland, a small number of researchers, as well as some companies, are exploring whether microorganisms might one day help feed the world’s growing population.

Two birds, one stone

According to Tender, DARPA’s call for proposals was aimed at solving two problems at once. First, the agency hoped to reduce what he called supply-chain vulnerability: During war, the military needs to transport supplies to troops in remote locations, which creates a safety risk for people in the vehicle. Additionally, the agency wanted to stop using hazardous burn pits as a means of dealing with plastic waste. “Getting those waste products off of those sites responsibly is a huge lift,” Tender said.

The Michigan Tech system begins with a mechanical shredder, which reduces the plastic to small shards that then move into a reactor, where they soak in ammonium hydroxide under high heat. Some plastics, such as PET, which is commonly used to make disposable water bottles, break down at this point. Other plastics used in military food packaging—namely polyethylene and polypropylene—are passed along to another reactor, where they are subject to much higher heat and an absence of oxygen.

Under these conditions, the polyethylene and polypropylene are converted into compounds that can be upcycled into fuels and lubricants. David Shonnard, a chemical engineer at Michigan Tech who oversaw this component of the project, has developed a startup company called Resurgent Innovation to commercialize some of the technology. (Other members of the research team, said Shonnard, are pursuing additional patents related to other parts of the system.)

From recycling to food: Can we eat plastic-munching microbes? Read More »

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“Energy-smart” bricks need less power to make, are better insulation

bricks, green, materials science, recycling, Science, Sustainability, waste / /
Image of a person holding a bag full of dirty looking material with jagged pieces in it.

Enlarge / Some of the waste material that ends up part of these bricks.

Seamus Daniel, RMIT University

Researchers at the Royal Melbourne Institute of Technology (RMIT) in Australia have developed special “energy-smart bricks” that can be made by mixing clay with glass waste and coal ash. These bricks can help mitigate the negative effects of traditional brick manufacturing, an energy-intensive process that requires large-scale clay mining, contributes heavily to CO2 emissions, and generates a lot of air pollution.

According to the RMIT researchers, “Brick kilns worldwide consume 375 million tonnes (~340 million metric tons) of coal in combustion annually, which is equivalent to 675 million tonnes of CO2 emission (~612 million metric tons).” This exceeds the combined annual carbon dioxide emissions of 130 million passenger vehicles in the US.

The energy-smart bricks rely on a material called RCF waste. It mostly contains fine pieces of glass (92 percent) left over from the recycling process, along with ceramic materials, plastic, paper, and ash. Most of this waste material generally ends up in landfills, where it can cause soil and water degradation. However, the study authors note, “The utilization of RCF waste in fired-clay bricks offers a potential solution to the increasing global waste crisis and reduces the burden on landfills.”

What makes the bricks “energy-smart”

Compared to traditional bricks, the newly developed energy-smart bricks have lower thermal conductivity: They retain heat longer and undergo more uniform heating. This means they can be manufactured at lower firing temperatures. For instance, while regular clay bricks are fired (a process during which bricks are baked in a kiln, so they become hard and durable) at 1,050° C, energy-smart bricks can achieve the required hardness at 950° C, saving 20 percent of the energy needed for traditional brickmaking.

Based on bricks produced in their lab, they estimated that “each firing cycle led to a potential value of up to $158,460 through a reduction of 417 tonnes of CO2, resulting from a 9.5 percent reduction in firing temperature.” So basically, if a manufacturer switches from regular clay bricks to energy-smart bricks, it will end up saving thousands of dollars on its power bill, and its kilns will release less CO2 into Earth’s atmosphere. Scaled up to the estimated 1.4 trillion bricks made each year, the savings are substantial.

But brick manufacturers aren’t the only ones who benefit. “Bricks characterized by low thermal conductivity contribute to efficient heat storage and absorption, creating a cooler environment during summer and a warmer comfort during winter. This advantage translates into energy savings for air conditioning, benefiting the occupants of the house or building,” the study authors explained.

Tests conducted by the researchers suggest that the residents of a single-story house built using energy-smart bricks will save up to 5 percent on their energy bills compared to those living in a house made with regular clay bricks.

“Energy-smart” bricks need less power to make, are better insulation Read More »

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Fairbuds are Fairphone’s proof that we really could make better tiny gadgets

airpods, Apple, e-waste, electronics recycling, fairbuds, fairphone, recycling, Tech, wireless earbuds / /

Wireless earbud repairability —

Swap the batteries, tips, charging case, shell, or even just individual buds.

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Fairbuds with all their components laid out on a blue background

Enlarge / The Fairbuds and their replaceable components, including the notably hand-friendly, non-soldered batteries.

Fairphone

Fairphone has spent years showing us that it could do what major phone manufacturers suggest is impossible: make a modern-looking phone, make it brazenly easy to open up, design it so battery swaps are something you could do on lunch break, and also provide software support for an unbelievable eight to 10 years.

Bluetooth headphones, specifically wireless earbuds, seemed destined to never receive this kind of eco-friendly, ownership-oriented upgrade, in large part because of how small they are. But the Fairbuds have arrived, and Fairphone has made them in its phones’ image. They’re only available in the EU at the moment, for 149 euro (or roughly $160 USD). Like the Fairphone 4, there’s a chance interest could bring them to the US.

The highlights include:

  • Seven replaceable parts from the buds and charging case, all sold by Fairphone
  • A two-year warranty, expanded to three if you register them
  • Batteries in both the case and buds that are replaceable
  • IP54 sweat and water resistance
  • Individual left or right buds and a charging case that Fairphone will sell to you
  • Made with “fair and recycled materials,” in “fair factories,” and “climate conscious and electronic waste neutral,” (as explained by Fairphone).

Of course, the buds also, you know, produce sound, with 11 mm titanium drivers. The Fairbuds sport active noise-canceling and ambient sound modes, Bluetooth 5.3 with “dual point connectivity” for quick-switching between devices, and a Fairbuds app for customizing EQ and preset settings. The buds’ 45 mAh batteries carry about six hours of listening per charge, and their 500 mAh case adds another 20 hours.

  • Fairbuds in exploded view.

    Fairphone

  • Fairbuds and their charging case, which also come in black.

    Fairphone

  • The battery removal process from a Fairbud.

    Fairphone

  • Closeup on the white Fairbuds.

    Fairphone

  • The back of the Fairbuds charging case and a battery you just… put into it. With your fingers. I’m sorry, it’s weird to type that now.

    Fairphone

It’s not Fairphone’s first foray into fair, repairable sound devices. The firm previously made the since-discontinued True Wireless Stereo Earbuds and still offers Fairbuds XL, which are not buds at all but full over-ear headphones (and also EU-only).

The best that major-brand earbuds have ever done in repairability is “maybe you can do it, if you’re careful, and you don’t mind losing water resistance.” Taylor Dixon took apart six buds for iFixit back in 2020, and only Sony’s WF-1000XM3 didn’t require soldering, cutting and re-applying glue, and a steady hand working in very small spaces.

AirPods? AirPods are something else. One firm, The Swap Club, has figured out some means of getting the battery out of AirPods and selling them refurbished. But they only accept regular AirPods, not AirPods Pro. Alternatively, Apple will send you a pre-paid label to send in your spent AirPods for recycling, though with no trade-in credit. Even if Apple gets some kind of material out of the AirPods, a lot of them (and nearly every other wireless earbud) end up as waste after 18 months or however long their batteries last.

Fairbuds may or may not take a big chunk out of the market for AirPods, Beats, Pixel Buds, or other use-and-toss airbuds. But at a minimum, they give people something to point to as proof this category could be a lot better.

Disclosure: Kevin Purdy used to work for iFixit. He has no financial ties to the company.

Listing image by Fairphone

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Urban agriculture’s carbon footprint can be worse than that of large farms

agriculture, farming, plants, recycling, Science, Sustainability, urban farming / /

Greening your greens —

Saving on the emissions associated with shipping doesn’t guarantee a lower footprint.

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Lots of plants in the foreground, and dense urban buildings in the background

A few years back, the Internet was abuzz with the idea of vertical farms running down the sides of urban towers, with the idea that growing crops where they’re actually consumed could eliminate the carbon emissions involved with shipping plant products long distances. But lifecycle analysis of those systems, which require a lot of infrastructure and energy, suggest they’d have a hard time doing better than more traditional agriculture.

But those systems represent only a small fraction of urban agriculture as it’s practiced. Most urban farming is a mix of local cooperative gardens and small-scale farms located within cities. And a lot less is known about the carbon footprint of this sort of farming. Now, a large international collaboration has worked with a number of these farms to get a handle on their emissions in order to compare those to large-scale agriculture.

The results suggest it’s possible that urban farming can have a lower impact. But it requires choosing the right crops and a long-term commitment to sustainability.

Tracking crops

Figuring out the carbon footprint of urban farms is a challenge, because it involves tracking all the inputs, from infrastructure to fertilizers, as well as the productivity of the farm. A lot of the urban farms, however, are nonprofits, cooperatives, and/or staffed primarily by volunteers, so detailed reporting can be a challenge. To get around this, the researchers worked with a lot of individual farms in France, Germany, Poland, the UK, and US in order to get accurate accounts of materials and practices.

Data from large-scale agriculture for comparison is widely available, and it includes factors like transport of the products to consumers. The researchers used data from the same countries as the urban farms.

On average, the results aren’t good for urban agriculture. An average serving from an urban farm was associated with 0.42 kg of carbon dioxide equivalents. By contrast, traditional produce resulted in emissions of about 0.07 kg per serving—six times less.

But that average obscures a lot of nuance. Of the 73 urban farms studied, 17 outperformed traditional agriculture by this measure. And, if the single highest-emitting farm was excluded from the analysis, the median of the urban farms ended up right around that 0.7 kg per serving.

All of this suggests the details of urban farming practices make a big difference. One thing that matters is the crop. Tomatoes tend to be fairly resource-intensive to grow and need to be shipped quickly in order to be consumed while ripe. Here, urban farms came in at 0.17 kg of carbon per serving, while conventional farming emits 0.27 kg/serving.

Difference-makers

One clear thing was that the intentions of those running the farms didn’t matter much. Organizations that had a mission of reducing environmental impact, or had taken steps like installing solar panels, were no better off at keeping their emissions low.

The researchers note two practical reasons for the differences they saw. One is infrastructure, which is the single largest source of carbon emissions at small sites. These include things like buildings, raised beds, and compost handling. The best sites the researchers saw did a lot of upcycling of things like construction waste into structures like the surrounds for raised beds.

Infrastructure in urban sites is also a challenge because of the often intense pressure on land, which can mean gardens have to relocate. This can shorten the lifetime of infrastructure and increase its environmental impact.

Another major factor was the use of urban waste streams for the consumables involved with farming. Composting from urban waste essentially eliminated fertilizer use (it was only 5 percent of the rate of conventional farming). Here, practices matter a great deal, as some composting techniques allow the material to become oxygen-free, which results in the anaerobic production of methane. Rainwater use also made a difference; in one case, the carbon impact of water treatment and distribution accounted for over two-thirds of an urban farm’s emissions.

These suggest that careful planning could make urban farms effective at avoiding some of the carbon emissions of conventional agriculture. This would involve figuring out best practices for infrastructure and consumables, as well as targeting crops that can have high carbon emissions when grown on conventional farms.

But any negatives are softened by a couple of additional considerations. One is that even the worst-performing produce seen in this analysis is far better in terms of carbon emissions than eating meat. The researchers also point out that many of the cooperative gardens provide a lot of social functions—things like after-school programs or informal classes—that can be difficult to put an emissions price on. Maximizing these could definitely boost the societal value of the operations, even if it doesn’t have a clear impact on the environment.

Nature Cities, 2019. DOI: 10.1038/s44284-023-00023-3  (About DOIs).

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