EarthTalk®

Dear EarthTalk: What’s the environmental impact of these dockless e-scooters I see all over town now? -- Jim M. Salisbury, CT

By now, you’ve certainly seen dockless e-scooters in your town or somewhere nearby. Some 85,000 of these electric-powered, phone-unlockable mini-vehicles crowd the streets and sidewalks of 100 different metro areas across the U.S. In 2018 they surpassed dockless e-bikes as the most common app-rentable transport option nationwide, with riders taking them on some 38.5 million trips.

These e-scooters are often marketed as “green” or “carbon-neutral” because they run off electric batteries instead of fossil fuels, but consumers shouldn’t think they’re getting a completely guilt-free ride. A recent lifecycle analysis from North Carolina State University assessing the “cradle-to-grave” environmental impact of e-scooters found that bicycling, walking and buses are all “greener” ways to get around.

A rider hopping on an e-scooter doesn’t necessarily think about the carbon emissions and other impacts involved with manufacturing, transporting and maintaining these otherwise low-impact electric vehicles. “If you only think about the segment of the life cycle you can see, which would be standing on the e-scooter where there’s no tailpipe, it’s easy to make that assumption,” says Jeremiah Johnson, an NC State professor and study co-author. “But if you take a step back, you can see all the other things that are a bit hidden in the process.”

While relatively light and small, e-scooters must carry a battery in addition to their basic frame and electronic systems. Producing these batteries takes a heavy toll on the environment, although no worse than similar types of batteries used in e-bikes and even electric cars. Besides the batteries, the aluminum used to create the e-scooters’ frames and the rubber for their tires add to their environmental footprint.

The NC State researchers found that about half of an e-scooter’s carbon footprint is created during production, while most of the rest (43 percent) comes from collecting and recharging them every night. In general, e-scooters are charged by freelance workers known as “juicers.” At the end of each day, they take e-scooters off the street and typically charge them up at home via their own power outlets (likely not from renewable sources). Furthermore, the majority of juicers pick up e-scooters in gas-powered cars or trucks. The upshot is that the common charging process is a long way from being carbon neutral.

That said, e-scooters are currently about twice as efficient as the average car in per passenger miles per gallon (in this case CO2 units emitted per passenger carried a distance of one mile). However, a car carrying more than one passenger can reach the same or even better levels of efficiency as an e-scooter. Buses, when fully loaded, easily beat e-scooters in per passenger efficiency, while bicycles easily beat buses.

Of course, e-scooters are sure to become more efficient in the future as both the production and pick-up processes get greener. As a consumer, you can improve the situation by using e-scooters to replace car trips, but bikes or buses are still a better choice as far as the planet is concerned.

CONTACT: “Are E-Scooters Polluters? The Environmental Impacts of Shared Dockless Electric Scooters,” iopscience.iop.org/article/10.1088/1748-9326/ab2da8

Dear EarthTalk: How is it that fungi can help clean up contaminated soils? – M. Sharpe, Canton, CT

Like animals, fungi derive energy by breaking down large molecules into smaller compounds. They do so by secreting enzymes and acids onto whatever it is they intend to consume, and then absorbing the byproducts of this digestion process. While fungi primarily consume biological matter (like dead wood), their enzymes can also break down a wide array of man-made compounds. In fact, fungi are so good at this, we’re now employing them to clean up contaminated soils via a technique known as mycoremediation.

Of course, these fungi are just doing what they evolved to do eons ago. Underneath our feet, massive fungal networks run through the soil, with many fungal species developing a symbiotic relationship with plants whereby a part of the fungus (the mycelium) grows adjacent to—and sometimes inside of—the roots of the plant. The mycelium is capable of breaking down and transporting nutrients and minerals essential for the plant’s survival. After detecting and digesting these compounds, the mycelium ferries them to the plant’s roots, where they’re absorbed. In exchange, the plant releases compounds that are vital for the fungi’s survival.

It’s the fungi’s ability to break down and/or transport compounds that make them useful for restoring damaged soils. Often, these soils have been saturated with compounds made up of dangerous—and relatively large—molecules. By breaking these molecules into smaller pieces, fungi help to reduce their toxicity. In other instances, soils are contaminated with fundamental elements such as cadmium, arsenic, and mercury, which can’t be broken down. However, fungi still have the ability to uptake and transport these substances, and to eventually concentrate them in their fruiting bodies (mushrooms). We can then remove the fruiting bodies, and the contaminated ecosystem will be one step closer to regaining health.

Fungi can break down and/or absorb a wide range of compounds, including oil and other petroleum products, PAHs, PCBs, PCPs, neurotoxins, airborne pollutants, synthetic dyes, cadmium, lead, arsenic, mercury, copper, dioxins and organophosphates.

If fungi are so effective at cleaning up our environment, why isn’t this technique more widespread? For starters, it’s a slow process. As with any biological strategy for environmental clean-up, mycoremediation is limited by the speed of metabolism. If a polluted area needs to be cleaned quickly, other options may be better. Another issue with mycoremediation is that it often fails to completely rid soil of a given toxic compound, instead simply reducing the concentration. It can also be hard to justify economically, as no one wants to eat a mushroom full of heavy metals.

However, the biggest reason for mycoremediation’s relative lack of fame and use might simply be a lack of data from field tests. It’s a relatively new technique, without many case studies to support its use (despite a good amount of lab testing). Thankfully, this situation is changing. In 2017, for example, a large batch of oyster mushrooms was used to remediate soil damaged by California wildfires. The same variety of fungus has also been used to clean up oil spills and other toxic messes.

CONTACTS: Fantastic Fungi Film, fantasticfungi.com; “Mushroom as a product and their role in mycoremediation,” ncbi.nlm.nih.gov/pmc/articles/PMC4052754/; “Untapped potential: exploiting fungi in bioremediation of hazardous chemicals,” nature.com/articles/nrmicro2519.

Dear EarthTalk: Is switching out meat for edible bugs to satisfy our protein needs a viable way to ratchet down our carbon emissions and overall environmental impact? -- J. Cruz., Gary, IN

It’s true that humans’ affinity for meat—especially beef, lamb, pork and to a lesser extent chicken—takes a huge toll on the environment given the resources and emissions expended to rear and then transport it to market. In fact, the UN’s Food & Agriculture Organization (FAO) reports that raising livestock accounts for some 18 percent of all greenhouse gas emissions globally. Meanwhile, on the consumption side, cutting meat out of our diets is perhaps the most efficient way we can slash our personal carbon footprints. But eating only vegetables can make it hard to get enough protein, and that’s where bugs—with half or more of their body weight consisting of proteins—could play an important role in providing us with enough sustenance to feed ourselves, especially as our population surges to nine billion by 2050.

Proponents of eating bugs argue that emissions from so-called “insect farming”—that is, growing bugs for the express purpose of feeding humans and/or animals with them—is a much more energy- and emissions-efficient way to produce protein than traditional forms of livestock agriculture. “If we bartered beef, pork or chicken for a handful of insects, the environmental impact of our animal-protein intake would drop dramatically,” says Canadian environmentalist David Suzuki. “Insects are especially effective at converting their food because they’re cold-blooded and therefore waste less energy to keep warm.”

If you’re curious about edible insects, why not try some? Lewiston, Maine-based EdibleInsects.com ships edible insects coast to coast. UK-based PureGym is a big proponent of deriving dietary protein from insects, and offers several seemingly tasty recipes on its website and YouTube channel. Creamy Mealworm and Coconut Noodles, anyone?

Of course, just because crickets, ants, cockroaches and worms are becoming more common as food delicacies doesn’t mean that eating them is new for humans. The FAO points out in its “Edible Insects” report that while bugs have always been part of human diets, recent innovations in so-called “mass-rearing systems” mean we can produce a lot more insect-based protein than we used to: “Insects offer a significant opportunity to merge traditional knowledge and modern science in both developed and developing countries.”

Suzuki couldn’t agree more: “Emerging entotechnologies (from the Greek root entomo, for ‘insect’) bring together applications that focus on what insects do best.” For instance, food waste or agricultural residue is fed to fly larvae, which in turn is used as a meat-free but protein-rich livestock feed. “[L]arvae have voracious appetites for fruit and vegetable residues and could help improve the way we handle...organic waste,” reports Suzuki. “It’s a way to give a second life to stale food, rather than sending it to compost bins or biogas plants.”

“Considering that nearly 45 percent of fruit and vegetables produced worldwide is wasted, this is not a fringe idea,” says Suzuki. “After feeding the hungry with the highest quality unsold portions of our food, we could feed our breeding animals with insects raised on organic residues from grocery stores and restaurant kitchens.”

CONTACTS: David Suzuki’s “Save The Planet: Eat An Insect,” davidsuzuki.org/story/save-planet-eat-insect/; FAO’s “Edible Insects,” fao.org/3/i3253e/i3253e.pdf; PureGym, puregym.com.

EarthTalk® is produced by Roddy Scheer & Doug Moss for the 501(c)3 nonprofit EarthTalk. See more at https://emagazine.com. To donate, visit https://earthtalk.org. Send questions to: question@earthtalk.org.