Enlarge / Airbus will be testing hydrogen power on a commercial airliner modified to carry an additional engine. (credit: Airbus )

A complete hydrogen fuel cell powertrain assembly occupied the pride of place in the pavilion of Beyond Aero at the recently concluded Paris Air Show. That a fuel cell system was the Toulouse-based startup’s centerpiece at the biennial aero event is an indication of the steps being taken by a range of companies, from startups to multinational corporations, toward realizing the goal of using hydrogen as fuel in the aviation sector.

“This 85 kilowatt subscale demonstrator was successfully tested a few months ago. Even though in its current form, it serves only ultralight aviation, the successful test of the powertrain is a crucial step in our technical development path for designing and building a business aircraft,” Beyond Aero co-founder Hugo Tarlé told Ars Technica.

Tarlé said that the business aircraft would have a range of 800 nautical miles and will be powered by a 1 MW powertrain. “For generating this power, there won’t be one big megawatt fuel cell. Instead, it will be multiple fuel cells. It will be based on the same technical choices that we made on the subscale demonstrator—i.e. gaseous hydrogen, fuel cell, hybridization of batteries and electric motors."

Enlarge / This woody desert shrub called guayule could be coming to a tire near you before too long. (credit: Cassidy Araiza/Bloomberg via Getty Images)

In 2022, the tire company Bridgestone used the IndyCar racing series to debut a new sustainable natural rubber that it has been testing as a replacement for less environmentally friendly rubber. The new tires used rubber from a desert shrub called guayule ( Parthenium argentatum ). Now, Bridgestone is ready to try the rubber in a more practical application and has produced a demonstration run of road-going tires using guayule rubber and a high percentage of recycled materials. The company will conduct tests with automakers to prove the concept.

The world produces about 2 billion tires each year, and while synthetic rubbers are used in modest amounts, most road tires use a lot of natural rubber from the para rubber tree ( Hevea brasiliensis ). But 90 percent of para rubber is grown in Southeast Asia and has to be shipped around the world to reach tire factories.

Bridgestone has been looking at guayule as an alternative for a little over a decade now. The guayule plant is a short, woody shrub that grows easily in the deserts of the American southwest and requires much less water than crops such as alfalfa or cotton, which are grown in places like Arizona, where Bridgestone has been breeding guayule and conducting research and development on its use in tire-making.

Enlarge / F1 cars use engines with thermal efficiencies that even a Prius could only dream about. They are not the cause of the sport's carbon footprint. (credit: Dan Istitene - Formula 1/Formula 1 via Getty Images)

Formula 1 might be a sport, but it's also a $2.6 billion business with shareholders, and like pretty much every other multibillion-dollar business with shareholders, that means it's under increasing scrutiny regarding the amount of carbon emissions it's responsible for. Currently, that's about 250,000 tons a year, but the sport says it wants to reduce that to net zero by 2030. I spoke with F1's chief sustainability to learn more about how it's doing that, and you may be surprised to learn that race cars have very little to do with it.

While F1's carbon footprint is just a fraction of other global sporting events like the Olympics or World Cup, it's a more visible target, considering it involves cars driving around a track burning gasoline. But focusing only on the cars is a mistake.

Forget the cars

For one thing, since the introduction of hybrid powertrains in 2014, F1 cars have become extremely efficient. There are a pair of hybrid systems —one that captures energy under braking and another that captures energy from exhaust gases—and the 1.6 L V6s burn their gasoline more efficiently than any other internal combustion engine ever made, approaching or perhaps even passing 50 percent now .

Enlarge (credit: Aurich Lawson | Getty Image)

On May 22, 2022, I began an experiment. I unplugged everything in my apartment, with the goal of drawing zero power from the electric grid for one month. I had no idea how I would make it past a few days.

Nevertheless, I opened the main circuit, disconnecting my apartment from the grid and committing myself to solving what problems arose as they came. As I type these words in January, I’m in my eighth month. My Con-Ed bills continue to show zero kilowatt-hours.

Ars Technica readers undoubtedly want to know about my equipment. We’ll get there, but first let me share my history, motivation, and constraints.

Enlarge / In addition to getting faster over the years, F1 cars have also gotten far more efficient. And that's only going to increase in the coming years. (credit: Jared C. Tilton/Getty Images)

When Formula 1 cars take to the track for the first time in 2026 , they'll do so powered by carbon-neutral synthetic fuels, part of the sport's "net zero by 2030" plan. It's a laudable goal, but, I confess, one I've sometimes questioned. After all, most of the carbon emitted during the course of an F1 weekend comes from the same sources as any other popular sport— the teams and fans traveling to and from the event. But after speaking with Pat Symonds, Formula 1's chief technical officer, I may have been missing the forest for the trees.

"In essence, yes, you're quite right. The total carbon footprint of the sport—of scope 1, 2—is just over a quarter million tonnes of CO ₂ equivalent, and the cars on the circuit represent 0.7 percent of that," Symonds explained to me. "So yes, your premise is true. But we try and take a much wider view. And what I think we have in developing a sustainable fuel and putting it in our race cars is an enormous multiplier effect. The 2 billion vehicles that are out there could use this fuel, and then the 400,000 people driving to [the US Grand Prix] isn't a problem," he said.

Formula 1 has changed quite a bit in the years since Liberty Media bought it at the end of 2016 with bigger ideas than simply sucking revenue out. Instead of pretending the Internet never happened, you can now watch races via F1's own streaming service, a service that has markedly improved over the past couple of years. In the US, a move to ESPN saw the sport go commercial-free during the actual races. And, of course, there's the whole Drive to Survive phenomena, which has boosted audiences worldwide—but particularly in North America, which next year will host grands prix in Austin, Texas; Miami; and Las Vegas.

Enlarge (credit: Yagi Studio )

While it’s relatively straightforward to compare the environmental footprint of producing apples versus oranges (or even beef), these calculations become much trickier when foods contain multiple ingredients—and these make up the majority of what’s sold in a typical grocery store. Up until now, there haven’t been good methods to determine the impact of such foods, but a team at Oxford has recently published some of the first work toward developing a sustainability metric for everything (edible) one might find at their local grocer.

Beyond the approach’s sustainability estimates, the Oxford team went on to cross-reference its results with the standard nutrition metric NutriScore. With this, they found that there were many “win-wins” where foods were both sustainable and nutritious—although there were a few notable exceptions. And, while the results weren’t too surprising, this method offers a new metric for consumers, retailers, and producers to make more informed choices.

Secret recipes

One of the biggest hurdles to calculating the sustainability of multi-ingredient foods is that producers are rarely required to list how much of each ingredient they put into a product. Quite the opposite—these details are often closely kept trade secrets.

Scientists from The Hebrew University of Jerusalem have created wood ink that can be extruded into flat wooden structures, self-morphing into complex 3D shapes as they dry and shrink. The researchers presented their research at last week's meeting of the American Chemical Society in Chicago. The technique could one day be used to make furniture or other wooden products that could be shipped flat to a destination and then dried to form the desired final shape.

As we've reported previously , developing novel shapeshifting materials is a very active area of research because there are so many promising applications, such as building artificial muscles—man-made materials, actuators, or similar devices that mimic the contraction, expansion, and rotation (torque) characteristics of the movement of natural muscle. The shape change comes about in response to an outside stimulus.

For instance, most artificial muscles are designed to respond to electric fields (such as electroactive polymers ), changes in temperature (such as shape-memory alloys and fishing line ), and changes in air pressure via pneumatics . In 2019, a team of Japanese researchers spiked a crystalline organic material with a polymer to make it more flexible, demonstrating their proof of concept by using their material to make an aluminum foil paper doll do sit-ups.

Enlarge (credit: Peter Dazeley )

Removing urine from wastewater and using it as fertilizer has the potential to decrease nutrient loading in water bodies and boost sustainability by making use of a common waste material.

In excess, nitrogen and phosphorus in our waste streams can stimulate algal blooms and create conditions dangerous to marine and lake ecosystems and human health. According to the website of the Rich Earth Institute, a Vermont-based company focused on using human waste as a resource, most of the nitrogen and phosphorus in wastewater comes from human urine, even though it makes up only 1 percent of wastewater. Removing urine could remove 75 percent of the nitrogen and 55 percent of the phosphorus from municipal wastewater treatment plants. And those nutrients could then be recycled for use as fertilizer.

The rub is against systems that are used to the way things are. Wastewater infrastructure is set up to get waste out of the house, without much thought, using pipes that already exist and toilets people are used to. Urine diversion would require changing some of these details, while putting the diverted material to use will need more acceptance of waste as valuable.

Enlarge (credit: Getty Images )

Almost every aspect of modern society relies on materials that are limited on Earth. In order to live within the limits set by our planet, we have to figure out how to make the most of what we extract and reuse whatever we have extracted. A new study released this week looks into how close we are to reaching that ideal for 61 different metals.

Along the way, its authors figure out how long different metals stay in circulation before they're lost and identify the stage at which those losses take place. While a lack of recycling is a major roadblock on the way to a circular economy, it's far from the only one. For many metals, including some critically important ones, we discard huge amounts that are present in ores we mine for different elements.

Mind your metals

Tracking that many metals through their entire life cycle is a huge task, but the authors were able to build on previous work by Japanese researchers who developed a software model called MaTrace . The model is designed to track the flow of materials from production to loss, estimating losses at each stage of the material's life cycle based on empirical data.