Engineering

Summer 2024’s record heat is creating problems for transportation infrastructure, from roads to rails. New York’s Third Avenue Bridge, which swings open for ship traffic on the Harlem River, was stuck for hours after its metal expanded in the heat and it couldn’t close. Roads have buckled on hot days in several states, including Washington and Wisconsin. Amtrak warned passengers to prepare for heat-related problems hours before a daylong outage between New York and New Jersey; the risks to power lines and rails during high temperatures are a growing source of delays for the train system. It doesn’t help that the worsening heat is hitting a U.S. infrastructure system that’s already in trouble. The American Society of Civil Engineers gave U.S. infrastructure an overall grade of C- in its latest national Infrastructure Report Card, released in 2021. While there has been some improvement – about 7.5% of U.S. bridges were in poor condition, compar...

Rechargeable batteries are great for storing energy and powering electronics from smartphones to electric vehicles. In cold environments, however, they can be more difficult to charge and may even catch on fire. I’m a mechanical engineering professor who’s been interested in batteries since college. I now lead a battery research group at Drexel University. In just this past decade, I have watched the price of lithium-ion batteries drop as the production market has grown much larger. Future projections predict the market could reach thousands of GWh per year by 2030, a significant increase. But, lithium-ion batteries aren’t perfect – this rise comes with risks, such as their tendency to slow down during cold weather and even catch on fire. Behind the Li-ion battery The electrochemical energy storage within batteries works by storing electricity in the form of ions. Ions are atoms that have a nonzero charge because they have either too many or not eno...

Acapulco wasn’t prepared when Hurricane Otis struck as a powerful Category 5 storm on Oct. 25, 2023. The short notice as the storm rapidly intensified over the Pacific Ocean wasn’t the only problem – the Mexican resort city’s buildings weren’t designed to handle anything close to Otis’ 165 mph winds. While Acapulco’s oceanfront high-rises were built to withstand the region’s powerful earthquakes, they had a weakness. Since powerful hurricanes are rare in Acapulco, Mexico’s building codes didn’t require that their exterior materials be able to hold up to extreme winds. In fact, those materials were often kept light to help meet earthquake building standards. Otis’ powerful winds ripped off exterior cladding and shattered windows, exposing bedrooms and offices to the wind and rain. The storm took dozens of lives and caused billions of dollars in damage. A US$130 million lu...

Hundreds of millions of tons of single-use plastic ends up in landfills every year, and even the small percentage of plastic that gets recycled can’t last forever. But our group of materials scientists has developed a new method for creating and deconstructing polymers that could lead to more easily recycled plastics – ones that don’t require you to carefully sort out all your recycling on trash day. In the century since their conception, people have come to understand the enormous impacts – beneficial as well as detrimental – plastics have on human lives and the environment. As a group of polymer scientists dedicated to inventing sustainable solutions for real-world problems, we set out to tackle this issue by rethinking the way polymers are designed and making plastics with recyclability built right in. Why use plastics, anyway? Everyday items including milk jugs, grocery bags, takeout containers and even ropes are made from a class of polymers...

Not only people need to stay cool, especially in a summer of record-breaking heat waves. Many machines, including cellphones, data centers, cars and airplanes, become less efficient and degrade more quickly in extreme heat. Machines generate their own heat, too, which can make hot temperatures around them even hotter. We are engineering researchers who study how machines manage heat and ways to effectively recover and reuse heat that is otherwise wasted. There are several ways extreme heat affects machines. No machine is perfectly efficient – all machines face some internal friction during operation. This friction causes machines to dissipate some heat, so the hotter it is outside, the hotter the machine will be. Cellphones and similar devices with lithium ion batteries stop working as well when operating in climates above 95 degrees Farenheit (35 degrees Celsius) – this is to avoid overheating and increased stress on the electronics. Cooling designs that use inn...