E-bikes

E-bikes have captured widespread attention across the U.S., and for good reason. They are the most energy-efficient way to move from place to place, providing exercise in the process, and offer enough assistance while pedaling uphill or into headwinds to make them usable for many types of riders. Greenhouse gas emissions from e-bikes are much lower than those from either gasoline-powered or electric cars. Some cities and states are encouraging the use of e-bikes by providing purchase incentives, often drawing on public funds dedicated to curbing climate change. Currently, over 100 cities and states have or plan to launch e-bike incentive programs, most funded by energy or environment initiatives. However, there has been little research on the effectiveness of these types of programs, how to design them or how to define goals. We study transportation from many angles, including innovation, sustainability and economics. Our new study, published in the journal Transportation Res...

In a newly published study, we describe our design for a self-extinguishing rechargeable battery. It replaces the most commonly used electrolyte, which is highly combustible – a medium composed of a lithium salt and an organic solvent – with materials found in a commercial fire extinguisher. An electrolyte allows lithium ions that carry an electric charge to move across a separator between the positive and negative terminals of a lithium-ion battery. By modifying affordable commercial coolants to function as battery electrolytes, we were able to produce a battery that puts out its own fire. Our electrolyte worked well across a wide temperature range, from about minus 100 to 175 degrees Fahrenheit (minus 75 to 80 degrees Celsius). Batteries that we produced in the lab with this electrolyte transferred heat away from the battery very well, and extinguished internal fires effectively. We subjected these batteries to the nail penetration test, a common method for ass...

In today’s electronic age, rechargeable lithium-ion batteries are ubiquitous. Compared with the lead-acid versions that have dominated the battery market for decades, lithium-ion batteries can charge faster and store more energy for the same amount of weight. These devices make our electronic gadgets and electric cars lighter and longer-lasting – but they also have disadvantages. They contain a lot of energy, and if they catch fire, they burn until all of that stored energy is released. A sudden release of huge amounts of energy can lead to explosions that threaten lives and property. As scientists who study energy generation, storage and conversion, and automotive engineering, we have a strong interest in the development of batteries that are energy-dense and safe. And we see encouraging signs that battery manufacturers are making progress toward solving this significant technical problem. Avoiding overcharging is one way to reduce the ris...

The race to decarbonize passenger cars and light-duty trucks in the U.S. is accelerating. Battery electric vehicles accounted for almost 6% of all new vehicle sales in 2022, up from close to 3% in 2021, and demand is outstripping supply, even as manufacturers roll out new models and designs. The Biden administration is spending billions of dollars to build out EV charging networks and providing incentives for purchasing new and used EVs. This shift offers big economic and environmental benefits, but they’re not spread equitably. People who bear the most burdens in our current transportation systems often receive the fewest benefits, and are least able to change their situations. I study the future of clean transportation and energy, and my research analyzes equity considerations in the design of these systems. As my colleagues and I see it, an equitable transition will require thinking broadly about all transportation users and their needs – especially those who are...

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to curiouskidsus@theconversation.com. How many Amazon packages get delivered each year? – Aya K., age 9, Illinois It’s incredibly convenient to buy something online, right from your computer or phone. Whether it’s a high-end telescope or a resupply of toothpaste, the goods appear right at your doorstep. This kind of shopping is called “e-commerce” and it’s becoming more popular each year. In the U.S., it has grown from a mere 7% of retail purchases in 2012 to 19.6% of retail and US$791.7 billion in sales in 2020. Amazon’s growing reach For Amazon, the biggest player in e-commerce, this means delivering lots of packages. In 2021 the company shipped an estimated 7.7 billion packages globally, based on its nearly $470 billion in sal...