Today: X-Energy is developing industrial-size modular reactors as demand for clean energy soars; rotary combustion engine could be bridge to hybrid electric vehicles; Bezos Earth Fund donates $34 million in fashion grants.

Welcome back: Less than three years ago, X-Energy scrapped a public offering after investors showed little interest.

The Wall Street Journal's Gregory Zuckerman reports that on Friday, the nuclear-energy company's shares closed up 27% in their stock market debut, giving the startup a market valuation of around $11.5 billion. 

Founded in 2009 by aerospace veteran Kamal “Kam” Ghaffarian, X-Energy spent years developing industrial-size modular nuclear reactors to produce energy for factories and other industrial facilities. 

In 2024, Amazon became both an investor and a client. The tech giant, which has backed nuclear-power projects across the U.S. and is eager to get energy from small, modular reactors, has received a commitment of more than five gigawatts of new nuclear energy from X-Energy.

Hyperscalers including Amazon, Microsoft and Meta have a growing demand for electricity to power massive data centers and manage AI processing, sparking enthusiasm for nuclear power.

• The U.S. still produces more electricity from nuclear energy than any other nation, but China’s buildout is closing the gap. (Canary Media)

Amid declining sales of electric vehicles in the U.S., one company is taking a fresh look at old combustion tech. LiquidPiston is developing a new type of rotary engine and is looking at new ways for gas and battery power to work together, the Journal's Christopher Mims writes.

The company's “inside-out Wankel” engine can run on everything from diesel to jet fuel, while being a fraction of the size of a comparable diesel engine, and up to 30% more efficient than a comparable gasoline one.

The U.S. Army and Air Force are both watching. Over the past decade, the Defense Department, including its cutting-edge research-funding body Darpa, has pumped tens of millions of dollars into the company. LiquidPiston’s engine is suited to powering long-range hybrid drones.

Some experts envisage a new kind of hybrid engine that could be a bridge technology to EVs. Instead of battery-powered electric motors working to support the gas powertrain, as in many contemporary hybrids, the gas motor serves as a generator to charge the electric powertrain’s battery.

Jeff Bezos and Lauren Sánchez Bezos are doubling down on their commitment to fashion.

The Journal's Chavie Lieber writes that the Bezos Earth Fund awarded $34 million in grants to institutions studying and developing materials that might someday replace polyester and cotton—the world’s most popular textiles and among the most reliant on natural resources.

Researchers are creating biodegradable textile fiber and plastic-free synthetic silk, among other alternatives, that are costly to produce but could reduce the climate impact of the clothing industry.

Synthetic materials such as polyester and viscose are common across fast-fashion and luxury, since they’re cheaper to buy and can be easier to work with than natural fibers. But the fabrics, made with oil and coal, have a high carbon footprint and aren’t biodegradable. 

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• America’s top logger Weyerhaeuser is using artifical intelligence to digitize the forest and grow profits. (WSJ)
   
• The Pentagon’s push to get its hands on the rarest of the rare-earth elements leads all the way to this small port city in Malaysia. (WSJ)
   
• The World Bank has teamed up with Amazon on a bond whose proceeds will go toward rehabilitating ecosystems in South Africa. (Bloomberg)
   
• Two people died and more than 20 were evaluated for injuries in a chemical release at a plant in West Virginia. (WSJ)
   
• More than 50 countries are due to gather in Colombia this week for the first international meeting dedicated to phasing out fossil fuels. (FT)
   
• Wildfires burning across the Florida-Georgia border destroyed dozens of homes and prompted evacuations, officials said. (WSJ)
   
• Damming the Bering Strait between Russia and Alaska could help stabilize a vulnerable system of ocean currents, scientists said. (NYT)

WSJ Pro Sustainable Business gives you an inside look at how companies are tackling sustainability. Send your comments to editor Perry Cleveland-Peck at perry.cleveland-peck@wsj.com. Follow the WSJ Pro Sustainable Business team on LinkedIn at perrycp, clara-hudson and yusuf_khan.