In Stockholm, Sweden, people ride diesel-powered ferries every day. But those boats produce pollution. Diesel fuel is expensive.
Designers at boat-making company Candela propose a solution. Their P-12 electric ferry uses less energy than traditional ferries. It can carry 30 passengers at a speed of 30 knots (about 55 miles per hour). Today, ferry passengers spend 55 minutes traveling from the suburb of Ekero to Stockholm’s city center. The P-12 makes that trip in 25 minutes.
This electric ferry barely makes a sound. In fact, it appears to hover three feet above the water.
How does it work? It’s all about hydrofoils.
Hydrofoils act like wings. Just like wings create lift in the air to raise an airplane, hydrofoils create lift underwater to raise a boat. Hydrofoils can lift an entire ferry above the water’s surface.
When a boat crosses water, it creates friction. The more the boat touches the water, the more friction it makes. That slows the boat and uses fuel. But when hydrofoils lift the boat above the water, friction lessens. Less friction allows for faster speeds and less fuel.
Plus, hydrofoils make smaller waves. In Stockholm, ferries face a 12-knot speed limit. If they move any faster, they make rough waves (called a wake) that disrupt water traffic. But that limit doesn’t apply to the P-12. Its hydrofoils cut through the water with barely a ripple.
It looks futuristic. But this technology has existed for over a century. Alexander Graham Bell (inventor of the telephone) designed his own hydrofoil boat in 1908. But hydrofoils didn’t take off (no pun intended) until recent years. New lightweight carbon fiber materials make hydrofoils feasible for larger boats. Combined with electric motors, they may offer cleaner options for public transportation. (How clean will depend in part on the source of electricity used to power the hydrofoil ferries.)
Candela plans to officially launch the P-12 in July. Someday, company officials hope to bring their electric ferry to other cities, such as New York, New York, and San Francisco, California. Other companies are designing their own electric hydrofoil ferries.
But this jump to the future could cost a pretty penny. It requires swapping out old diesel ferries with completely new boats. It also means updating infrastructure.
“One important part of the electrification is when the ships connect to the ports through the onshore power supply,” says Robin Cook from the Swedish Transport Agency.
In the United States, the federal government will soon give ferry operators $220 million dollars to modernize. That includes electric boats and upgraded infrastructure. But of course, that money ultimately comes from taxpayers.
We have the technology for electric ferries. But do cities have the money—and the political support—to make it work?
can offer new solutions or adaptations to challenges like fuel use and
pollution, but it takes more than just technology to get positive results.
For more about boats, see The Boys in the Boat by Daniel James Brown in our Recommended Reading.