The Region of Stockholm is partnering with Candela Speedboats to launch the world’s fastest electric ferry as the Swedish capital joins cities all over the world in taking take up the challenge to reduce traffic congestion and CO2.
More than 900,000 people travel by public transport in Stockholm County each day. They ride on everything from buses to commuter trains to local rail to a fleet of 60 diesel ferries that service the tens of thousands of nearby islands and islets. Lidingo is an island in the inner circle of that archipelago, and also the home of the Candela boatworks and its revolutionary electric hydrofoiling technology.
Candela’s mission is to ‘speed up the transition to fossil fuel-free marine transportation’. To achieve this, founder Gustav Hasselskog started the company back in 2015 and assembled a team of experts with success in everything from structural composite engineering to flight control electronics to hydraulics, software algorithms and the hydrodynamics of America’s Cup entries.
The goal was to overcome the inherent challenges of electric motors on planing boats by combining hydrofoils, an all-electric drive train, carbon fiber composites and a sophisticated computer system to create a new kind of electric boat that would “not only match, but beat its fossil fuel competitors.”
Global sales success
A traditional planing boat has an enormous amount of drag as it goes through the water and requires an energy input that challenges even the largest and most energy dense battery packages. The Candela team developed a system of submerged hydrofoils that eliminates that friction with the water by lifting the hull completely out of it and then controls the boat and keeps it steady with an onboard computer that adjusts the struts of the foil 100 times per second. This elimination of the drag allows high speeds and extended range.
Since 2018 they have sold 30 of their Candela 7 recreational hydrofoiling speedboats all over the world and test drives are available in Sweden, Austria, Switzerland, Germany, Finland, New York and San Francisco. Along the way they have won numerous awards and accolades and been written up in Forbes, The Economist, Reuters and, of course, Plugboats. You can view a video virtual sea trial »» here
Candela hydrofoiling key to fastest electric ferry
The P-30 is a larger model (12 metres / 40 feet) that brings those hydrofoiling benefits and advantages to public transport. The computer-controlled hydrofoils enable a top speed of 30 knots – which the company says is the fastest electric ferry in the world – and the ability to cruise for 3 hours at 20 knots. This consumes 80% less energy than conventional ships, and a report from the municipality of Stockholm anticipates the annual cost of operation will be about 50% lower than for existing diesel ferries.
The ferry is powered by two 60kW pod drive motors with energy supplied from a 180kWh li-ion battery pack that can provide a range of 60 nautical miles on battery power alone. This is enough to cover even the longest routes on 60 kilometre (37mi) Stockholm archipelago. Candela’s chart at the bottom of this page shows that the similar sized diesel ferries now on those routes emit about 150kg of CO2 every hour.
The other advantages hydrofoiling has over those diesel ferries are speed and comfort. Because the P-30 creates very little wake it can operate in urban waterways where the current vessels have to creep at low speeds in order to avoid damage to the shore and other boats.
Speed and comfort
As for comfort, the on-board flight controller adjusting the foils ‘on the fly’ analyzes every environmental factor, including storm gusts and big waves. Candela’s Mikael Mahlberg told The Engineer “There are six different types of sensors. Ultrasonic sensors in the bow measure wave height in front of the boat at 100Hz, or 100 times per second, to angle the foil optimally and counter the waves.” This means a 95% reduction of wave G force compared to conventional ships. The controller prevents the P-30 from rolling and heaving altogether, providing a silky smooth ride – no sea sickness!
The P-30 has a flexible interior with space for up to 30 commuters, a far cry from some of the commuter ferries in Stockholm that can carry as many as 300 passengers. Candela maintains that a flexible fleet of P-30 shuttles is a cost-effective replacement for diesel ferries in the 300-500 passenger range.
Economical and efficient enough to replace buses
“Today, most of our waterways are unused for mass transit, even though most highways are congested during rush-hour traffic” said Candela Founder and CEO Hasselskog. “Opening up urban waterways for high-speed electric transport can revolutionize commuting in cities such as San Francisco, Seoul or Amsterdam – at a very low cost. There’s no need to build new infrastructure.”
He says that the ability to travel at an average speed of 60 km/h between stops makes it not just the fastest electric ferry but also a compelling alternative to cars and buses. Energy consumption per passenger data from the Swedish Energy Agency, Stockholm Region and others show the P-30 uses less energy than other boats, but also less than diesel and even hybrid buses. (click chart to enlarge)
The company sees a big enough future in public transport that they have a division dedicated to it and a Director of Public Transportation, Erik Eklund. “Our goal is to prove that our electric hydrofoil ferries are much cheaper, more comfortable and a lot more versatile than conventional vessels.” said Mr. Eklund. “It’s not just an alternative to other ships, but a whole new take on of public transport.”
Candela is also advertising for a Director of Autonomous Driving who will be responsible for developing an automated on-demand system for the public transportation vessels to make time tables and fixed routes things of the past. The job notice says “This will allow us to tap into the huge potential for fast and emission-free transporting the largest and busiest cities of the world.”
Comparison: Candela P-30 vs Diesel*
|Candela P30||Diesel Ferry|
|Power needed – 85% reduction||88 kW||589 kW|
|Energy consumption at 20 knots – 87% reduction||3 kWh/nautical mile||24 kWh/nautical mile|
|Cost of fuel/electricity per hour – 85% reduction||5€||35€|
|Service costs per hour – 90% reduction||1€||10€|
|CO2 hourly emissions – 100% reduction||0 kg||152.4 kg|
|*Source: Candela website: “A comparison between the Candela P-30, our 11 meter ship for 30 passengers, and the most efficient light-weight diesel ferries of the same size.”|