Rotor Sails Could Cut Shipping Fuel Use by Up to 50%

Shipping moves 90% of global trade – and yet it’s one of the hardest sectors to decarbonise. In this episode of Climate Confident, I sit down with Heikki Pöntynen, CEO of Finnish cleantech pioneer Norsepower, to explore a solution that’s both elegantly simple and radically effective: modern rotor sails.

Heikki explains how Norsepower has revived and re-engineered the century-old Flettner rotor to deliver real-world fuel savings of 5–25%, with some transatlantic routes targeting a staggering 50% reduction. We dig into the physics of the Magnus effect, why side winds are a ship’s best friend, and how AI-driven automation ensures crews get maximum performance with minimal effort.

We also discuss why retrofits dominate current adoption, the growing trend of building “rotor sail ready” vessels, and how stricter IMO regulations are shortening payback times to as little as one year. Heikki shares insights on compatibility with biofuels and electric ships, and why wind propulsion will be a common sight by 2040.

This isn’t about prototypes or pilot projects – these sails are already cutting CO₂ at scale, with 26,000 tonnes saved to date. If you want to understand a proven, scalable technology that can help shipping hit net zero by 2050, this conversation will change how you see the horizon.

Listen now to learn how wind, engineering, and smart regulation could reshape maritime decarbonisation.

Sign up to Climate Confident+ for deep dive analysis of the major climate and energy stories of the day.

Transcript

Copy

0:03

We use some kilowatts of power to make the rotor spin, to create megawatts of power to pull the ship forward. We are really talking about megawatts because at times the power of the sails can be even higher than what's coming out of the main engine. So mid-size tanker in our fleet does eight knots with our two sails only. I think this is a significant speed, what we talk about here. Good morning, good afternoon, or good evening, wherever you are in the world. Welcome to episode 233 of the Climate Confident Podcast, the go-to show for best practices in climate emission reductions. I'm your host, Tom Raftery, and if you haven't already, be sure to follow the podcast in your podcast app of choice, so you never miss an episode. Before we get going, a huge thank you to this show's incredible supporters, Jerry Sweeney, Andreas Werner, Steven Carroll, and Roger Arnold. Your guys your backing helps keep this podcast going and I really appreciate your help. If you're not currently a supporter and you do get value from this podcast, you can help me enormously by supporting the show. It's just three euros or dollars a month, less than the cost of a coffee. All you need to do is click the support link in the show notes of this episode or visit tiny url.com/climate pod. Now imagine taking one of the world's biggest climate challenges, shipping's stubborn emissions, and tackling it not with futuristic fuels or billion dollar overhauls, but by re-engineering something sailors figured out millennia ago wind power. My guest today has taken that ancient idea, bolted it to cutting edge engineering, and turned it into a technology that can slash a ship's fuel burn by up to 25% with some voyages aiming for 50%. His tech works so well, it can even push a tanker along at eight knots without using the main engine. This isn't theory, this isn't wishful thinking. It's happening right now on the high seas and the man at the helm, a third generation naval architect from a Finnish ship building family that's been working with the oceans since the 1600's. Heikki Pöntynen is the CEO of Norse Power. But before we get into that, in the coming weeks, I'll be speaking with Emily Wilkinson, a director at ODI, Gary Yo, climate Economist, and IPCC author, Sheri Nelson, senior Director of Responsibility and Wellness for Elior North America, and Christopher Carrick, founder and CTO of Lignin Industries. Now back to today's episode, and as I mentioned, my special yesterday is Heikki. Heikki, welcome to the podcast. Would you like to introduce yourself? Hi Tom. Thanks for having me here. Yeah. My name is Heikki Pöntynen. I'm the CEO of a, Finnish cleantech company, Norsepower. I'm also a naval architect, marine enthusiast, and very concerned about the wellbeing of our planet. Okay, and tell me a little bit Heikki about your professional journey into where you are today. I come from a family of long traditions in the maritime industry. My family has been building ships since 1600's already. And, and I'm a third generation of naval architect in the modern era. I've been in, in the marine industry for 30 years of my life. Lived in different parts of the world been in different parts of the value chain. Working for a ship owner, as a shipyard, CEO equipment manufacturer, engineering company, turnkey company. So, seen really the crosscut of the industry in my history and now actually very nice to be with a cleantech company. Completely different perspective that I've had before actually into the industry. And. Tell us a little bit about Norsepower. You say it's a clean tech company. What is it that Norsepower is doing? Norsepower is bringing sails back to shipping. Our product is an invention that was made a hundred years ago. It's called Flettner rotor. A rotating cylinder that acts like a sail, bringing the ship forward. So sailing is what we do actually, and produce sails to ships. It's interesting that you're based in Finland, just given that 95% of ships today are manufactured in China, Korea, or Japan. So how come you're based in Finland and not in one of those countries? Well, actually the Finnish maritime industry is extremely strong. The ecosystem in the country is, is what, 600 company? It's, it's almost 10 billion euros industry in in the country. We are building the biggest cruise liners in the world. Very specialised ships like icebreakers research vessels in Finland. So the, the maritimes industry and the ecosystem in that, in this country is very strong. And, and that also triggers innovation, of course, into the industry like ourselves, producing now sails. Okay. And why, just taking a big picture view here, why has shipping the, the shipping industry in general been so slow to decarbonise compared to other sectors? Well, I mean, my from my perspective, I could say that we are somewhat old fashioned, very traditional industry. The profits have not been very good in, in the history. So, unfortunately, fortunately, the bottom line has a meaning in this industry. Companies need to make profits in order to be able to, to leverage other aspects like sustainability, environmental aspects. But having said that, I mean, it, it's not only the, the dollar on the bottom line, it's, it's. It has something else to do. I mean, we have a new generation coming up into the industry. We have very environmentally conscious people now growing up and taking higher positions. I mean, maritime transportation is part of the, the intermodal journey of, of transporting goods, and, and the sea leg has to also carry responsibility of those, if I would call it a green corridor. So all, all other aspects in sustainability corporate social responsibility has to, has to play a more significant role in the future. Okay, and do you think the IMOs net zero by 2050 target is realistic or is it wishful thinking? We think that it, it is realistic. I mean, all industries, it's, it's not only, only IMO, I mean many other industries are moving towards the same target. And when we do it together, it is possible that we can achieve that. And what about the levers that we have for maritime decarbonisation? Where do you think wind propulsion comes in, in that kind of hierarchy? Wind propulsion is, is sort of it is a CapEx, it is a capital investment that has a payback time. It is sort of a different ball game in instead of or in comparison of having alternative fuels biofuels, which in turn today, not so widely available in the scale that would be required. They are quite costly. The efficiency of those fuels are not that great at the moment, but in combination together with the wind assisted propulsion for instance we can create sort of a tandem to be able really make a significant impact on the reduction of the emissions. And I mean sails alone can reduce the, the emissions and, and the fuel consumption from what, five to 25% or even more. It is sort of a joint effort with, with different type of of measures and means in the industry. Okay, and that five to 25% range, what influences that? Well actually the trade pattern of the ship has a significant role. Where to ship sails and what type of winds do you have in the area? And of course, the number of sails, installed on board has, has a meaning. So if the ship sails in environment will have a strong side winds, that is the best environment for our product really to, to make an effort, an impact on the ship's fuel economy. And we should talk a little bit about your sails because for people who are not watching this video, but listening to the audio, they can't see the ship behind you. And so we talk about sails, people traditionally think of cloth sails or when you talk about wind assisted sailing we've seen other companies who might have things like very large spinnaker type sails, almost like big parachutes pulling the ship forward. Your technology is different. So walk me through that a little bit. It's, it's these kind of cylindrical towers, metal towers on the ship, which as you say, are spinning themselves. How does that work? All right. The product itself, or in the invention is called a Flettner rotor that's originally invented a hundred years ago. Our highest tallest cylinders are 35 meters tall. It has a composite rotor that rotates around a, a steel tower, making like 200 rounds per minute. And, and that phenomenon is called a Magnus effect. It creates a higher pressure on the other side on the other side of this, tower and lower pressure on the other side of the tower, you know, a little bit in a similar way as an airplane wing does. So the air goes longer journey on top side of the wing than on the bottom side. And in layman's terms, I could say that. I mean, if you play golf, at least what happens to me when I tee off the, the golf ball, it, it takes a unfortunate spin and disappears into the woods. And it's the same phenomenon. It makes a curve because of the pressure differences on, on different sides of the ball. So just make a point here actually, because this is not a generator that's a misconception that many people have. We use a small part of the ship's electrical power to make the rotor spin. And this spinning effect creates this, this sort of pressure difference to push the ship forward. And actually, I mean to talk about kilowatts not going too much into the the physics, but we use some kilowatts of power to make the rotor spin, to create megawatts of power to pull the ship forward. We are really talking about megawatts because at times the power of the sails can be even higher than what's coming out of the main engine? So mid-size tanker in our fleet does eight knots with our two sails only. I think this is a significant speed, what we talk about here. Indeed, indeed. And when you talk about a golf ball, obviously golf balls are kind of dimpled and that helps, you know, with that effect. Hmm. Are the surfaces of your towers also kind of dimpled or in some way patterned or do they have something on them that increases the Magnus effect is, is I guess the best way to put it. Actually we've done some research about this and, and we've seen that the, the quality of the surface doesn't really make any big difference on that. The same thing is with football, for instance, or basketball or whatever type of thing that you make spin. It takes a curve effect when it, when the surface was very, very clear or smooth or, or golf ball like it doesn't really make a huge difference on the, on the equation. Interesting. And what's the biggest myth that you hear about rotor sails or wind assisted ships? I already touch upon the issue. So many people at first instance think that it's collecting electricity. So it's, it's like a generator. Wind makes it spin and, and we collect the energy. This is the, the first thing I need to really explain to people that it exactly the other way around completely. Okay. And the second thing is actually that it is a tall tower. So people might think that what about in, in high winds and ship stability, how does that affect the overall performance of the ship? It is, is it scary or not? Actually I would say that it's, it's on the contrary. We've seen, one of the ships in our fleet that sails in the North Sea had exactly a stabilising effect on the rotor sails. In very rough seas, high in poor weather conditions the ship set, set sails and went off to the ocean. And what happened is that the ship was pretty okay with the wind with the, sail effect on the ship.'cause some other ships stayed in the port. So it has a in turn. It has a stabilising effect on the ship's seakeeping ability. Hmm. And the system is so effective, why aren't more vessels already using it? We are, uh, we're in the situation when we, the industry itself is pretty much doubling everything. What's happening now is, is that the fleet, powered with wind assisted propulsion, whether it's a rotor sail or other solution, the amount of those ships are doubling year on year. And of course there is a very healthy push from different regulatory bodies of the world, giving sort of a kick. And, and triggered the interest of, of the operators and the ship owners. They would have to do something to save the planet and save emissions save fuel and, and take measures to overcome the, the regulatory framework. And you said that the fuel or emission savings are between 5 and 25%. Is that data coming from yourselves or is it coming from the ship owners, or is it a combination, you know, where you, where are you getting those numbers from? The data comes, I mean, we always rely on third party verified data. So this is something significant. I mean what we do in, in our desk with our desktop studies is completely different when it comes to the full scale measures and third party verified results. So we have in our fleet already we've collected 500,000 hours of data data stream. So along with the product that we call a true performance, it's a sort of, mixture of sensor technology, automation control, artificial intelligence, and in combination of all these, we can measure the output, the thrust from the propeller, in combination with the wind assisted propulsion. So we can really see what's the true performance, what the sails are giving, and that in turn is easy then to, to convert into the figures when it comes to CO2 emission savings or fuel savings in turn. So this is true data. This is not a desktop analysis that we've made. We can really prove this, and we always rely on third party verified data on this. Okay. Very good. And do the ship owners care more about emissions or cost savings when they knock on your door? Well, I mean, the, the first question is obviously, what's the payback time of, of this investment? So this is may, this might be the starting point of, of or in the discussions. Good news to us was that the, the, the recent conference, the MEPC 83 set even stricter standards. So some of our clients enjoy now 50% less in their payback periods. So what has been three years in the past could be one or two years now, in terms of payback times. Very good. And were you happy with the outcome of the MEPC 83. Extremely happy. I mean, I mean, I think the whole industry welcomes the, the decisions taken there. First time in, in the industry that we've been able to, decide on, on global measures to reduce really the, the emissions. And this is something that you're doing not just for new build, but also you can retrofit them on older ships as well, correct? That's correct. And actually two thirds of our business have been retrofits. So only one third is, is picked up by new buildings, but quite, quite interesting in the industry is that the, the, if you think of the, the overall naval architecture of the ships, the whole hull shape, general arrangement, hydrodynamics is taking different format now. I mean, ships are built and designed to cater for the wind assisted propulsion power. The deck house superstructure is in the fore. The, the hull is prepared for maybe air lubrication system as well. So in combination with all these, we, we see different type of ships coming to the, to the markets. And actually quite interesting phenomenon is also that some of the, the owners are not ready to, to make a decision yet to purchase, invest in the, in the rotor sails. However, they make the ships what we call rotor sail ready. So the foundations are prepared already at, at the shipyards for installations that could take place at the later stage. So sort of, I would see that the, the industry is preparing itself for, for this type of phenomenon or technology, I would say. And are there any particular ship types that are suited or not suited? Because I can imagine the container ships, for example, would be unsuitable for this technology given the deck space it that's required for them. Right. I mean, with container ships, it's, it's simply a problem of not having deck space available. Height might be an an issue even though we have a, a tiltable a rotor sails available. However, we have a, of course, a program to investigate how. Could we also install rotor sails onboard container ships? Different type of technologies could enable that. And actually the second ship type that is not really suitable or it could be suitable, but not so lucrative, I would say is are the big cruise liners. Maybe the, the owners or passengers don't wanna see huge towers even on top of the tall ships So, so those are two ship types. All the others are, are really or in our addressable market. Can this technology work well alongside, you know, biofuels or even better electric ships? Oh, yes. I mean, I would say that they are all complimentary. I mean, I don't think there's, there would be one without the other one. It, it, they would be run in tandem if I would say so. And when it comes to electric ships, I mean, the sails are extremely well suited on, on an electric ship to work like an range extender onboard those. So it, it is really complimentary to other technologies I would say. What do you think would be the trickiest retrofit you've had to do to date? Trickiest retrofit I mean, technically I don't see a big issue making a retrofit. Of course we need to take into account visibility, stability, all the technical aspects. The retrofits are not really different from, from new buildings, from our perspective at all. The thing is to prove really advantages and the real savings coming out of the installation, and that is so closely correlated to the sailing pattern and the wind conditions on along the routes. So it is not a challenge because we can make a very accurate estimate as long as we, as long as we are aware of the ship's trading pattern. Of course, every time we get an inquiry, we make a quite thorough feasibility study and see what could be achieved with, with our installation. So this is the dialogue we need to do together with the client and we need really be trustworthy on that one. I mean, this is not salesman talking, this is really scientist talking at that point, Okay. I would say And you mentioned as well that your largest one is 35 meters tall, and if I remember, about five meters wide. correct. How, I mean, how do you size these sails for the particular vessels that they're going to be installed on? And how many do you install on a vessel?'Cause on the one behind you, there's two, and I've seen some pictures with one. So you know, how many do you put on, what's the maximum you put on and how do you decide and you know, talk to me about that. Alright, I mean the size depends really on, on the ship size, the speed the trading pattern as I, as I said, the wind conditions along the, the, the route, the amount is also dependent on, on the available fuel savings that could be achieved with different positioning on deck, deck, space and, and free area is, is also an issue. We have a project ongoing where we have an on order for three ships, six sails each, and they're all 35 meter tall, carrying products from France to US crossing Atlantic. And our customer has made a very thorough three year study before they made the, the purchase that they can achieve even five zero, 50% savings on the route. That means that the whole ship will sail without the main engine, a big portion of, of the journey completely. So that'll be a very interesting installation coming up in the near future we, we have really full scale data from, from those ships setting perhaps new standards in the future. And it's, it's typically side winds as opposed to you can't sail directly into the wind. Similar as, as you can't with cloth sails. So would that require ships if they had a headwind, to maybe zigzag the same way that sail ships have to do in, in headwinds. Right. I mean, the direct headwinds are not really favorable for us. That's the only condition actually where our sails don't really work well. We put a lot of emphasis on the control automation. We have the artificial intelligence, driven control systems. We have something called sentient control, which is based on, on different type of sensor technology combined with, with the control system, it is fully autonomous. So the crew only needs to press a button and switch it on and switch it off. Basically everything is, done by the system. And when we, we combine our system with any voyage optimisation system. I mean, they are, they can all be bridged together. So then this combination can, can perhaps bring the best result to the ship owner. So, I mean. When, when we do this, this like voyage optimisation with the wind assisted propulsion power, it is exactly what you said. It's not direct line from A to B. It is really zig zaging taking into account the weather pattern conditions, waves the big data from the weather, weather conditions, and all this put together at the ship. Should arrive to the port just exactly on the right time, not too early, not too late with the best fuel economy achieved on the, on the journey. Okay. And what do you think shipping is going to look like in 2040? What will ships look like? Will they all have rotor sails like yours? Or how do you think the market is going to evolve? I think it's, gonna be a very common sight to have sails on onboard ships. Whether they are rotor sails or other solutions. There will be sails. I mean, like I said, currently we are doubling everything. The ships will look somewhat different. The new builds that are built cater for, they are tailor for wind assisted propulsion power. When I look at the technologies today, there obvious this means to, to sort of survive the rules and, reduce emissions, save the fuel cost, alternative fuels biofuels, all these type of things. Or then there are these, these like other types of solutions that enables the ship move forward, which is what the wind power is actually really that on, on top. So I would say that, I mean, what else would you do? To create the more thrust besides the main engine than to use wind currently. You have air lubrication and it doesn't give any thrust to the ship, but it saves fuel, which all these are significant. And like I said before, they, they, they go in tandem. They all contribute to each other, and, and the future will look like a, a combination of all this in my view. And what's the next maritime innovation you're keeping a close eye on? We put a lot of emphasis on on the software controls and, and all these, these type of things. It is really important that we can validate and prove the performance of the sail. I mean, it is a, a rotating cylinder making like little bit humming sign on deck, how much thrust that really gives and, and ship owners need to prove that to the regulatory bodies to, to overcome, the rules and, and sort of comply with, with the saving targets instead of paying penalties. That's really something that we put a lot of emphasis that we can prove in real time what is the true effect of, of our sail. So that enables and helps the ship owner also to do their job with, with the regulatory bodies, for instance. And what do financiers and insurers need to see before they bet big on wind propulsion? We are all in, in the same community, I would say. I mean, we should all work together towards a more greener planet and, and, take all these measures together. I mean, what we talk about is, is, also recyclability of our product. Can it be recycled when, when the lifetime comes to an end? At the moment, what we see is, is that the, the lifetime of a rotor sail could be even longer than the ship's lifetime, which could create a secondhand market for the product itself. Different type of leasing solutions and, and all this type of would definitely surface in the coming years. You mentioned at the start that you've worked across several marine firms and that you are third generation marine architect in your family. Is that what's kept you in the maritime world or is it just love of the sea or tradition, or why? Why do you stay in that? In this in the sea world? Well, I mean, it, it is obvious that I, my, my family brought me up with, with ships. I've been on board ships since I was a little boy, even a baby, and, and sort of a living in that environment, breathing the spirit of the industry. So for me it was very, very simple choice. I want to be part of this. I want to develop the, this industry further. And, it is very nice to have traditions also in, in in this life. And what's one thing that people outside the industry always get wrong about shipping? When you look at ships, it's, it's uh, like a heavy smoke coming out of the chimney. It, it is polluting. Don't go on the aft deck of all the ship. You get your, your shirt dirty and all this. And whereas it is really, washing the industry is washing its face definitely at the moment to see the, the ferries calling ports. With electric powers currently, there's no smoke coming out of the chimney anymore. It, it is getting very clean. And this is a global thing. It's not only happening in some countries. It is triggered and forced by regulations and, and these bodies. But like I said earlier, I mean, the green sentiment is really taking taking effect in the industry and in the, in the end user, the client base. So they, they will start to require and demand ship owners to also take measures for a greener planet. We're coming towards the end of the podcast now. Heikki. Is there any question I didn't ask that you wish I did or any aspect of this we haven't touched on that you think it's important for people to be aware of? I think we covered pretty much everything already now, and, and I think it's important that the, besides all the, the technological aspects and, and the regulatory framework, I think it's, it's quite substantial and interesting and very important for me at least personally, and, and people in my company. And actually, why not? People in general that we start to think about the environment. We are environmentally conscious, and it's not always the bottom line euro that counts. Also, some other aspects need to be taken into to consideration, and this already we touch upon in, in the interview, but sort of still I like to highlight that issue for us all to understand this. Great. Okay. Super Heikki. If people would like to know more about yourself or any of the things we discussed in the podcast today, where would you have me direct them? You can find me from Norsepower in, in our website through our contacts. And, and that's where I am pleasure having or having discussion with, with anyone and, and discuss about the future with, with me alone or with my team. It is, it is very interesting, yup. Great. I'll put the link to the website in the podcast show notes. That way everyone Heikki will have access to it. Okay. Heikki, that's been fascinating. Thanks a million for coming on the podcast today. Thanks Tom. Thanks for your time. Okay, we've come to the end of the show. Thanks everyone for listening. If you'd like to know more about the Climate Confident podcast, feel free to drop me an email to tomraftery at outlook. com or message me on LinkedIn or Twitter. If you like the show, please don't forget to click follow on it in your podcast application of choice to get new episodes as soon as they're published. Also, please don't forget to rate and review the podcast. It really does help new people to find the show. Thanks. Catch you all next time.