Circumnavigating the globe with solar power
PlanetSolar, a solar powered catamaran, became the first ever solar electric vehicle to circumnavigate the globe in May after 584 days (19 months!) at sea. The impressive ship departed from Monaco on September 2010.
GrabCAD is lucky to have caught an interview with Christian Ochsenbein, a lead engineer with PlanetSolar.
Lauri: What is your background?
Christian: After an apprenticeship in electronics I studied electrotechnical engineering at the Bern University of applied science. My interests were power electronics, electric motors and mechatronic. Then I began work for Bystronic Laser. This Swiss company builds laser cutting machines to cut steel, aluminum and other materials. I was developing power electronics and control algorithms for the electric motors.
Lauri: What engineering problems have you solved in your work?
Christian: Before PlanetSolar I was developing servo drives for electric motors. Hardware design, software and laboratory work…
On board of PlanetSolar I was mostly responsible for the energy system and the board electric. At the beginning we had to optimize lots of parameters in the software. Twice, we had a black-out of the energy system. During these black-outs, it is very important to understand the system to be able to find and solve the problem. But, all in all, I am very happy how all the new technologies, like batteries, solar generator, motors and energy system worked on board. We had very few issues with the high-tech equipment on board. More problems made us low-tech, like the desalination or the water system.
Lauri: What CAD software are you mainly using?
Christian: All the drawings were made with AutoCAD.
Lauri: How are you connected with the PlanetSolar project? What is the nature of your work there?
Christian: We were a crew of four on board- A captain, an expedition leader, a bosun and me as the engineer. So of course I was responsible for all technology on board like the energy system with the solar generator, the battery and electric motors, the steering system and all the electronics. But I was also maintaining the propulsion system. A big part of the job was also to do the shift on the bridge, that means I was responsible for the navigation for three hours stretches twice every day.
Lauri: What was the goal of this project? To prove something to the world? To test technology? Or anything else?
Christian: First of all nobody had ever tried to boat around the world with a vessel powered only by the sun. So we are the first to have achieved that. But it is much more than that. PlanetSolar is an eco-adventure. We did this adventure not only for ourselves, but we carried a message that solar technology works around the world. We visited 27 countries during our tour and showed the vessel to professors, politicians among many other people. Photovoltaics and solar boats is no longer just in “the future”– we have all the technologies to change now. With PlanetSolar, we crossed the largest oceans, passed under the monsoon rain and navigated through huge storms. I think that’s the perfect example to prove that solar technology works.
Lauri: What were the biggest technical obstacles in this project?
Christian: All the technologies to build a solar boat were on the market before we started to build the MS Tûranor PlanetSolar. The difficulty was to bring all the technologies together. To construct a solar boat that can cross the largest oceans in the world is not done with putting some solar generators on top of the boat. The boat has to be very efficient in the water. Also the ratio between the size of the boat, the energy production and the stockage of energy is very important. The wish of the owner was to have a real yacht. That means, the boat becomes heavier, because it is big. What follows is that you need more energy to navigate and for this you need bigger batteries to store energy. For example we had a very big lithium-ion battery on board which could store more than 1.1MWh.
Lauri: What is the hardest part in your work?
Christian: A solar boat needs much less maintenance than a diesel powered boat. Normally you don’t need to maintain electric motors and the gear system we have on board is simple. Also for the battery and all electric components you do regular checks, but not maintenance. But we were only four on board, so it was a big job to keep everything running perfectly. I had to switch immediately between technical aspects and preparing a long trip, like buying food for several weeks. And every night I had to stay up at two o’clock in the morning to stay in the cockpit and navigate.
Lauri: Did you consider several ship designs? Why did you pick the current one?
Christian: Yes there were several designs at the beginning. The overall design decision was made the owner of the boat. He wanted to have a real yacht, not just an expedition boat. The MS Tûranor PlanetSolar has six big cabins, three showers and toilets and lots of space in the inside. The owners idea was not only to show that it is possible to circumnavigate the globe with a solar yacht. He also likes to show now, after the world tour, that it is possible to use a solar boat commercially.
Lauri: What is the innovation in this ship besides the huge solar panels on the deck?
Christian: The electric motors are extremely quiet and we don’t have the noise of the wind in the sails. So a trip with a solar boat is silent and you can really enjoy the nature of the oceans. But it is more than that. For about three days we were completely without any sunlight. A sailing boat can sail only with wind, but we can navigate for three days without sunlight using only energy stored in the batteries. But of course for long navigation we need sunlight to recharge the batteries.
Now after the world tour we can say that this concept works very well- we never had empty batteries.
Lauri: Would it be possible today to build even larger ships which operate on solar power?
Christian: Yes I am sure that it is possible to build bigger ships. Of course not big container ships: They need such gigantic amount of energy that it is not possible to run only with solar power. When you build a solar boat you have to reduce the energy consumption everywhere. You especially need a design which is very efficient in the water, like a catamaran.
Lauri: How long did it take to test the ship? What technical problems did you encounter?
Christian: We did a few short test navigations near Kiel, Germany. After those tests, we navigated the boat down from the Baltic sea to Monaco, our start and end destination of the world tour. So this was a long test in itself with difficult sections, like the channel between France and England. We are very happy with the technic of boat. Specially all high tech components. During the whole tour we broke only three solar panels out of more than 800. The panels broke only because a person fell down onto them. We didn’t change any battery cells out of 648. Not to forget that it was the largest lithium ion battery in the world when we started our tour. Problems were mostly composed of mechanical issues, especially the propeller system. Twice we had accidents with the propeller, but luckily we were able to fix the problems by ourselves and return to port safely.
Lauri: How did you select the components – lithium-ion batteries, engine, solar panels? Why the particular ones?
Christian: The most important factor on a solar boat is efficiency. So we took the solar cells with the highest efficiency. Solon then built solar panels for us with glass on top that is light and strong enough to endure our walking on them each day. It is also important that we didn’t lose much energy when we converted the current from DC to AC. The energy system with the battery runs on 400 VDC, so quite a high voltage for a battery. But with the higher voltage we could save lots of weight. For all the components in the boat we did some engineering optimization, to get everything as efficient and light as possible.
Lauri: Almost 2 years have passed since the introduction of the vessel. Are there more efficient technologies available? What could be improved in the ship?
Christian: Yes, luckily! There are more efficient solar cells for example. We know today, that we could build a faster, lighter and cheaper solar boat.
Lauri: Are you satisfied with the result of the project?
Christian: Absolutely! Of course when you are such a long time on the boat, you are complaining all the time a little bit about this and that! But at the end the result is counting. We are the first to navigate around the world by solar energy- it was complete Terra Incognita for solar energy. It is like Magellan, engrained in history, but we all forgot how long he needed to complete his world tour. A first stays forever.
Lauri: What are you working on now? What are your future goals, projects?
Christian: My first project is vacation. After my vacation I don’t know yet what will be my job in the future, but I would like to stay in the business of renewable energies and doing maybe anther crazy project one day….
Lauri: What happens to PlanetSolar now? Are you going to auction it?
Christian: For this summer the Tûranor PlanetSolar will stay in the Mediterranean Sea and will go to different events in various cities.
Lauri: Why is solar power not used more often in the marine industry?
Christian: That’s a good question. I have the feeling that the maritime business is still a bit old fashioned. I hope we can serve as inspiration to the industry! I see big opportunities, for example for hybrid boat, but it needs still an effort to build an simple system for hybrid boat…a little bit of engineering work!
Lauri: How was the crossing of Atlantic and Pacific oceans? Did you have any problems?
Christian: We started the transatlantic crossing early in the season. The timing actually still put us in a risk of hurricanes. Two thirds of the way across the Atlantic, the weather changed dramatically and we had to change our route to escape from a hurricane. But that hurricane brought us bad weather with lots of rain and wind opposing our progress. The hurricane altered the weather system in the Atlantic for about two weeks, before the trade winds came back. The Pacific ocean let us suffer on the last meters. Between New Caledonia and Brisbane in Australia we encountered a winter storm for four days with waves up to 7m high.
Lauri: If you were to start this project now, what would you do differently? What were the lessons learned?
Christian: Of course we gained lots of experience with this boat and we would built lots of things different. I think that’s normal by a prototype. But all in all the Tûranor PlanetSolar was good boat for us and brought us through all the difficulties during the circumnavigation.
Lauri: Thanks you so much for this interview and good luck with your future projects!
PlanetSolar was initiated by the Swiss Raphaël Domjan and has its headquarters in Yverdon-les-Bains, Switzerland. The MS Tûranor PlanetSolar, built in Kiel, Germany, is a catamaran powered exclusively by solar energy. It is covered with 537 m2 of photovoltaic panels. After two years of design and construction, PlanetSolar is behind many technological advances, especially in the field of composite manufacturing and storage of solar energy. PlanetSolar is primarily funded by private partners, the Swiss watchmaker Candino and German specialist in energy management Immosolar, but also by public institutions, including the Swiss Confederation, with “Presence Suisse”. Moreover, PlanetSolar uses weather forecasts offered by MeteoFrance. An innovative routing software has been developed specifically for this expedition thanks to the support of the HEIG-VD in Yverdon-les-Bains and the French firm ADRENA.
Details on MS Tûranor PlanetSolar
- World Tour Duration: 585 days
- Stopovers : 52
- Countries visited : 28
- Oceans crossed : 3
- Seas crossed : 11
- Kilometers covered : 60’006
- Nautical miles covered : 37’000
- Fuel consumption : 0 liter
- Energy yield: roughly 260’000 kWh
- Length : 35 m / Width : 23 m
- Height : 6.10 m / Weight : 95 t
- Solar Cells: 38’000 with 18,8% yield
- Maximum engine power : 120 kW
- Average engine consumption : 20 kW (26.8 HP)
- Crew : min 4 people
You can see technical details of the ship here: http://www.planetsolar.org/the-boat