Just the sea, the sun - and us.

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<font color="#ffff00">-=Alternative Energien=- sync:ßÇÈâÈâ Michael Köhler and his wife Heike (top right) are passionate sailors. But they were tired of being dependent on a diesel engine during calm periods. Their solution: an electric motor driven by solar cells. Today her company Solarwave is the most important supplier of solar yachts.

Whenever their time permitted, the Carinthian lawyer Michael Köhler and his wife Heike were on the move on the nearby Adriatic. They covered about 30000 nautical miles with monohulls, later about the same distance with sailing catamarans. But sometime in 2003 they had to admit to themselves: "We run far too many hours under engine. The wind is a rather unreliable partner. We have to call on the help of Rudolf Diesel far too often."

Unfortunately Diesel is not an ideal sailing partner. Combustion engines generate noise, heat, vibrations, exhaust gases and a film of dirt on the water. The (also noisy) generator also needs diesel or petrol to supply power guzzlers such as the refrigerator, seawater desalination system and navigation devices as well as the air conditioning system. Yachts that carry little fuel are limited in range to a few hundred nautical miles. The great feeling of freedom and adventure looks different. "We thought to ourselves: Perhaps we should give Werner von Siemens a chance, who had his first electric boat tested as early as 1886 on the Spree in Berlin. Wouldn't it be a wonderful idea to convert a conventional yacht into a solar yacht with panels that drive electric motors?"

So the Köhlers take a look at what the market has to offer. They quickly realize: That's not much. They quickly discard their original idea of buying and converting a Lagoon catamaran. It is simply not possible to accommodate large solar modules: "You can't turn a Ferrari into a truck."

In 2005, the two start the first tests for their own solar catalytic converter. How and where do the panels have to be installed? How much space is required? How many shadows do the mast and other superstructures cast? How much electricity do the panels have to generate to feed an electric motor? What is the power requirement for the on-board electronics, the air conditioning, the stove? How strong do the batteries that drive the electric motor have to be? They will cover 15,000 nautical miles with these questions in their luggage in the coming years - in the Mediterranean, in the Caribbean, on an Atlantic crossing. The lawyer and Captain Köhler is becoming more and more of an engineer: "I was fascinated by the new possibilities. It is tempting to make your own boat completely self-sufficient with solar cells and electric motors."

The catamaran seems to be the ideal type of ship for this. This is the only place where sufficient solar panels can be placed on the roof to generate sufficient electricity.

In 2009 the first Köhlers e-yacht will be built in a shipyard in Niederkassel near Bonn. After the "Solarwave 46" has been launched, it will travel via the Rhine, Main, Danube and Black Sea to the Aegean Sea. During this voyage over 12000 nautical miles there are regularly eight persons on board. It is electrically cooked and driven in any weather. During calm and storm, sunshine and rain. During this time (net test duration: 141 weeks) no repair or maintenance work is required, neither on the solar system nor on the electric drive. The generator only runs for about 50 hours - primarily to prevent rusting. The electric motors, on the other hand, purr for more than 2500 hours. For this success, the Solarwave system was awarded the Energy Globe Award.

"Our boat had surprisingly few teething troubles," stresses the tinkerer. Of course, there have been changes: Over the years, lead batteries have become lithium cells that are lighter, smaller and more durable. The eight battery blocks he has installed on the 64-foot long "Solarwave", for example, require just 0.6 cubic meters of space. "In principle, these are the same cells you find in a Tesla. We had the feeling that we had discovered a very interesting market."

Now it's time for the Carinthians to turn the solar yachts into a lucrative business. Prototypes for a lot of money were finally also built by others. However, they were almost never ready for series production. On the one hand, they were thought to be too large, so that they became too expensive even for very wealthy private individuals. On the other hand, the founders got bogged down because they wanted to offer everything from a single source and at the same time be a planning office, design forge, shipyard and marketing company.

But that was never exactly the intention of the Köhlers: "We did not want to become a full-range supplier under any circumstances. Building yachts is far too complex a business for that. It should be our part to bring the know-how together." The crucial questions were: Which shipyard builds the ships? Which design office should be on board? The core team consists of just half a dozen employees, and the headquarters of Solarwave Yachts AG is relocated to Switzerland for tax reasons. "The design office is based in Hamburg, the 64-foot model is currently still being built in Turkey, and we have commissioned the German-Chinese shipyard Mazarin German Yachts to build the 55 and 72-foot models," explains Köhler.

The company currently offers several model variants. With pure electric drive, the "Cruiser" is available as an economical variant (displacer, speed up to ten knots) and the "E-Power" version for speeds up to 20 knots (glider with two 135 kW electric motors). The third variant currently available is the "Hybrid Power" model, in which, in addition to the two electric motors, two powerful diesel engines are installed which together provide the drive. "Depending on your mood, the electric motors can be driven almost indefinitely at lower speeds. If things need to go faster, the diesel generator can be started if necessary," explains Köhler.

The "Solarwave Sailor" has an additional option: it can even be used to set sails. "In strong winds, you can cross the oceans at more than ten knots." The rigg of the Sailor can be equipped with the serial hybrid drive of the "Cruiser" and the "E-Power" as well as with the diesel aggregates of the "Hybrid-Power" version.

"All models are configured so that they are completely self-sufficient under 'normal' conditions, as they prevail in normal holiday and leisure regions. For months on end," promises Köhler. A 15 kilowatt photovoltaic system manufactured in Austria by DAS-Energy ensures that not only the electric motor runs, but also that the electrical appliances on board always have the juice. An entire armada of lithium cells stores the electricity and keeps it ready for retrieval. The battery capacity as well as the design of the motors depends on the requirements of the buyer - every Solarwave is a made-to-measure product. According to Köhler, even if the yacht buyer wants a lot of batteries, there is still room for a 4.5 meter long dinghy garage, a complete kitchen, a lounge, three or four guest cabins next to the cabin for the crew, two sun decks and a generous table for meals outside. In order to consume as little electricity as possible for propulsion, the ship's hull is made of super-light carbon composite fibres.

The small diesel generator, which is even part of the equipment of the thoroughbred "E-Cruiser", is only an insurance in case the electric motor does not get enough juice from the solar cells after all. After all, no one wants to wander across the open sea without a propulsion system. At some point in the future, Köhler hopes, neither the emergency generator for the pure "E-Cruiser" nor the more powerful diesel engines for the hybrid variant - as with cars - will be needed: "The panels of the next generation will produce enough electric power and more powerful batteries will then be able to store it for a longer period of time without any problems.

Speaking of next generation. Köhler attaches great importance to the fact that its yachts can be retrofitted. In the future, lithium batteries will be cheaper and have a higher energy density. This makes it possible to travel longer distances at higher speeds. "The replacement currently costs about five percent of the total cost of the yacht, in a few years it will be even less," explains the Carinthian. "The solar panels can be replaced just as easily in a few years' time when new cells with significantly higher efficiency are available - we're talking about 0.5 percent of the boat's total costs here."

The basic price for a 55-foot solar yacht is just under 1.2 million euros. "It's no more expensive than a conventional motor yacht." The 64-foot long model costs almost two million euros. Meanwhile, there is a solid demand for the Austrian yachts, the order book for all models is well filled, partly fully booked: "We have already delivered half a dozen boats, another half a dozen are already under construction, further yachts have been ordered. Our Turkish shipyard, which is building the 64-foot variant, is fully booked until 2020."

After a "black zero" in the years 2015/2016, 2017 would be "for the first time in the black". However, he could not say with any certainty how many millions of euros in start-up investments he had raised: "Much was a hobby, a private joke at the beginning". In the meantime, there have been the first imitators who have pursued a similar business model. "A completely self-sufficient, seaworthy solar motor yacht can be offered at present but nobody except us in series", he emphasizes.

Its buyers findet Solarwave primarily in Europe and the USA. These are very technical, belong to the avant-garde, which also prefers Tesla. And they consciously accepted that motor yachts on long distances are still significantly faster than electric yachts. "We don't even compare our boats with a classic diesel motor yacht, which produces a lot of noise and exhaust fumes. Our benchmark are sailing yachts, which all too often run under engine. And their speeds and ranges we'll always manage."

He had been on the Balearic Islands this summer for six weeks, with guests, with the air conditioning switched on, more than 60 nautical miles in one day, at times also at full throttle, which corresponds to about eleven knots for the "Solarwave 64 Cruiser". He said he managed completely without diesel. And during the crossing from Ibiza to the Spanish mainland to Cartagena (135 nautical miles), the generator had only run for six hours during the night: "At a lower speed, we wouldn't even have needed it at all".

Obviously, the solar future has now also begun in the yacht sector. "And the best thing about it," laughs Köhler. "She's pretty fast."

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How electric motors conquer lakes and seas.

Experiments with electric motors are not limited to yachts. In 2012, the Swiss manufacturer Planet Solar presented the "Tûranor", the largest solar catamaran ever built with 100 tons. For the premiere there was an entry in the Guinness Book of Records. Today the "Tûranor" is used for scientific expeditions. The researchers like the fact that samples can be taken from the sea without being polluted by ship diesel exhaust fumes. However, the scientists do not have much space there. In order to reach a speed of five knots, the "Tûranor" needs a good 29000 silicon solar modules. They cover large parts of the ship's surface via cantilevers. This makes it clear that solar yachts still have a long way to go before they become cruise ships or even freighters. To drive a container ship carrying up to 150000 tons of freight with solar-powered electric motors, entire football pitches on deck panels would be required today. Gerard D'Aboville, captain of the "Tûranor", said in an interview: "Personally I do not think that solar energy is suitable for large ships and freight traffic. It'd be a dream, but a crazy one. You wouldn't get enough power." The construction of the "Tûranor" was therefore nothing more than a symbolic gesture. More interesting is the world's first and to date only electrically powered car ferry, which Siemens developed together with the Norwegian shipyard Fjellstrand. The electric ship commissioned in spring 2015 does not have any solar panels, but thanks to the green electricity from Norway it also does not emit any carbon dioxide into the atmosphere. The Norwegian Siemens engineer Odd Moen was in charge, whose vision became reality after years of tinkering and countless laboratory tests. "For more than 100 years, there have been battery-powered submarines that run purely on electricity," says Moen. "We asked ourselves, "Why can't this drive concept be brought to the surface? The decisive impetus came from the Norwegian Ministry of Transport, which is responsible for all the country's shipping routes. It announced a competition to develop the most environmentally friendly ferry. The prize: The concession for the ferry connection between the villages Lavik and Oppedal in the Sognefjord. Conventional diesel-powered ships, whose operating licence expired in 2015, operated there. According to the ministry's plan, as little noise and pollutants as possible should disturb the idyll. Today a fully electric ferry crosses the fjord 34 times a day. The "Ampere" takes about 20 minutes to complete the six-kilometer stretch. The 80 meter long ship is driven by two electric motors with 450 kilowatts each, which suck their energy from lithium-ion batteries. The total battery capacity of 1000 kilowatt hours is just enough for a handful of trips between the two fjord communities. The engineers solved the range problem with a simple trick. "Between each ferry trip, the ship's batteries are recharged in the port," explains Moen: "There are ten minutes left for this, while the passengers and cars disembark." On domestic inland waterways, combustion engines are almost a thing of the past. In Germany and Austria, many lakes with burners may no longer be navigated at all or only to a limited extent. In addition, a sufficient charging infrastructure has existed here for a long time. The Starnberg entrepreneur Christoph Ballin with his Torqeedo GmbH has become the world market leader in this segment (private wealth issue 03/2015). Even the elegant Swiss luxury wooden boats from Boesch have recently been delivered with an electric motor. Markus Boesch, junior head of the Zurich shipyard, says: "Despite an extra charge, the electric surfers already account for one third of the turnover. Of course, this is only really ecological if the electricity from the socket comes from renewable energy sources. The 80 kilowatt (108 hp) electric motors installed by Boesch generate a speed of almost 55 kilometres per hour. One of the pioneers of e-mobility on (inland) waters is the Berlin company SolarWaterWorld AG founded in 2001, which emerged from the former Institute for Solar Shipbuilding. Since 2011, the company has been offering the "SunCat 46", according to its own statement "the world's first larger solar yacht without emissions to be mass-produced". The basic version of the 14-meter yacht, which costs around one million euros, was designed by Juan Carlos Espinosa and is being built in cooperation with the Taiwanese yacht manufacturer Horizon. It has a large roof area on which Solon solar modules with a total output of up to six kilowatts are mounted. The power of the modules is sufficient to generate the necessary traction current and sufficient power for the on-board systems with two low-noise and low-vibration Kräutler electric motors. The energy is stored in battery units, which provide the power for propulsion or life on board as required. Thanks to solar energy, the boat has an almost unlimited range - as long as the sun is shining. On cloudy days, the range drops to eight hours. And even this can only be achieved if the maximum speed of 14 kilometres per hour is not reached. The biggest challenge with "normal", slim solar sailing yachts is to be able to mount enough panels. This is why most providers use the catamaran. An alternative could be to integrate solar cells directly into the sails. PowerSails is one of these systems. It was developed by Alain Janet, the owner of the British sailmaker France. Each square meter of the material can generate 100 watts of power per day and does not even need direct sunlight. Of course, this only works if the wind conditions allow the sails to be set. Because this is not always the case, experts also advocate hybrid solutions for these models. At least until the solar cells become even smaller and take up less space. An interesting variant - in addition to back-up by a combustion engine - is the use of wind power, which generates electricity on board using propellers.

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Author: Dr. Günter Kast

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