Electric boat
An electric boat is a motor boat that is electrically powered. This is usually done by charging electrical energy from the power grid into an accumulator using a charger . Most of it can be fed to an electric motor connected to a propeller while driving . A solar boat is a special form of an electric boat in which the energy is mainly provided by solar cells installed on board .
history
The first functional electric boat
The first successful attempts with an electric boat drive were carried out on September 13, 1839 by Moritz Hermann von Jacobi with a converted rowing boat. This made it the first functional electric boat in the world. Jacobi undertook another test drive in the following years with a DC motor that he had optimized and improved galvanic cells from William Grove . Further technical improvements to the electric drive motor, which Jacobi carried out in the following years, made further trips necessary in October 1841.
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Further development until today
For the International Electrical Exhibition in 1883 , an electric boat carried 40 people on the Danube from Vienna to Pressburg (now Bratislava) in four hours.
From 1886 onwards, the Electra was used for targeted test drives on the Spree to solve the local traffic problem in Berlin; however, this form of drive could not prevail.
Electrically powered excursion boats have operated on the Königssee from 1909 until today.
In 1957, the Heistracher shipyard built electric boats that were supplied with energy from lead-acid batteries.
With the first oil price crisis in 1973/74 and the oil embargo of some oil exporting countries in the 1970s, interest in electric boats reappeared. In addition, there were improved options for charging batteries electrically using solar cells . With these solar boats it became possible for the first time to simultaneously achieve both a theoretically unlimited range, as with sailing boats, and maneuverability, as with motor boats. The first practical solar boat was probably constructed in England in 1975.
There are inland waterways , for example dams, on which the use of boats with combustion engines is regulated or prohibited. This boosts the demand for boats with alternative propulsion systems such as solar and fuel cell boats (using methanol from hydropower).
In 2014, the FährBär, the first battery-powered passenger ferry, was used in Berlin , and now there are 5 ferries, which, surprisingly, are not operated by Berlin companies, but by the White Fleet in Stralsund .
In 2015, the Ampere went into operation as the first battery-electric ferry for cars in Norway north of Bergen . There are charging stations at both landing stages, on either side of a fjord. Since then, more and more battery-powered ferries have been operating in Norway's archipelago.
BB Green is a battery-powered 80% hovercraft that was launched in March 2017 in Riga, Latvia. The demonstration ship is the result of EU-funded research and, with a cruising speed of 30 knots, is a particularly fast electric boat for 99 passengers and a distance of 14 nautical miles, after which it requires 20 minutes of charging time (super charging). BB Green is an acronym from B attery-powered B oats, providing G reening, R esistance reduction, e lectric, e fficiency and N ovelty.
In 2017, the Elektra (ship, 2017) was the first electric ferry in Finland.
A battery-powered ferry has been operating in Taiwan since June 2017 . It also has a diesel engine plus a generator as a range extender .
In 2019, the Kibitz shipyard in Havelberg delivered the Suncat 120, the first of two battery-powered passenger ships for 180 passengers to the Berlin shipping company Solar Cicle Line . The Association for Electric Shipping and Charging Infrastructure was therefore founded in Berlin in spring 2018 to set up the corresponding charging infrastructure.
Components
Like all vehicles, electric boats need a primary source of energy, a storage facility and a conversion into mechanical propulsion, usually electric motors and propellers or paddle wheels.
Energy source
- In most electric boats, the batteries are charged using a charger on the shore-side power grid. The environmental friendliness of such electric boats consists in the low direct noise and pollutant emissions of the boat itself, but it depends indirectly on the electricity mix purchased. The efficiency and environmental friendliness of a thermal power plant are usually better than that of individual combustion engines. Electric charging options are common in marinas . In some areas they can be found in harbors and at tourist docks.
- Wind generators are common on sailing yachts. Like the towing generators, they are useful in strong winds on the move, but even more so when berthed in port or at anchor. With the usual sizes, however, they are at best auxiliary drives. There are some yachts with wind turbines large enough to provide the main propulsion. However, they work purely mechanically; there are no known electric boats primarily powered by wind. Larger wind turbines present a difficult safety problem to solve on a small boat.
- Solar cells can be installed on existing or specially constructed surfaces. Most solar boats have horizontal solar roofs, as these are relatively insensitive to strong winds. However, a surface that is inclined towards the sun can provide more power and adjustable surfaces are essential if solar boats are to be operated in northern latitudes in winter. The size of the solar area determines performance and range. Solar boats with relatively large areas that can be used by solar energy reach their cruising speed under good conditions without taking energy from the battery, or they can drive and charge the battery at the same time. Such boats can drive even when it is cloudy without using the battery and therefore usually have an unlimited range.
- Solar cells can also be installed on the shore at the berth of an electric boat or solar boat and are thus available during the mostly long lay times of the boats. Such systems are usually connected to the power grid so that the excess solar energy can be fed into the grid when the boat battery is fully charged, or, on the contrary, can be charged from the power grid when the irradiation is insufficient. In some solar boats, the solar cells on board are also included in the network. Such boats usually deliver an average surplus into the power grid over the year.
- Tow generators are common on sailing yachts that travel long distances. In strong winds, the boat will sail close to the hull speed . The additional resistance of the generator is then hardly significant. When there is calm, the energy stored in this way can be used again when the towing generator is brought in. Some boats use the normal propeller and boat electric motor in this way instead of a towed generator. However, in a conventional propeller, the blades for generator operation are the wrong way round.
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Heat engines can also be used with generators to generate electrical energy. Diesel-electric drives without electrical energy storage are used in large ships. However, they are not counted among the electric vehicles as they cannot be operated without a combustion engine. With electrical energy storage, this mixed drive is referred to as a hybrid drive . Well-known representatives are conventional military submarines . Basically, two variants are common in shipping:
- In the series hybrid , a small generator with a combustion engine or Stirling engine charges the battery. The boat is powered exclusively by the electric motor.
- With the parallel hybrid, both the combustion engine and the electric motor act on the drive shaft and can also be used independently of one another. When the internal combustion engine is running, the electric motor can act as a generator and then charges the battery. The waste heat from the internal combustion engine can also be used for heating or preparing hot water through heat exchangers.
- Fuel cells have been used for diving trips in German class 212 A submarines since 2003 . A prototype for the combination of photovoltaics and reversibly operated hydrogen fuel cells, the " Solgenia ", is being developed as a research ship at the University of Konstanz and has been in practical operation on Lake Constance since the beginning of 2007.
battery
As with land vehicles, the battery is also the component in boats that limits the properties of the vehicle the most, since the energy density is lower than that of chemical energy storage devices. At least in the case of slow displacement boats, however, this is less due to the weight than to the costs, especially since all electrochemical batteries have a very limited service life.
Lead-acid or lead-gel batteries are still common in small drives, but they reach their performance limit very quickly due to the slow ion exchange and only have a short service life when overloaded.
More than any other component, the size of the battery determines the usability of the electric or solar boat. A large battery allows a decent range at low speeds; a single charge has already covered over 200 km. Extreme solar boats have no or only a very small battery.
Pleasure boats are usually equipped with an accumulator that is sufficient for a day trip. On the other hand, with an electric cabin boat on the Chiemsee with 8 lead-gel batteries from the German manufacturer Sehmataler Akkuwerk, ranges of up to approx. 200 km at approx. 6 km / h are possible (corresponds to a journey time of over 30 hours). According to the manufacturer, the chemical durability is approx. 12 years or 700 charging cycles.
Electric motor
The electric motor is a component of every electric boat. In addition to inboard engines of any type, there is a large selection of outboards for small boats. In order to maneuver the boat, at least one forward and reverse switch is required, preferably with a few steps. Today electronic regulators are common, which allow a step-by-step adjustment down to the lowest speeds. Such boats are particularly easy to drive. Modern controllers allow 4-quadrant operation, i.e. drive and braking are possible forwards and backwards. Usually, however, it is braked by driving in the reverse position. High-performance motors are mostly inboard three-phase motors (asynchronous or synchronous) with two-circuit water cooling. The motor controller converts the direct current coming from lithium batteries and / or supercaps into three-phase current according to the specification from the drive lever. So that steering drives (Z-drives) can also be used, there are also high-speed motors up to about 5000 1 / min in vibration class S1. With these drives, multi-engine luxury yachts can also sail on waters where combustion drives are prohibited. This drive concept was worked out by Bootshop Rust in collaboration with Aquamot, so speeds of over 100 km / h are no longer utopian. The advantage of this technology is the extremely high torque, it achieves acceleration values that cannot be achieved by much more powerful internal combustion engines. The acceleration ramp even has to be programmed to be flatter in order not to overload the mechanics.
Propulsion generation
The propeller is absolutely the modern boat drive , although paddle wheels are also possible, which have their advantages when starting and braking. In order to obtain a satisfactory range, a particularly high level of efficiency is necessary for electric boats. Therefore, rather large, slow-turning propellers are used, although a compromise has to be found with the functional properties, especially with regard to depth and susceptibility to seaweed. The required low speeds can only be achieved with special motors, particularly large motors or with gearboxes.
The magneto-hydrodynamic drive has so far only been implemented as a prototype and is the subject of research.
Types
- Historic electric boats are particularly popular in Great Britain.
- Electric boats for inland waters: Many canals, rivers and lakes are relatively small and sheltered from the wind and often have speed restrictions. On some bodies of water, electric boats are the only approved types of motor boats. Due to the low energy density, electric boats are not suitable for applications with permanent high performance requirements (for example continuously high speeds or long journeys against currents, wind and weather). There are applications as ferries (e.g. FährBär in Berlin), to car ferries (e.g. Ampere in Norway).
- Open motor boats in the classic style, which can reach planing speeds with lithium batteries and powerful electric motors.
- Electric outboard motors: The electric outboard motors for smaller boats, which are available as a mass product, are rather poor in efficiency due to the small, fast rotating propellers, but they are fully developed. Some outboards manufactured in small series or as prototypes have higher efficiencies and are suitable for pleasure boats. The service life of some types is insufficient for professional use without intensive maintenance, for example on ferries.
- Today sailing yachts almost always have an auxiliary engine. There are two main uses, one as a slack slide and the other to maneuver in harbors or narrow entrances. An electric drive can serve both purposes well, because when driving slowly in calm conditions, very little power is required and it can be driven for a very long time with a small accumulator. Harbor maneuvers, on the other hand, usually last a few minutes and even small electric motors can provide greater power during this time and are very finely controllable. The emission-free, low-maintenance and low-noise generation of electric drives also suit this application.
- Hybrid boats, as described above, mostly use an internal combustion engine and an electric motor. For small or particularly low-resistance boats, muscle power drives have proven their worth instead.
- Solar boats. Photovoltaics are also used in boats. In contrast to electric boats, solar boats use direct solar radiation as an energy source. However, there is a smooth transition between pure electric boats and pure solar boats. There are solar boats without a battery for record purposes, those with a very small battery for racing purposes, utility solar boats for travel purposes and pleasure boats with few solar cells. In the latter type of boat, the batteries are designed in such a way that they can cover consumption on weekends. The few solar cells will recharge the battery until the next weekend. For further information and references, see solar vehicle .
- Overhead line ferries get their energy from an overhead line similar to trolleybuses.
- Electrically operated chain ships are still used in France today to negotiate long, poorly ventilated tunnels.
- Most submarines are electric when submerged, while civil submarines are mostly electric.
Classic style open motor boats
- Electric motor-driven, open, small motor boats with the classic shape of the hull are called "electric runabouts". They can transport up to eight people. The achievable performances are already sufficient for the operation of further water sports. For example, water skiing is possible in the wake of an electric runabout.
- Design goals: In contrast to previous electric boats, the design goal of an electric runabout is to achieve a maximum of driving pleasure.
- Driving pleasure maximization: The maximum driving pleasure as a design goal is achieved through special focus (?) On the sub-areas of drive technology, hydrodynamics and aerodynamics. Drive technology, in particular, is currently offering major advances in the area of electromotive concepts.
- Weight minimization: The total mass of an electric runabout depends crucially on its energy requirements. That implies another design goal. The minimization of the total mass. In order to maintain driving pleasure, the overriding goal, the (above) other areas (hydrodynamics, aerodynamics) must be optimized.
- Technical details:
- Drive technology: The conception of the electric runabouts presupposes a high efficiency of the accumulator cells. Cells based on lithium technology offer the necessary performance.
- Energy storage: The electric runabout uses batteries as energy storage. They are placed in several units (so-called battery cells) at suitable locations on board the boats. The size and number of battery cells depends on the energy requirements of the boat.
- Propulsion systems: All common as well as "unusual" systems come into consideration as propulsion systems.
- Fluid mechanics: The flow conditions are optimized by analyzing the current along the boat.
- Hydrodynamics: The hydrodynamics are optimal when the resistance of the boat to the water is minimized.
- Aerodynamics: The aerodynamics are optimal when the resistance of the boat to the air is minimized.
literature
- Use of electro-magnetism as a driving force for shipping. In: Polytechnisches Journal . 71, 1839, Miszelle 2, pp. 411-413.
- Electric boat . In: Brockhaus Konversations-Lexikon 1894–1896, Volume 5, pp. 1000–1001.
Web links
- eLexicon Proven knowledge in current form (PDF)
- Photos with details of Jacobi's replica electric motor. eti.kit.edu
Individual evidence
- ↑ vdi.de: PDF (p. 1)
- ↑ Bootswerft Heistracher, History ( Memento of the original from June 25, 2017 in the Internet Archive ) Info: The archive link was inserted automatically and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. . Retrieved August 29, 2016
- ↑ Electrical Review Vol. 201 No. 7, August 12, 1977
- ↑ The world's first electric ferry in use in Norway . In: ingenieur.de - job exchange and news portal for engineers . May 20, 2015 ( ingenieur.de [accessed March 3, 2018]).
- ↑ “World's First” Electric Car Ferry Goes Live insideevs.com, 2015, accessed November 12, 2017. - Pictures and technical discussion.
- ↑ latitudeyachts.eu , accessed January 15, 2020.
- ↑ BB Green greencityferries.com, 2017, accessed November 11, 2017.
- ↑ BB Green project website
- ↑ Visedo powers Asia's first E-ferry in Taiwan ( Memento of the original from November 11, 2017 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. visedo.com, June 16, 2017, accessed November 11, 2017.
- ^ Electric Boat News , Vol. 14 No. 4, Winter 2001/2002
- ↑ This boat can be seen here. ( Memento of the original from June 2, 2013 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Chiemsee-Classic-Yacht.de
- ↑ Mary Gordon Electroboot ( Memento of the original from June 7, 2010 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (English)
