# Developments in Electric and Green Marine Ships
## 3 Technologies that Did or Will Shape the Future of Naval Travel and Trade
### More Conventional Ideas Already Implemented or Close to Implementation in the Last Five Years  
Above was mentioned a complete example of a green ship, combining solar and wind power, having an optimizing control system that monitors and optimizes the rigid sails, calculating the wind direction and the solar radiation, simultaneously reducing the emissions, and finally having a battery system of 95% recyclable batteries. Although the example of the EcoMarinePower (EMP) ship is still in research and trying to implement more technologies, there are more current examples of ships that have managed to implement, or are currently implementing some of the latest technologies contributing to the global demand of cutting down emissions.  
First, E-Ship 1 has successfully implemented the Flettner rotors since 2010. The vessel is owned by one of the largest wind manufacturers and has been built to transport wind turbine components, and was built at two different shipyards in Germany. The technical characteristics of the ship are a length of 130 m, beam of 22.5 m, maximum speed of 17.5 knots, and engines of total output 3.5 MW. It uses four 27-m high and 4-m diameter Flettner rotors that save around 35% of the fuel consumption [51].  
The first electric cargo ship was launched in 2017 in Guangzhou, China [52]. The vessel is 70.5 m in length and travels in the inland section of the Pearl River, covering a distance of around 80 km with a single charge. In battery capacity, this translates to 2.4 MWh and 2-h charging time. The batteries are made of lithium and able to provide power for transporting 2000 metric tons of goods. The electric power required for the ship's movement is not only more environmentally friendly, but also cheaper compared to the fossil fuel power. In addition to that, further battery installments are proposed that will raise the maximum cargo that the ship could carry to above 2000 tons.  
Electric shipping is not only implemented in Asia, but in the European Union (EU), too. One of the first the first all-electric ferry was launched in Sweden. There is quite an interest in the city where these ferries were introduced. The Swedish city of Gothenburg is a great example of a low-emission city, trying to implement any new technology contributing to that goal, through the ElectriCity project. The ferry is expected to enter commercial service by the end of 2020 [53]. Another all-electric vessel is expected to be commercially ready, but this time it is a small cargo ship. The all-electric inland vessels are being built by a Dutch company. The initial plan was to start operation of the electric inland vessel in August 2018, but until now, no solid proof could be found. However, the plan includes five small and six large electric container badgers that are being built and will be used to travel between the Netherlands and Belgium. These vessels are not only all-electric, cutting emissions down to zero rates, but also autonomous. This characteristic offers an additional 10% cargo capacity and will be implemented after the first years of operation, during which it will operate with an on-board crew. The first electric inland vessel is 52 m long and contains a large lithium battery that is 6 m long, which makes it possible to sail for 15 h, carrying around 400 tons of goods. According to Port-Liner, these vessels will be able to successfully substitute over 20,000 diesel vans annually, which are currently trading the products between the Netherlands and Belgium.  
However, the above vessels are not the only autonomous electric vessels. The Yara Birkeland according to [54; 55], will be the world's first autonomous electric vessel. This vessel is going to travel between ports in Norway, substituting for the use of diesel-powered trucks and vans. The vessel is 70 m long and 14 m wide, with a carrying capacity of 120 containers. Its battery system has a capacity of 7.5-9 MWh, making it capable of only short-route traveling, and it will be fully operational by 2022.