Everywhere you go in Japan, you see cars and home electronics products made to be friendlier to the global environment. And not just on land. By using the most advanced high technology in the world, Japanese companies are building ocean-going vessels called “eco-ships” which use less fuel and release less CO2 into the air. Japan is a shipbuilding superpower; one in every five ships made in the world is built in Japan. Building eco-ships is one of the ways in which Japan intends to contribute to preserving the global environment. Large cargo ships carry many things, including foods such as wheat and soybeans, liquefied natural gas (LNG), iron ore and cars. The largest car carrier made in Japan has 14 floors, is about 200 meters long, and can carry 6,400 cars on a single voyage. A giant ship like that needs a lot of fuel because it is heavy and because it faces great resistance from the waves. Eco-ships reduce CO2 emissions by using less fuel and reducing wave resistance. One way to do so is to use solar energy. The Auriga Leader, a Japanese car carrier which went into service in December 2008, is the world’s first ship to put solar energy to actual use.
The ship has 328 solar panels, spread over 250 square meters on the deck. Solar energy provides less than 1% of all the energy the ship uses. However, for the first time in the world, the Japanese ship also has large-volume batteries to store solar energy. In June 2012, the Emerald Ace, also a car carrier, went into service with 768 solar panels on its deck. This ship does not need fuel to generate electricity when in harbor. While out at sea, the ship generates electricity by solar energy and stores it in lithium-ion batteries on board.
Once in harbor, its diesel generators are stopped and solar power is used. The onboard solar panels can generate about 160 kilowatts of electricity, enough to power about 50 homes. Ships just began to take advantage of solar energy and more solar ships are on the horizon.
Eco-ships are also built to reduce the frictional resistance of waves and wind. In probably the most interesting way of doing so, some Japanese ships have a system for generating air bubbles at the bottom of the bow and sending them by a blower from bow to stern. The bubbles reduce frictional resistance between the ship and seawater, helping to propel the vessel. The bubble effect was known theoretically before, but it was Japan that actually built ships to take advantage of air bubbles for the first time in the world.
Three bubble ships entered service since 2010, including the Yamato, a “module carrier” that transports modularized heavy and large loads. The ships have proven to reduce CO2 emissions by about 6%. It is a unique idea that a ship rides on air bubbles, isn’t it? Also, the City of St. Petersburg, a car carrier commissioned in December 2010, has a hemisphere-shaped bow. The rounded bow of the ship, which travels back and forth across the North Atlantic carrying a Japanese carmaker’s vehicles, helps reduce wind resistance by up to 50%, slashing CO2 emissions by about 2,500 tons per year as a result.
There is an ongoing plan to combine the two technologies – the hemispheric bow and solar panels on board – to build very fuel-efficient ships capable of curbing wind resistance and taking advantage of solar energy. In addition, Japan is recently experimenting with new methods for painting the ship hull. Inspired by Mother Nature, new sorts of surface painting, such as one likened to the skin of sharks moving swiftly through the water or to lotus leaves repelling water, are being developed with nanotechnology. Alloys such as aluminum as well as carbon fiber used for aircraft are also under consideration to reduce ship weight.
There is a plan in Japan to build a “Super Eco-Ship” using both solar and wind power by 2030. The ship, 352 meters long, will have solar panels as well as eight large masts to take advantage of wind propulsion. It looks like a honeybee gliding on the water. In additional to these natural energy sources, the ship is supposed to mainly use fuel-cell power derived from LNG. The ship will have a total of 16 modular fuel cells, each the size of a standard freight container, which can be replaced with new ones during a port call. In 2030, the dream eco-ship will be partially powered by LNG.
Compared with current ships powered by diesel engines which burn heavy oil, the dream ship will cut CO2 emissions by 69%. Eventually, the ship will aim at zero waste emission. Ships all over the world are said to emit 1.05 billion tons of CO2 per year, accounting for 3.3% of total global CO2 emissions. That is more than the total amount of CO2 emitted by Germany per year. Now that emerging countries are developing rapidly, the world’s ocean-going ships in 2050 will be emitting 2.5 times more CO2 than today, according to some experts. There is much hope in the world for Japan’s eco-ship technologies to help preserve the global environment. ( 5elected from www.web-japan.org )