International Journal of Advancements in Research & Technology, Volume 2, Issue4, April 2013 388 Wave Power Generating Ships Environmental Hazards by ship on port Ships stay on power generated internally through diesel powered generators (auxiliary engines). Ships throughout the world have been using Heavy Fuel Oil residual petroleum as the optimal choice of fuel. This fuel, the reverse of gas oil is high on particulate matter; and studies show that a single ship can produce emissions (like SOX and NOX) equal to the same amount as 50 million cars annually. For every kilowatt hour (kw h) of electricity, about 200 gm of bunker fuel is consumed. Each 1kg of bunker oil =3.125kg of carbon dioxide. It is assessed that globally ships use 411,223,484 tonnes of fuel annually. There is a solution to these problem that is shore power. Shore power Shorepower is the process of providing shore side electrical power to a ship at berth while its main and auxiliary engines are turned off. For its operational requirements a power source from land is used The source for land based power may be grid power from an electric utility company, but also possibly an external remote generator. The reasons for using shorepower would include: To save fuel, To allow maintenance of on board generators,
International Journal of Advancements in Research & Technology, Volume 2, Issue4, April 2013 389 To eliminate emission of toxic fumes including, but not limited to NOx, SOx and CO 2, To reduce noise level in port, To comply with local anti idling laws. To allow for a ship's drydocking routines. POWER CONSUMPTION ON PORTS Different power forms may be used to transfer electrical energy from port to the ship: 6600 V AC (standard for container vessels) 660 V AC 400 V AC 11000 V AC (standard for cruise vessels) [4] One obstacle is the use of different frequencies like 60 Hz instead of 50 Hz, which may cost 300 000 500 000 EUR to convert, where required. Amount invested The amount of power for an ocean going ship is usually 2,0 10 MW. Cable to connect larger ships may cost 25 30 $/meter. Transformer substations cost 18774 37548 $. Operation and maintenance costs of the onboard auxiliary engines are estimated to be around 8$/MWh for electricity generated. Fuel cost for sea diesel, with sulphur content less than 0,5% cost approximately 23 $/MWh (12 months sliding average in 2005). So definitely we are putting load if we use conventional source of power hence another way is we can use renewable energy.
International Journal of Advancements in Research & Technology, Volume 2, Issue4, April 2013 390 What is tidal energy? Tidal power, also called tidal energy, is a form of hydropower that converts the energy of tides into electricity or other useful forms of power. The tide moves a huge amount of water twice each day, and harnessing it could provide a great deal of energy around 20% of Britain's needs. Although the energy supply is reliable and plentiful, converting it into useful electrical power is not easy. Only around 20 sites in the world have been identified as possible tidal power stations. Limitations of tidal power plants It is not cost effective because fossil fuel power stations do not pay for the cost of their carbon emissions to the planet. Power produced from tidal fences is still a bit expensive than that using conventional plants using coal and natural gas (but it can be cheaper if improved technologies and large scale generation is applied). The barrage systems disrupts fish migration and results in destruction of ecosystem that rely on the coming and going of tides. It is limited because the tide never speeds up or slows down, and occurs on 6 hour cycles. The main detriment is the cost of those plants, for constructing and running this facility with an annual output of 3423 GWh, is a cost about 1.2 billions, but this doesn't include operational and maintenance cost (coal and oil are cheaper).
International Journal of Advancements in Research & Technology, Volume 2, Issue4, April 2013 391 Hence now we need another way to use this renewable source of energy and it could be WAVE POWER SHIP. Wave power ships Fleets of Wave Power Ships Could Harvest Cheap Energy from the Motion of the Ocean Wave power ships could bring cheaper clean electricity SHIPS that harvest energy from the waves and store it in batteries could generate electricity from the world's oceans more cheaply than wavepower devices. These ships would sail to a suitable location according to wave energy atlas and generate power. This energy would then be stored in on board batteries, and once fully charged the ships would return to shore where the energy could be distributed into the grid. Working of wave power ships: The 50 metre long ships would harvest wave energy via buoys attached to their sides by pivoting arms. While the hull remains relatively stable, the buoys would bob up and down on the waves, causing the arms to pivot back and forth and drive a generator producing up to 1 megawatt of electrical power.
International Journal of Advancements in Research & Technology, Volume 2, Issue4, April 2013 392 The batteries are planned to have a capacity of 20 megawatt hours, so the ships would have to stay at sea for at least 20 hours for a full charge. After 20 hours at sea, the barge heads back to the dock with fully charged batteries and plugs into a device known as an inverter this converts the stored direct current electricity into alternating current, which is what the power grid needs. Why Mobile Wave Power: Ship Based Energy? Ocean waves carry a lot of energy. And all of that energy, clean and relatively consistent, looks pretty good to a world that is continuing to search for ways to ramp up generation of electricity from carbon dioxide free sources. Acc to the math on every conceivable source of electricity storage,the estimated costs and logistics would include: flywheels molten salt storage gravity based systems, and numerous battery technologies The batteries alone would cost close to $10 million for a single boat. The energy harvesting devices adds another $4 million. Ultimately it turned out that we had to use batteries. The reason for this is efficiency of the storage mechanism. Storing it in a battery, though, saves much more of the original energy taken from the ocean wave. As per requirements lithium ion batteries are considered as best option
International Journal of Advancements in Research & Technology, Volume 2, Issue4, April 2013 393 Lithium ion battery During charging, an external electrical power source (the charging circuit) applies an over voltage than that produced by the battery, forcing the current to pass in the reverse direction. During discharge, lithium ions Li + carry the current from the negative to the positive electrode, through the non aqueous electrolyte and separator diaphragm. LITHIUM ION BATTERY RECYCLING LOOP The earth s resources, no matter how abundant we think they are, are finite, and precious to all of us Cost comparison As per calculations that the system should generate electricity at a cost of $0.15 per kilowatt hour. This would make it cheaper than energy from existing wave systems, which costs between $0.30 and $0.65 per kwh. Offshore wind energy costs from $0.15 to $0.24 per kwh, and solar power around $0.30 per kwh.
International Journal of Advancements in Research & Technology, Volume 2, Issue4, April 2013 394 Advantages of wave power ships: Once you've built it, tidal power is free. It produces no greenhouse gases or other waste. It needs no fuel. It produces electricity reliably. Not expensive to maintain. Tides are totally predictable. By: Ch. Divya(+917845818757) Bhagyashri Gawali.(+91 8144669648) B.Tech 3 rd year (Marine Engineering) Indian Maritime University, Chennai.