With the implementation of international fuel efficiency standards, the development of energy-efficient and environmentally friendly ships is booming. In the context of soaring crude oil prices, many energy-saving technologies have now become economically cost-effective.
Affected by international fuel efficiency regulations and the surge in crude oil, ships equipped with revolutionary energy-saving technologies have been put into practical use.
Driven by factors such as economic development in emerging market countries, maritime traffic is increasing year by year. International shipping has about 3% of the world's total CO2 emissions. It is equivalent to the emissions of Germany.
Under such circumstances, the International Maritime Organization (IMO) in 2011 amended the International Convention for the Prevention of Pollution from Ships, which aims to prevent marine pollution, and introduced the world's first international fuel efficiency standard for ships. The standard constraint object is the international shipping vessel, which came into effect in January 2013.
The standard is based on the average CO2 emissions per unit weight distance (ton nautical miles) of ships built between 1999 and 2008. Ships contracted for construction after January 2013 shall not be required to be lower than the benchmark. The benchmarks are not only gradually strengthened in phases, but also require existing ships to develop energy-saving shipping plans.
CO2 for international shipping has been outside the scope of the Kyoto Protocol because it is difficult to define emissions. The introduction of the above standards means that the ship finally has a formal emission limit standard.
Moreover, the surge in crude oil prices has also driven the development of energy-saving technologies. The ship's fuel – C heavy oil was around $100 per ton more than 10 years ago and has now reached $600 to $700. "The energy-saving technology that was not seen in the past due to cost constraints has finally become cost-effective," said Chichi Tetsu, director of the Japan Institute of Maritime Technology and Security.
Use air bubbles to reduce friction
Every year, the Japan Society of Marine and Marine Engineering selects the “Year of the Ship†to recognize innovative ships. In 2013, Oshima Shipbuilding’s coal carrier “Shuangyang†built for the Japanese mail ship won this award.
The "Shuangyang" (left) coal carrier of the Japanese mail ship built by Oshima Shipyard has saved 4 to 8% of energy by using an air lubrication system (top).
Shuangyang is equipped with the latest energy-saving equipment "air lubrication system": it can reduce the frictional resistance of the hull and water by blowing air from the bottom of the ship, thereby reducing fuel consumption. This can reduce CO2 emissions by 4 to 8%.
However, a blower that blows air from the bottom of the ship consumes electrical energy. Moreover, the more cargo loaded, the deeper the draft (the depth of the underwater part), the greater the water pressure at the bottom of the ship, and the more energy it consumes when blowing air. In some cases it may even offset the energy savings.
To this end, Shuangyang has taken the lead in adopting a “sweep bypass†in the world. Scavenging means that the supercharger (Turbocharger) outputs compressed air to the engine due to the increased power of the engine. In recent years, as the performance of the supercharger has increased, the scavenging has a margin. By diverting the scavenging air to air lubrication, the use of the blower can be reduced, resulting in significant energy savings.
Wind-resistance residential area (left, front) and old-fashioned residential area (left, rear). Mitsui Shipbuilding's Power Assist Sail (right) changes the number of sails depending on the size of the ship.
When the ship is sailing, it is subject to various obstacles such as waves and sea breeze. It is generally believed that the frictional resistance of the hull and seawater accounts for 50-80%. As a technology to reduce this friction, new marine primers are also being developed.
Antifouling paints that prevent the attachment of organisms such as barnacles, and low-friction paints that reduce the friction by making the surface of the hull smooth have been put into practical use. Applying such a paint to the bottom of the ship can receive several percentage points of energy saving effect.
The aforementioned Qiantian also said that new low-friction coatings are also under development and are expected to be put into practical use in a few years. When the ship is sailing, the seawater in contact with the hull will roll up tiny eddies. This is the cause of the frictional resistance. When a new type of coating is used, the polymer (polymer) will dissolve in the seawater a little bit, which will reduce the generation of vortices and smooth the flow of water. Experiments using the model show that friction can be reduced by nearly 20%.
Using wind-assisted navigation
On the other hand, the technology that uses natural energy has also been put into practical use. Its representative is the "Power Assist Sail" completed by Mitsui Shipbuilding in 2013.
This technology uses a movable sail that is 20 meters long and 10 meters wide on the deck to capture the wind to supplement the driving force. The angle of the sail can be adjusted automatically according to the wind direction and wind speed, and it is expected to receive 2 to 5% energy saving effect. In the event of storms and windless winds, the sails can be folded and strolled, sailing like a normal ship. Moreover, sails can be added to existing ships. If 5 to 6 sails are installed on a large tanker, energy saving can be 2%. Then, by reducing the fuel cost, it is expected to recover the investment in about 5 years.
The wind will become a driving force and it may become a drag. In order to reduce the wind resistance, Japan Marine United (JMU) repeatedly carried out wind tunnel experiments and computer simulations on the new generation of energy-saving bulk carrier "Cape Green" built in August 2013, and carefully adjusted the shape of the stern residential area. . Successfully reduced the frontal wind resistance by 20 to 30% and saved about 2.5%.
Cape Green is also equipped with a new drive system that completely consumes fuel heat. High temperature gases are generated when the main engine is operating. These gases will be transported to the "mixed booster" of the built-in generator. The energy of the gas is used to drive the supercharger and then the remaining energy is used to generate electricity. Moreover, after passing through the supercharger, the gas is also sent to the boiler to prepare the vapor. Drive the turbine to rotate and generate electricity again. By using the produced electrical energy to drive the motor and assisting the engine's power, approximately 5% of the energy can be saved.
In the past, “composite power generation†that used steam to produce steam for power generation was only used in the most advanced thermal power stations. Nowadays, such high-end technology is also applied to the latest environmentally friendly ships.
Follow SOx and NOx regulations
On the other hand, attempts to convert fuel from past heavy oil to liquefied natural gas (LNG) have also begun. The use of LNG can reduce 20 to 30% of CO2, about 80% of nitrogen oxides (NOx), and completely eliminate sulfur oxides (SOx).
Nippon Yusen decided to build an LNG fuel ship in December 2013. The development of the engine is over and the ship will strive to be built in the 2015 fiscal year. In addition to the LNG carrier, this will be Japan's first LNG-fueled vessel.
In addition to CO2, the International Convention for the Prevention of Pollution from Ships has added provisions to strengthen NOx and SOx standards. Especially for SOx, the Convention requires that the sulphur content of fuels be significantly reduced from the current 3.5% to 0.5% as early as 2020. If the desulfurization cost is to be superimposed on the basis of the high crude oil price, LNG may also have an advantage in cost.
However, ports with equipment that supplies LNG to ships exist only in parts such as Northern Europe. To be practical, it is also necessary to improve the aerated fuel infrastructure.
Use big data
In addition to the hardware such as the hull, there has also been a trend in the software field to promote energy conservation.
"The ship with the same performance is sailing on the same route, but the fuel efficiency can vary by 30% in actual voyage. If the weather, currents, shipping conditions, etc. are huge," said Ando Yoshiyuki, head of the ship intelligence unit of MTI, a Japanese ship. Based on the information, calculating the best route and driving method, and notifying the ship, can significantly reduce fuel consumption."
Based on the huge information such as weather, current, and shipping status, calculate the best route and driving method, and give instructions to the ship.
In the past, operators who carried out ship shipping management on land only had a regular email and fax to understand the shipping situation. But in the last two years or so, it has become possible to use satellites to maintain broadband communication connections between ships and land.
Land-based shipping data for ships such as engine revolutions and loads, ship speed, fuel consumption, hull sway, waves and current measurements can be obtained in real time. Ships can also get the latest data on the weather and currents of the route. By sharing information, the two can develop a safe and wasteful shipping plan.
Mitsubishi Heavy Industries and NEC also announced in November 2013 that they will use "big data" that collects large amounts of data to jointly develop systems designed to achieve energy-efficient shipping.
Nippon Yusen is striving to build LNG fuel tugs in the fiscal year 2015 (small vessels that help large ships enter and exit the port)
As the former world's largest shipbuilding country, Japan has lost to China and South Korea in terms of shipbuilding capacity, and now ranks third. However, factors such as the strengthening of environmental regulations and the rise in crude oil prices may give Japan the opportunity to fight back. Because nowadays, the conditions for using energy-saving technology as a powerful weapon are already in place.
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