Swedes create the Ecoship

A new concept for short-sea trade, the Ecoship, has recently emerged onto the shipping scene. It sports sleek lines with low water resistance. It has an advanced engine configuration and comprehensive exhaust gas cleaning equipment. And it is the result of some radical thinking within the Swedish marine industry. The idea was first conceived in 1996. An approach was made to Gothenburg-based engine manufacturer Volvo Penta to develop a diesel-electric propulsion system. This would power a container ship designed to trade on the Swedish inland waterways. Volvo soon realised, however, that to achieve the optimum solution, it was not enough to develop just the propulsion system. Development also required looking at the rest of the ship and in particular the hull design. To achieve this other skills were brought in to the project. The original intention to construct four containerships never materialised. But last year Ecoship Engineering, the company formed by the project participants, received a proposal from Gothenburg-based Rederi AB Brevik. This involved building an 8,500 dwt coastal products tanker. According to Bjorn Carlsson, managing director of Ecoship Engineering, completion of the tanker design work is imminent. It is then planned to build a ship as a trial vessel for the Ecoship concept. Invitations to tender have been sent to Scandinavian and other shipyards, with an order potentially being placed later this year. Container to tanker Tanker hull design is based on a different set of parameters to that of a container or roro ship. Nevertheless, the initial Ecoship concept was applied to the new hull without any difficulty. It met the three main criteria of low energy, optimum environmental adaptation and improved cargo capacity. The ship can be built in modules and assembled at a central point. The engine-room, for instance, can be built and equipped as a complete module and then lifted onboard at the appropriate time. Brevik will own and operate the prototype. The Swedish National Energy Administration will pay 35% (SEK 8.7 million/$820,000) of the development costs. This is on condition of the ship being built and it being the first of its kind. High environmental spec drives design The Ecoship design is meant to allow the short sea shipping trades to compete more effectively with road and rail. Its high cargo capacity and low emissions should help in this respect. The plan is for Ecoship to cut standard emission levels. It will do this through specific design features intended to lower fuel consumption and through the use of catalytic converters. The hull is slender and has a lower block coefficient than a conventional tanker. Its lines are softly curving. Welding of the single bent plates will, as far as possible, follow the flow of the water in a longitudinal direction. This will decrease turbulence and water resistance. Tests have indicated it reduces their impact by about 10% compared to a similar-sized conventional hull. The ships diesel-electric power plant consists of 10 truck-type Volvo Penta high-speed low-emission diesel engines. When each engine is run, it will be at a constant speed of 70-90% mcr. Running the engines at such an optimal load will provide fuel economy. It gives the added benefit of easier servicing and repair. It would also allow subsequent technology updates. The engines are also envisaged to contain remote diagnostic tools. Each 428kW engine, weighing about 4t, will have its own exhaust pipe, to avoid backpressure. Redundancy features, such as two engine rooms, will help minimise the risk of an accident. Five engines are located in each engine room. A fire resistant bulkhead runs between the engine rooms. Engine controls are also duplicated, making the ship less vulnerable in event of machinery failure. Electric propulsion If the ship is built according to ice class 1A, it will need two podded propulsion units with asynchronous motors. If the ship is built without ice class only one podded unit is required with two contra-rotating propellers. Each engine will be connected to an electrical generator running at 1,800 rev/min. Both the pods and the cargo pumps will use 690 volts. The computer system and other electrical systems will get 440 and 220 volts, via rotating transformers. Deck machinery will have both electric and hydraulic operating capability. Loads on the propulsion and cargo-handling systems are controlled by a frequency converter. This means power alters in accordance with the rotation speed. Capacity of the cargo pumps is adjusted by reducing or increasing the pump-motor speed. All 10 generating sets are continuously and automatically controlled through a computerised power management system. This ensures the number of engines running matches the power demand. At normal service speed, about 14 knots, nine generators will be needed. Cargo capacity up 15% The Ecoship design has a 15% greater cargo capacity than a similar standard design tanker. This is achieved by moving the engines further aft of their location in traditional tankers. The potential for environmental damage in event of an accident is minimised through the ship?s double hull. This, unusually, includes the vessel?s bunker fuel tanks. The tanker has 11 cargo tanks, built according to MARPOL regulations. They have a total capacity of about 10,600m3. The tank bulkheads are smooth to aid cleaning. This is achieved by locating all reinforcement brackets and other stiffeners on the outside of the tanks. All the tanks are heated by heat-oil supplied by two low NOx boilers. A deck-drain pipe to a designated tank is fitted to prevent waste oil ending up in the sea. It is also proposed to fit the vessel with a ballast water cleaning system. This would incorporate cyclonic cleaning for the larger particles and UV-radiation for the smaller. The design and construction of the ship will comply with existing Swedish Maritime Administration and international environment and safety rules. In addition, the vessel will comply with DNV?s classification rules. It will have additional DNV notation for safety arrangement (DNV RPS – redundant propulsion system) and environmental safety demands (DNV CLEAN Design). The cost? The designers of Ecoship reckon it will cost about 5% more than a conventional ship, mainly due to the diesel-electric propulsion machinery. But they believe the extra capacity will allow this to be recouped within a couple of years. They also think that operational crew could be cut back to seven to nine people. Cooperative venture At an early stage in the project, Volvo Penta enlisted the cooperation of Swedish hull-designer Ocke Mannerfelt. The company specialises in energy optimised hull design as well as virtual ship models and operation analysis programs. It also brought in Kockums Engineering (with extensive experience in overall ship design and offshore technology), El-Marine/Callenberg Engineering (providing expertise in electrical engineering, bridge and communication systems), and IUC Skane AB (an industrial development organisation providing venture capital for R&D projects). In 1999, the project participants established Ecoship Engineering AB. Each of the companies involved took a financial stake in the joint venture. Earlier this year, FKAB, a marine consultancy company involved in designing small and medium size ships, joined the consortium. It purchased a 13% stake. ABB is involved in the project as a research partner. Other cooperating organisations include the Swedish Shipowners? Association, Chalmers University of Technology and the National Swedish Administration of Shipping and Navigation. The involvement of all of these companies gives Ecoship access to a wide spectrum of skills and experience in modern ship designing. It is this holistic approach to ship design, drive systems, IT facilities etc. which has enabled optimisation of both cargo carrying capacity and hull design.