Volvo Penta has launch a new ship design, the Ecoship, in order to minimize environmental impact, reduce energy consumption, and improve safety levels. Although initially developed for large cargo ships, the Ecoship design is adaptable for all types of boats including offshore supply boats and standby vessels.
The company has been the driving force behind this project, involving a network of other Swedish companies including Sjovwalls, Ocke Mannerfelt Design, and Kockums Engineering. The Ecoship has unique patented hull shape which reduces water resistance by more that 10% resulting in lower energy consumption.
The vessel has a diesel electric propulsion system consisting of 10 Volvo Penta diesel engines which drives the generators. These supply power to ABB electric motors which in turn drive twin KaMeWa drive units. Volvo Penta has also collaborated with ABB Flakt Marlin to develop a highly efficient emission control system.
Volvo Penta claims that due to the hull shape and drive system, Ecoship uses around 15% less energy that comparable conventional vessels. The engines run on low sulphur diesel oil and, with an advanced catalytic conversion system, NOx emission levels are 95% lower with carbon dioxide and hydrocarbons reduced by 70%. The new hull design also creates a smaller wake at higher speeds up to 16 knots, thereby reducing seabed erosion and improving safety around the vessel.
One of the benefits is that the location of the diesel engines is flexible, in turn giving greater flexibility for cargo stowage. The engine and generators are also installed in soundproof housings to minimize the noise level and improve the working environment onboard. The diesel-electric propulsion system further aids flexibility since the number of engines in operation can be precisely matched to the actual load characteristics. By using a substantial number of diesel engines, each rated around 500kW redundancy and flexibility can be further improved.
Safety and economySafety was also an important priority during the development of Ecoship. The entire propulsion system has full redundancy since all components are duplicated and this ensures good operational reliability.
The vessel has complete double hull to prevent leakage in the event of grounding and has a closed sewage system with all sewage and wastewater stored in tanks for treatment onshore. The shape of the hull, combined with the twin propeller units, also ensures better maneuverability and shorter maneuvering times.
Ecoship uses modular and component systems so that construction is faster, lower capital is tied up and production is more flexible. The versatility of the Ecoship concept, both in terms of propulsion and cargo stowage, ensures good operating economy, while lower energy consumption also benefits the environment.
Electronic diesel controlVolvo Penta has further developed it's range of marine diesel engines equipped with Electronic Diesel Control (EDC), an electronically controlled processing system which optimizes engine efficiency. The system determines the precise quantity of fuel required at any given time, taking full account of variations in operating temperatures and other contributing factors such as air pressure.
A new, fresh-water cooled turbo-charger with integrated wastegate gives good torque characteristics with high torque at low speed. Engine power ratings range from around 100 kW to 450 kW. The largest six-cylinder engine, for example, has a dry weight of 1340 kg and crankshaft power rating of 450 kW (610 hp).
"For cargo boats we supply 2-12 engines. depending on the size of the boat," says marketing manager Stig Andersson. "A typical supply boat has four to six engines - electric power needed is used to calculate the number required from there. We monitor the engines very precisely to provide multiple engines finely tuned to each other. This is particularly important when matching 12 engines at one time."
The EDC system gives improved engine response with low and stable idling and, with a vibration-free operation, it produces low noise levels. High pressure injection using five-hole injection nozzles optimizes the fuel-air mixture and this contributes to efficient combustion and low exhaust emissions. The EDC systems includes a self diagnostic facility and the control and governing systems have very few moving parts, so that servicing and maintenance is kept to a minimum.
"We are supplying lots of engines and generator sets for supply and crew boats," says Andersson. "Over 95% of our products are now exported throughout the world and one of our latest achievements has been to supply crew boats for Lake Maracaibo in Venezuela, an area previously dominated by our US competitors."
Copyright 1997 Oil & Gas Journal. All Rights Reserved.