While the basic concept of air lubrication is old, limited serious research has been performed. It was the PELS project, a Dutch national project, that made a positive change. This project demonstrated that a positive overall energy gain can be achieved in all operational conditions with air lubrication.
The required technology itself is new and requires further exploration. Based on the findings from the PELS project, the SMOOTH consortium estimated that ship hull efficiency improvements of up to 20% would be feasible. Such a step forward would be beneficial to the environment since the considerable reduction of fuel consumption will have its effect on the CO2 , NOx and soot discharges. A reduction of fuel consumption will, of course, also be welcomed by the European shipping business since it will result in a reduction of costs.
European policies are addressed in a number of ways: the noticeable reduction of the operational costs by reducing the ship's resistance, the enhancement of the quality and operational safety of the transport process, and the safer transport of crude oil and other dangerous and potentially polluting goods.
Furthermore, as air lubrication has been successfully tested for model ships, new products (in terms of suitable ultra repelant painting systems, ambient and functional air distribution and control systems) need to be developed further to apply this technique to vessels.
The SMOOTH project facilitated the inter-European knowledge exchange, by providing a platform of co-operation for SMEs, companies and research institutes from six different European states, including the candidate country Turkey.
The strategic objective of SMOOTH was to cover all aspects of air-lubricated ships still requiring research and assessment to enable the technology transfer of air-lubrication into daily European ship building and operation practice of both inland and coastal navigating ships.
The project intended to apply air lubrication to ships and to provide the necessary new products in terms of control and paint systems to introduce air-lubricated ships. These ships may utilise micro-bubble (MB), air-film or air-cavity systems (ACS), for inland and coastal navigating ships with relatively shallow drafts.
The resulting verifiable and measurable objectives are:
- to provide validated (finally tested on model scale) computational tools for a real ship design;
- to validate scale effects of air lubrication;
- to evaluate the economy of air lubrication in practice and demonstrate the concept at full size on an inland vessel;
- to prepare the safe introduction of air-lubricated ships in practice.
SMOOTH defined different groups of activities:
- experiments on air films;
- scale effects and sea trials;
- model tests on air films;
- model tests on micro-bubbles and air-cavity ships;
- economic plus risk evaluation.
The techniques surveyed in SMOOTH for practical application and implementation in the coming generation of European ships included, in addition to improved drag and power-reduction, other innovations such as better stopping and manoeuverability.
Novel painting systems for ships and new air-control systems aboard ships will strengthen the position of the European shipbuilding industry represented within the SMOOTH consortium.
If drag reduction techniques are applicable to (full scale) ships, fuel costs and inherently discharge of hazardous gasses are reduced. This is beneficial to the operator but also to society, as it can help to fulfil the targets of the Kyoto protocol. The technique could also be applied when fluids are actively moved in transport systems, e.g. pipelines, as a reduced drag is reducing the energy demand of the pumps.
The impact of the technique subject of the SMOOTH project was noticeable
a) There are about 5 000 Dutch inland vessels sailing European inland waterways;
b) The average installed engine power is 800kW;
c) Considering a
- loading of 80%,
- 180 g/kWh specific fuel consumption,
- 4 500 operating hours on annual basis.
d) This yields
- 2 592 000 tons fuel a year,
- 8 084 448 tons CO2 a year.
SMOOTH targeted a 15% reduction of the consumed energy by drag reduction by means of air lubrication techniques. This would mean a decrease of CO2 in 'European' skies 1 212 667 tonnes. This example indicates the remarkable impact of the project.
One outstanding aspect of the project is that geometrical similar (GeoSim) ship designs have been surveyed up to full scale. In this respect, even operational aspects such as manoeuvring were investigated as well.
- GeoSim tests from model- up to full scale;
- Development of control systems at either scale;
- Development of devoted CFD codes;
- Considering of operational aspects.