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7. Reducing Fuel Consumption of Merchant Ships using Tidal Currents

Reducing Fuel Consumption of Merchant Ships using Tidal Currents

The analysis and conclusions contained in this case study are those of the authors alone and do not necessarily represent the point of view of the Government of Canada.

Organization
Innovation Maritime

Major Finding
Optide software synchronizes voyages up the lower St. Lawrence River with favourable tides and can reduce fuel consumption by up to 25%

Project Timeline
November 2004 to April 2005

Please note that some figures such cost savings on fuel are based on data from the period that this project took place.

Introduction

The tides of the St. Lawrence River have always challenged navigators. When tall ships were sailing to trading posts at Quebec City and Montreal, navigators had to quickly learn to use favourable currents in the St. Lawrence estuary, and anchor their vessels to let opposing currents pass. But times changed with the introduction of vessels equipped with motors powerful enough to fight the tidal currents. For many merchant ships, it is no longer the currents that slow their progress, but rather the depth of the water.

With rising fuel prices, navigators are once again questioning the way they travel on the St. Lawrence, because travelling against the current has financial and environmental costs. The constant evolution of navigation methods on the St. Lawrence has pushed researchers to explore modifying modern merchant ships’ voyage plans. Inspired by ancient navigators, they proposed taking advantage of the tidal currents. This research has resulted in a new piece of software.

The objective of this project was to validate a mathematical model for synchronizing merchant ship voyages with tidal currents between Les Escoumins and Trois-Rivières. Innovation Maritime was the project’s principal contractor, working with Transport Canada, the Canadian Coast Guard, the Canadian Hydrographic Service, the Corporation of Lower St. Lawrence Pilots and the Corporation of Mid St. Lawrence Pilots to learn:

• if synchronizing merchant ship voyages with tidal currents will save money;
• the pros and cons of such a practice; and
• the significance of pros and cons that can be measured.

Project Description

This project developed a decision support system in the form of software and made available to owners and fleet managers, to enable them to save money while reducing greenhouse gas emissions.

The technology uses a mathematical model onto which a real-time data entry and calculation system was added. This mathematical software can calculate, for a vessel en route on the St. Lawrence and whose destination is upstream of Les Escoumins, the best time to pass through the Les Escoumins pilot station – based on the tides. Using the software, the vessel can travel with the current instead of against it, thus saving time, money and fuel.

The testing took place between Les Escoumins and Trois-Rivières, for vessels travelling upstream, since currents have no significant effect on downstream transit time.

One hundred sixty-six voyages between Les Escoumins and Trois-Rivières served as samples to validate this voyage planning technique. The samples were taken over a six-month period, from July to December 2004.

This graph shows vessel transit time from Les Escoumins to Trois Rivières over a tide cycle at Pointe-au-Père. The blue curve represents the actual time, and the yellow curve represents the time predicted by the model.

Project Goals and Objectives

This project aims to develop and validate software that will help ship owners use tides, winds and currents to optimize vessel speed and take advantage of tidal currents during transit. The software’s main advantage is its use of environmental factors affecting transport to make the voyage more profitable.

More specifically, the project’s objectives were to:

• Reduce vessel-operating costs by improving the quality of arrival time estimates;
• Reduce vessel fuel consumption and greenhouse gas emissions; and
• Find a way to apply the model and adapt it to the needs of navigators and fleet managers.

The planned method of achieving the first two objectives was to develop a new decision support system. In order to achieve the third objective, the decision support system became a computer-based tool.

Project Methodology

To develop a reliable decision support system, the components needed to be validated. The methodology of this project consisted of validating, through analysis and observations of vessels’ voyages, the tide-based transit time calculation models and the speed-based fuel consumption models. The computer application interfaces were also user-tested.

The diagram below shows the model for calculating transit time.

The diagram below shows the model for calculating vessel fuel consumption.

Once the models were validated, they were integrated into the computing application and it was deployed in software form, allowing users to use less fuel by synchronizing with tidal currents.

Results

The results were very significant. First, they showed beyond any doubt, the environmental and economic benefits of using tidal currents to reduce merchant ships’ fuel consumption.

Tidal cycles and amplitudes obtained from the Canadian Hydrographic Service are embedded in the software. The software user, usually a ship owner, charter or fleet manager, enters all the other variables for a particular vessel.

The results vary from vessel to vessel based on fuel consumption, speed, operating costs, fuel costs and tidal amplitudes.

Typical Canadian Great Lakes vessel

Based on a typical vessel on the Canadian Great Lakes, and the price of fuel in March 2006, using the software for a transit from 66° west longitude to Les Escoumins to Trois-Rivières helps realize the following savings in certain cases:

• Reduced greenhouse gas emissions - 29 tonnes
• Reduced fuel consumption - 25%
• Reduced time spent in confined waters - 3 hours, 35 minutes
• Net financial savings - $2,650

Operation and Implementation Costs

After consulting potential users, it was found that the best approach was to offer users an online Web application. That made it possible to promptly update data on tidal currents, time changes, and the other variables so that users could work with software that is always up to date.

The maintenance and operating costs to the user are zero since the online service provider absorbs them through user fees. The service provider will have to offer a reliable system that can respond to user demand, and keep it online and operational 24 hours a day, 7 days a week.

In light of the number and diversity of vessels that traverse the St. Lawrence each year, to obtain suitable results on greenhouse gas emission reduction would require another study. What the software can do is provide specific data to help a vessel reduce its greenhouse gas emissions for a specific transit. As already mentioned, the average reduction is 29 tonnes per transit for a typical merchant ship.

Conclusion

This project validated a software application that helps reduce greenhouse gas emissions and save money. Unlike many other measures, where reducing greenhouse gases comes at a financial cost, this software helps save money while reducing greenhouse gases.

It is also important to understand the implications of this new software. It is not just a computing tool; it also provides a new way to navigate the St. Lawrence. This new approach could revolutionize the methods that have been used since the introduction of motor vessels.

The software has been tested and proven very reliable when the input data is accurate. It is easy to learn and to use. It allows a vessel to reduce fuel consumption up to 25% for the Les Escoumins to Trois-Rivières portion of the voyage.

This technology will enable navigators to use expertise related to sea currents in the St. Lawrence to optimize vessel transit.

Additional Information

• Innovation Maritime
• St. Lawrence Observatory
• Innav
• Tides in Canada
• Ocean currents

Alternative Format

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Date modified:

2012-03-14

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