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Although CO2 emissions from shipping are relatively limited — about 3 % of global output according to the International Maritime Organization — ships carry over 80 % of world trade and so are responsible for a large portion of emissions from the transport sector.
The EU-funded project MINI-CHIP is helping shipping companies reduce emissions by finding the most economical speeds to sail between ports.
Because water resistance increases sharply with speed, the only way for ships to consume less fuel is to sail more slowly, says project coordinator Habin Lee of Brunel University in London, UK. Since the financial crisis of 2008, long-distance operators have adopted a practice of ‘slow steaming’ to cut fuel costs, but at the expense of longer transit times.
“But shipping companies always have the pressure of a service-level agreement to deliver a cargo to a designated port on time,” he points out. “There’s a trade-off relationship between the CO2 emissions, the speed and the service level agreement.”
To address these conflicting demands, the project has developed a web-based software tool to guide ship operators in planning the most fuel-efficient speeds between ports.
Windows and weather forecasts
Lee’s group at Brunel University teamed up with Promatech, a Turkish software house specialising in maritime applications, and shipping company Arkas.
“We are taking two innovative approaches,” says Lee. “The first is to apply a dynamic programming model to consider uncertainties at the ports.”
Busy ports will specify a time window when a vessel is booked to arrive. If it arrives too early, the port may not be ready for it; if it arrives too late, it may miss the window and have to wait, perhaps days, before it can berth. Either way it will consume more fuel than necessary.
A second innovation is the use of weather forecasts to help predict the optimum sailing speeds. By comparing historical archives of wind and sea conditions in the Mediterranean with records of fuel consumption by Arkas’s ships, the partners constructed a model that factors in the weather to more accurately predict vessels’ fuel consumption.
The result is MINI-CHIP’s ‘decision support system’ (DSS), a web-based service that recommends a ‘portfolio’ of speeds for different legs of a sea route, taking account of uncertainties at the ports and also likely weather conditions.
MINI-CHIP, many applications
“Our DSS shows the relationship between fuel consumption and service level,” says Lee. “So if the company wants to reduce the fuel by 10 % they can ask what would be the likely impact on the service level agreement at the next port. They can then decide whether to minimise fuel consumption or maximise service level.”
By running tests with historical data provided by Arkas, the partners showed that fuel savings of 6 % would have been achievable on the company’s routes in the Mediterranean. The MINI-CHIP system is now in service with Arkas while Promatech is working to make it available to other shipping lines as a commercial product.
These optimisation principles could also have applications in other EU-funded projects. Promatech is coordinator of CLOUD-VAS, where the methods developed in MINI-CHIP are being used to help shipping companies decide which vessels to allocate to specific services — again to reduce fuel costs and CO2 emissions.
At the same time, Lee’s Brunel group has been working with partners in the DAREED project to apply similar optimisation principles to the design of energy-efficient buildings and is coordinating GREENDC, a new project to reduce energy consumption in computer data centres.