Swedish company Lean Marine has worked closely with chemical tanker operator Laurin/Team Tankers to develop a “cruise control” system to optimise fuel consumption
Optimising fuel consumption by changing engine revolutions and propeller pitch, while maintaining a given speed, is no easy task. A small change of the propeller pitch lever will impact the required speed of the engine (rpm) and only after such changes have been made and the system stabilised can the impact on fuel consumption be measured.
In explaining the problem, Lean Marine director of development and product management Linus Ideskog used the analogy of a cyclist taking part in the Alpine stages of the Tour de France: “Rarely would you see these athletes trying to maintain the same speed both uphill and downhill. If they did, they would quickly run out of energy climbing the mountain and that strategy would be illogical. However, this strategy is often adopted as the norm for ship operations.”
Mr Ideskog also noted that a tanker is given a speed or rpm order which it maintains throughout changing conditions along its route, with the result being varying power and wasted energy.
Achieving optimal fuel consumption requires keeping a real-time eye on the vessel’s output power and adjusting propulsive parameters throughout a voyage.
Thus, a tanker equipped with a controllable pitch propeller can waste a lot of energy if it is not being used efficiently, according to Lean Marine. Such tankers typically run on either a fixed propeller rpm, letting the angle (pitch) of the propeller blades dictate the propulsive power, or in a combinator mode, with a static setting for different pitch and rpm levels. As most vessels rarely need their full engine power and operate in varying load and weather conditions, they consistently operate with a lower pitch, which is a proven source of wasted hydrodynamic energy.
“Achieving optimal fuel consumption requires keeping a real-time eye on the vessel’s output power and adjusting propulsive parameters throughout a voyage”
As such, there is potential to save a lot of fuel by allowing the pitch and rpm to be controlled separately, targeting maximum propeller thrust for the least power.
But this is easier said than done. It takes a long time and is expensive to constantly monitor and tweak an engine’s output, while manually adjusting the propeller pitch lever.
The solution: automate the process, which was the challenge set by Lean Marine, a group of Swedish innovators with extensive experience in shipbuilding, naval architecture, propulsion and marine control system technology.
As a start-up just five years ago, it proposed and installed an automated solution on six Team Tankers vessels. These were equipped with fixed-pitch propellers, which was an advantage as it allowed data to be collected without the additional complications introduced by a variable-pitch unit.
The resulting data was developed and the algorithms and technology marketed as FuelOpt, a control system installed as an addition to the existing onboard system. The technology optimises a vessel’s performance in real time. Whenever a vessel is in transit (and using most of its power for propulsion) FuelOpt will step in and minimize costly variations in speed and power due to human operational factors, while optimising pitch and rpm for maximum efficiency.
The system is simple to operate and the technology can be installed into any vessel during operation in just a few days, according to its makers.
“FuelOpt allows owners the ability [to extract the] full potential of their investments in existing equipment,” said Mr Ideskog. “The fuel savings mean that the payback time on FuelOpt can be measured in months.”
Lean Marine is willing to back this up, offering a financial package where the owner can pay for the FuelOpt system in monthly payments.
Analysis leads to efficiency
In addition to optimising fuel consumption in real time, all the data produced by FuelOpt is recorded and available in an analysis tool called Fleet Analytics; this verifies any reductions in fuel use achieved by the system, giving shipowner’s a better understanding of their vessel’s operations.
As a further benefit, Fleet Analytics can be used to illustrate fuel consumption savings, providing fuel consumption performance data when chartering out a tanker. To date, Lean Marine has installed FuelOpt on nearly 100 vessels, with the milestone 100th installation due to take place during 2018.
“As most vessels rarely need their full engine power and operate in varying load and weather conditions, they consistently operate with a lower pitch, which is a proven source of wasted hydrodynamic energy”
Mr Ideskog attributes the success of the system to its ability to deliver direct and tangible results, explaining why new orders keep coming and existing customers are now requesting fleet-wide installations.
Bergen-based chemical tanker owner/operators Rederiet Stenersen,
Rederiet Stenersen, a Bergen-based chemical tanker owner/operator, is one such advocate of Lean Marine’s system, having achieved fuel savings when FuelOpt was installed across its entire fleet of tankers.
Discussing the results, Rederi Stenersen director John Stenersen said: “We have seen that the system has delivered the fuel savings promised. In addition to the automated fuel saving, we can now also follow up on our vessels using Fleet Analytics.”
Rederiet Stenersen has 15 vessels equipped with FuelOpt and Fleet Analytics, with the system used at all times during transit. Consequently, FuelOpt has now clocked up almost 4,000 days in operation across the Rederiet Stenersen fleet. With estimated potential savings of up to two tons every 24 hours, FuelOpt has now helped Rederiet Stenersen save more than 8,000 tons of fuel.
Lean Marine noted there is no limitation on vessel size, and while small- and medium-size tankers have been fitted with FuelOpt, there is no reason the system could not be fitted to a VLCC.
As Mr Ideskog explained: “Our product development is driven by business. We are not developing products for [their] own sake.”