In marine vessels around the world, fuel consumption is commonly measured manually, despite the significant problems associated with doing so. Automated systems are now available to address these problems and to provide a host of benefits, including a reduction in consumption of 10% or greater across fleets.
The methods used by most vessels to measure fuel usage hasn’t changed in decades, with manual tank sounding as the most widely used method. During the sounding procedure, crew members insert a dipstick into a fuel tank and estimate how much fuel has been consumed since the last measurement.
But this situation is now changing and improving rapidly as vessels worldwide adapt modern, automated systems to measure fuel consumption in real-time, display results to crew onboard, and transmit this information to onshore monitoring facilities via satellite (Figure 1). These systems allow the crew to optimize fuel consumption, and also to detect engine performance changes and fuel quality issues while bunkering. The results is increased accountability for management personnel onshore.
One system able to accomplish these tasks is FUELTRAX, a smart, real-time marine fuel management solution that allows fleet operators to optimize performance and reduce costs. In addition to use aboard vessels, FUELTRAX is also being used onshore at terminals to measure fuel loaded onto vessels (Figure 2).
At the heart of these systems are Endress+Hauser Coriolis mass flowmeters. These are installed at each supply and return use point of each fuel consumer onboard — e.g., diesel engines, generators, incinerators, and boilers — to directly measure the mass of fuel consumption in real-time, along with density and temperature. A meter is also installed at a single entry/exit point to capture all fuel bunkers or transfers. This information is then used by FUELTRAX to convert consumption and transfer values from mass into desired volumetric units — gallons, liters, etc.
This article examines the challenges with conventional methods of measuring fuel and shows how automated fuel management systems address these issues. Use cases show these systems in action, demonstrating how they are being applied around the world to deliver fuel savings of up to 10% or greater across fleets, along with other added performance and operational benefits.
Many vessels still rely on conventional fuel consumption reporting, calculated during daily manual tank sounding by inserting a dipstick into fuel tanks and referencing the strapping tables. This method has many problems, including:
• Inaccurate measurements
• Long delays between fuel consumption and delivery of data
• Labor intensive
• HSE exposure to ship personnel
• Fuel consumption information is not automatically transmitted to shore
Inaccurate measurements are a natural consequence of manual tank sounding. The tank must be dead level, which is rare in the normal pitch and roll of a vessel at sea. The person making the measurement must record results with a high degree of accuracy, despite considerable potential for error. Fuel consumption is then assessed by calculating the difference between measurements, typically taken once a day. A single inaccurate reading will skew subsequent measurements.
Long delays between fuel consumption and delivery of data is expected with the manual tank sounding measurement, as well as with all other methods of manual measurement. The vessel crew will only become aware of fuel consumption at least 24 hours after the fact, making it impossible to use these measurements to optimize consumption during real-time operations. Likewise, indications of fuel tampering or theft won’t be discovered by onshore management until long after the fact.
Labor intensive manual measurements are a poor use of the limited manpower onboard vessels. Making and recording these measurements, and then calculating fuel consumption based on the difference from one measurement to the next, takes time. The written records which are produced must be transcribed and shared with onshore management, another time-consuming task.
Making manual measurements increases HSE exposure to ship personnel, as they must gain access to the top of a tank, often during times when the vessel is pitching and rolling. Slippery conditions are common, and falls are an ongoing risk. Personnel carrying out the measurements are exposed to hazardous fuel fumes on a regular basis.
Fuel consumption information is not automatically transmitted to shore, but typically sent with daily noon reports. This precludes the use of fuel data to provide immediate and automated optimizations for fuel consumption.
These are the main issues with manual measurement of fuel consumption, each of which can be solved with an automated fuel management system as described below.
A crucial component of the automated fuel management system are the Endress+Hauser Coriolis mass flowmeters. There are many different technologies for measuring flow, but Coriolis was selected because of the increased accuracy of mass flow measurements, as opposed to volumetric flow.
Mass flowmeters generate precise measurements and fuel quality readings, while volumetric flowmeters cannot differentiate measurement based on quality or spec. This is because Coriolis meters measure mass, along with density and temperature, used by the system to determine fuel quantity and quality. In addition, many volumetric meters contain moving parts which require frequent maintenance.
While Coriolis mass flowmeters are available from many different vendors, Endress+Hauser was selected because of the quality and reliability of their meter, as well as their willingness to work with FUELTRAX to provide local stocking and to accommodate other business needs.
Each flowmeter sends mass flow, density, temperature, status and diagnostic data to the FUELTRAX Field Termination Unit (FTU) via a Modbus RTU digital data link. The FUELTRAX FTU then sends this data to the Master Electronics Unit (MEU). The MEU processes processes the data from the mass flowmeters and sends it to the FUELTRAX satellite antenna for transmission to a shore-based data center via Iridium satellite network. A GPS antenna is included with each system antenna unit to transmit location data, which can be correlated with fuel consumption data. With FUELNET, this information is then overlaid on Google Maps to show a complete, minute-by-minute history of the vessel’s movements, combined with exact information on what engines and generators are running, along with speed, and fuel consumption data for each.
The MEU performs the calculations necessary to turn the mass flowmeter data into actionable information to assist the crew onboard. A Wheelhouse Monitor displays this information and live recommendations to optimize the vessel’s fuel consumption in relation to speed. A second display in the Engine Control Room (ECR) enables close watch of individual engine performance, as well as monitoring of real-time fuel consumption and quality. This display also allows the Chief Engineer to inspect the density quality during bunkers or transfer. A density siren is alarmed with strobe light to alert on fuel outside the predefined density ranges, indicating a fuel quality issues; an onscreen notification is then flashed on all FUELTRAX Monitors onboard.
The automated fuel management system onboard combined with the web reporting platform FUELNET (Figure 3), work hand in hand to solve all of the problems associated with manual measurement systems and deliver the following additional benefits:
• Optimizes fuel consumption
• Detects fuel quality
• Deters fuel theft
• Details and analyzes fuel consumption
• Tracks vessel location in real-time
The main benefit of an automated fuel management system is optimization of fuel consumption. The crew of the vessel uses the information displayed on the FUELTRAX Wheelhouse Monitor to adjust the throttle and optimize consumption in real-time. As shown in the example below, this can cut consumption by up to 20% (Figure 5).
In many cases, optimizing fuel consumption must be balanced without sacrificing speed to ensure prompt delivery of cargo. An automated fuel management system provides the information required to reduce fuel consumption at the greatest maximum speed possible for the vessel. This delivers substantial financial benefits for on time delivery of the cargo with the least amount of fuel consumed during transit.
Critical fuel quality issues are promptly detected by automated fuel management systems. The Coriolis mass flowmeters used in these systems measure density and temperature, revealing problems related to entrained air, or the presence of water or other contaminants. This information is reported back to the FUELNET web platform for further review and analysis. Since the monitoring is carried out in real-time, problems are detected sooner and more efficiently than is possible with manual systems, allowing for timely remedial action.
Fuel accountability is a major issue for many fleet operators. Any signs of pilfering or slippage need to be detected in real-time. This is best achieved with an automated fuel management system with advanced capability to transmit fuel data, and visualized through a web-based platform accessible anywhere in the world. The system can also send email and text alerts to smartphones, tablets and other devices—allowing fleet managers and others to take action immediately and mitigate losses.
There are two main types of fuel accountability issues. The first occurs during fuel loading due to poor quality control or outright attempts at pilfering, or a combination of both. Air, water or other impurities are mixed with the fuel, which not only results in less fuel being loaded than expected, but can also affect the performance of engines and generators. The density and temperature measurements from the mass flowmeter indicate issues, triggering the onboard density alarm as described above. The second accountability issue arises when unauthorized transfers are made in port or at sea, which can be detected by the mass flowmeter(s) placed at each loading point or a common header.
As shown in Figure 3, fuel consumption and quality data, along with vessel position, is transmitted via satellite link to shore, allowing for detailed analysis in a timely and efficient manner. In FUELNET, detailed reports are generated for data analysis revealing opportunities for fuel savings across the fleet. Alerts can also be generated to warn of existing or potential maintenance problems, thus allowing timely resolution.
The following use case shows how the FUELTRAX automated fuel management system is being used worldwide.
As shown in Figure 4, vessel data can be categorized into custom operating Modes, such as:
• “Underway” or “In-Transit”
• Dynamic Positioning (DP)
• DP outside 500m
• Fuel Transfer
Additional Modes can be customized according to the needs of the vessel operator, which are automatically tracked and recorded based on the vessel operating parameters in FUELNET such as speed, engine run count, and GPS location.
For a fleet operator with 26 vessels, just four out of eight operating modes accounted for nearly 80% of annual fuel spend. Through collaboration with FUELTRAX Support team, the operator focused attention on the top four Modes to achieve the greatest fuel savings. The operator saw significant savings across these modes by implementing operational recommendations derived from FUELTRAX Support analysis and advanced analytics. In the following use case, we will examine the savings found by this operator in Underway Mode.
In August 2016, Underway Mode savings year-to-date were on average 6% per vessel. The operator achieved these savings through the crew’s activation of FUELTRAX onboard throttle optimizations. Crews activating the onboard settings at least 50% of time spent in Underway Mode achieved an average of 6% savings compared to typical fuel consumption (Figure 4).
As each crew increases utilization of the onboard throttle optimizations, more savings can be achieved. For example, one vessel activating the onboard optimization settings 78% of the time spent in Underway Mode reported year to date savings over 14%.
By increasing the activation of the onboard optimization settings to 80% for all vessels, the operator has potential savings of up to 10% across all Underway Mode operations. The two onboard settings used are BestSpeed and BestEconomy, activated by the crew when operating conditions permit (Figure 5). Further details about how these throttle settings reduce fuel consumption in real-time can be found in the following section.
With a goal of increasing savings in each of the four Modes, the operator performed similar operational studies of each Mode in collaboration with FUELTRAX Support team. In all Mode optimization cases such as this, the operational recommendations are validated by FUELNET data. Verified operational changes are replicated across the entire fleet to maximize savings.
As fuel consumption is analyzed by the system in real-time, appropriate adjustments to the vessel’s operation can be made, reducing fuel consumption by on average, and in some cases up to 20%. To assist the crew, the FUELTRAX automated fuel management system offers real-time recommendations on throttle placement in order to reduce consumption while vessel is in transit. These settings — BestSpeed and BestEconomy — provide recommendations based on optimal fuel consumption at maximum or reduced speed, respectively.
Each marine vessel has a non-linear speed versus fuel consumption curve, so optimal operation is not simply a case of maintaining the same speed at all times. In this example, the Captain was able to create the graph shown in Figure 5 by using the FUELTRAX onboard recommendations to adjust throttles in real-time. As the top graph illustrates, burn rate dropped from 60 gallon per hour (GPH) to 40 GPH, with very little reduction in speed as shown in the bottom graph.
The BestSpeed algorithm recommended the optimal maximum speed with minimum fuel consumption, resulting in savings of 21.3% compared to the typical burn rate. By calculating the optimal throttle setting, the decrease in speed from 10 knots was very minimal while resulting in large savings on total fuel consumed during the voyage.
More than 2000 Endress+Hauser Coriolis mass flowmeters have been installed on over 200 vessels worldwide, resulting in an average fuel savings of 10% and a ROI of less than 12 months across fleets of 10 vessels or more. The meters have operated reliably with little to no maintenance required, as has the rest of the fuel management system.
Optimization of operations through analysis of the data provided by the FUELTRAX system can help fleet operators reduce consumption even more, by up to 20% in some cases. Because fuel consumption is typically a vessel’s second largest expense, a reliable fuel management system and analytics platform can cut total operating expenditure substantially. In addition to savings and theft prevention, these automated systems also improve safety and allow operators to easily track vessel location at all times.
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