From Vision to Reality
Innovations in Mining by Deep Sea Sampling
Net Zero and Productivity
Mobile mining equipment relies to a large share on diesel-powered machines and hydraulic drivetrains. Reduced efficiency by hydraulic losses, especially in systems with long loops, is causing higher fuel consumption and larger system dimensions. Electrifying the drivetrain will eliminate most of the losses, resulting in a higher system efficiency and reduced fuel amounts – a step on the path toward net zero. During the Deep-Sea Sampling Project (DSS) a trench cutter was transformed into an electrified mining tool. The project is focusing on mining seabed massive sulfides (SMS), which are rich in copper ores and other necessary minerals at depths down to 4.000 meters below sea level. The extreme conditions of the deep-sea work as a blueprint to develop new technologies for mining operations in harsh conditions. With smaller system dimensions and a higher productivity mining can take place at spots currently not applicable to mining.
A path toward autonomous mining tools
Conventional trench cutters use a hydraulic drive with pumps on the carrier vehicle, transmitting oil through long hoses to a hydraulic motor that drives the cutter wheels via a gearbox. First approaches to electrify the trench cutter left the gearbox untouched and placed an electric instead of an hydraulic motor. The DSS approach integrates the electric motor directly into the gearbox (direct drive), eliminating long hydraulic lines and external gearboxes, reducing energy losses, and improving the controllability of the drive.
Key requirements include torque up to 50 kNm, power of not less than 150 kW, and speeds up to 40 rpm or more, strict dimensional and weight constraints for underwater operations, and reliable, continuous cutting performance under varying soil conditions. Pressures up to 400 bar, temperatures around 2°C and operability without user interference had to be observed, but where not applied for the initial steps of the project.
Figure 1: speed-torque-diagram of the direct-drive e-motor, allowing higher rotational speeds of the cutter wheels, thus improving operational behavior of the cutter head and reducing cycle times
Figure 2: the V-shape system design approach applied to the development of a complex deep sea mining tool during the three year development program
Electrification and Direct Drive Benefits
After defining direct drive as the drivetrain principle an iterative process of designing, simulating, evaluating, and redesigning started, to define the final dimensions of both electric motor and gearbox while still fulfilling both performance and dimensional requirements. Basic design is a permanent magnet synchronous motor. A plug-in coil single tooth winding was chosen for the stator, combining minimized winding heads to reduce length with still good performance values, and was then optimized regarding iron length and diameter. The rotor was built in a permanent magnet design with surface magnets. A separate cooling was integrated between stator and gearbox to allow longer runs at full or overspeed. Several sensors were applied to monitor and control the motor during testing and operation. At that stage, engineering focused on designing a component for initial testing to prove simulation results without having neither the entire system nor the intended environmental conditions at hand. With having current and voltage as well as vibration and temperature as easy-to-measure signals, controlling the motor during operation allows to react quicker and to run at maximum speeds without breaking the drivetrain.
Figure 3: the electric motor integrated inside the gearbox housing: minimizing gearbox dimensions, reducing number of gears and maximizing efficiency
Motor, Gearbox and Field Validation
Basic electric motor design and testing
Using 690 V as voltage layout allows the use of a wide range of standardized control and connection equipment, which was supportive regarding the timeframe of the project. To test the components, additional bearings and provisions were necessary, e.g. to simulate the gearbox environment regarding systems responses and temperatures. A test stand was built where both motors could run back-to-back, one motor simulating the systems response, one being tested and measured. With those tests component readiness was proven and validated, data for further improvement of both stator winding, dimensional opportunities and cooling conditions was collected.
Gearbox validation testing
After the two motors were successfully tested, the gearboxes were assembled and then tested again back-to-back, this time one gearbox acting as the environment simulation while the other one was measured and tested. A torque measurement flange was integrated to measure performance levels and torque output. Even designing both test and test stand contributed valuable insights for further design steps. At this stage, the sub-system – the gearbox – proved not only readiness but for the first time efficiency levels higher than expected.
Application at test site
The system was assembled to a Bauer RG27 in February 2025 and tested at Aresing test site and in a soil mixing use case. In soils of relatively low compressive strengths six columns each 20 meters deep were cut with much higher speed (ca. 75% faster) and an overall system efficiency of 86% (up from currently ≈65%), allowing a first commercial application of the full-electric drivetrain design. Test with different wheel designs for higher compressive strengths are scheduled. By analyzing data from both sub-system and field test considerable inputs regarding cooling requirements and electric circuit design for the second stage demonstrator could be obtained.
Figure 4: Component and Sub-System Testing prior to field testing delivered valuable data to improve the next cycle of engineering regarding voltage, cooling, and design features.
Figure 5: Temperature during ramp-up run (examplary diagram)
Efficiency and Productivity will drive electrification
The electrically driven trench cutter handled changing soil conditions smoothly, reacting instantly without speed loss. Both higher power and speed increased output, reduced time per meter, and improved efficiency by nearly 30%, supporting both Net Zero goals and economic gains through higher productivity and lower fuel use.
The road ahead
Having shown both technical and commercial usefulness of electrifying a trench cutter, Deep-Sea Sampling is now moving to the next engineering requirements:
a lightweight design for deep-sea operations
improved control systems to semi-automate processes, and
electrifying further rotating applications by using the direct drive approach.
Measures to move toward these requirements include motor designs for higher voltage levels to lower system weight by reducing the weight of copper wiring and further improvement of sensor systems to get the position data in real-time to implement control signals into the cutter-run procedure. Beside product engineering tasks a test stand to simulate different soil characteristics during gearbox, motor, and sensor development is being engineered. With Deep-Sea Sampling progressing into the next stage, tough requirements from harsh conditions will drive the innovation in mining equipment electrification.
Figure 6: the fully electric cutter head mounted to a Bauer RG27 at Aresing test site after successfully passing all field testing (with 86% system efficiency)