Rethinking energy savings on bulk carriers: The VraquiUS projects!
Scientifically speakingThe bulk carriers of tomorrow must drastically reduce their energy consumption to successfully transition to renewable energy and align themselves with the maritime sector's decarbonization targets. How can this be achieved?
For this Scientifically Speaking column, Green Marine Magazine looks at VraquiUS, a series of final-year projects by University of Sherbrooke electrical engineering students who explored technologies and methods to improve the energy efficiency of Fednav's bulk carriers. The projects were supervised in collaboration with the e-TESC Lab at the University of Sherbrooke. Two projects have been completed and two remain in progress:
- VraquiUS1.0: regenerative braking with bulk carrier
- VraquiUS2.0: Microgrid solution for a bulk carrier
- VraquiUS3.0 (in progress): Technical and economic design of a shore power system including a bulk terminal and a bulk carrier
- Net0-VraquiUS (in progress): Design of a zero-emission bulk carrier
VraquiUS1.0: Recovering energy from cranes
The VraquiUS 1.0 team studied the energy gains from regenerative braking in cranes. Just as an electric car can recover energy from braking, the VraquiUS 1.0 system can recover the energy used to brake the descent of cargo being loaded and unloaded from a bulk carrier.
The figure below shows an example whereby the battery is recharged when the cargo is lowered, then discharged when the load is raised.
The team modelled a hybrid crane system for bulk carriers. The hoisting motors provide regenerative braking. The assembly comprises four blocks: auxiliary loads, generators, battery (65 kWh) and energy management.
The overall results of the project are as follows:
- Capital expenditure (CAPEX): $350 k (equipment only)
- Annual operating expenses (OPEX): $12 k of marine diesel oil (MDO)
- Reduction: 115t CO2e/annually
- Return on investment (ROI): 19 years, but 12 years if the battery is also used to improve the fuel consumption of diesel generators at sea.
The main obstacle to achieving a good return on investment remains the limited use of 25 days annually.
VraquiUS1.0 has distinguished itself with an innovative solution to improve the economics of bulk carriers. However, the project shows that the system should be installed during ship construction to ensure a realistic return on investment.
Furthermore, integrating technologies that include batteries becomes much more cost-effective when they are made part of multiple systems, as the investment can then be spread across several projects. For example, a battery enables regenerative braking in cranes, but it could also optimize the operation of generators, and connect solar panels as well as other renewable energy sources, etc.
This led to the launch of the VraquiUS2.0 project, which aims to build on the results of VraquiUS1.0 and explore microgrid options for bulk carriers.
VraquiUS2.0: Improving the energy efficiency of bulk carriers with microgrid solutions
VraquiUS2.0 aimed to advise Fednav on the advantages and constraints of hybrid and microgrid solutions for bulk carriers.
What is a microgrid? It is a group of interconnected loads (e.g. lights, kitchen appliances, electronic devices, electric motors, etc.) that are powered by multiple energy sources in a network that operates independently of the region's electrical grid.
We are accustomed to seeing microgrids on land with solar panels and wind turbines, but bulk carriers are real floating microgrids!
The figure below shows a diagram of the various additional microgrid energy sources considered by VraquiUS2.0: solar panels, a battery, and a shaft generator.
The VraquiUS2.0 team overcame several challenges, including putting forth practical solar panel management solutions for bulk carrier operations.
A containerized solution that can quickly be deployed and stored was chosen to give the system flexibility. Although small compared to hatch covers, the sternis a key location where panel integration is easy and prioritized. This space can accommodate up to 17 420-W panels, while hatch covers can hold about 160 in all.
The shaft generator converts energy from the main engine into electricity instead of using less efficient diesel generators. However, it can only operate when the ship is moving.
The project’s overall results are as follows:
- Solar panels: 40% average efficiency
- Shaft generator: 667 kW (including inverters)
- Battery: 1 MWh
- Total CAPEX: $670 k
The figures below help to visualize the benefits of the different scenarios researched by VraquiUS2.0. The first figure shows the emissions saved (in blue) and the investment required (in orange). The second image shows the ratio of emissions reduction per million dollars invested (in green).
Although a large number of solar panels offers the solution that most reduces greenhouse gas (GHG) emissions, installing the shaft generator alone offers the solution with the best return on investment (ROI), followed by the battery and solar panels on the stern deck. Installing the battery also completely eliminates the need for a generator, making the project more attractive from an economic standpoint.
Conclusion regarding past projects
Every percentage point of reduction counts! To achieve a successful energy transition, multiple solutions must be gradually integrated and mastered. The VraquiUS1.0 and VraquiUS2.0 projects clearly illustrate the significant potential of microgrid technologies in the maritime sector for saving energy and reducing GHG emissions.
The projects also demonstrate that integrating certain basic components into a bulk carrier (battery and inverters) is a gateway to a range of microgrid technologies such as regenerative braking and solar power. Since they share the same basic system, the increased costs are spread across the different systems, making them more affordable.
Current and upcoming projects
The current projects with Electrical Engineering students at the University of Sherbrooke include a technical and economic analysis of a shore power system for bulk carriers at the Port of Montreal and the design of a zero-emission bulk carrier to meet the maritime sector's decarbonization targets.
Hugo Daniel, CPI, Doctoral candidate in Electrical Engineering. Hugo Daniel received his Master’s Degree in Electrical Engineering from l’Université de Sherbrooke in 2022, and is currently pursuing his Ph.D. in the same field at the university.
Hugo is also a member of the International Electrotechnical Commission (IEC) shore power working group since 2022. His Ph.D. project is being done in partnership with Fednav, and his research interests include maritime electrification, shore power, zero-emission vessels, hybrid systems and multi-objective resolutions.
For more information:
*Note: these documents and videos were produced entirely by the student teams in the Bachelor’s degree program in Electrical Engineering at l’Université de Sherbrooke. VraquiUS1.0 et VraquiUS2.0.
i : Amounts are in CAD
VraquiUS1.0 team’s Presentation
VraquiUS1.0 team’s scientific article (in French)
VraquiUS1.0 team's Video
VraquiUS2.0 team’s Summary presentation
VraquiUS2.0 team’s Detailed presentation (in French)
VraquiUS2.0 team's Video