Why DC distribution for offshore vessels?

Electrification is the marine industry’s obvious choice in its efforts to reach net zero emissions. DC distribution is a useful option for many types of vessels for a wide variety of reasons.

Common benefits include:

• Higher efficiency due to fewer system components
• Efficient use of regenerated energy
• Smaller footprint
• Lower fuel consumption thanks to variable speed generators
• Easy integration with different energy sources, like batteries
• Future-flexible solution adjustable to meet changing regulations. This extends a vessel’s lifetime and allows step-by-step investment.
• Very high fault tolerance and system redundancy, thanks to semiconductor-based protection devices

Offshore vessels have features which benefit greatly from DC distribution. According to DNV statistics, nearly 200 offshore vessels are already equipped with batteries and 100 more have battery installations on order.

Let’s take a look at some reasons why they’re making the switch.

Reason #1 – DC distribution lowers fuel consumption and increases efficiency, allowing vessels to operate for longer over greater distances

Offshore vessels – especially those with dynamic positioning (DP) operations – use multiple generators onboard due to redundancy requirements. Most of the time, these are running a partial load with poor efficiency. Even if green fuels were used to reduce emissions, fuel economy would still remain poor with constant speed gensets carrying only a partial load. 

With DC distribution, variable speed gensets can be used and batteries are easy to connect to the system. The combination of variable speed gensets and batteries allows optimal load sharing in every use scenario. Most of the use cases are hybrid, where gensets run at optimal loads and batteries take care of the cyclic load and boost power when needed, but fully electric operation is also possible. With fewer generators running, less fuel is consumed, and less vibration occurs. In addition, regenerated energy – from cranes, for example – can be fed to batteries and re-used later, further enhancing efficiency.

Reason #2 – DC distribution increases system redundancy and fault tolerance in DP operations

The technology enabler is The Switch Electronic bus link which connects multiple DC-Hubs together with ultra-fast protection devices between. This ensures closed bus tie operations even with DP3, because the protection activates in 10 microseconds to remove the faulty part from the system while the rest of the system continues operating.

This enables fuel savings in DP mode, because closed bus tie operation allows the number of gensets running during DP operation to be reduced. Many of the gensets can be replaced by battery power backed up with only one generator running. This reduces fuel consumption significantly, since the total number of gensets running is lower. Moreover, since the running hours of each genset is less, the need for maintenance is also reduced.

Reason #3 – DC distribution is easy to operate and maintain

DC-Hubs also offers benefits from an operational point of view. Designed for marine environments, The Switch products have many features that maximize uptime:

• Ultrafast protection devices ensure ride-through functionality in failure cases. Protection is always predictable and resettable because it is based on active semiconductors.
• Enclosed modules prevent faults from spreading and eliminate the need to clean after a fault.
• Simple connectors permit fast inverter module changes easy for the crew to handle.
• Direct connection to the vessel cooling system minimizes components and cooling system service needs.
• Balanced load between gensets and batteries reduces genset running hours and maintenance.

DC distribution IS the future

It’s no surprise that many owners and operators are choosing DC distribution for its significant emission reductions and attractive OPEX.

The Switch has DC-Hubs and ultra-fast protection devices ready to further expand the fleet of electrified offshore vessels equipped with future-flexible solutions.

Get in touch with us to learn more!