big weakness of conventional AC electrical systems on ships is that they´re generally cumbersome, inefficient and potentially expensive to maintain. Switching to a DC grid based on state-of-the-art modular technology offers a unique degree of flexibility, improving energy efficiency and helping to curb fuel burn. It´s a great way to reduce pollution right now while saving money in the long run, says Carlo Cecchi, Director, Business Development, Yaskawa Environmental Energy / The Switch. As new energy carriers emerge, future-proofing vessels for any type of power source is a shrewd investment. Compact size and lighter weight also make a DC grid the best answer from a vessel design perspective.
As we move deeper into the green shift globally, around 80% of vessels in future will be either fully electric or powered by hybrid systems. Many will have multiple power sources in addition to main engine gensets running on diesel, LNG or a combination of both. Renewable power from hydrogen and potentially ammonia fuel cells, solar and even wind may increasingly be part of the mix as shipping adapts to the changing energy landscape to combat emissions. Other onboard power sources will include stored power from batteries, power from shore, and shaft generators converting mechanical power into electricity.
The art is in making the complex simple
Managing and distributing all that energy effectively is an intricate business amid a proliferation of load demands ranging from main propulsion and thruster drives to all sorts of electric actuators (winches, cranes, pumps, chargers etc). Not to mention onboard data systems and hotel demand.
At Yaskawa Environmental Energy / The Switch we hit on the ultimate solution for power management that takes that complexity and simplifies it. Switching from an AC to a DC grid delivers better fuel consumption and other cost savings, along with unbeatable reliability. Our DC Hub can reduce fuel burn by 20% up to 35% – depending of course on the ship´s operational profile and fuel hedging – while boosting energy efficiency resulting in less emissions. It also guarantees overall lesser opex and a reduction in maintenance costs of 10% to 20%.
A future-proof system requires components that can produce, transmit and consume energy as efficiently as possible. Our DC Hub uses standardized independent power drives (inverter and rectifier modules) fully integrated into one coherent solution. The Hub works with any power source giving new meaning to the word flexible. This is cutting-edge, multi-megawatt technology that´s unique in the industry and helping owners achieve new levels of energy efficiency. Frequency converters ensure a constant supply of power that is 100% reliable, which is absolutely essential for specialized tonnage such as offshore vessels and wind-turbine service vessels using dynamic positioning for precise steady-state operations. Our innovative modular design offers unparalleled malleability in that module cabinets can be added in series to match changing requirements. Before that would have required a complete electrical redesign, now it´s as easy as arranging Lego bricks and scalable to any number of actuators.
The problem with AC
Power sources feeding in parallel into an AC system means you have to match frequency, voltage and phase to the running grid. That means an array of bulky components like transformers and gears, causing waste and losses in the system. The rectifiers in a DC system convert the AC generator voltage to the DC main bus voltage resulting in very fast power-generation response. DC Hubs are also especially efficient for DC energy sources like batteries and fuel cells, minimizing the number of conversions required. Managing stored electric power effectively is particularly important when vessels need to sail pollution-free, that is in electric mode – for example, a superyacht sailing into a protected bay, ferries carrying passengers in emission-free zones, or a cruiseship navigating an urban port.
Space saving and time saving
By reducing the number of bits in a conventional AC system, the DC Hub is both lighter in mass and more compact, requiring less valuable space below deck. We´ll have an ingenious solution whatever the vessel type – even mounted in a deck unit if it´s a containership. Another big advantage is that the control software is located in a separate control cabinet, not in the drive modules themselves. That means each cabinet can, if necessary, easily be unplugged and replaced. A crew member can do this in under half an hour with no lengthy specialized training. This cuts down not only wear and tear, but also the need for spare parts and downtime for maintenance – no need to call in a gang of electronics experts.
In my book it’s also a smart investment from a lifecycle perspective; choosing a DC Hub is guaranteed to extend the lifetime of vessels and ensure their residual value remains high. Fitting out newbuildings is obviously easier in terms of optimal design because you´re starting from scratch, whereas on a retrofit you have to work with the space that´s already there. Whatever the vessel, we´re calling them E-vessels, where the E stands for engineered. Our revolutionary permanent magnet (PM) technology complements the package to drive efficiency to a new level.
Don´t be fooled by cheap options
Thinking about money, there are of course people out there touting solutions for variable speed frequency conversion on the cheap. But I very much doubt if such suppliers can guarantee performance. While they might look good in terms of short-term capex, in the long run such solutions will likely require a lot more TLC (tender loving care). Which means operating expenses go up, eating away at the profit an asset is generating. Surely it´s wiser to spend money now on a more expensive, but robust, system that will make a ship cheaper to run over its lifetime?
I´ve also had quite a few conversations with shipping bankers who really like our approach. Some have told me it could be easier for owners to get a loan at preferential interest rates if they choose our technology; in other words, it can shine up an owner´s bankability, to steal a word from the solar industry. That´s a strong intrinsic advantage.
We´re all in it together
But the main point is lowering a vessel´s carbon footprint. The onus is on our industry to do all we can to curb emissions for a cleaner world. Helping to make that happen motivates all of us every day at Yaskawa Environmental Energy/The Switch. Just like we´re seeing with the Corona virus threat, we´re all in the same boat and this is a communal effort. Forward-looking shipowners are already there, saving money in the long run. It´s a win-win for everyone, especially the climate.