Why should you choose a DC grid for your vessel?

By Carlo Cecchi, Director, Business Development, Yaskawa Environmental Energy/The Switch
Tuesday, 30 June, 2020

Why should you choose a DC grid for your vessel?

As the world seeks greener sources of power, around 80% of vessels in the future are expected to be 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 AC electrical systems typically used on ships tend to be inefficient and expensive to maintain. On the other hand, switching to a DC grid based on state-of-the-art modular technology offers greater flexibility, improves energy efficiency and helps to curb fuel burn. Compact size and lighter weight also make a DC grid more suitable from a vessel design perspective.

Switching from an AC to a DC grid delivers better fuel consumption and other cost savings, along with improved reliability. The Yaskawa Environmental Energy/The Switch DC Hub can reduce fuel burn by 20% up to 35% — depending on the ship’s operational profile and fuel hedging — while boosting energy efficiency resulting in less emissions.

Power sources feeding in parallel into an AC system makes it necessary 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 systems are also especially efficient for DC energy sources like batteries and fuel cells, minimising 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 cruise ship navigating an urban port.

Effective energy management and distribution 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.

In a world where the goal is to lower carbon emissions as much as possible, it is important for industry to do its bit and choose the most energy-efficient equipment. Forward-looking shipowners are already doing this, and are saving money in the long run. This is a win-win for everyone — especially the climate.

Image credit: ©stock.adobe.com/au/metamorworks

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