Towards the conclusion of the 19th Century a battle raged between Thomas Edison and George Westinghouse, this conflict became known as the War of the Currents. With Edison backing direct current (DC) and Westinghouse – safely in possession of Nikola Tesla’s patents – backing alternating current (AC) the two did battle to decide which form of current would populate the national grid.
In the end, AC won the day due to its ability to change voltage with ease. Swiftly being adopted by all industries it was largely assumed that AC’s dominance would persevere ad infinitum. However, now it appears that DC is in the midst of resurgence. So much so that Imtech Marine is making a bid to ‘revolutionise’ on board power networks by implementing ‘Smart DC Grids’ on vessels within the next three years. spoke to Peter Rampen, a consultant at Imtech, about the new technology.
The advent of the digital age; phones, laptops, televisions and bridge equipment as well as renewable energy sources and storage batteries have seen the use of DC sky-rocket on board superyachts. Traditionally, on board loads were characterised by their linear nature, induction motors, lighting and heating are some such examples. Changes in technology have led to vast increases in the amount of non-linear loads on board vessels, to the extent where electric vessels have up to 90 per cent non-linear loads, contributed to immensely by large lithium-ion batteries, the likes of which the superyacht industry is hitching its wagon to.

AC grids are comparatively limited in their ability to provide efficient, smaller and safer electrical networks. With regards to efficiency, constantly needing to convert AC into DC for the multitude of on board appliances wastes a significant amount of energy and is therefore fiscally irresponsible. “The total power system volume, footprint and weight is reduced [using a smart DC grid] and power sources can be operated at their most efficient operation points,” says Rampen.
“The issue of safety is largely to do with AC’s capacity for high short-circuit energy”, continues Rampen. “The smart DC grids will use newly developed ‘Current Routers’ to enable power electronics and data communications to realise a fully controlled gird with a low short-circuit energy.” The current routers will also decouple two power buses and manage the protection and load control functions.
The superyacht industry is in a unique and opportune position with regards to its ability to adopt self-contained technologies. The processes and benefits discussed within this article are not marine specific. However, because superyachts control their own energy production and delivery, owners, architects and designers can choose for themselves how best their systems should operate. Much has been said of solar sails and other renewable or hybrid technologies, all of which directly produce DC current. The numerous inefficiencies of the AC-based national grid are not likely to be handled for a great many years, but on the waves Edison may have the last laugh sooner rather than later.

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