Shore power converters can be a game-changer for yachts, offering cost savings, environmental benefits, and enhanced safety.
While running generators is necessary when at sea, many yachts still run them dockside because they can’t utilize shore power. This could be due to inadequate shore power due to frequency or voltage or that a ship’s original electrical system design won’t accept a different voltage from shore power.
Running generators 24/7 is expensive. A case in point is the 197ft motor yacht Caipirinha. While based in Abu Dhabi, United Arab Emirates (UAE), the vessel could not run on shore power because its original system only offered 250kVA while it needed at least 300kVA — much of that is necessary to run three chiller plants in the UAE’s summer heat. To get that power, it needed to run one of its three 330kW generators day in and day out, with fuel consumption averaging more than 300 gallons per day. For the previous three years, she had been docked full time. Her annual fuel cost, at an average of $1 per liter (in the UAE), was approximately $438,000. Added to this was the cost of servicing each of the generators every few hundred hours and replacing filters and buying hundreds of quarts of oil and the cost of disposing the used oil. Then there was the cost of tearing down and rebuilding each generator at the 8,500- to 10,000-hour mark. While switching between three generators extended each unit’s service interval, a single generator running full time racks up about 8,500 hours each year. And rebuilding a generator takes the ship out of service.
The solution for Caipirinha came from Blake Holloway of Shore Power Services in Dubai. He solved the problem with two ASEA Power Systems 165 Q series with a total output of 330kVA. The system easily upgraded the shore power from 250 to 330kVA, which eliminated the need for using the generators when berthed, meaning a significant reduction in fuel consumption and an extended service life of the generators.
Return on investment, based on fuel consumption only, was estimated to be just over 18 months — but even less when the other service and replacement costs are factored in.
Moreover, when dockside, because the vessel isn’t relying on generator power, it wasn’t necessary to run and maintain fuel purifiers, engine room cooling fans, exhaust filtration systems, seawater pumps and other systems that require regular servicing and replacement. This significantly reduced the ship’s carbon footprint.
Such systems allow seamless transfers when switching between generator and shore power. This avoids the problem of blackouts when having to turn off a generator before turning on the shore power, and vice versa, so there are zero interruptions to the ship’s electrical system — or to guest activities while they are on board.
It also solves the problem of being unable to use shore power in different countries that use different frequencies in their power grids. Most yachts’ electrical systems can only use 50Hz (typical of Europe and the Middle East) or 60Hz (typical of North America). Converters can utilize either frequency.
In the case of Caipirinha, the cost of two 165kVA shore power converters came to $495,000, including a significant amount of other related work. However, Blake normally ballparks costs at about $1,000 per kVA. Return on investment, based on fuel consumption only, was estimated to be just over 18 months — but even less when the other service and replacement costs are factored in. The ship can now realize significant cost savings of fuel, fewer service intervals and lower running hours on the generators. Just as important is a more enjoyable atmosphere due to the lack of generator noise and the elimination of generator exhaust fumes. The ship’s resale value is now higher due to its shore power converter system and the resultant lower operational costs. In essence, Caipirinha’s shore power converter could be considered the greenest upgraded product on the vessel.
What's more, shore power converters significantly enhance vessel safety by addressing critical electrical issues, including correcting polarity faults from unreliable shore power supplies. Reversed polarity allows current to flow through AC-powered appliances even when off, energizing metal casings and posing electrocution risks. Shore power converters ensure a steady and safe voltage and frequency, preventing these scenarios. Additionally, these converters protect against galvanic corrosion, which occurs when boats in a marina share a common AC shore power ground. By preventing corrosive damage to underwater fittings, shore power converters reduce maintenance costs and enhance vessel safety and longevity.
Excerpts from a white paper based on a real-life installation project by Blake Holloway of Shore Power Services, written by Peter Robson for ASEA Power Systems.