A Hi Rocky Relationship Is it Not? Water & Electricity!

A Hi Rocky Relationship Is it Not? Water & Electricity! 

Mixing water and electricity doesn’t usually end well, but marine engineering group Knud E Hansen A/S sees this rocky relationship as a challenge.

According to the Handy Shipping Guide, the company has designed a new ferry capable of making an entire voyage on electric power. 

Many shipbuilders are following suit, looking for ways to create more eco-friendly, sustainable seafaring options, but all-electric propulsion systems come with their own unique issues especially in terms of maintenance; how do engineers and operators make sure their boats stay afloat?

Slow & Steady:

The new ferry comes in at 35 meters in length with a beam of 11 meters, capable of carrying 170 passengers and 12 cars from Nolsoy island to Torshavn and back again on single battery charge. 

It can also withstand waves of up to three meters high and was designed with energy conservation in mind, featuring both batteries and a heat recovery system. 

It won’t win any speed records, since it’s nowhere near the 100 km/hr or better ships designed to run on liquid natural gas (LNG), but the ability to run entirely on battery power and survive a potentially rough sea crossing is no mean feat. 

Simply put, the Knud E Hansen A/S ferry speaks to function more than form—and eschews traditional fuel-based thrust for clean and reliable electricity. 

Emerging Issues:

According to a Hitachi white paper, on board electrical propulsion systems come with a number of advantages including reduced noise and the integration of both power and thrust systems, but they aren’t without issues: Electric systems come with a higher initial cost, increased energy conversion loss and large overall “footprint” owing to more total component parts. 

Water infiltration can cause serious issues, anything from short circuits to total system failure.For example, Cruise Critic reports that last year a Carnival Cruise ship was forced to cut out a port of call after an electrical transformer malfunction, which limited the ship’s overall speed. In the case of a complete electrical drive system, such a short could be disastrous.

The New Maintenance:

What does this mean for shipping companies and marine organizations? That in an era of clean power, new maintenance tools are needed. 

Marine Insight argues that on board engineers must now be able to tackle challenges such as electrical motor overhauling and shore power supply connection, in addition to having complete knowledge of an engine’s automation system. 

Scale deposits also pose an issue, potentially inhibiting electrical connections and leaving a ship dead in the water; regular and precise descaling is required to keep engines in top shape.

The rise of Eco-friendly ship propulsion systems means less waste and better ROI for companies, but also comes with unique maintenance challenges—even the best electric system generates no profit in dry dock. 

Dealing with Scale Deposits in Maritime Environments:

Within ocean water, dissolved solids lead to lime scale deposits in offshore equipment systems.

Build-up of lime scale (calcium carbonate) deposits present problems, particularly in water cooled engine jackets as well as heat ex changers for production of hot water service for crew and passengers. In ship waste water piping, scale deposits will block off lines and scale up tanks as well causing adverse effects on pump seals and valves.

Boilers, steam turbines and ballast systems are also vulnerable to scale build-up of and subsequent problems of overheat, shut down or blockages.

Lime Scale deposits in these equipment systems can be effectively remedied by the use of inhibited acid descaling. 

Descalers quickly dissolve calcium, lime, rust, lithium carbonate and other types of deposits from passages in water cooled or heated equipment as described.

Hi International Shipping Goes Green:

Hi International Shipping Goes Green:

The world's economy continues to be buoyed by its oceans. Approximately 90 percent of all international trade is exchanged by vessels, and between tankers and intermodal container transport ships, they represent 65 of the 68 largest ships in operation.

Of course, the negative environmental effects of huge shipping vessels are well documented. International Maritime Organization predicts that carbon dioxide emissions from shipping would constitute 72 percent of human-made emissions by the year 2020. Considering cargo weight and transport distance, shipping via sea is the most efficient and economical, but annual increases in the amount of tonnage traded and distances traveled mean most efficiency gains are offset by increased usage.

A variety of engineering solutions have been implemented to keep mega-ships financially afloat.

Wind power returns:

In 2007, German shipping company Beluga Group launched MS Baluga Skysails, a 433 ft. long container ship. Notably, the ship receives auxiliary power from a paraglider attached to the front of the ship that reduces fuel consumption between 20 and 30 percent. The largest of the paragliders, up to 6,500 ft.², can exert as much towing power as a 6,800 hp engine. A pod-based logic controller system links the canopy and the towline to determine the optimal flying height (up to 1,600 ft.), wind direction, and speed.

Overall, Skysails have been slow to catch on, though the company says 40,000 container ships can be retrofitted with the system.

Dual props, slower speeds:

International shipping operator Maersk operates the current largest ships in the world, their Triple E class of container ships, of which there are 20. The handful of vessels larger than their Triple E Class have all been retired and dismantled because they weren't sustainable enough. So when Maersk launched their first Triple E in 2013, they knew that many operational changes were necessary in order to keep the ships viable.

Despite being the largest ships ever, Maersk claims there is a 20 percent improvement in operational efficiency over their second largest fleet of ships, the E class. This savings comes primarily from reduced throttle speeds. Most of Triple E transit is conducted at 19 knots, and the ship have maximum speed of 23 knots. This is considerably slower than other container ships (up to 28 knots), but it is considered the optimum operating speed which reduces power consumption. This adds 2-6 days to each journey.

Efficiency also stems from a unique twin propeller arrangement. Most container ships utilize just a single propeller, as they're more efficient because the dueling draughts of two propellers often result in parasitic drag. But the Triple E class has two 9.8 m four-bladed screw propellers, compared to the single 9.9 m six-bladed screw propellers, contributing 4 percent better efficiency and better pressure distribution. In this instance, the significantly larger disc area of the propellers compensates for conflicting vortices. The ship is also fitted with an innovative, $10 million waste heat recovery system, and Maersk is considering adding exhaust treatment systems as well.

LNG tankers run via boil-off:

While the Triple E is the largest container ship, the Q-max is the largest liquefied natural gas tanker, as it's 80 percent larger than most LNG carriers. Just as LNG trade has increased, LNG carriers have become more prominent. But it would be an oxymoron for a ship that provides for essential services for a booming green industry to also be an emissions giant. As such, the ship uses two low power diesel engines to power a dual propeller arrangement. Since the natural gas needs to be supercooled, the vessel maintains an internal membrane which waffles or compresses to minimize thermal effects on the vessel hull. Naturally, some of the gas transitions to vapor, where a system captures it and returns it to a liquefied state. Most LNG carriers recapture LNG at rates of 99 percent or more.

But the tankers can also run on the boil-off gas from its recapture system. The company that owns the 14 Q-maxs has initiated conversion on its fleet, so the diesel engines can also run via recaptured LNG. The result is a tanker that has a significant reduction in emissions, engines that require less periodic maintenance, fuel supply flexibility, and ultimately risk reduction.

Like many industries, international shipping businesses are adjusting to new environmental regulations that determine in which nations they can do business. Efficiency equals increased profitability, so it's ultimately a business decision to create a new generation of shipping vessels. Until a true bridge-over-the-ocean engineering project comes true, even more efficient ships are needed to offset the increasingly global marketplace.

!!!Hi GREEN DISCLOSURE!!!