Winning Combination

Requiring minimal refining, LNG is the least CO2-emitting fossil fuel out there, both in the well-to-tank process and in burning as a fuel.

Recently, however, its primacy has been supplanted by hydrogen, particularly in Europe, as hydrogen is zero-emissions at the point of burning. While hydrogen might be an effective strategy in the future when new renewables’ capacity can be built and dedicated to its production, currently all hydrogen is produced using LNG as a precursor. And in the process of steam-reforming, hydrogen actually incurs greater well-to-tank CO2 emissions than heavy fuel oil. 

LNG eliminates 20 percent of CO2 emissions when burned, and in newer engines concerns surrounding “methane slip” – methane being 25 times more potent a greenhouse gas than carbon dioxide – are dramatically reduced. It also provides a handy answer to the industry’s immediate worries. Scrubbers, which remove the unpleasant by-products of burning HFO, ultimately increase carbon emissions with their energy-intensive treatment process, and many countries – including China – are now taking steps against them. 

LNG, then, remains the more intelligent medium-term option. But an industry-wide switch will not be enough to meet IMO CO2 regulations, which call for a 70 percent improvement by 2050 in vessel emissions’ profiles versus 2008 numbers. Even engine makers, whose technology is reaching the limits of its maturity, are well aware of this. 

Frank Starke, CEO of Caterpillar Motoren GmbH, said the propulsion system of 2050 would not use fossil fuels: “It might be running on hydrocarbon fuel, but it’s not going to run on fossil fuel. And is it an internal combustion engine? Maybe. I don’t know that for a fact. We are not excluding other concepts. Wherever you burn fossil fuel, you will not achieve that efficiency or that greenhouse gas reduction.” 

New Breed

On those vessels that aren’t large box ships, bulkers or tankers, engines are diesel-electric generators, feeding energy to Azipods or other electric thrusters and ramping-up or down to match demand. This is frightfully inefficient, however. Gensets suffer gearing losses, operate at sub-optimal rev ranges, use much more fuel to accelerate and waste it when they decelerate. Switching to LNG does nothing to address this. 

Fortunately, companies have at their disposal a new technology for eliminating these losses – batteries. Through load-levelling, batteries can take in a constant supply of power from engines running at their most efficient load range – around 70-80 percent, according to Egil Hystad, Wärtsilä’s General Manager of Concept Development – and dole out more or less electric power to the thrusters as needed. 

For vessels with a particularly capricious propulsion-loading profile, the savings can be massive. Recently, ESL Shipping took delivery of MS Viikki, a geared bulker that will be operating in the Gulf of Bothnia, the northernmost area of the Baltic. Here, the vessel would be subject not only to the world’s strictest sulfur limits (0.1 percent) – which ESL addressed by substituting LNG propulsion – but also to ice conditions, meaning rapid fluctuations in propulsion load. 

In a collaborative effort involving WE Tech, Wärtsilä, Yaskawa Energy Solutions (formerly The Switch) and Corvus, the vessel was outfitted with a battery-hybrid system. The complex electrical system compensates for propulsion-load changes in ice and, in combination with LNG, offers CO2 emissions’ reductions of around 50 percent compared with a conventional HFO propulsion system.

Meanwhile, on offshore and subsea construction vessel North Sea Giant, built in 2011, three generators operate at 20 percent RPM at times of low load, such as in DP mode, which Yaskawa’s Asbjørn Halsebakke describes as “burning money.” However, the recent installation of a Yaskawa DC Hub and Wärtsilä battery makes it possible for only one generator to run at such times, at optimal load, and still feed the right amount of power to the propulsion system. 

Halsebakke explains, “We are estimating a fuel savings of around two million liters per year as well as less maintenance cost, less wear-and-tear on the equipment. As far as we know, there are no other vessels capable of operating on DP3 using a single engine.”

Hybridization

Hybridization has become an increasingly popular strategy – as much for saving fuel as for cutting emissions. It’s an arrangement that, if not fathered by, was at least pioneered by Eidesvik Offshore, which currently has five LNG-battery hybrid offshore vessels. 

“We thought in 2003 that most companies would convert to gas-powered vessels,” explains CEO Jan Fredrik Meling. “That has not taken place. There are, today, 12 or 13 PSVs powered by gas. Of those we own five. We are in the employ of an industry that pollutes the most in the world – the oil and gas segment. And so we decided that while we are in this industry we would do this in as fuel-efficient a manner as possible: Burn less and pollute less, and cost less to customers. In oil and gas there are rules for everything apart from logistics services to and from the platform. If nobody has told you to pollute less, few have the inclination.”

Eidesvik can save a considerable amount of fuel by operating this way, some 30 percent according to Meling. Running in hybrid also reduces maintenance requirements since for much more of the time the engines are running at a steady rate. For larger vessels, Meling sees advantages in terms of approaching and leaving ports on battery power, which would be an easy way of complying with just about any ECA regulation in existence. 

“We don’t believe in sitting and waiting until someone invents a zero-emission engine – that has never happened in any industry in human history,” he says. “It’s about evolution. We say to politicians and those who allocate research and development funds: We should be extremely happy if people manage a 20 percent reduction because they’re on the way to 30 percent and so on. That’s how we reduce carbon emissions by 50 percent by 2050.”

Pushing the Envelope

Four Havila Kystruten cruise ferries, under construction by Turkish shipbuilder Tersan and Spain’s Barreras, will carry 700 passengers along the Norwegian coast between Bergen and Kirkenes. They will be powered by LNG and fitted with a large 6MW battery bank. 

Supplied by Corvus Energy, these are the largest battery installations in its history, and for strictly load-levelling and efficiency purposes such a major installation would be unnecessary. However, a recent ruling by Norway’s government demands that, for ships travelling in its UNESCO World Heritage Fjords, such as the Havila Kystruten vessels, there must be no emissions of any kind. 

The law becomes effective in 2026. However, it’s being regarded as a bellwether throughout the country, and newer vessels are being designed to meet this standard – at least during the time it takes to transit the fjords.

A challenge is that many of the vessels transiting these fjords today are large cruise vessels carrying thousands of passengers. For them, complying with this new regulation with today’s technology is impossible barring the retrofit of some sort of nuclear reactor. 

But Corvus is about to unveil a new product line, Blue Whale, making installations of 12MW and more feasible. The new batteries are designed to take up as little space as possible and require less cooling thanks to their low rate of discharge.

For Brent Perry, CEO of Plan B Energy Solutions (PBES), his company’s biggest installation is an ABB-integrated 4.2MW system on the ForSea ferries Tycho Brahe and Aurora. But shipping should expect much larger battery installations in the future, he says: “The cost has come down a lot, and there’s a huge market out there today. It would take a long time to fulfill the market requirement as it is today, and demand will only grow in the future.”

Perry does not expect that cars will lead the way in terms of driving improved battery technology. Vessels offer much greater flexibility: “In a car, high energy density and low cost are the main criteria. But on a ship, energy density is really only impactful relative to calendar life. We plan for our batteries to last between five and 10 years.”

PBES is already undertaking preliminary engineering for an unheard-of 30MW battery installation aboard a vessel for a major, but undisclosed, cruise line. By itself, it still won’t be enough to run the vessel, and engines will still be needed. But, says Perry, “It will be able to run it at peak performance all the time. What we’re going to see in the next seven years is that from 2010 to 2025, there will have been a total energy density increase of 35-40 percent while maintaining calendar life.”