Climate-change campaigners turn up heat in debate over ship operations.
Is the ocean shipping industry moving fast enough to make its vessels more efficient?
Containership operators in recent years have put into service behemoth new ships, which have reduced the amount of fuel needed to move a container and sailing them at a much slower pace. However, several studies raise questions about whether the entire shipping industry can still do more to increase its level of efficiency.
The first of two papers released by the Dutch firm CE Delft this year analyzed the development of the design efficiency of new ships during the past 50 years and concluded “after a period of deteriorating or constantly poor efficiency in the 1970s, efficiency improved considerably for all ship types and all size categories in the 1980s, reaching an optimum around 1990. In the 1990s and 2000s, the efficiency deteriorated again.”
That conclusion was seized upon by the two environmental groups that commissioned the study—Seas at Risk and Transport & Environment—as evidence that the Energy Efficiency Design Index (EEDI), which the International Maritime Organization (IMO) has set for new ships, needs to be made more stringent.
Bill Hemmings, clean shipping manager at Transport & Environment, contended “the IMO’s design efficiency standard for new ships itself needs a redesign and strengthening if the standard is not supposed to merely bring us back to levels achieved 25 years ago.”
Transport & Environment said the study suggested “ships can improve their design efficiency by 5 percent to 15 percent on average just by going back to 1990s designs.”
A second paper by CE Delft, which analyzed the design efficiency of ships that have entered the fleet since 2009, stated it “would appear to show this has in fact been happening. And since hull, rudder and propeller and engine designs have likely improved in the past 25 years because of technological progress, such as the development of computational fluid dynamics, much larger efficiency improvements are probably within reach. Lower design speeds could improve design efficiencies even more where appropriate.”
CE Delft noted its methodology compared similar ships and not how the fleet average design efficiency has evolved due to changes in ship size. It also noted that its conclusions related to design efficiency and did not make claims about operational fuel efficiency.
So it ignored two of the factors that have been particularly important in the container industry—the influx of much larger ships and the decision to operate them at lower speeds.
CE Delft’s first paper, Historical Trends In Ship Design Efficiency, studied the development of the Estimated Index Value (EIV) of bulkers and tankers since 1960 and containerships since 1970, explaining that the EIV formula is a simplified form of the EEDI that was used by the IMO to calculate EEDI “reference lines.”
Annex VI of the International Convention for the Prevention of Pollution from Ships (MARPOL) requires all ships to have an energy-efficiency management plan, specifying how they monitor and control operational efficiency.
“In addition, as of 2013, new ships are required to establish their Energy Efficiency Design Index (EEDI) and to prove that the ship is more efficient than a minimum standard. Over time, the standard is set to become more stringent. In the first phase, the design efficiency of most new ships needs to be better than the average efficiency of ships that entered the fleet in the period 1999-2008. From 2015, ships have to be 10 percent better, five years later, 20 percent better, and starting 2025, the EEDI has to be 30 percent better than the reference line,” CE Delft explained.
EEDIs were set as the best fit average lines of all EIVs during the period 1999-2009, and CE Delft said its study showed the EIV of new ships was on average worse than the EEDI reference line for ships built in the 1960s and 1970s, improved considerably in the 1980s, and then deteriorated again.
“This means that, on average, a ship built around 2010 had a design efficiency (as represented by the EIV) that was worse than a similar ship (same ship type, same size) built around 1990,” it said.
Jasper Faber, coordinator of aviation and shipping at CE Delft, said the measure the firm used to analyze design efficiency was “a fairly holistic one and it divides the engine power of the ship by the speed and the capacity of the ship. So it basically says how much power was needed to propel the ship at the design speed through the water.”
The formula takes into account the fact that large ships are naturally more efficient than smaller ones and allows smaller vessels to be somewhat less efficient than their larger counterparts.
Faber noted because CE Delft used a formula that the IMO also uses, which doesn’t take into account the efficiency improvements in engines, “we probably overestimate somewhat the deterioration of the efficiency in the last 20 years. But it was quite surprising to see that the efficiency in using our formula, or the IMO formula, was at its peak around 1990.”
The report looked at dry-bulk vessels, tankers and containerships and found “in general for the three ship types we looked at was somewhere between 88 and 92—that five-year period—the ships were designed most efficiently.
“We dug into the literature, the naval architecture literature, and we found some explanations for this. During the 80s, because of the oil crisis in the 70s, there was a very strong emphasis on fuel efficiency for newbuild ships,” Faber said.
He said propellers and hull dimensions were optimized during this period, so that on average, shipyards built more slender ships.
“Back in the 90s the ships were built a little bit finer, meaning they had a lower block coefficient,” said Dave St. Amand, a naval architect and president of Navigistics Consulting in Boxborough, Mass. “The easiest way to think of a block coefficient is if you take a rectangular box and you drop a ship into it, the block coefficient is basically the percentage of that box that gets filled. So the finer the ship, the lower the block coefficient and usually the better it is at going through the ocean… You’re not just pushing a big square block through the water.”
Faber said “when the pressure from the oil prices reduced, say in the 1980s and 1990s, they went back to ships that were cheaper to build but also a little bit less efficient. And so fuller hull forms, probably smaller propellers that were a lot cheaper but not too hydro-dynamically efficient as the larger propellers they were using around 1990.
“When everybody believed that fuel prices would be high and freight rates would be low, they emphasized fuel efficiency because that was more important. When fuel prices were low, that wasn’t so important anymore, so capital costs became more important and they opted for cheaper ships,” he added.
“Especially in the 2000s when freight rates were booming, when you bought a new ship that you wanted to have delivered as quickly as possible, and that means simple designs and also a fuller or plumper hull form which is much simpler to build because it doesn’t need as much strengthening as a slender ship. And, as a result, the fuel efficiency deteriorated,” Faber said.
CE Delft’s second paper, Analysis Of EIVs Of Ships That Have Entered The Fleet Since 2009, found “designs have improved and maybe not so much on average but at least there are more and more ships that are much more efficient than the standard that the IMO has set,” Faber said.
“There appear to be more operators that are really paying much more attention to fuel efficiency, which is logical because freight rates are low and fuel prices are high and fuel efficiency becomes more important in the analysis of the lifetime cost of the ship,” he said.
Analyzing the containerships that entered the fleet between January 2009 and July 2014, CE Delft found 90 percent had EIVs below the reference line for ships built between 1999 and 2009. It found that 51 percent of containerships in 2013 and 61 percent of those built in 2014 met or exceeded the EEDI for 2020.
The percentages for other types of ships is much lower: in 2014 CE Delft said the share of ships built that met the EEDI for 2020 was 50 percent for general cargo ships, 8 percent for bulkers, 26 percent for tankers, 13 percent for gas tankers, and 13 percent for combination carriers
Uwe Hollenbach, a senior consultant in fluid engineering at the classification society DNV GL, said the CE Delft study aimed to show the main dimensions of ships are less efficient than in the past and that “partly they are right and partly they are wrong from my point of view.”
Compare a Panamax containership that is relatively long and thin—about 300 meters in length and 32 meters wide—to a wide-beam containership that has the same nominal container intake.
He said a lot of the wide-beam designs have almost the same power consumption and in some cases it is a little worse.
“From this you may have the impression indeed that these wide-beam vessels are less efficient because they have less deadweight and they have a higher power consumption. But that is only half of the story.
“These wide-beam vessels do not need any ballast or little ballast,” he said. “So instead of carrying 8,000 to 10,000 tons of ballast, they can carry containers.
“Wide-beam vessels, although having less deadweight but higher power consumption per deadweight ton, have much larger intake of the loaded containers and therefore are much more efficient if you relate the power consumption to the transported container,” Hollenbach said. “I have an example here which shows that very similar vessels in respect of nominal containers, the wide-beam vessel is almost 15 percent more efficient than the old Panamax vessels.”
The wide-beam vessels are able to reduce ballast, because the wider beam gives them the stability they need while at sea.
CE Delft suggested that in the past there have been times when owners had difficulty getting shipyards to customize or improve vessel designs.
“When freight rates are high, new ships are in high demand and yards can build standard designs with a low risk and a high profit margin. In these circumstances, it may not be rational for yards to build higher risk innovative designs. Conversely, when freight rates are low, shipyards compete for clients and may be willing to build more efficient ships,” CE Delft said.
But Hollenbach said “competition between the shipyards today is so strong that everybody wants to offer you the best vessel.”
He also said that even wide-beam containerships have relatively fine hulls which are similar to those of the Panamax containerships below the water line.
The story for bulk ships is different, he said, with their hull forms becoming blunter over the years.
Hollenbach said this is the case because it is difficult for the owners or charterers to come up with a ship of the same deadweight tonnage, but with different main dimensions.
“It would be possible to save or reduce consumption just by making the vessel longer and more slender to have a finer underwater shape, but you cannot use them in the market because they have such unusual main dimensions,” he said.
The bulk market has developed so that shippers expect Handymax, Panamax or Suezmax to have certain dimensions.
Chris Koch, president and chief executive officer of the World Shipping Council, the leading trade organization for the container shipping industry, noted there have been major operational changes in the past decade that have resulted in containerships becoming more efficient and less polluting.
“The biggest single variable on ship design as to efficiency is going to be speed,” he noted.
An article in the April issue of Nature Climate Change said, “The theoretical cubic relationship between ship speed and main engine power demand means CO2 emissions from shipping are particularly sensitive to changes in speed.”
Where containerships were once built to operate at 24 or 25 knots, the spike in fuel prices means ships are now being operated at much lower speeds than those design speeds used in the CE Delft study.
Nature cited an IMO report that found “between 2007 and 2012, the average speed of containerships reduced between 6 percent (for the smallest ship size band) and 24 percent (for the size band between 8,000 and 12,000 TEUs).”
The article’s authors expressed concern that “an upturn in economic conditions could lead to ‘latent emissions’ being released as the available capacity is taken advantage of and ships revert to faster speeds.”
But Koch also said “a number of ships have had their designs modified to accommodate super-slow steaming.”
Ship hulls, propellers, and engines are optimized for a particular operating speed, and Koch said “I don’t see any evidence that anybody is going back to higher speeds, even with the current low fuel costs which won’t last forever.”
Maersk, for example, has been replacing the bulbous bows of existing ships, because the shape and configuration is designed for the particular speed at which a ship travels.
On high-speed containerships, a bulbous bow can be used to cancel out a bow wave and make a ship more fuel efficient, but at slower speeds it may actually increase the resistance as a ship passes through the water at a slower speed, St. Armand explained.
Giving a “nose job” can help a ship originally designed to operate at a higher speed once again become more efficient.
“Can one simply cut off the bulbous bow of a ship and put another one on? Yes, it is actually possible. And you can save up to 5 percent in fuel from doing it,” Maersk Line said.
The London-based consulting firm Drewry stated “as the average ship size in the trade between Asia and North Europe increased by 40 percent over the five-year period to 2013, carbon dioxide emissions per round-trip voyage slot dropped by 35 percent.
“Furthermore as average containership sizes increased by a further 23 percent between 2013 and 2015, it follows that emissions per unit of capacity must have continued to fall,” Drewry said.
The IMO Marine Environment Protection Committee (MEPC) held its 68th session from May 11-15 and said a working group would continue reviewing technological developments to implement phase 2 of the EEDI regulations that call for a 20 percent reduction in emissions beginning in 2020.
Tony de Brum, foreign minister of the Marshall Islands, proposed an emissions reduction target for the shipping industry.
“The goal of keeping global temperature rise under 1.5 to 2 degrees Celsius requires action from all countries, and all sectors of the global economy. International shipping must be part of the action. While the sector currently contributes only 2-3 percent of global emissions, its projected growth is a real cause for concern. Without urgent action, it is estimated that the sector could soon account for between 6 and 14 percent of global emissions – as much as the entire European Union emits today,” he said.
Press accounts said the motion was tabled.
Transport & Environment and Seas at Risk complained the IMO decided “that business as usual is more important than agreeing that international shipping must make its fair contribution to combatting climate change” and said it would be up to the UN Framework Convention on Climate Change, which meets in Paris at the end of this year, “to make clear that global action on the climate requires all sectors to act.”
This article was published in the July 2015 issue of American Shipper.