Modern fuel systems must cope with harsh operational conditions while meeting tough new standards. By doing so, significant savings are possible
In the quest for the economic delivery of cleaner fuel, manufacturers are chasing ever higher injection pressures, more accurate flow measurements and alternative fuel systems.
And, as the Brent and other indexes start to climb off the floor, there is even more incentive not to waste a drop. As the head of shipping advisory at classification society DNV GL, Hans Merten Stein presciently explained in a late-2017 paper How to achieve energy efficiency excellence, “as fuel prices will most likely rise again, shipping companies cannot afford to leave this stone unturned.”
Surprising then, that a lot of shipping companies are doing just that. As the paper cautions, “few vessels achieve the savings they could reap in practice”.
The technology is certainly there to do so. Cummins recently released X15 engine for instance, uses the latest iteration of its XPI common rail fuel system that delivers the highest injection pressure of rival products, according to the American manufacturer. The X15 is also allied with Cummins CM2350 engine control module, which diagnoses and monitors the X15’s performance. The CM2350 system can automatically de-rate the engine and even shut it down if something goes seriously amiss and catastrophic failure is imminent.
Twinned with the XPI system, CM2350 also features sensors that monitor fuel use, an increasingly important function given that fuel accounts for roughly half the operational costs of running a ship.
IMO is putting increasing pressure on fuel system manufacturers to deliver frugal and efficient technology, as it tightens up regulations on energy efficiency in new ships. The Marine Environment Protection Committee (MEPC) recently adopted draft amendments to regulation 21 of Marpol Annex VI, which covers the Energy Efficiency Design Index (EEDI).
These latest amendments refer in particular to cargo and roro passenger ships, but it is an ongoing programme. One outcome of these mandatory regulations will be that operators must start collecting reams of data on their use of fuel oil, beginning in January 2019. This information is then fed into the IMO’s database on the consumption of shipping fuel. First launched in March 2018, the database is literally growing by the minute.
MEPC is also enforcing closer oversight on the quality of the fuel pumped through the systems, which has a direct affect on manufacturers. Such is the organisation’s determination to clean up the ocean air that it is considering drawing up guidance for purchasers, users and providers of fuel oil. As IMO formally puts it: “The best practices are intended to assist in assuring the quality of fuel oil delivered to – and used – onboard ships, with respect to both compliance with the Marpol requirements and the safe and efficient operation of the ship.”
Further pressure is being heaped on fuel system manufacturers in the form of the global cap on the use of marine fuel sulphur. Due to be enforced in 2020, the new standards will require ships to use marine fuels with a sulphur content of no more than 0.5%. That is a whole lot less than the current limit of 3.5% and the impact will be commensurately profound. As Shell noted in an early-2018 study entitled IMO 2020: What’s Next?: “The impact of this transition represents approximately 75% of global marine fuel demand when compared with emission control areas (ECA – which require 0.1% sulphur content.”
According to Shell’s calculations, bunkers holding a total of 3M b/d of high-sulphur fuel oil will need to switch to the 0.5% standard through blending with gasoil. That means that fuel systems will have to rise to the occasion and handle different mixes. As Shell summarises: “There will be a need for a larger variability in fuel quality.”
Most of the current crop of fuel management systems rely on sensors that measure the flow right down to the last drop. As ABB pointed out in an explanation of how its CoriolisMaster system works: “Fuel consumption is energy consumption and energy is directly related to the mass of the fuel. Therefore direct mass flow measurement is the key to highly accurate energy management.”
But accurately measuring fuel at sea is more challenging that doing so on terra firma. On the ocean waves systems must keep working at full efficiency under heavy vibrations, not only within the engineroom but when the vessel encounters rough conditions. Even in this most testing of environments, the CoriolisMaster delivers mass flow measurement down to 0.1%accuracy.
The system works at high frequencies of about 400 hz, isolated from the usual noisy vibration frequencies ranging from minus 10 hz to 200 hz that are normally encountered in enginerooms. Flow measurement equipment must be extremely robust and the CoriolisMaster can withstand outer installation forces of up to 40 tonnes.
“Only few vessels achieve the savings they could reap in practice”
The Ship Energy Efficiency Management Plan (SEEMP), introduced in 2013, was one of the first steps in the campaign to clean up marine engine emissions. The plan – which provides guidelines for measuring fuel flow - applies to every vessel over 400 gt.
SEEMP is considered a gold standard when it comes to cost-management and helping operators get the most from their fuel. Thus, systems such as ABB’s CoriolisMaster have to be SEEMP-compliant.
Embedded within SEEMP is yet another acronym, the Energy Efficiency Operational Indicator (EEOI). This is a template that enables operators to gauge the effect of any changes they make in the way they run their vessels. “The SEEMP urges the shipowner and operator at each stage of the plan to consider new technologies and practices when seeking to optimise the performance of a ship,” IMO says.
And there are a lot of new technologies and practices, ranging from better planning of voyages so less fuel is consumed between ports, to more frequent cleaning of the propeller to prevent fouling, and even the installation of a new propeller (many operators are surprised at the improvement in fuel economy achieved by installing the latest design). One of the more expensive but effective technical fuel-saving measures cited by SEEMP is the fitting of waste heat recovery systems, that convert otherwise lost energy into power.
Hence SEEMP is one of the drivers behind the constant improvement in fuel systems. Under the umbrella of the EEDI, which mandates a minimum fuel-efficiency level for different ship types and sizes, IMO keeps on tightening the screws. Following the introduction of the EEDI in January 2013, the level is tightened incrementally every five years; 2018 marks the first five-year increment.
The purpose of the EEDI was to speed up the development of the technology underpinning the many components involved in fuel efficiency, from the design phase up. The regulations are not however prescriptive; they do not tell shipowners exactly how to make their vessels as fuel efficient as possible. Rather, they allow them to adopt those technologies that, in their judgement, offer the best route to fuel economy.
According to the EEDI, as long as the required energy level is attained, ship designers and builders are free to use the most cost-efficient solutions for the ship to comply with the regulations.
As the relevant bunkering infrastructure improves, alternative fuels are finding favour with operators who had initially been nervous of investing in technology before the shore-side industry was ready. In tandem, fuel systems are being reconfigured to accommodate low flashpoint fuels under the IGF code, another mandatory IMO instrument applying to all gaseous and low flashpoint fuels, such as LNG and CNG, in the maritime sector. (The exception is gas carriers, which come under a different code applying to vessels carrying liquefied gases in bulk.)
Fuel systems are increasingly being configured for LPT and other alternative fuels
As under the EEDI code, shipowners are free to choose what system they believe best meets the regulations. All they need to do is demonstrate that the design of their ship meets the general requirements of the IGF code.
However, as DNV GL’s Mr Stein suggests, there is mounting evidence that a lot of potential savings are being left on the table. DNV GL believes that a comprehensive strategy that takes every element into account, including fuel systems, is necessary to take a vessel’s operations to the next level. “Especially medium-sized and large fleet owners, managers and operators can improve their energy management significantly,” he said.
There may not however be a quick fix. “Often many smaller measures add up to substantial savings. Taking a holistic approach by combining these measures to deliver the greatest possible benefit is the key,” said Mr Stein.
But when fuel systems and all the related infrastructure, human and technological, is in place, the results are impressive. According to DNV GL’s experience with several large clients, the benefits are easily quantified. A bulk carrier can save between 7 to 13.5% in ship operations alone (quite apart from savings achieved through purchasing, bunkering and other avenues).
And, reflecting the SEEMP methodology, further savings still come from better management of the general condition of the ship. According to DNV GL’s calculations, another 5 to 10% can often be gained from cleaning the hull (and propeller) at the right time, or from choosing the most efficient coating for the hull. Typically, the biggest savings are achieved from improvements in the operation of the ship, rather than from engine monitoring.
But the latter is still important. Engine monitoring provides real-time read-outs of how well – or otherwise -- the entire power unit is functioning. And if auxiliary engines are included in the monitoring process, another 1.5 to 5% of savings can be delivered, estimates DNV GL.
In the drive to use every drop, no stone can be left unturned.
Considered little short of fantasy a few years ago, a range of alternative power systems that would revolutionise – or even eliminate -- fuel systems is coming closer to reality. The main alternative systems are the usual suspects of batteries and fuel cells. But wind power is also being treated seriously. An inexhaustible source of energy, it is making a comeback after being largely replaced in commercial maritime traffic since the advent of the steam age.
As classification society DNV GL noted in a paper entitled Alternative fuels and technologies for greener shipping: “For thousands of years wind was the primary energy source used to propel ships, apart from human muscles. Today, wind-assisted propulsion is understood to be a potential method of reducing fossil energy consumption.”
At the forefront of this technology is Norsepower’s Rotor Sail, which the UN’s Global Compact sees as a game-changer. Already installed on a tanker vessel and on the ferry Viking Grace, the Rotor Sail harnesses the so-called Magnus Effect, created as the wind meets the spinning rotor, accelerating on one side and slowing down on the other. The result is a lift force that creates an extra forward propulsion. The Helsinki-based group estimates that the device can reduce the fuel consumption of long-haul vessels by about 20%.
But while wind power remains an interesting topic, it is battery power that remains the most likely technology to become mainstream. Plummeting costs in battery manufacturing, allied to big leaps forward in storage capacity, make this technology very attractive to shipping.
As are fuel cells, the preferred option of many engineers and scientists. These convert the chemical energy contained in a fuel directly into electrical and thermal energy through a process known as electrochemical oxidation. Depending on the type of fuel cell and fuel that is used, a direct conversion could enable electrical efficiencies of up to 60%.
Fuel cell systems also offer the huge advantage of greatly reducing the vibration and noise that have long been the bane of combustion-driven vessels. As fuel-celled power plants and other alternatives start to emerge on a commercial scale, the IMO codes will have to be re-designed accordingly and appropriate regulations are already under development.
One of the first manufacturers to commit to the development of maritime fuel cells is ABB, working in collaboration with Ballard Power Systems. In a joint release in May, the companies were optimistic that fuel cell power systems have a big future. “The [system] is anticipated to play a significant part in accelerating the industry-wide adoption of sustainable solutions for marine e-mobility and help ship-owners meet the increasingly tough demands for clean operations,” they said.
There is a long way to go though, as the collaborators acknowledge. At present, fuel cell technology lacks the grunt required by commercial shipping, operating on a kW scale. But ABB and Ballard are confident they can come up with the kind of MW-sized power required by larger ships.
They have already done a lot of homework on the benefits. A power plant with an electrical generating capacity of 3 MW, equivalent to 4,000 hp, would fit within a single module no bigger than a traditional marine engine running on fossil fuels. Encouragingly, Ballard has already proved the potential for the maritime sector by building a working MW-scale, land-based fuel cell system.
ABB has also been working independently on fuel cells for marine applications for some time. The group has a pilot installation project up and running and president of ABB’s industrial automation division Peter Terwiesch sees virtually unlimited potential in providing power systems for a new era.
“The next generation of ships – electrical, digital and connected – will require energy sources that are not only able to meet the increasing demand for fuel efficiency, but will also enable cleaner and safer shipping,” he said.