fuel cell pospaper final_tcm4-525872

8/9/2019 Fuel Cell Pospaper Final_tcm4-525872

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Fuel cells for ships

Research and Innovation, Position Paper 13 - 2012


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Contact details:Kristine Bruun Ludvigsen - [email protected]

Eirik Ovrum - [email protected]

Research andInnovation in

DNV

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The objective of strategic researchis through new knowledge andservices to enable long terminnovation and business growth insupport of the overall strategy ofDNV. Such research is carried outin selected areas that are believedto be of particular significancefor DNV in the future. A PositionPaper from DNV Research and

Innovation is intended to highlightfindings from our researchprogrammes.

DNV is a global provider of servicesfor managing risk. Establishedin 1864, DNV is an independentfoundation with the purpose ofsafeguarding life, property, and theenvironment. DNV comprises 300offices in 100 countries with 9,000employees. Our vision is to createa global impact towards ensuring asafe and sustainable future.


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Fuel cell technology has recently been proven successful in large maritime

demonstration projects. Although fuel cell technology is not new, this success

means that it has become relevant to discuss the potential for fuel cell

technology in on-board applications and the current status of the technology, as

done in the present paper. This paper also discusses certain safety aspects, and

highlights the development of mathematical models for assessing performance

and operational aspects of shipboard fuel cell systems via simulation.

The main drivers for developing maritime fuel cell technology are reduction

in fuel consumption and less local and global impacts of emissions to air from

ships. Additional benefits include insignificant noise and vibration levels,

and lower maintenance requirements compared with traditional combustion

engines. Key challenges include the demand for clean, low carbon fuel and the

need to decrease investment costs, improve service lifetime, and reduce the

current size and weight of fuel cell installations.

DNV Research and Innovation has taken a leading role in facilitating

the demonstration of safe and reliable fuel cell applications for ships. Inthe FellowSHIP project, a 330 kW fuel cell was successfully installed, and

demonstrated smooth operation for more than 7000 hours on board the

offshore supply vessel Viking Lady . This is the first fuel cell unit to operate on

a merchant ship, and proves that fuel cells can be adapted for stable, high-

efficiency, low-emission on-board operation. When internal consumption was

taken into account, the electric efficiency was estimated to be 44.5 %, and no

NOX, SOX and PM emissions were detectable. When heat recovery was enabled,

the overall fuel efficiency was increased to 55 %. Nevertheless, there remains

potential for further increasing these performance levels.

Although operational experiences have shown that fuel cell technologyperforms well in a maritime environment, further R&D is necessary before fuel

cells can be used to complement existing powering technologies for ships.

Summary


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RISING FUEL PRICES and impending environmental

regulations have created a pressure for ships to operate

more efficiently and in an environmentally friendly

manner. Fuel cell power production is a technology that

can eliminate NOX, SOX and particle (PM) emissions,

and reduce CO2 emissions compared with emissions from

diesel engines. Fuel cells powered by low carbon fuels

(e.g. natural gas) will have local and regional benefits as

both emissions and noise are reduced. In the longer term,

hydrogen fuel generated from renewables could lead to

ships with zero carbon emissions.

The use of the fuel cell as an electricity generator was

invented by William Grove in 1842 (Vielstich et al., 2001).

Due to the success and efficiency of combustion engines,

fuel cells have not been widely considered for general

use, and, until recently, fuel cells have been applied

only for special purposes, such as space exploration and

submarines. However, rising fuel prices and a strong focus

on reduction of global and local emissions have led to

an increasing focus on the development of fuel cells for

application in other areas as well. Recent market studies

(Fuel Cell Today, 2011) have revealed that fuel cells shouldno longer be considered as a technology for the future;

they are already commercially available today for a diverse

range of applications (e.g. portable electronics, power

plants for residential use, and uninterruptible power

supply).

The FellowSHIP1 project designed, developed, built, and

tested a 330 kW marine fuel cell power pack installed on

board the Norwegian supply vessel Viking Lady (owner:

Eidesvik Offshore ASA). With this first large-scale fuel cell

1 www.vikinglady.no

pilot in operation, Viking Lady docked in Copenhagen

during the COP-15 international climate conference in

December 2009, (Biello, 2009), (Figure 1). This not only

demonstrated that fuel cells can operate successfully

in a marine environment, but also confirmed the long-

term efforts of DNV and our project partners towards

developing and facilitating the introduction of new

greener technologies (Eide and Endresen, 2010).

DNV recognized the potential of fuel cells in ships at

an early stage, and has taken a leading role in research,

development, and demonstration in order to facilitatesafe and reliable introduction of this technology on board

(Tronstad and Endresen, 2005; Mangset et al., 2008; DNV,

2008; Ovrum and Dimopoulos, 2011; Ludvigsen, 2012).

Early efforts to evaluate fuel cells for marine applications

include feasibility studies in the projects FCSHIP (FCSHIP,

2004) and FellowSHIP (Sandaker et al., 2005).

Large-scale marine concepts have been tested onshore in

the US Ship Service Fuel Cell (SSFC) project (Hoffman,

2011) and in two EU projects, FELICITAS (2006) and

MC-WAP2

. While the FellowSHIP installation on VikingLady adapted land-based technology for on-board

testing, the METHAPU3 project developed solid oxide

fuel cell technology that was tailored for use in marine

applications. METHAPU resulted in a 20 kW installation

on a car-carrier. The currently on-going PaXell4 project

aims towards developing and building fuel cell units for

power supply on board cruise vessels. A summary of fuel

cells installed on ships and boats until 2009 is provided

in McConnell (2010) where also a number of small-scale

2 www.mc-wap.cetena.it 3 www.methapu.eu4 www.e4ships.de/e4ships-home.html

Introduction


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applications such as pleasure boats, sailboats, ferries, and

water taxis are listed.

DNV has supported a number of the R&D projects

mentioned above (e.g., FCSHIP, FellowSHIP, METHAPU

and PaXell), conducting feasibility studies, safety and

risk assessments, and rule development. Through these

projects, significant competence has been built, enabling

us to facilitate future introduction of fuel cells on DNV

classed vessels. DNV also initiated the development of a

modelling platform for analysing and optimising the new

increasingly complex energy systems launched for ships(Kakalis and Dimopoulos 2012).

The first part of this paper introduces fuel cell technology

and highlights its advantages and challenges for marine

applications. Operational experience gained through the

FellowSHIP project is presented in the following section,

and the FellowSHIP installation is used as a case study

illustrating how advanced modelling and simulations can

facilitate safe and optimal installation of future fuel cell

power packs in a ship environment. Finally, the paper

focuses on the safety of fuel cell installations.

Figure 1: Viking Lady in Copenhagen during COP-15, 15-17 December 2009 (Photo: Sten Donsby).


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A FUEL CELL POWER PACK consists of a fuel and gas

processing system (the balance of plant), and a stack of

fuel cells that convert the chemical energy of the fuel to

electric power through electrochemical reactions. The

process can be described similar to that of a battery,

with electrochemical reactions occuring at the interface

between the anode or cathode and the electrolyte

membrane, but with continuous fuel and air supplies, see

Figure 2. Different fuel cell types are available, and can be

characterized by the materials used in the membrane. The

most relevant types of fuel cells for ship applications are

introduced in the next section. For further information onfuel cell technology see e.g. Larimine (2003).

The main advantages and challenges related to introducing

fuel cell technology onto ships are presented below.

Figure 2: Basic principles of fuel cells (courtesy of FuelCellToday)

ADVANTAGES:

Improved efficiency

Figure 3 shows how the direct electrochemical conversion

of fuel energy to electricity in fuel cells provides fewer

sources of loss than in combustion engines. At optimal

load, the best fuel cell stacks have an electric efficiency

of 50-55 %, giving a fuel to electric efficiency of 45-50 %

when internal consumption is included. These values are

slightly higher than the typical values of fuel to electric

efficiency for state-of-the-art marine diesel generators,

which are just above 40 %. New gas engines claim to achieve

efficiencies greater than 45 %. For part load operation, where combustion engines have lower efficiencies and

emissions of local pollutants are higher, fuel cell power

packs generally maintain or even increase their efficiency.

Figure 3: Electricity from electrochemical vs. combustion process

(illustration from www.vikinglady.no)

Losses in the electrochemical conversion process generate

heat that is recoverable. Depending on the type of fuel cell

technology, the amount and quality of exhaust from fuel

cell stacks are high compared with combustion engines.

Thermal integration with steam turbines or some form of

Fuel cells- advantages and challenges


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a Rankine cycle (i.e., converting heat into work) can thus

increase the electric efficiency significantly, as discussed in

the next section.

Reduced emissions to air

CO2 emissions lead to global warming. By using fuels such as

liquid natural gas (LNG) or methanol that have less carbon

content than conventional ship fuels, these emissions can

be reduced. CO and CH4 emissions can occur from fuel

cells depending on the choice of fuel, but are significantly

lower than for combustion engines running on LNG.

When hydrogen is used as fuel, no carbon compounds areemitted.

PM, NOX, and SOX emissions from ships can result in severe

consequences to human health and the environment (e.g.

Corbett et al. 2007; Eide et al. 2012). In the long-term, the

potential uptake of fuel cells on board could contribute

to reducing these consequences. NOX is formed by

combustion at high temperatures, a process that does not

occur in fuel cells, and thus NOX emissions from fuel cells

are negligible. As sulphur must be removed from the fuel

before it is supplied to the fuel cell, SOX emissions areeliminated. PM is not emitted from fuel cells, as the fuel

cannot contain heavy hydrocarbons.

Other advantages

Due to fewer moving parts, use of a fuel cell power

plant instead of a combustion engine will reduce

noise and vibrations, improving comfort for crew and

passengers. Fewer moving parts also lead to a reduction

in maintenance requirements during operation compared

with combustion engines. Fuel cell technologies that

have a small balance of plant, i.e. when limited space is

required for fuel and gas processing, can easily be installed

in independent modules. This makes the total installation

less vulnerable to single failures and, in principle, the

modules could be placed in several different locations

around the ship. Together with lower vibrations and noise,

modularity makes the engine room location less critical.

Given that safety issues are handled appropriately, this

provides a high degree of design flexibility.

CHALLENGES:

New fuels

All fuel cell types require either pure hydrogen or fuels that

can be reformed to hydrogen and CO, either before entering

the fuel cell or inside the fuel cell. The gas entering the cellsmust be sulphur-free, and low temperature fuel cells have

restrictions on the amount of CO that can be tolerated.

Some projects have aimed towards reforming marine

diesel oil (MDO) to hydrogen for use with fuel cells. These

projects have not yet been successful and it seems that fuel

cells have greater potential when alternative fuels to MDO

or heavy fuel oil (HFO) can be applied on board. Thus, the

relevant short-term options are fuels such as methanol or

LNG. However, the distribution network for such fuels is

currently limited. Should hydrogen become more readily

available in the future, this will also be a relevant option.

Investment costs

The current cost of fuel cells is high. This is due to limited

market penetration and because only a few large-scale

installations are in operation. For fuel cells to be relevant for

ships, fuel cell manufacturing costs must be reduced. The

investment costs are not expected to compete directly with

combustion engines at 3-400 $/kW, and thus the lifetime

costs of the installation must be compared (investments

and operation). Fuel cell prices vary significantly between

different fuel cell technologies. For MCFC modules, prices

have been reported to be as low as 3000 $/kW, but also

significantly higher. A target of 1500 $/kW has frequently


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been used as a development goal for commercialisation of

fuel cells (Escombe, 2008). Fuel cell producers claim that

this target will be achieved between 2020 and 2025.

Lifetime

Daily maintenance requirements for fuel cells are low, but

stack replacement is necessary. Fuel cell stacks have not

yet reached the goal of 40000 operating hours without

suffering from significant performance degradation. Due

to continuous R&D efforts, fuel cell lifetime is increasing.

System design must therefore allow for replacement of

the fuel cell stacks approximately every 5 years, while theremaining balance of plant typically has a 20-year lifetime.

Operational costs

The costs of stack replacement can be partly offset by

reduced maintenance costs compared with a combustion

engine. Due to the higher investment outlay, fuel costs need

to be lower than that of a comparable combustion engine

over the lifetime of the installation. As indicated by Mangset

et al. (2008), reduced fuel costs due to increased efficiency

and a shift to cheaper alternative fuels (e.g., LNG) may

favour fuel cells in terms of life cycle costs. A possibleintroduction of carbon taxes may also mean that alternatives

to MDO become more profitable. In general, economics of

installation are significantly dependent on the assumptions

made about an individual ship’s operating profile and fuel

consumption, and each ship must be considered on a case-

by-case basis.

Life Cycle Assessments

Life Cycle Assessments for marine fuel cell applications

have been carried out, for example by Reenaas (2005) and

Alkaner and Zhou (2006). These assessments concluded

that the environmental footprint favours fuel cells over

conventional power generator sets (diesel engines), mainly

because higher fuel efficiency is assumed for the fuel cells.

In comparison with diesel engines, the production phase

has significantly higher impact on a fuel cell unit’s life cycle

performance. If fuel consumption is not decreased when

replacing combustion engines with fuel cell technology,

then the environmental footprint will generally increase.

However, there is a considerable potential for lowering

energy consumption under the production phase as the

technology matures (Alkaner and Zhou, 2006).

Size

The size of fuel cell installations varies with the type oftechnology chosen. However, in terms of volume and weight

per kW installed, it will be hard to compete with combustion

engines, especially for fuel cell types that require a complex

balance of plant. Estimated electric efficiency based on

lower heating value of the relevant fuel, specific power, and

power density are compared for two types of fuel cells power

packs (cf. next section) and two types of internal combustion

engines (4-stroke diesel and lean burn gas) in Table 1.

Electric powergenerator

Electric

efficiency (%)

Specific

power(kW/m3)

Power

density ( W/kg)

Fuel cell (MCFC) 45-50 3 15

Fuel cell (HTPEM) ~45 30 60

Marine diesel(4-stroke) 40 80 90

Marine gas(4-stroke) 45 80 90

Table 1: Characteristic properties of two fuel cell types and two types of

combustion engines. Numbers are roughly estimated based on available

product documentation for the fuel cells and DNV internal Report No

2010-0605 for the combustion engines.


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SEVERAL FUEL CELL TYPES exist, and their names reflect

the materials used in the electrolyte. The properties of

the electrolyte membrane affect the allowable operating

temperatures and the nature of electrochemical reactions

and fuel requirements (Larminie, 2003; U.S. DOE,

2011). During the last decades several different fuel cell

technologies have been proposed and developed, and

their levels of maturity, realistic efficiency potential, and

future prospects vary significantly. Table 2 shows operating

temperatures, and average reported fuel to electric

efficiencies (when internal consumption is included), for

the fuel cell types considered to be of most relevance formarine applications.

Fuel cell typeTemperature

(°C)

Electric

efficiency

(%)

Proton Exchange

Membrane (PEM)30-100 35-40

High Temperature PEM

(HT-PEM)160-200 ~45

Molten Carbonate

(MCFC)~650 45-50

Solid Oxide (SOFC) 500-1100 45-50

Table 2: Fuel cell properties, (Escombe, 2008; McConnell, 2009).

Proton Exchange Membrane Fuel Cell (PEMFC) fuelled by

hydrogen is the most widespread and developed fuel cell

technology. It operates on hydrogen, and this needs to be

of high quality as impurities will damage the membranes.

High temperature PEM (HTPEM) is a modified version

of PEMFC with a novel membrane that can withstand

temperatures up to 200°C.

Higher temperature of operation enable a simpler

balance of plant, because the needs for cooling, water

management, and purification are reduced compared

with PEMFC. HTPEM fuels cells also have a higher

tolerance for CO, and are therefore more suitable for

use with reformed fuels (methanol, natural gas, and

ethanol). The PEM technologies have excellent dynamic

capabilities, and electric efficiencies of around 40 % have

been demonstrated. Higher efficiencies (45-50 %) have

been claimed for HTPEM due to less internal energy

consumption, but data derived from operating experience

are limited (McConnell, 2009).

PEMFC are produced in smaller units, up to 100 kW,

and are thus suited for distributed power supply. Typical

applications are cars, stationary power generation, small-

scale power sources, and combined heat and power systems.

HTPEM fuel cell units consist of independent modules,

typically 5-15 kW, with small built-in reformer units. The

modules can easily be assembled into larger power packs,

and up to 1 MW has been suggested. These technologies

are significantly more compact than the high temperature

technologies presented in the following section.

Submarines, yachts, ferries and recreational boats have

been fitted with PEM fuel cells running on hydrogen.

Examples are the 2 x 50 kW units on the ferry FCS

Alsterwasser in Hamburg5 and the 60-70 kW installation on

the ferry Nemo H 2 in Amsterdam6. A 12 kW HTPEM has also

been installed on the harbour ferry MF Vågen in Bergen,

Norway 7. A larger installation of HTPEM on a cruise vessel

will be demonstrated through the PaXell project.

5 www.zemships.eu/en/index.php6 www.lovers.nl/co2zero/factsheet/7 www.tu.no/industri/article263210.ece (in Norwegian)

Fuel cell types


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Molten Carbonate Fuel Cell (MCFC) and Solid Oxide

Fuel Cell (SOFC) technologies are high-temperature fuel

cells that are flexible regarding choice of fuel: methanol,

ethanol, natural gas, biogas, and hydrogen are most

commonly used. MCFC is the more mature of these two

technologies, while SOFC is considered to have the greatest

potential in terms of efficiency and power density. As an

example, Figure 4 shows the electrochemical reactions

inside a MCFC, in which both carbonate and hydrogen

ions are involved in electricity production.

An electric stack efficiency of 50-55 % has been obtainedfrom both MCFC and SOFC installations, and when internal

consumption is included this is lowered to 45-50 %. High

operating temperatures lead to high exhaust temperatures

(400-800 °C) that, together with a large volume flux of

exhaust, yield a significant potential for heat recovery. The

fuel to electric efficiency can be increased to 55-60 % for

MCFC plants and to above 60 % for SOFC plants when

heat recovery is included (Escombe, 2008).

A complex balance of plant to handle fuel and air

treatment is required for both technologies and largerunits are therefore preferred. MCFC units generally have

one fuel cell stack of about 200–500 kW, while an SOFC

unit is built from several smaller stacks of 1-20 kW each.

The SOFC units can be built to be significantly more

compact than MCFC units, but the complete power packs

remain large in volume compared with diesel generators.

High-temperature fuel cells must operate at stable

temperatures, and therefore have low tolerance to rapid

load changes. In general, these fuel cell types can only be

justified in applications where power and heat demands

are high and stable.

High-temperature fuel cells are currently used for

uninterruptable power supplies in hospitals and server

parks, as well as for power generation from landfill or

industrial biogas. The lack of dynamic capabilities means

that these fuel cells are best suited for providing base-load

electric power on ships. A methanol-fuelled marine SOFC

plant of 20 kW was tested on board the car carrier Undine

in 20108. The largest marine fuel cell installation to date is

the 330 kW MCFC installed on board Viking Lady 9.

The uptake of these technologies is hard to project due

to high market uncertainty and current investment costs.The most promising avenues, to date, are the following:

• Harbour-mode solutions, with the possibility of

decreasing the detrimental health effects of chemical

emissions and noise from ship traffic in urban areas,

are currently of considerable interest. Fuel cells can be

used as an alternative to cold ironing for all ship types

that have space available for fuel cells as an auxiliary

unit. The preferred fuel cell alternatives would then

be HTPEM, or a hybrid combination of batteries and

MCFC or SOFC, all running on low carbon fuels. Ifhydrogen is available, PEM or HTPEM would be the

preferred choices.

• Ferries operating on short routes are suitable

candidates for the first ships powered only by fuel

cells due to their relatively low power requirements

and frequent refuelling possibilities. The same is

true for ships operating on inland waterways. Hybrid

installations, with PEM fuel cells and batteries, already

exist as pilot installations, and would provide a zero

8 www.methapu.eu9 www.vikinglady.no


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emission alternative if hydrogen can be produced from

renewable sources.

• Cruise ships will benefit from the reduction of noise

and vibrations, as well as from reduced local emissions

while in port and cruising in environmentally sensitive

areas. Most cruise ships today are diesel-electric, and a

fuel cell installation could easily be integrated into the

designs. The public perspective of a soot-free cruise will

be a huge advantage for the first fuel cell powered cruise

ships. HTPEM units are the most realistic alternatives

due to their high specific power, see Table 1.

Figure 4: Chemical processes inside an MCFC (courtesy of MTU Onsite Energy)


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THE SUPPLY VESSEL Viking Lady is the first merchant

ship to have a large-scale fuel cell installation operating

on board. It is also the first vessel to use high-temperature

fuel cell technology. The choice of fuel cell technology

was based on fuel availability and the maturity of the

available technologies. The MCFC power unit, developed

by MTU in Germany, had been successfully demonstrated

for several land-based installations, and was modified for

operation in a marine environment. The FellowSHIP

project (phase II)10 was responsible for the modification,

installation, testing, and operation of the power pack.

When the project closed in July 2010, the system hadoperated for 7000 hours, demonstrating unequivocally

that existing fuel cell technology can be integrated into a

ship environment.

LNG is the main fuel in the gas-electric propulsion system

of Viking Lady , and the vessel therefore provided a good

test-bed for MCFCs, since no additional fuel system was

needed. In the current installation, the MCFC delivers

power to a direct current (DC) link that is connected to

the ship’s alternating current (AC) bus through power

converters. The ship’s electric propulsion system thereforeconsume fuel cell power equivalently to power provided by

the main generators.

The fuel cell stack, together with the required balance

of plant, is located in a large, purpose-built container

(13 x 5 x 4.4 m). Project-specific electrical components

(transformers, converters and DC bus) designed to protect

the fuel cell from potentially harmful disturbances on the

10 Partners of the FellowSHIP project, phase II, were the ship-owner Eidesvik

Offshore ASA, Wärtsilä Ship Design AS, Wärtsilä Norway AS, MTU OnsiteEnergy, and DNV Research & Innovation, financially supported through theResearch Council of Norway, Innovation Norway, and the German FederalMinistry of Economics and Technology.

power grid, are situated in a standard 20-ft container; see

Figure 5. The total weight of the containers is 110 tons, but

both weight and volume could be significantly reduced

in future fully integrated systems. Since the FellowSHIP

installation was retrofitted, the current design allows for

temporary installation on deck, as well as an onshore test

period for the whole power pack, and therefore the size

and weight were not optimised.

An onshore test period ensured proper functionality of all

power and control interfaces between the two containers

and the overall safety systems, and minimised the timeneeded for hook-up and modifications on board. Viking

Lady was delivered for operation on the North Sea in

April 2009, and, in September of the same year, the 330

kW MCFC power pack was installed. The fuel cell was

connected to the main switchboard for the first time in

December 2009. After initial testing, Viking Lady became

the first vessel to obtain the class notation FC-Safety, as

described in the DNV Rules (DNV, 2008).

During its first year in operation, the fuel cell stack showed

no signs of degradation, indicating that the measurestaken to protect the fuel cells were appropriate. The stack

was protected against electric disturbances. In addition,

ship movements, hull vibrations, and air salinity were also

taken into consideration when designing the fuel cell

stack and its container and support systems. In January

2012, the fuel cell was cooled down and conserved for

future demonstration projects. A total of 18 500 operating

hours were logged without signs of severe performance

degradation. Approximately half of the time logged was

in idling mode.

Fully loaded, the fuel cells produced electricity at a

measured electric efficiency of 52.1 % based on the lower

Fuel cell testingon-board Viking Lady


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Figure 5: Stord, Norway, September 2009: Installing containers on Viking Lady, the white for fuel cells and the blue for power electronics.

heating value of the LNG. Although exact measurements

of gas to grid efficiency were not possible for the

current system setup, this was estimated to be 48.5 %

including internal consumption, and 44.5 % when DC/

AC conversion was also accounted for. A heat exchanger

that produced warm water from the fuel cell exhaust was

tested, with about 80 kW heat recovered. This increased

the overall fuel efficiency to slightly above 55 %. With

optimal system integration, there is the potential for

increasing the electrical efficiency to close to 50 %, and

the fuel efficiency up to 60 %.

The FellowSHIP installation is not classed as main or

auxiliary power, but is considered as supplementary power.


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Viking Lady’s main engines must always be on-line. In

some operating conditions, e.g., in calm weather and while

docked in harbour, a load reduction is required for the

fuel cell in order to avoid the main engines operating at

unfavourable load conditions. Load changes on an MCFC

must be slow, but when load changes are performed in

a controlled manner, operating at low-load conditions is

not dangerous for these fuel cells and may even prolong

the lifetime of the stack. Nevertheless, the aim is for

continuous operation at close to full load in order to allow

full exploration of the environmental benefits and fuel-

saving potential of this technology.

Although the cost, weight, and volume of the test installation

were high, the feasibility of installing and operating a fuel

cell power pack in a marine environment was successfully

demonstrated on board Viking Lady . In future marine

MCFC designs, more focus should be directed towards

thermal integration, utilizing the high quality exhaust

heat, and on including some form of energy storage to

allow for stable load conditions for the fuel cell.

In order to explore the potential benefits of combining

fuel cells and engines with energy storage, Viking Lady will

host another large-scale technology demonstrator. The

FellowSHIP project is to be continued, and a battery pack

for hybrid operation with the combustion engines and the

fuel cell will be installed within 2013 (Eason, 2012). The

project will also make modifications to allow the ship to be

powered only by the combined fuel cell and battery power

pack during certain test runs and in harbour mode.


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IN THE FELLOWSHIP PROJECT, DNV developed a detailed

mathematical model describing the thermodynamic

behaviour and transport phenomena inside the marine

MCFC installed on Viking Lady . The main focus of the model

development was to analyse operation and performance of

the fuel cells under steady and dynamic conditions. The

model was calibrated by measurements on board Viking

Lady , and details of the implemented model and results

have been published in Ovrum and Dimopoulos (2011).

A similar modelling approach will be followed for the

HTPEM fuel cells in the on-going PaXell project.

Modelling and simulation have been used extensively

to analyse fuel cells and their potential in marine power

systems (Bruun, 2009; Bensaid et al., 2009; San et al.,

2010). Our modelling work follows the key concepts and

approach developed in the DNV COSSMOS (acronym

for Complex Ship Systems Modelling & Simulation)

framework (Dimopoulos and Kakalis, 2010). Within

this framework, DNV develops model-based methods

and a computer tool for the synthesis, design, and

optimisation of integrated marine machinery systems

(Kakalis and Dimopoulos, 2012). The fuel cell models

enable investigation of thermal and electrical integration

of the fuel cell for design and optimisation of ship power

production systems for different modes of operation.

Figure 6 shows that the model predictions agreed well with

the actual MCFC unit on board Viking Lady . The model

was calibrated against a range of data from on-board

measurements, and finally validated against a different set

of test data. The model shows an average error of about4 %, as seen in the figure below, where all the values are

relative to a reference value and therefore dimensionless.

The following examples show the model in use:

Dynamic modellingof fuel cells

Figure 6: Calibration and validation of the MCFC (Ovrum and Dimopoulos, 2011).


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Reliability of power production is of paramount

importance in the marine setting, as a ship should always

have the power to return to port. Studies of temperature

distribution, shown in Figure 7, can provide valuable

information on how the use of the fuel cell affects its

lifetime, since hot spots and large temperature variations

in time degrade the cell performance. By simulating the

dynamics of the system, the loads and fuel utilization that

the fuel cell must endure on ships with different operating

profiles can also be investigated. Thus, modelling can

manage, and potentially improve, the lifetime and

reliability of a fuel cell system.

Capability of representing transients is essential in order

to estimate how a novel system responds to critical events.

As an example, loss of fuel flow can be simulated as shown in

Figure 8. The fuel flow is reduced by 1 % of its original flow

every second, increasing the fuel utilization, until after 40

seconds the system regains control. Another critical event

is overheating of a fuel cell system due to loss of gas flow.

With such high values of fuel utilization or temperatures,

the MCFC might be degraded, reducing its performance

and lifetime. These are examples of using modelling to

supplement potentially destructive experiments for design

studies of novel marine machinery systems.

Figure 7: Temperature distribution in fuel cell membrane at 100 % load

(Ovrum and Dimopoulos, 2011).

Figure 8: Loss of fuel flow and the consequences for current density

(Ovrum and Dimopoulos, 2011).


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Preliminary studies of marine fuel cells (FCSHIP, 2004)

focused on gaining a common understanding of basic

safety requirements. The studies concluded that safe fuel

cell systems are technically possible, but that there was

a lack of standard guidelines and rules to facilitate the

design and approval process. The first rules for fuel cells

were published by DNV in 2008 (DNV, 2008), and class

guidelines were issued by GL in 2003 (GL, 2003). In the

DNV rules, there are two different class notations for fuel

cells; FC-SAFETY is mandatory for all fuel cell installations,

and, if the fuel cell unit is used for main or auxiliary

power, the class notation FC-POWER is also mandatory(Table 3). An important part of the FellowSHIP project

was to develop and implement these rules to allow for safe

installation on Viking Lady .

The main safety hazard to be handled with on-board fuel

cells is the introduction of new fuels with low flammability

limits such as LNG, methanol, or hydrogen. This sets

requirements for sufficient ventilation, alarm systems, and

fire protection, as well as introducing other measures to

limit the likelihood and consequences of a gas leakage.

LNG as a fuel is well-covered by rules, and there issignificant experience with such installations.

However, there is far less experience with ship-borne

hydrogen or methanol installations. The use of methanol

on board was demonstrated in the METHAPU project. In

the FellowSHIP project, in which LNG was used as main

fuel and hydrogen as auxiliary gas, safety measures were

implemented that resulted in a FC-SAFETY notation for

Viking Lady .

Reliability and redundancy are very important issues if

fuel cells provide propulsion or auxiliary power, according

to the FC-POWER notation. This also sets requirements

to the control systems and the interface with the ship’s

overall power distribution.

In order to stay ahead of the technological development,

DNV is positioned at the forefront of development of

rules for new technologies. In this context, a continuation

of the FellowSHIP project was kicked-off in 2011. This

project, named HybridShip, is concerned with introducing

batteries for on-board energy storage, integrated with fuelcells and gas engines.

A 200 Class notation

201 Ships where the fuel cell power is used for essential,

important or emergency services shall satisfy the

requirements in this rule chapter and will be given class

notation FC-POWER.

202 Ships where the fuel cell power is not used for essential,

important or emergency users shall satisfy the safety andenvironmental requirements. Installations complying with the

requirements in this chapter, except Section 2 will be given

class notation FC-SAFETY.

Table 3: Extract from DNV Rules for classification of Ships, Pt.6 Ch.23:

“Fuel cell installations”

Safe operation


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18

The FellowSHIP demonstration project, led by DNV,

developed and installed a 330 kW fuel cell power pack

on board the offshore supply vessel Viking Lady . This

was the first large-scale fuel cell unit to be installed on a

commercial ship. The system delivered power to the ship

grid for over 7000 hours, demonstrating unequivocally

the applicability of fuel cells for ships. The fuel cell unit

on board Viking Lady had an overall efficiency of above

55 % when heat recovery was included. DNV rules for

introducing fuel cells were developed, and the DNV

class notation FC-SAFETY was obtained by Viking Lady .

This ensured safe integration of new fuels (LNG andhydrogen), as well as safe integration of fuel cells into the

ship’s power system.

High fuel efficiency over a wide range of loads and

elimination of emissions of SOX, NOX, and PM, thereby

avoiding local consequences of air pollution from ships

on human health and the environment, are, together

with reductions in noise and vibrations, the main benefits

from introducing fuel cells to ships. CO2 emissions are

also reduced, or even completely eliminated if hydrogen

from renewables becomes available, thus lowering thecontribution from shipping to global warming.

The electrical efficiency of fuel cell stacks depends upon

the fuel cell technology, with values ranging from 35-50

%. This efficiency is only slightly higher than the values

claimed from generating electricity using state-of-the-

art combustion engines. Therefore, optimal system

integration, resulting in additional electric and thermal

power, is essential. Significant reduction in costs is also

required if the fuel cell technologies discussed in this

paper are to become competitive for ships. With the

recent commercialisation of certain land-based fuel cell

applications, there is reason to believe that costs will fall.

For ship applications, reductions in size and weight are

also of immense importance.

DNV recognizes that fuel cells can become a part of

the future power production on ships. By leading and

participating in large R&D and pilot projects, we have

built competence and developed rules, thereby paving

the way for safe and smooth introduction of fuel cells

for ships. Methods to enable assessments of new fuel cell

designs and their system integration through modelling

and simulation have also been developed, in support of

DNV’s class and advisory services. We recognize that it willtake time before fuel cells can become a realistic on-board

alternative; this is mostly because of price, but also because

of limited product development tailored to the maritime

market. National and regional incentive schemes for

environmentally friendly technologies could also play a

central role regarding when fuel cells can become cost-

competitive. Increased availability of alternative fuels, such

as LNG and hydrogen, may also accelerate introduction.

The FellowSHIP project has taken some important first

steps towards a possible future for fuel cells on ships.

It is concluded that fuel cells for shipping require further

R&D before this technology can complement existing

powering technologies. However, in the near future we

might expect to see successful niche applications for some

specialised ships, particularly with hybrid systems.

Conclusions


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19

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