Repurposing LNG terminals for Hydrogen Ammonia: Feasibility and Cost Saving

REPURPOSING
LNG TERMINALS FOR
HYDROGEN
AND AMMONIA:
FEASIBILITY AND COST SAVING
COPYRIGHT POTEN & PARTNERS 2024

Natural gas and LNG, as the cleanest among fossil fuels, play an important role in energy
transition. They are viewed as an important bridging fuel to support the global
decarbonization effort.
The world’s LNG demand currently stands at 405 MMt/y. The global LNG import
capacity has reached ~1 billion ton/year, spread across 180 LNG import terminals in 48
countries.
While Poten forecasts LNG demand to continue to increase to 630 MMt/y by 2040, the
growth will slow down as LNG will eventually be replaced by renewables and cleaner
fuels such as low carbon hydrogen and its derivatives such as ammonia.
Considering the vast number of existing LNG import terminals across the globe, re-
purposing LNG terminals to receive carbon neutral fuels has become a point of
discussion, particularly for new terminals. A number of proposed terminals are
considering how their facilities could be designed to be “Hydrogen Ready”. It’s seen as a
potential option to mitigate the risks of LNG assets being stranded and to facilitate an
easier switch to carbon-neutral fuels.
In this article we look specifically at repurposing LNG terminals for either liquid
hydrogen or liquid ammonia, as one of the key hydrogen derivatives. Poten currently
views ammonia as a more feasible means of transporting hydrogen than liquid
hydrogen, due to safety, higher heating value per unit volume, lower boil-off rate, much
lower production and shipping costs and being a demonstrated technology with an
existing shipping fleet and terminals and decades of proven export experience.
REPURPOSING LNG TERMINALS FOR HYDROGEN AND AMMONIA: FEASIBILITY AND COST SAVING
LNG TERMINAL CONVERSION

Properties Value LNG vs Ammonia LNG vs Liquid H2
Boiling Point LNG: -162°C
Ammonia: -33°C
Liquid H2: -253°C
At atmospheric pressure, ammonia
has a much higher boiling point than
LNG. This reduces the thermal
stress on process equipment and
the level of insulation required.
Liquid H2 has a much lower boiling
point than LNG. This significantly
increases thermal stress on process
equipment and the level of insulation
required, potentially changes the
storage tank materials.
Density LNG: 422 Kg/m3
Ammonia: 674 Kg/m3
Liquid H2: 71 kg/m3
Liquid ammonia is denser than LNG,
increasing the weight of liquid
inventory. This will increase the
stress on storage tanks, pipe,
support structures and
foundations.
Liquid H2 is less dense than LNG,
reducing the weight of liquid
inventory. This will reduce the stress
on storage tanks, pipe, support
structures and foundations.
Heat of Vaporization LNG: 216 MJ/m3
Ammonia: 938 MJ/m3
Liquid H2: 32.7 MJ/m3
Ammonia has a significantly higher
heat of vaporization than LNG per
unit volume stored, resulting in a
lower boil-off gas from storage
tanks, but increasing the duty for
vaporisers.
Liquid H2 has a significantly lower
heat of vaporization than LNG per
unit volume stored, resulting in a
higher boil-off gas from storage
tanks, but lower duty for vaporisers.
Heat of Combustion
(Lower Heating Value)
LNG: 22.2 MJ/L
Ammonia: 12.7 MJ/L
Liquid H2: 8.5 MJ/L
The lower heat of combustion per
unit volume of liquid ammonia will
result in a smaller amount (57%) of
combustion energy per unit volume
of storage, reducing the useful
capacity of a terminal facility.
The lower heat of combustion per
unit volume of liquid hydrogen will
result in a smaller amount (38%) of
combustion energy per unit volume
of storage, reducing the useful
capacity of a terminal facility.
Corrosivity, Toxicity,
Flammability
- Ammonia can be stored in mild
steel vessels but will attack some
sealing materials and copper-
containing metals such as brass. It
is also toxic, introducing different
HSE risks compared to LNG. Its
pungent smell is unpleasant
although provides an intrinsically
safe early warning of the tiniest
leakage.
Hydrogen has a much wider
flammability range compared to
methane. Storing hydrogen in large
volumes (180K – 200K m3) introduces
a major hazard. Currently, the largest
Hydrogen tank design is 11,200 m3,
which was prepared in December
2020 by Kawasaki Heavy Industries.
Liquid hydrogen is the smallest
molecule and prone to leakage. Like
methane it has no smell to provide
any warning.
LNG, liquid hydrogen and ammonia have different physical properties which impact the
characteristics of the facilities required in a receiving terminal. The key properties
include boiling point, density, heat of vaporization, heat of combustion, corrosivity and
toxicity – all of which need to be addressed in the design of a receiving terminal. The
physical properties of LNG, liquid hydrogen and ammonia, and their implications on
terminal design are summarised in Table 1.
Table 1. LNG, Hydrogen and Ammonia Properties – Impacts on Terminal Design
LNG, HYDROGEN AND
AMMONIA PROPERTIES
Source: Poten & Partners

LNG Equipment / System Re-use for Ammonia Re-use for Liquid H2
Storage Tanks The higher density ammonia increases stress
on the storage tank structure. Our initial
estimate of the impact is derived by allowing
the same mass of ammonia to be stored in the
repurposed tank, resulting in a 62% fill level
for ammonia. No modification is required to
storage tank insulation as ammonia is stored
at higher temperatures.
The significantly lower temperature of liquid
hydrogen will require major modifications to an
LNG tank. The tank insulation and 9% nickel
steel inner tank is unlikely to be suitable for the
lower temperature and would need to be
replaced. Storing hydrogen in a tank insulated
for LNG service would result in an increase in
boil off by a factor of 10 and the metallurgy of
the steel lining in an LNG tank is unlikely to be
suitable for hydrogen service at -253 deg C.
BOG Compressor and
Recondenser
The BOG system can potentially be reused but
will need to be modified for the lower
flowrates, higher temperature and corrosive
nature of ammonia. Ammonia will also behave
differently under pressure, possibly requiring
a change in compressor design.
BOG compressor needs to be replaced to
accommodate the significantly lower operating
temperature and different physical properties
of hydrogen.
Due to the differences in LNG, hydrogen and ammonia properties, the infrastructure of
an existing LNG import terminal is not a perfect fit for the re-purposed service.
However, there are components of LNG terminals that can be re-used, as discussed in
the table below. Re-using selected components of LNG terminals can deliver potential
cost saving of between $100 million in the case of liquid hydrogen, to $300-400 million
in the case of ammonia based on Poten’s assessment.
For ammonia, much of the LNG infrastructure can be considered for re-use. However,
there will need to be extensive design checks or redesign of static equipment,
replacement of rotating equipment and replacement of control and safety systems. The
effective capacity of the terminal will also be reduced. Restrictions on fill limit (62%)
and lower heating value per m3 of ammonia compared to LNG (57%) reduce the
effective storage capacity of an LNG tank to 35% of its design capacity.
The scope for re-use of infrastructure for liquid hydrogen is limited to the terminal land,
jetty structure and ship berth dredging, primarily due to the extreme low temperature
of liquid hydrogen storage. The jetty structure could be re-used in its current form,
provided hydrogen carrier vessel dimensions are similar to LNG carriers. It may be
possible to re-use the outer concrete shell of a full containment LNG tank but the
insulation and steel lining would need to be replaced, requiring extensive
refurbishment.
COST SAVING FROM RE-USE OF
LNG TERMINAL COMPONENTS

LNG Equipment / System Re-use for Ammonia Re-use for Liquid H2
Send-Out Pumps Existing LNG pumps (in-tank submerged low
pressure pump and high pressure send-out
pump) may need to be replaced as ammonia
service is corrosive and has a significantly
higher operating temperature. The higher
density of ammonia will also increase the
discharge pressure required from such
pumps.
Existing LNG pumps (in-tank submerged low
pressure pump and high pressure send-out
pump) needs to be replaced to accommodate
the significantly lower operating temperature
of hydrogen and lower outlet pressure required.
Piping Existing piping and associated supports can
potentially be reused but the design will need
to be reviewed for the greater weight of
ammonia in the piping system which may
require modification to piping structures and
supports. Materials will need to be checked
for resistance to ammonia.
Existing piping and insulation need to be
replaced to accommodate the significantly
lower operating temperature of hydrogen.
Vaporizer Probably not required since ammonia is
usually delivered in liquid form to customers
and can easily be vaporized if needed. If used,
the existing LNG vaporizer would need to be
evaluated for the higher fluid mass and
corrosivity of ammonia service. The lower
combustion heating value and higher heat of
vaporization of ammonia will increase the
heat input to vaporize and warm ammonia per
unit combustion energy content by a factor of
5 times compared to LNG, reducing the
capacity of the vaporizer system.
Vaporizer needs to be replaced to
accommodate the significantly lower operating
temperature of hydrogen.
Fire and Gas Detection
System
The entire system needs to be replaced as it
is designed for hydrocarbons and is not
applicable for ammonia service.
The entire system needs to be replaced as it is
designed for hydrocarbons and is not
applicable for hydrogen service.
Instrument & Control
System
All associated equipment (instrumentation,
valves, metering package, control panels etc.)
need to be evaluated and potentially replaced
/ modified accordingly to handle ammonia.
All associated equipment (instrumentation,
valves, metering package, control panels etc.)
need to be replaced to accommodate the
significantly lower operating temperature of
hydrogen.
Ship Unloading Arms/Hoses Existing loading arms and associated
supports can potentially be reused but the
design will need to be reviewed for the
greater weight of ammonia in the piping
system which may require modification to
piping structures and supports. Materials will
need to be checked for resistance to
ammonia.
The entire system needs to be replaced.
Jetty The jetty mooring system can potentially be
reused to handle ammonia carriers on the
assumption that ammonia carriers of a similar
size to current LNGCs would be developed for
this trade. The loading platform or product
arms may need modification to allow for the
lower freeboard typically found in ammonia
carriers compared to LNG vessels. The jetty
will require modification to handle existing
smaller ammonia carriers.
The jetty can be potentially reused to handle
hydrogen carriers. Although no commercial size
hydrogen vessels are in service or under
construction to date, the dimensions and layout
of the vessel may require some modification to
mooring equipment and the potentially higher
freeboard of a hydrogen carrier vessel.

VIEW AGENDA
Regardless of the specific fuel being imported and the extent to which LNG terminal
components can be re-used, access to an industrial site connected to existing fuel
transport infrastructure with an existing jetty can be of significant value to a terminal
development project, provided regulatory approvals can be obtained to re-purpose the
site from LNG to ammonia or hydrogen.
Gaining access to a suitable site is a major step in the development of a fuel terminal,
and the ability to re-use an existing terminal site would have value to a terminal
developer well above the indicative land acquisition costs carried in the notional
terminal cost summary. However, the following site-related safety issues will need to be
considered and carefully addressed:
Ammonia is toxic and noxious and there may be more stringent constraints on
proximity of the terminal to existing areas of habitation and the restrictions it may
place on development of adjacent port areas.
Hydrogen is significantly more flammable than LNG and safety zoning around a
hydrogen terminal may be more restrictive than for LNG.
ACCESS TO SITE IS INVALUABLE
WANT TO LEARN MORE?
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CONVERSION OF TRANSPORT VESSELS
- LPG AND PRODUCT TANKERS
While there are no instances yet to date of existing LNG import terminals being
converted to receive a carbon neutral fuel, a number of planned terminals are
considering how their facilities could be designed to be “Hydrogen Ready”. Terminal
designers are considering options for receiving alternative fuels and / or producing
hydrogen. Some examples include:
The LNG terminal is left largely intact receiving synthetic or green LNG which can
then be cracked to hydrogen on an adjacent site with the resulting CO2 captured
for sequestration or re-export; or
The jetty and flowlines are designed to accommodate ammonia as a second import
commodity with space left for ammonia storage and export or cracking to hydrogen
in the terminal layout.
Both approaches would accommodate a gradual shift from fossil to carbon neutral
fuels, by allowing the additional infrastructure to be built and expanded over time.
Terminals designed in this way could reduce the cost of future transition to carbon
neutral fuels by making allowances in terminal plot space for additional facilities and
potentially also by seeking in principle agreement from regulators for future import of
other carbon neutral fuels, such as ammonia. The viability of such conversions will be
driven by the supply chain economics and regulatory view of the alternative fuels at the
time owners seek to implement the conversion.
INDUSTRY RESPONSE TO
TERMINAL CONVERSION
As demand for hydrogen and ammonia grows and starts to
displace conventional fossil fuels, there will be a need to expand,
and in some cases re-purpose, the international shipping fleet to
carry alternative carbon neutral fuels to consumers. In this
section we look at repurposing LPG carriers for ammonia and oil
product tankers for methanol.
The issues around re-purposing of vessels to carry renewable or
green ammonia, hydrogen and methanol are considered at a high
level from two perspectives: the technical hurdles to using
existing vessels for carbon neutral fuels; and the commercial
drivers for establishing carbon neutral supply chains.

Technically, ammonia is currently transported in vessels of similar design to LPG
carriers. Existing ammonia carriers will continue to service their current markets,
primarily for fertilizer and chemical industries, and so transport of additional ammonia
volumes as carbon neutral fuel will need additional ammonia shipping capacity. LPG
carriers that have ammonia on their Certificate of Fitness will likely already be able to
carry ammonia, but if ammonia is not listed on their certificate of fitness, it may be
necessary to carry out modifications mainly related to materials in the cargo system
and safety equipment. Conversion of LPG carriers to ammonia is not technically
challenging, however the requirements for cleaning if the operator decides to return the
vessel to LPG service are extensive. In this case, any re-purposing to ammonia service
would need a medium-long term justification.
Most methanol carriers are purpose built with appropriate tank and cargo system
coatings. Re-purposing a products tanker for example, would require all cargo tanks
recoated and possibly cargo lines replaced. Chemical carriers often have stainless steel
tanks for the more aggressive cargoes but those carrying less aggressive chemicals may
have coated tanks, which may or may not be compatible with e.g. methanol. Chemical
carriers handling the more hazardous cargoes have as many as 50 tanks of various sizes
as the products are carried in small quantities – methanol would require vessels with far
fewer larger tanks for ease and speed of loading/discharging.
On repurposing transport vessels for liquid hydrogen, for the reasons explored above,
the extreme properties of liquid hydrogen mean that conversion of any existing vessel
to liquid hydrogen service is not viable.
From the supply chain perspective, while re-purposing of existing vessels for transport
of green ammonia or methanol as a bulk fuel is technically viable, the number of vessels
used in this way may be relatively small. Use of existing ammonia or methanol carriers,
or re-purposing of similar vessels may occur on a small scale to deliver green fuel from
the first few production projects at a relatively small scale. However, if either fuel is
adopted on a large scale to displace coal or LNG, the volumes that must be transported
to dedicated import terminals will grow rapidly, particularly given the lower energy
density of liquid ammonia of a fuel equivalency basis compared to LNG. The growth in
traded volume will drive the introduction of larger purpose-built vessels to reduce
transport costs, which may limit the need for repurposing existing smaller vessels. Given
the time period over which the energy industry as a whole will transition to carbon
neutral fuels, and volumes of such fuels that must be transported, the introduction of
new larger purpose-built vessels may eclipse the need for wide-spread vessel re-
purposing.

Repurposing LNG terminals for Hydrogen Ammonia: Feasibility and Cost Saving

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