H2Tech - Q4 2022 - 8

INFRASTRUCTURE AND DISTRIBUTION
A feasibility study: Decarbonization
through H2
fuel
A. AL-QAHTANI, W. AL- BLAIES, A. AL-RUMAIH and M. RITHAUDDEEN,
Saudi Aramco, Dhahran, Saudi Arabia,
The author's company's decarbonization initiatives have
been implemented to reduce carbon emissions and achieve
future net-zero aspirations. This aligns with Saudi Arabia's
Green Initiative to cut domestic carbon output through a carbon
circular economy roadmap by 2060.
One method explored was decarbonizing domestic gas
networks by replacing natural gas with hydrogen (H2
) to reduce
emissions from industrial natural gas networks. This is
achievable by creating a blended stream within the existing
gas network. The addition of H2
resulting in reduced carbon dioxide (CO2
decreases the carbon content,
) emissions when
used as a combustion fuel at the end user's facility. Upstream
TABLE 1. Assessment of existing gas networks
No.
WS1
WS 2A
WS 2B
WS 3
WS 4A
WS 4B
WS 4C
Workstream
Process
Custody meters
Field instruments
Pipelines
Fired heaters and boilers
Gas turbines and compressors
Valves
Workstream
Process
TABLE 2. The H2 blending limits for the various components
Study's findings
The study showed up to 10% H2 limitation due to the minimum of 930 Btu/sft3
specifications of the blended sales gas received by end users.
Custody meters
Field instruments
Pipelines
Fired heaters
Boilers
Gas turbines
Compressors
Valves
8 Q4 2022 | H2-Tech.com
of higher heating value
Components are expected to handle up to 10% H2 without major modifications. Some gas chromatograph
changes and software updates may be required for flow and supervisory computers.
All field instrumentation is expected to handle up to 10% H2
some instrumentation may need to be replaced.
without requiring changes. Above this limit,
Uncertainty on the threshold blending limit at high pressure is subject to research, with further testing
results expected to be published in literature, JIPs and industry codes.
Can handle more than 10% H2 without requiring any major modifications.
Can handle more than 10% H2 without requiring any major modifications.
Blending up to 5% H2 is expected to be a low-cost impact scenario, and turbines are restricted to
a maximum 30% blending limit due to technological constraints.
Blending up to 9% H2 for a variable-speed compressor is expected to maintain performance at a low added
cost. Fixed-speed machines will experience a significant drop in performance, even at low H2
Are expected to handle up to 7 bar partial pressure without any modifications, after which they may
need to be replaced.
concentrations.
blue or green H2
gain the decarbonization benefits of H2
methods of H2
production methods must be employed to
-blended gas.
As a result, a feasibility study was performed to evaluate
blending. This study presented multiple options
at various cost levels, leading to varying degrees of decarbonization
benefits.
The assessment focused on the existing gas network-every
gas network is unique in terms of the design limitation
and type of end users silicification. As shown in FIG. 1, several
workstreams were evaluated and summarized in TABLE 1.
The study provided two options: blending H2
the grid, and blending H2
supplying H2
directly into
at the end user's battery limit by
through a dedicated pipeline.
Blending H2
directly into the grid was studied based on
various components, which included process, pipelines, custody
meters, field instrumentation, gas turbines, compressors,
fired heaters, boilers and valves. Seven cases were studied covering
a range of injection percentages for H2
to assess the impact
on the network.
All components showed an acceptance limit of up to 5%-
10%, except pipelines that showed a lower limit due to highgrade
materials operating at high pressure. The same challenge
has been encountered elsewhere in the oil and gas industry
when operating a high-pressure natural gas network. It is
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