H2Tech - Q2 2021 - 22


Technical and economic pathways
for sustainable hydrogen production
D. B. ENGEL, Nexo Solutions, NEOX Consulting Division, Houston, Texas

In the past few years, increased focus has been devoted to
sustainable energy sources and green fuel alternatives due to
a series of social, environmental and health-related concerns.
This attention seems to be exacerbated during the COVID-19
pandemic and the rethinking of the way in which we live, the
impact we make on the ecosystem and the implications these
will have to future generations.
In addition, large corporations are witnessing how sustainable green energy companies are gaining in importance and
public favor while directly affecting their bottom lines. " Sustainable energy " indicates that the production and use of the energy
does not create harmful effects to people and the environment,
such as emissions and waste, insensible water use, deforestation or negative impacts on animal life. This sustainable energy
would be replenished at an established rate and should, in theory, be able to do so perpetually, with proper maintenance.
While fossil fuels and carbon-based energy and fuel sources
still dominate the market today, alternative energy sources have
experienced significant growth in recent years. Among these alternative sources of energy is hydrogen gas (H2 ). This source
has the potential to achieve a high level of sustainability because
of its generation pathways.
H2 production modes and sustainability. When talking
about H2 , some basics must be covered in terms of its properties and environmental impact. H2 is the most abundant element
in the universe. On earth, its production can follow a number
of different avenues that have been coded by " color, " or production mode. The most-often-used modes are gray, blue and green,
which are related to the actual H2 production pathway in terms
of carbon emissions (sometimes referred to as carbon footprint).
" Gray " H2 production employs fossil fuels that release carbon emissions into the atmosphere primarily as CO2 or greenhouse gas emissions (GHG). Therefore, gray H2 is not an acceptable pathway to sustainability because of the associated
CO2 emissions. " Blue " H2 production is similar to gray H2 in
terms of production; however, it uses carbon-capture technology to remove and sequester GHG emissions before they can
enter the atmosphere.
A common route for CO2 sequestration is reinjection into
the ground; however, it can be argued that CO2 rejection might
not be a true pathway to sustainability, as CO2 leaks from the
ground can often occur. A portion of gaseous CO2 can be safely
stored and utilized in other industrial processes, but there is still
a long way to go in terms of creating an effective carbon seques22

Q2 2021 | H2-Tech.com

tration or immobilization methodology. Color-coding H2 according to its source sometimes can be misinterpreted because
of process details and post-production effects. Nonetheless,
" green " H2 should be characterized by having zero GHG emissions during its generation.
Green H2 -i.e., H2 produced from renewable energy sources not requiring the use of fossil fuels or any other method that
creates byproducts that negatively impact the ecosystem-can,
in principle, have zero carbon emissions. Green H2 can be a potential sustainable energy source if only the production aspect
is considered. However, if the various steps beyond production
are evaluated and the full H2 manufacturing chain is considered,
a different perspective may arise, posing a fundamental question: Will H2 ever be truly and fully green, with zero emissions
of any type? A positive answer seems difficult because green energy sources, such as hydric (water), geothermal, eolic (wind)
and photonic (solar) still have carbon footprints and waste
generation. For example, the production of photovoltaic (PV)
cells for the conversion of light to electricity are associated with
some emissions, as are H2 storage and transmission.
A more realistic approach to the ecosystem impact characterization of energies should be based on their sustainability. Numerous color codes for H2 production have been assigned depending
on the production mode. This designation is a good initial approach; however, in some cases, it can be confusing or misleading. For example, pink H2 , produced using nuclear energy, is not
considered a green energy source, nor can it be considered sustainable even though it has low GHG emissions. This is because,
at some point, a nuclear facility and its components will need to
be decommissioned. The process can be incompatible with, or
damaging to, populations and the ecosystem. In addition, the carbon-intensive cement production process for the construction of
these large facilities also should be considered as part of the total
carbon footprint, in addition to a number of other factors.
As stated previously, many methods exist to produce H2 , and
several are under development. However, the focus here is on
methods for sustainable H2 production. While most of the pathways to green H2 are still in the earlier stages of development,
some are much further along and are even in the initial stages
of commercialization. At present, however, more than 95% of
the world's H2 is produced using steam reforming of natural gas
(gray H2 ). This process releases considerable emissions of CO2
into the atmosphere. Blue H2 , in contrast, uses the same process
in combination with carbon capture and sequestration protocols for trapping and disposing of CO2 emissions.


H2Tech - Q2 2021

Table of Contents for the Digital Edition of H2Tech - Q2 2021

H2Tech - Q2 2021 - Cover1
H2Tech - Q2 2021 - Cover2
H2Tech - Q2 2021 - Contents
H2Tech - Q2 2021 - 4
H2Tech - Q2 2021 - 5
H2Tech - Q2 2021 - 6
H2Tech - Q2 2021 - 7
H2Tech - Q2 2021 - 8
H2Tech - Q2 2021 - 9
H2Tech - Q2 2021 - 10
H2Tech - Q2 2021 - 11
H2Tech - Q2 2021 - 12
H2Tech - Q2 2021 - 13
H2Tech - Q2 2021 - 14
H2Tech - Q2 2021 - 15
H2Tech - Q2 2021 - 16
H2Tech - Q2 2021 - 17
H2Tech - Q2 2021 - 18
H2Tech - Q2 2021 - 19
H2Tech - Q2 2021 - 20
H2Tech - Q2 2021 - 21
H2Tech - Q2 2021 - 22
H2Tech - Q2 2021 - 23
H2Tech - Q2 2021 - 24
H2Tech - Q2 2021 - 25
H2Tech - Q2 2021 - 26
H2Tech - Q2 2021 - 27
H2Tech - Q2 2021 - 28
H2Tech - Q2 2021 - 29
H2Tech - Q2 2021 - 30
H2Tech - Q2 2021 - 31
H2Tech - Q2 2021 - 32
H2Tech - Q2 2021 - 33
H2Tech - Q2 2021 - 34
H2Tech - Q2 2021 - 35
H2Tech - Q2 2021 - 36
H2Tech - Q2 2021 - 37
H2Tech - Q2 2021 - 38
H2Tech - Q2 2021 - 39
H2Tech - Q2 2021 - 40
H2Tech - Q2 2021 - 41
H2Tech - Q2 2021 - 42
H2Tech - Q2 2021 - 43
H2Tech - Q2 2021 - 44
H2Tech - Q2 2021 - 45
H2Tech - Q2 2021 - 46
H2Tech - Q2 2021 - 47
H2Tech - Q2 2021 - 48
H2Tech - Q2 2021 - 49
H2Tech - Q2 2021 - 50
H2Tech - Q2 2021 - Cover3
H2Tech - Q2 2021 - Cover4