H2Tech - Q4 2022 - 26

SPECIAL FOCUS: FUTURE OF HYDROGEN ENERGY
Water intensity is tantamount to carbon
intensity for climate-friendly fuels
M. MURDOCK, Raven SR, Pinedale, Wyoming
Any serious undertaking to combat climate change requires
fuel production with a negative carbon intensity, but
an often-overlooked consideration is water usage. Traditional
energy production requires extensive water usage. Power plant
cooling systems and hydraulic fracturing can use reclaimed or
recycled water.
However, what about new energy generated with water?
Much of the attention on renewable hydrogen (H2
) focuses on
electrolyzers that use electricity generated from solar and/or
wind power to split water molecules into H2
term green H2 has become synonymous with the electrolyzer
process. Green H2 sourced from renewable power is touted
as being free of greenhouse gas (GHG) emissions. However,
is an energy source truly sustainable if it entails a heavy water
usage footprint?
According to " The Water Planetary Boundary: Interrogation
and Revision, " we use nearly 70% (2,800 km3
) of the planetary
boundary of 4,000 km3/yr of freshwater consumption.1
could equate to 12% of
the energy sector's water consumption. In addition, the IEA's
2021 Global Hydrogen Review2
found that to use seawater instead
of fresh water, the cost of desalination must come down,
or researchers must find a way to process seawater without corroding
equipment.2
life-sustaining resource-to produce energy is suboptimal.
Nonetheless, electrolysis is being widely pursued for green
H2 production, which seems oxymoronic when considering its
source of H2
feedstock. To avoid using fresh water, another option
being pursued is utilizing wastewater. That, of course, will
require a water purification process, adding a significant step.
What if solid or gaseous waste was directly used as a feedstock
instead of renewable power and water to support H2
) or fugitive CH4
producemistion?
This could be solid municipal waste filling landfills, green/
food waste that generates methane (CH4
sions waste from conventional oil and natural gas operations.
The term waste-to-energy often connotes incineration,
which only adds to the GHG and criteria pollutants' emissions
problem that needs many forms of abatement, such as direct
air capture technologies being pursued by many companies.
There are more convenient, shovel-ready ways to tackle waste.
For instance, some waste management companies are already
expanding their renewable natural gas production, which entails
capturing CH4
with wells embedded into completed sections
of landfills.
26 Q4 2022 | H2-Tech.com
In short, using more water-a limited vital
Furthermore, the International Energy Agency (IEA) estimates
that total water demand for H2
and oxygen. The
There is no single CH4 abatement and capture solution, and
the widespread need for containment requires an all-handson-deck
response. The author's company has a modular, noncombustion
steam/CO2
reforming system that processes CH4
, sustainable aviation fuel, renewable diesel
into H2-rich syngas (~60%), which can be upgraded into transportation
grade H2
or methanol. No added water is needed; it can process multiple
feedstocks at once, without separation, with a moisture content
of 30%-55%.
A simple way to visualize this is with a simple takeout food
container. The organic material in leftovers, paper-based and
plastic food containers can be left together, dumped in a landfill
and then converted to produce a negative carbon intensity
fuel. The process is emissions free, as well as the clean H2
it
produces. Alternatively, higher energy, lower emissions synthetic
fuels can be produced this way, as well.
This presents a solution to a global problem, too. The
World Bank estimates that urban populations generate more
than 2.2 Btpy of solid waste, and projected population growth
would bring that figure to 3.88 Btpy in 2050. That is a lot of
feedstock for non-combustion steam/CO2
reforming to produce
clean energy where the waste is generated.3
The author's company intends to install its gas-to-gas technology
in the spring of 2023 in California; this technology can
produce 4,500 kg of H2
utilize stranded, flared, low CH4
monetized gas to create affordable H2
/d from renewable or natural gas. It can
landfill gas or otherwise unefficiently.
In
addition, the company recently trialed its full-scale second-stage
equilibrium steam/CO2
reformer at its California
manufacturing facility, demonstrating methane conversion to
transportation-grade H2
at a rate exceeding other commercially
available technologies, such as steam methane reforming.
The Fischer-Tropsch method for synthetic fuels is well-established
with coal, but instead of mining for resources, the author's
company applies the process to garbage and other waste streams
to produce diesel, Jet A, Jet B and military-specified JP-8 aviation
fuels from waste. Fischer-Tropsch creates fuels out of H2
and carbon, as opposed to conventional fuels refined from existing
hydrocarbons. In other words, Fischer-Tropsch synthetic
fuels are combined instead of taken apart. As a result, these synthetic
fuels are higher purity and burn cleaner. Unlike biofuels
that depend on food crops, synthetic fuels based on waste provide
the dual benefit needed to improve the environment.
The steam/CO2
reforming process converts 100% of waste.
In addition, about 15% of feedstock is converted into a solid
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