Hydrogen and Oxygen
Carbon Capture Using the Oxygen Produced by Electrolysis
Bruce Barbour - July 2020 - Updated September 2021
At some stage in the future the much talked about hydrogen
production will get off the ground. Hydrogen will have many uses on
the way to and in a post carbon society:- fuel for automobiles and
trucks, as a store of energy for later conversion into electricity,
as a heat source for industry and an export commodity for all those
Hydrogen can be produced in a number of ways. The two main ways are
by: (1) splitting hydrocarbons / fossil fuels, and (2) electrolysis
of water, which uses electrical energy to split water (H2O)
into hydrogen and oxygen. The first method produces carbon dioxide
as a byproduct and is not sustainable/renewable. The second method,
electrolysis, can either be unsustainable if fossil fuel generated
electricity is used in the process or can be fully sustainable if
the electricity used is generated from renewable sources, such as
solar or wind. The production of hydrogen by electrolysis using
renewable energy is the preferred method, and hopefully this method
will be utilised as more renewable energy is generated into the
Production of hydrogen by electrolysis means that a lot of pure
oxygen (O2) will also be produced - in fact exactly half
the volume of the hydrogen produced. While it could be released into
the atmosphere without any impact that would be a waste. Instead
this oxygen produced as a byproduct of hydrogen generation should be
looked on as a great opportunity in a number of areas.
A lot of the commentary that I read on tackling climate change
indicate that it is quite likely that we, that is humanity, are
going to overshoot the desirable maximum target of carbon dioxide
concentration in the atmosphere. This means that not only do we have
cut our net carbon dioxide emissions to zero, we have to also start
removing existing carbon dioxide from the atmosphere to bring the
carbon dioxide concentration down to acceptable levels somewhat
closer to pre-industrial concentrations.
One way to do this is via carbon capture and storage (CCS). CCS up
until now is usually discussed in relation to the burning of fossil
fuels, capturing the exhaust gases and then usually extracting the
carbon dioxide from the exhaust gases and pumping the concentrated
carbon dioxide into underground storage caverns where it will
hopefully be stored for a very long time. One of the big issues with
this process has been the difficulty and the cost of extracting the
carbon dioxide from the exhaust gases for storage. While all the
exhaust gases could be put underground this would waste limited
storage space. Most of the exhaust gases would be the inert gas
nitrogen, as nitrogen constitutes approximately 78% of air.
Capture and Storage (CCS)
CCS is extremely controversial in Australia and around the
world. The main reason is that CCS has been championed by
the fossil fuel industry as a way to prolong their
The fossil fuel industry use it in two ways. Firstly to
provide a veneer of cleanliness over a dirty industry -
e.g. the whole "clean coal" crap. The second is as a
delaying tactic - "We're working on this technology to
clean up our product - just give us a bit more time and we
will get there, we will be clean. And give us a few more
million dollars of taxpayer money." It is solely a PR tool
for them. In the meantime they continue business as usual
- raking in the money and polluting the atmosphere.
The trouble is despite all of their claims of being able
to implement CCS and despite millions of dollars of
Government subsidies they
have been singularly unsuccessful in implementing it on
any meaningful scale - in Australia and around the
world. Not one cent of Government money should go to the
fossil fuel industry - for CCS research or any other
subsidy. In fact they should be paying us for the damage
they have caused.
CCS should not be used by the fossil fuel industry to
prolong its life. However given that the World is
going to overshoot its so called carbon budget humanity is
going to have to draw down the existing carbon from the
atmosphere. This could be done by a number of technologies
- biochar, deep ocean storage, rewilding/tree planting. In
conjunction with these direct air capture with CCS and
also OFBECCS as discussed on this page, may be part of the
long term solution.
This is where the use of the generated pure oxygen comes in.
Instead of combusting the fuel to generate electricity with
atmospheric air it could be combusted with pure oxygen or, more
likely, oxygen mixed with exhaust gases, primarily CO2,
for better controlled combustion. Effectively the nitrogen from air
has been removed from the combustion chamber and therefore does not
have to be removed from the exhaust gases for CCS. For example a mix
of, say, 30% oxygen and 70% exhaust flue gases / carbon dioxide,
whatever percentage mix is found to work the best, could be used.
The burning of the fuel is going to consume most, if not all, of the
oxygen in the CO2 / oxygen mix. As a consequence of this
the exhaust gases will be primarily carbon dioxide. The flue gases
would be captured. A proportion of the gases (70% in the case of the
example concentration used earlier) would be sent back to the
combustion chamber after having been mixed with the appropriate
concentration (30%) of oxygen to continue the process. The remainder
would be pumped into subterranean storage with minimal further
concentration or refinement. For example it may be decided that the
removal of moisture generated from the burning process - moisture
that came from the fuel being not perfectly dry prior to burning -
was warranted as the process of removing most of the moisture is
relatively easy. For other gases - probably some nitrogen and some
toxic gases from the combustion of some waste products - it may be
decided not to remove them due to the cost.
Burning of fuel in an oxygen rich environment is called Oxy Fuel
Combustion. When it is combined with burning of natural organic
material using carbon capture and storage it could be referred to as
Oxy Fuel combustion for Bio Energy with Carbon Capture and Storage.
(OFBECCS). References: (1)
Science Direct, (3)
Science Direct 2).
So what fuel would be used in this process? While any carbon based
fuel could be used the preferred fuel would be an organic waste
product. Waste is ideal as a fuel as it doesn't require further
energy input for its production. Just some additional energy input
for the collection, transport and some pre-treatment (e.g. cutting
and drying) of the waste.
The advantage of using organic waste product is that the process
will result in the removal of carbon from the atmosphere. In the
photosynthesis and growth process organic food and crops take in
carbon dioxide from the atmosphere. Normally an organic waste
product would be allowed to rot in the field or in landfill or in a
composting area. In the process of rotting it would release the
carbon dioxide back into the atmosphere. This is not generally
thought of as harmful as it is part of the normal carbon cycle -
except if methane is produced in the process which it can be,
especially in landfill. The OFBECCS process would divert the carbon
dioxide from returning to the atmosphere instead it would go into
underground storage, decreasing the amount of carbon in the
atmosphere. And of course the electricity generated would be
completely renewable, in fact better than 100% renewable as it
removes the extra carbon from the atmosphere through the capture and
The ash generated from crop waste and crop burning also contains
carbon, as well as other chemicals. The ash could also be buried as
carbon storage or there could be other uses for it.
What sources of organic waste products could be used?
Domestic household organic waste from food waste and also cuttings
from residential gardens is one source. Victoria is introducing a 4
bin waste/recyclables collection system which will have a separate
bin for the collection of food scrap waste and garden cuttings.
While it was planned that the organic waste would be composted it
may be determined that a better use would be this OFBECCS process.
(It also may not be the best use of organic waste. The world is
going to have to decrease its use of artificial fertiliser. Compost
material may be valuable as a replacement fertiliser.) The moisture
content of household domestic waste is an issue if the waste is to
be burnt, meaning that the waste would have to dried (in the sun)
prior to burning. While paper and cardboard could also be combusted
it may have a better carbon balance to recycle it. A proportion of
domestic hard waste is comprised of timber/wood (e.g. from
furniture). This would also be suitable as a fuel.
Victoria is planning energy from waste plants. Energy from waste
plants are also very common overseas. The waste will probably be
partially organic and partially from fossil fuel based materials
(plastics). If these plants in Victoria were to go ahead they should
involve carbon capture and storage technology as well a toxic gases
capture and storage.
If a crop waste was to used, the normal food crop would be harvested
and sent to market. The waste stems and leaves and other plant
product would also be collected and sent to be used as the fuel.
Waste from the plantation timber industry could also be used.
Another option for a waste fuel source is dried sewage farm sludge.
A crop could be grown specifically as a fuel source, i.e. no other
crop is harvested. This, of course, is not waste product. The crop
could be some kind of fast growing plant - perhaps a bamboo??
However there is an additional energy input and financial cost
associated with that. And it could displace other food production
crops which may become more of an issue as the impacts of climate
change are felt more heavily. This might still be considered if it
was determined that this OFBECCS process was a good means of capture
and storage of carbon.
Plastic waste, for example supermarket food and drink containers,
while it would work as a fuel, would not result in carbon removal
from the atmosphere. It would effectively be fossil fuel generated
electricity with carbon capture. The oxy fuel combustion process
should not be used to prolong the fossil fuel electricity generating
The OFBECCS process would generate heat from the burning of the
waste, which would be used to boil water for generating electricity
in the usual manner.
As this would be a new process for Australia the first step would be
to set up a trial site to determine the technical difficulties prior
to wider adoption.
The ideal trial site would be somewhere adjacent to a significant
natural gas distribution pipeline, say coming from the Bass Strait
gas fields off the coast of Gippsland (in Victoria, Australia). It
would also have to be adjacent to potential carbon storage sites.
The site should also have a source of renewable electricity although
the renewable electricity can always come in through a sufficiently
large grid connection and the process could use some of its own
generated electricity. The site would also have to have a
significant source of organic waste, so maybe adjacent to a largish
rural city in Gippsland, where the domestic organic waste collection
could be used as the primary fuel source, and sewage sludge, crop
waste and a dedicated crop could be trialed.
For the trial, a plant to produce hydrogen and oxygen from water
electrolysis would be built. The hydrogen could be pumped into the
natural gas line, if there is no other better use for it. Hydrogen
can be mixed with natural gas at a concentration of up to 10%
without requiring any modification to the pipelines or the gas
appliances. The oxygen would be used in the OFBECCS process. The
generated electricity would be used to run the electrolysis process
and excess sold back to the grid.
When fully up and running the OFBECCS process would make the
production of hydrogen by electrolysis more economical and therefore
a more attractive proposition. The oxygen generated would value add
to the whole process, instead of being wasted or a produced as a low
value byproduct. Is it actually competitive with other electrical
generation? I don't know. However it is one of these processes that
would greatly benefit if Australia had a system of carbon taxes or
Regardless of the economics of the electricity generated the real
benefit is that OFBECCS has negative carbon generation. It takes
carbon out of the atmosphere - which is desperately required at this
time and this by itself may be sufficient to recommend this process.
The generation of clean electricity from the process may come to be
considered as the very useful byproduct.
Going into the future we are going to have to remove large amounts
of carbon from the atmosphere. OFBECCS may be part of this approach
however it could not work as a sole solution. If it was it would
require a significant proportion of the arable land to be devoted to
growing crops for OFBECCS, displacing food production in a time when
it is likely that the food productivity of the land will be
declining. It would have to work in conjunction with other methods
of atmospheric carbon removal such as (deep) ocean and soil
sequestration (biochar) and direct air carbon capture and storage
(DACCS). However the most important requirement, without which all
of the other action is futile, is to stop putting carbon into the
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