Hydrogen production methods

Comparison of hydrogen production methods

Process Description Feedstock Efficiency Hydrogen cost Capital cost (M$) Advantages Disadvantages
(%) ($/kg)
Steam Steam reforming (SR) method Natural Gas 74–85 SMR with CCS-2.27 SMR with CCS-226.4 Most developed CO2 byproduct,
reforming basically involves a catalytic SMR without CCS- technology, dependence on fossil
(SR) conversion of the hydrocarbon 2,08 SMR without CCS- 180,7 existing fuels
and steam to hydrogen and infrastructure
carbon oxides, and consists of The component costs
the main steps of reforming or as a percentage of the
synthesis gas (syngas) overall H2 production
generation, water-gas shift cost for SMR are as
(WGS) and methanation or gas follows: 60.7%
purification. feedstock, 29.1%
Hydrocarbon Reforming

capital investment and

10.2% O&M.
Partial Partial oxidation (POX) method Coal, heavy oil 60-75 The component costs Proven CO2 byproduct,
oxidation basically involves the as a percentage of the technology, dependence on fossil
Fossil fuels

(POX) conversion of steam, oxygen overall H2 production existing fuels

and hydrocarbons to hydrogen cost for POX of residual infrastructure.
and carbon oxides. fuel oil are as follows:
34.8% feedstock,
47.9% capital
investment and 17.3%
O&M
Autothermal Autothermal reforming (ATR) Natural Gas 60–75 ATR with CCS- 1.48 ATR of methane with CCS- Proven CO2 byproduct,
reforming method uses the exothermic 183.8 (1) technology, dependence on fossil
(ATR) partial oxidation to provide the existing fuels
heat and endothermic steam The investment costs are infrastructure.
reforming to increase the about 15–25% and 50%
hydrogen production. lower than SMR and coal
gasification respectively,
whereas advanced large-
scale ATR plants with 90%
CO2 capture at an
efficiency of 73% and
investment costs at nearly
499.23 $/kWH
 Hydrocarbon Hydrocarbon (CHs) pyrolysis is Natural Gas - 1.59–1.70 Capital investments for Emission-free, Carbon byproduct,
pyrolysis (CHs) a well-known process in which large plants are lower than reduced-step dependence on fossil
the only source of hydrogen is for the processes of steam procedure. fuels.
the hydrocarbon itself, which conversion or partial
undergoes thermal oxidation resulting in 25–
decomposition. 30% lower hydrogen
production cost. capital
investments for large plants
are lower than for the
processes of steam
conversion or partial
oxidation resulting in 25–
30% lower hydrogen
production cost.
Biomass Biomass gasification is the Woody - 1.77–2.05 149.3–6.4 (2) CO2-neutral, Tar formation, varying
gasification thermochemical conversion of Biomass abundant and H2 content due to
biomass into a gaseous fuel It is estimated that a cheap feedstock. seasonal availability
(syngas) in a gasification typical route of biomass and feedstock
medium such as air, oxygen gasification-steam impurities.
and/or steam. After the reforming-PSA,
transformation of biomass into requires 2.4 TJ of
syngas, the gas mixture is primary energy input
further treated in the same way per TJ of hydrogen, and
as the product gas of the for a plant with an
pyrolysis process. expected hydrogen
RENEWABLE SORCES

output of 139,700
kg/day and cost of
biomass in the range of
Biomass

46–80 $/dry-ton the

hydrogen production
cost is expected to be
1.77–2.05 $/kg.
Biomass Biomass pyrolysis is the Woody 35-50 CO2-neutral, Tar formation, varying
pyrolysis thermochemical process of Biomass abundant and H2 content due to
generating liquid oils, solid cheap feedstock. seasonal availability
charcoal and gaseous and feedstock
compounds by heating the impurities.
biomass at a temperature of
650–800 K at 0.1–0.5 MPa. It
takes place in the total absence
of oxygen except in cases
where partial combustion is
allowed to provide the thermal
energy needed for the process.
Bio- Bio-photolysis is a biological Water+Algae 10 Direct Bio-photolysis- Direct Bio-photolysis - 50 CO2-consumed, Requires sunlight, low
photolysis process using the same 2.13 $/m2 O2 is the only H2 rates and yields,
principles found in plants and byproduct, requirement of large
 algal photosynthesis, but Indirect Bio- Indirect Bio-photolysis- operation under reactor volume, O2
adapts them for the generation photolysis- 1.42 135 $/m2 mild conditions sensitivity, high raw
of hydrogen gas. In green material cost, the
plants only CO2 reduction requirement of
takes place, as the enzymes significant surface
that catalyze hydrogen area to collect
formation are absent. sufficient light and no
waste utilization.
Dark Dark fermentation uses Organic 60-80 2.57 CO2-neutral, Fatty acids removal,
fermentation primarily anaerobic bacteria on Biomass simple, can low H2 rates and
carbohydrate rich substrates produce H2 yields, low conversion
under anoxic (no oxygen without light, efficiency,
present), dark conditions. contributes to requirement of large
waste recycling. reactor volume
Photo- Photo-fermentation is realized Organic 0,1 CO2-neutral, Requires sunlight, low
fermentation in deficient nitrogen conditions Biomass contributes to H2 rates and yields,
using solar energy and organic waste recycling, low conversion
acids. Due to the presence of can use different efficiency,
nitrogenase, some organic wastes requirement of large
photosynthetic bacteria are and wastewaters reactor volume, O2
capable of converting the sensitivity.
organic acids (acetic, lactic and
butyric) into hydrogen and
carbon dioxide.
Alkaline Alkaline electrolysis is a mature Water 40-60 Nuclear (97% No pollution with Low overall efficiency,
electrolysis and commercial technology. capacity)- 4,15 renewable high capital costs
Alkaline electrolysis is Solar thermal (40% sources, proven
characterised by relatively low capacity)- 7 technology,
capital costs compared to other Solar PV (28% existing
electrolyser technologies due to capacity)- 10,49 (3) infrastructure,
the avoidance of precious Wind (65% capacity)- abundant
Electrolysis

materials. The energy 6,46 (3) feedstock, O2 is

consumption for converting the only
electricity to hydrogen varies byproduct,
between electrolyser contributes to
technologies and is subject to RES integration
continuous improvement. as an electricity
Alkaline electrolysers consume storage option.
50–51 kWh/kg, proton
exchange membrane (PEM)
electrolysers 55–58 kWh/kg,
and solid oxide electrolysis
(SOE) 40–41 kWh/kg3, with a
downward trend
 PEM They are able to produce highly Water
electrolysers compressed hydrogen for
decentralised production and
storage at refuelling stations
(30–60 bar without an
additional compressor and up
to 100–200 bar in some
systems, compared to 1–30 bar
for alkaline electrolysers) and
offer flexible operation,
including the capability to
provide frequency reserve and
other grid services. Their
operating range can go from
zero load to 160% of design
capacity (so it is possible to
overload the electrolyser for
some time, if the plant and
power electronics have been
designed accordingly).
SOEC SOECs are the least developed Water
electrolysis technology. They
have not yet been
commercialised, although
individual companies are now
aiming to bring them to market.
They operate at high
temperatures and with a high
degree of electrical efficiency.
Because they use steam for
electrolysis, they need a heat
sources. Nuclear power plants,
solar thermal or geothermal
heat systems could also be
heat sources for high-
temperature electrolysis. Unlike
alkaline and PEM electrolysers,
it is possible to operate an
SOEC electrolyser in reverse
mode as a fuel cell, converting
hydrogen back into electricity,
which means it could provide
balancing services to the grid in
combination with hydrogen
storage facilities. This would
increase the overall utilisation
rate of the equipment. One key
challenge for those developing
 SOEC electrolysers is
addressing the degradation of
materials that results from the
high operating temperatures.

Thermolysis Thermolysis or thermochemical Water 20–45 Nuclear– 2,45-2,63 Nuclear– 39,6–2107,6 (4) Clean and Elements toxicity,
water splitting is the process at Solar- 7,98-8,40 Solar- 5.7–16 (5) sustainable, corrosive problems,
which water is heated to a high abundant high capital costs
temperature until decomposed feedstock, O2 is
to hydrogen and oxygen. The the only
still high temperature required byproduct.
can be supplied by solar heat or
nuclear energy, with the
interest be focused to the
progress on solar collectors
Photo-electrolysis Photolysis, in general, is Water 0.06 10.36 Emission-free, Requires sunlight, low
effected when the energy of abundant conversion efficiency,
visible light is absorbed with the feedstock, O2 is non-effective
help of some photo-catalysts the only photocatalytic materia
and is then utilized to byproduct.
decompose water into H2 and
O2 [28]. In photo-electrolysis,
the sunlight is absorbed
through some semiconducting
materials and the process of
water splitting is similar to
electrolysis.

1. Based on a 600 MWH2 power plant with a capital cost of 306.35 $/kWH2.
2. The capital cost of 149.3 M$ corresponds to a plant capacity of 139.7 tn/day, 6.4 M$ is referred to a 2tn/day plant output.
3. Based on electrolyzer cost of 500 $/kW.
4. The capital cost of 39,6 M$ corresponds to a Cu-Cl plant capacity of 7 tn/day, 2107,6 M$ is referred to a 583 tn/day S-I plant output
5. The capital cost of 5.7 M$ corresponds to a plant capacity of 1.2 tn/day, 16 M$ is referred to a 6 tn/day plant output.
Appendix (Electrolizers)