Hydrogendecarbonization
pathways
Introduction to the two reports: “Hydrogen
Decarbonization Pathways: A Life-Cycle
Assessment” and “Hydrogen Decarbonization
Pathways: Potential Supply Scenarios”
January 2021

Hydrogen momentum is accelerating further
In the studies “Hydrogen, Scaling Up” (2017) and “Path to Hydrogen Competitiveness: A Cost
Perspective” (2020), the Hydrogen Council has laid out a cross-industry plan for a step-change
in hydrogen deployment globally. They showed that hydrogen can play an important role in thedecarbonized energy system, and that hydrogen can be a cost-competitive decarbonized solution ina large number of applications before 2030.
Since then, hydrogen has built unprecedented momentum. Large-scale projects have beenannounced, companies have undertaken strategic moves across the value chain, and there are
increasing M&A and investment activities in the sector. In parallel, governments are committing tohydrogen as a part of their climate change strategies, with some deploying significant funds, policies,and regulatory support through newly launched hydrogen strategies and funding programs in thecontext of Covid-19 economic recovery packages.

Life-cycle emissions are coming into focus
Given that hydrogen is one of the keys to the energy transition, it is not only important to make it
economically viable, but also to maximize the decarbonization impact and minimize its resource
requirements. The European hydrogen strategy and the targets of many EU member states, among
others, are geared to place most of their support on renewable hydrogen production. Countries
such as China, Korea, Japan, as well as regions of the United States are increasingly introducing
support for low-carbon hydrogen routes. Countries with abundant renewable and/or fossil and CCSpotential are looking to optimize the value of these attributes in destination markets. In all cases,
the decarbonization potential of hydrogen is critical. An evaluation of the carbon-saving potential ofhydrogen over the life-cycle is therefore an important piece of the Hydrogen Council’s perspective.
Hydrogen supply pathways
In the study “Hydrogen Decarbonization Pathways – A Life-Cycle Assessment” different sustainability
aspects have been assessed for hydrogen production and supply.
— As an energy source for hydrogen production, both renewable power for water electrolysis andnatural gas with very high shares of CCS can achieve marginal to low greenhouse gas (GHG)
emissions, respectively, when considered well to use, including end-of-life emissions. For fossil
primary energies with CCS, a number of requirements must be met, namely sweet natural gas
sources1, highest capture rates2, and best available technologies and operational practices.
— Biogenic feedstock for hydrogen production can result in a wide range of GHG emissions.
While energy crops are between natural gas-based and renewable electricity-based pathways,
GHG emissions from biogenic wastes can be as low as the best renewable power-to-hydrogen
pathways (or even negative in case of bio + CCS) but with waste streams somewhat limited atglobal scale.
— In this study, capex-related emissions of energy production assets and a number of hydrogen
applications have been calculated where data was available (generally weak) based on a global
average electricity mix with a decreasing carbon intensity towards 2050.

1

Reserves providing a high-quality natural gas with low-carbon footprint for its production.

2

98% carbon capture assumed in this study.

2

Hydrogen decarbonization pathways
Introduction

— Capex-related GHG emissions for the manufacturing of assets are low across the board forhydrogen supply options compared to the carbon intensity of incumbent fossil pathways, andhave been calculated based on global average carbon intensities for energies used in plant andasset manufacturing. Some manufacturers already today excel with below-average emissions
by using renewable and low-carbon energy sources.
— GHG emissions of renewable power-to-hydrogen pathways are dominated by capex-related
emissions, albeit at very low levels compared to fossil incumbents and alternatives.
— The impact of selected metal recycling on the GHG emissions balance well to use is somewhat
limited. GHG reductions from recycling of selected metals is most pronounced with solar and wind
power pathways, where recycling tends to yield GHG savings of about 30% for the manufacturing ofphotovoltaic plants and 40% for wind power plants in 2030 versus using virgin material). Recycling
is of wider strategic relevance for deep decarbonization in the context of a circular economy.
— With a view to sustainability aspects other than GHG emissions, specific gross water demandhas been assessed for hydrogen supply pathways.
— Gross water demand is most pronounced in biomass cultivation and cooling of thermal power
plants; hence, the focus should be on biogenic waste streams and dry-cooling systems inregions prone to water supply stress or already under supply risk.
— Gross water demand for water electrolysis using PV and wind power is very low with 9 kg ofwater per kg of hydrogen; SMR/ATR are in the same order of magnitude. Plants at gigawattscale nevertheless can be a significant point-demand for water especially in arid regions. Sitespecific water supply and demand assessments are regular tasks in environmental impact
assessments prior to plant approvals. For large plants in dry regions, seawater desalination withadequate effluent management is an option. Water desalination for Power-to-X plants requires
marginal additional energy.
Eight illustrative hydrogen value chains
The LCA analysis has not been limited to hydrogen supply routes alone, but addresses every
aspect of the supply chain, from primary energy extraction to end use. For illustrative purposes,
eight primary-energy-to-hydrogen value chains have been selected, and GHG emissions for 2030
and 2050 were calculated, including capex-related GHG emissions, where possible. Thereof, four
pathways describe mobility and industry applications each. Half of the eight illustrative pathways
comprise green value chains, and the other half represent blue hydrogen value chains. Across thehydrogen pathways and applications depicted, very high (around 90%+) to high (around 60%+)
GHG emission reduction can be demonstrated using green (solar, wind) and blue (ATR + 98% CCS)
hydrogen, respectively. Further GHG emission reductions observed from 2030 to 2050 are driven bya strongly improving global grid mix assumed for achieving Paris Agreement targets.
LCA results in context
In the LCA study, renewables + electrolysis shows strongest GHG reduction of the different hydrogen
supply pathways assessed in this study, with a best-case blue hydrogen pathway also coming into
the same order of magnitude. The blue options considered in this study show a noticeable but wide

Hydrogen decarbonization pathways
Introduction3range of GHG reduction versus incumbent (grey) hydrogen production. Renewables + electrolysis
and reforming + CCS pathways do come with different risks. Though they have not been analyzed
in the study, we note that there are discussions related to long-term carbon storage and technology
path dependencies, potentially impacting post-2050 emission-reduction trajectories, especially as
energy infrastructure assets typically show investment cycles in the range of 30 to 40 years or evenlonger. Policymakers are thus encouraged to develop clear, long-term frameworks that enable anddrive efficient investments to develop and deploy, in a quick and economically efficient manner, themost relevant deep-decarbonization options.

Hydrogen supply can and must be decarbonizedCurrently, the vast majority of hydrogen is produced by fossil pathways. To take the role in theenergy transition that the Hydrogen Council envisaged in its “Scaling Up” report, the existing use ofhydrogen – and all its many potential new roles – need to be met by decarbonized sources. Basedon the results of life-cycle emissions of various hydrogen production pathways, the Council therefore
assessed what fully decarbonized hydrogen supply would entail.
The study “Hydrogen Decarbonization Pathways – Potential Supply Scenarios” lays out different
supply scenarios that can achieve the ambitious ten-fold build-out of hydrogen supply by 2050
(outlined in the “Scaling Up” report) with decarbonized hydrogen sources – starting with an ambitious
near-term phase-out of conventional “grey” hydrogen to already decarbonize more than half of thehydrogen supply by 2030.
We consider three hypothetical scenarios as thought experiments on ways to decarbonize thesupply: a “green-only,” renewables-based world, a “blue-only” world relying on carbon sequestration,
and a combined scenario that uses a region-specific combination of green and blue hydrogen basedon the expected regional cost development of each source.
The first finding is that a decarbonized hydrogen supply is possible regardless of the production
pathway: while both the green and blue boundary scenario would be highly ambitious regarding therequired speed of scale-up, they do not exceed the world’s resources on either renewable energy
or carbon sequestration capabilities. The renewable energy resources required to provide 78 EJ
of green hydrogen would be equivalent to solar panels covering the area of Italy and wind turbinescovering almost half of China’s coastal waters – however, that is still less than 10% of the estimatedaccessible global renewables potential. In the “blue world”, carbon sequestration capacities would
need to be built out to 50 Gt by 2050 – a huge scale-up compared to today (and one that is not
currently compatible with regulations in many regions), but less than 0.2% of estimated geologicalstorage reserves. While both boundary scenarios would drastically reduce emissions compared tocurrent “grey” hydrogen supply pathways, overall emissions would be even lower in the “green world”(approximately 10 Gt of CO2 from 2020 to 2050, 8 Gt of which generated during the phase-out ofgrey hydrogen) than the “blue world” (20 to 25 Gt of CO2 over the same time period)3.
While both boundary scenarios are theoretically feasible, a combination of green and blue production
pathways appears to result in the least-cost global supply over the entire period of scale-up. It doesso by making best use of the near-term cost advantage of blue in some regions while simultaneously
achieving a scale-up in electrolysis. This allows to achieve very low-cost green hydrogen in the34

The blue world assumes a region-specific natural gas and coal supply and a mix of SMR and ATR technologies with carbon
capture rates between 90% and 98%. For comparison: Meeting the same hydrogen demand with grey hydrogen would
generate approximately 65 Gt of emissions, compared to a remaining carbon budget of 235-985 Gt CO2 until 2050 to stay within
the 1.5°C-2°C global warming pathway.

Hydrogen decarbonization pathways
Introduction

medium and long term. A combined scenario also makes best use of complementary global
resources: each region can follow a different build-out path and trade with other energy-rich regions,if advantageous. While the required build-out rates for electrolyzers and reformers (and hence thedevelopment of the required supply chains) still exceed 30% per year, this does not exceed the speedof build-out that has proven feasible in the solar and wind industry over the last decade. Cumulative
CO2 emissions from hydrogen would lie between the green- and blue-only boundary cases, making
a major contribution to the decarbonization of the global energy system (but not fully maximizing thedecarbonization promise of green hydrogen).
In reality, the decarbonized supply scenario will combine a range of different renewable andlow-carbon hydrogen production pathways that are optimally suited to local conditions, politicaland societal preferences and regulations, as well as industrial and cost developments fordifferent technologies. While a decarbonized hydrogen build-out is ambitious in any scenario, it isachievable both in the short and long term and is a prerequisite for growing hydrogen’s role in theenergy system.

Hydrogen decarbonization pathways
Introduction

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