The Hydrological and Systemic Implications of a Global Green Hydrogen Economy

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1. Introduction and Macro-Energy Context

The transition toward a fully decarbonized global energy system necessitates the deployment of energy carriers capable of displacing fossil fuels in hard-to-abate sectors, including heavy-duty transportation, maritime shipping, aviation, and high-heat industrial processes. Green hydrogen, produced via the electrolysis of water powered by renewable electricity, has emerged as a central pillar of this transition. However, the premise of mass water hydrolysis has raised persistent concerns regarding the potential strain on the planet’s freshwater supplies, the timeline and threshold for adverse hydrological effects, and the broader systemic side effects of adopting water electrolysis at a planetary scale. To evaluate these impacts, it is first necessary to establish the scale of "mass adoption." Global energy consumption is projected to peak at approximately 677 exajoules (EJ) by 2040, driven by population growth and rising per capita energy consumption in developing regions, before plateauing or slightly declining toward 20501. Simultaneously, global electricity generation is expected to nearly double, rising from roughly 26,800 terawatt-hours (TWh) in 2020 to over 50,000 TWh in 2050 under ambitious climate scenarios3. Within this rapidly expanding electrical ecosystem, the demand for clean hydrogen is forecasted to grow exponentially. The Hydrogen Council projects a global demand of 660 million metric tons (MMT) of clean hydrogen annually by 20504. More extreme models, which envision a near-total displacement of fossil fuels across all end-use sectors, including chemical synthesis and energy storage, forecast a theoretical maximum hydrogen demand of up to 2.3 gigatons (Gt) per year6. This report provides an exhaustive analysis of the hydrological, environmental, and systemic side effects of meeting this immense demand through water electrolysis. By evaluating the thermodynamic limits of hydrogen production, global and localized hydrological budgets, and comparative life-cycle water footprints, this analysis determines the precise impact of a hydrogen economy on global water resources. Furthermore, the report explores the critical secondary side effects of mass adoption, including the management of desalination brine, the impact of localized water vapor emissions from automobile fuel cells, the global warming potential of hydrogen leakage, and the severe material supply chain constraints threatening the physical scale-up of electrolyzer manufacturing.

2. The Thermodynamics and Hydrology of Water Electrolysis

Assessing the impact of mass hydrogen production on global water resources requires establishing the absolute thermodynamic and operational water requirements of the electrolysis process.

2.1 Stoichiometric Fundamentals and Balance of Plant

Green hydrogen is produced by splitting water ([Figure omitted from source export]) into hydrogen ([Figure omitted from source export]) and oxygen ([Figure omitted from source export]) using a direct electric current. The fundamental chemical reaction dictates a fixed stoichiometric requirement based on the molar masses of hydrogen and water. [Figure omitted from source export] Under perfect conditions, producing exactly 1 kilogram of hydrogen requires the consumption of 9 kilograms (or 9 liters) of water4. However, commercial electrolyzer plants cannot operate on raw water; they require highly purified, demineralized feedwater to prevent the rapid degradation and fouling of catalytic membranes. The "balance of plant" (BOP) requirements encompasses this raw water purification process, as well as the water utilized for process cooling and periodic system cleaning. When factoring in the reject rates of standard demineralization arrays and the evaporative losses from cooling towers, a modern commercial electrolysis facility requires a gross water withdrawal of 20 to 30 liters of water per kilogram of hydrogen ([Figure omitted from source export])4.

2.2 Comparative Water Intensity of Hydrogen Production Pathways

The operational water consumption of 20–30 [Figure omitted from source export] for green hydrogen must be contextualized against alternative hydrogen production methods and the existing fossil fuel infrastructure it intends to replace.

When accounting for the full life-cycle, fossil-based hydrogen pathways demand significantly more water than green hydrogen. This is largely due to the substantial upstream water consumption required for natural gas drilling, hydraulic fracturing, and raw material processing, which can add over 5 liters of water per kilogram of hydrogen produced5. Waste-to-hydrogen (W2H) gasification presents a highly water-compatible alternative for extremely arid regions, requiring only 10 [Figure omitted from source export], but it currently lacks the scalability of electrolysis8. Viewed through a comprehensive life-cycle lens, water electrolysis powered by wind and solar energy is the most water-efficient pathway for mass hydrogen production.

3. Global Water Supply Impact Assessment

The core apprehension regarding the mass adoption of water hydrolysis is the assumption that it will systematically deplete the planet's freshwater reserves. Analyzing forecasted hydrogen demand against global hydrological data reveals that this fear is mathematically unfounded at a macro scale.

3.1 Projections of Global Water Demand for Electrolysis

To determine the severity and timeline of any adverse effects, the projected water demand of the hydrogen economy must be quantified. Assuming the higher end of operational water intensity (30 [Figure omitted from source export]), producing the 660 MMT of hydrogen forecasted by the Hydrogen Council for 2050 would require approximately 19.8 billion cubic meters ([Figure omitted from source export]) of water annually5. In the most extreme hypothetical scenario, where the global economy completely shifts to a 2.3 Gt per year hydrogen demand, the stoichiometric consumption alone would require 20.5 billion [Figure omitted from source export] of freshwater, with total practical withdrawals reaching up to 69 billion [Figure omitted from source export] annually6. The Earth's total water volume is approximately 1.39 billion cubic kilometers, though only about 2.5% to 3% of this is freshwater, and a fraction of that is accessible in lakes, rivers, and shallow aquifers10. Currently, human civilization withdraws approximately 4 trillion cubic meters of freshwater annually across all sectors5. Meeting the baseline 660 MMT hydrogen demand would account for roughly 0.33% to 0.5% of current global freshwater usage4. Even under the extreme 2.3 Gt scenario, the water required for global electrolysis accounts for only 1.5 parts per million (ppm) of the Earth's total available freshwater6. By comparison, the global irrigated agricultural sector is responsible for over 70% of total freshwater withdrawals, consuming over 2,700 billion [Figure omitted from source export] annually6. The water required to support an entire planetary green hydrogen economy is substantially less than the water used globally to irrigate golf courses or sustain minor agricultural sub-sectors5. Therefore, at a planetary scale, the mass adoption of water hydrolysis will never trigger a global water shortage, nor will it have a globally adverse effect on planetary water volumes over any time horizon.

3.2 The Net-Positive Water Effect of Fossil Fuel Displacement

A critical second-order insight is that green hydrogen does not simply add a new layer of water demand to the global economy; it actively displaces the highly water-intensive fossil fuel industry. The extraction, refining, and combustion of fossil fuels require immense volumes of freshwater. Petroleum refining requires between 1 and 2.5 gallons of water per gallon of refined product, and upstream extraction (including hydraulic fracturing) consumes billions of additional gallons annually12. Extensive life-cycle analyses demonstrate that producing conventional gasoline withdraws approximately 13 liters of water per liter of fuel14. Biofuels present an even more severe hydrological burden; producing a single gallon of corn ethanol in the United States requires an average of 992 gallons of freshwater when factoring in crop irrigation15. Furthermore, conventional thermoelectric power generation relies heavily on water cooling. Coal-fired power stations typically evaporate 1.9 liters of water for every kilowatt-hour (kWh) of electricity generated4. When analyzing end-use transportation efficiency, the hydrological disparities become stark. An average residential bathtub holds approximately 300 liters of water. Allocating this 300 liters to the production of green hydrogen yields enough fuel to drive a heavy-duty fuel cell truck 235 kilometers. Conversely, allocating that same 300 liters of water to the extraction, refining, and cooling processes required for petroleum would only yield enough diesel to drive the same truck 141 kilometers, owing to the inherent inefficiency of internal combustion engines and the heavy water footprint of crude oil refinement5. In 2014, the fossil fuel energy production and power generation sector withdrew 251 billion [Figure omitted from source export] of freshwater and consumed 31 billion [Figure omitted from source export] directly for cooling, mining, fracking, and refining6. By transitioning from fossil fuels to wind and solar-powered electrolysis, the global economy will decommission these highly water-intensive operations. The 20.5 billion [Figure omitted from source export] required for a future global green hydrogen economy is 33% less than the water currently consumed by fossil fuel energy-related operations6. Consequently, the mass adoption of green hydrogen is projected to result in massive systemic water savings, driving a net reduction in global industrial water withdrawals.

4. Localized Vulnerabilities and the Temporal Horizon for Adverse Effects

While global arithmetic proves that hydrogen will not drain the planet's aggregate water supply, water availability is inherently a localized phenomenon. The most significant challenge for the hydrogen economy is a geographical mismatch: the regions with the most abundant, low-cost renewable energy potential (solar and wind) are frequently located in the world's most arid environments.

4.1 The Conflict of Geography and Aquifer Depletion

Nations poised to become green hydrogen export superpowers—such as Australia, Chile, Namibia, and the Gulf Cooperation Council (GCC) states—face severe freshwater scarcity7. In the Middle East and North Africa, per capita renewable freshwater resources are among the lowest globally, and existing economies already depend critically on energy-intensive desalination for municipal needs7. If hydrogen developers in these arid regions attempt to source water from local freshwater aquifers or constrained river systems, the time horizon for adverse effects would not be measured in decades, but in years. Gigawatt-scale industrial withdrawals would immediately outpace the natural recharge rates of local hydrological cycles. The adverse effects would include rapid aquifer depletion, severe land subsidence, saltwater intrusion into coastal groundwater, and direct competition with agricultural and municipal drinking supplies, leading to profound socioeconomic conflict7. For example, in Utah, the Advanced Clean Energy Storage (ACES) project will produce 100 tons per day of clean hydrogen using 220 megawatts of electrolyzers. This facility will require 730,000 [Figure omitted from source export] of water per year. While this represents only 0.012% of Utah's current yearly water usage, placing multiple such facilities in highly water-stressed regions without diversifying raw water sources would rapidly strain local ecosystems5.

4.2 Seawater Reverse Osmosis (SWRO) as the Default Solution

To bypass these immediate local constraints, the hydrogen industry must rely on the Earth's oceans, which contain 96.5% of the planet's total water volume6. The integration of Seawater Reverse Osmosis (SWRO) desalination plants into hydrogen facilities provides an essentially infinite feedstock, fully decoupling the hydrogen economy from the terrestrial freshwater cycle. Historically, desalination was viewed as prohibitively energy-intensive and expensive. However, modern SWRO technology has achieved significant efficiency gains that make it highly compatible with electrolysis.

• Energy Penalty: State-of-the-art SWRO plants consume just 2.5 to 3.5 kWh of electricity per cubic meter ([Figure omitted from source export]) of purified water produced4. Producing 1 kg of hydrogen requires approximately 50 to 65 kWh of electricity for the electrolysis process itself9. Therefore, the energy required to desalinate the feedwater adds less than 1% to the electrolyzer's total energy demand4.
• Economic Penalty: Assuming renewable electricity costs of $0.13 per kWh, desalinating one cubic meter of seawater costs approximately $0.454. Because it takes roughly 0.02 to 0.03 [Figure omitted from source export] of water to produce a kilogram of hydrogen, desalination adds under one U.S. cent (or roughly 0.7%) to the target production cost of a kilogram of green hydrogen4.

Because the economic and energetic penalties of desalination are negligible, dedicated SWRO plants are positioned as the standard design configuration for coastal gigawatt-scale hydrogen hubs. Massive projects, such as the NEOM facility in Saudi Arabia and Hyphen Energy’s planned three-gigawatt electrolyzer near Lüderitz in Namibia, are actively deploying this integrated model4. In Namibia, the desalination capacity built for hydrogen production is designed to be oversized, allowing excess clean water to be piped to local municipalities, thereby turning a potential resource drain into a net benefit for the region4.

5. Secondary Side Effect I: Brine Management and Marine Ecosystems

The reliance on seawater desalination to feed the global hydrogen economy introduces the first major adverse side effect of mass adoption: the continuous generation and disposal of hypersaline brine.

5.1 The Environmental Threat of Brine Discharge

Reverse osmosis plants typically operate at a 50% recovery rate, meaning that for every two liters of seawater withdrawn, one liter of clean water is produced for the electrolyzer, and one liter is rejected back into the environment as highly concentrated brine6. This brine contains not only elevated salt concentrations—often double the salinity of natural seawater—but also residual anti-scalants, coagulants, heavy metals, and cleaning chemicals utilized in the desalination infrastructure16. If gigawatt-scale hydrogen facilities rely on conventional marine outfall pipes to dispose of this waste, the ecological impact on marine environments could be severe. Because brine is denser than standard seawater, it sinks to the ocean floor upon discharge, forming toxic, low-oxygen (hypoxic) plumes17. These highly concentrated plumes disrupt benthic ecosystems, causing osmotic stress and mortality in seagrass beds, coral reefs, and localized marine food webs16. In geographically constrained bodies of water with low natural tidal dilution—such as the Arabian Gulf, the Red Sea, or the Mediterranean Sea—the cumulative, decades-long discharge from multiple hydrogen mega-projects could permanently alter regional marine salinity and severely degrade biodiversity16.

5.2 Brine Mining and Zero Liquid Discharge (ZLD)

To mitigate this severe marine side effect, the hydrogen industry is accelerating the integration of "brine mining" and Zero Liquid Discharge (ZLD) technologies. Rather than treating brine as a hazardous waste stream necessitating dilution, these advanced thermodynamic processes view brine as a highly concentrated liquid ore17. Desalination brine contains vast quantities of valuable minerals. It is estimated that global desalination brine streams contain billions of dollars worth of magnesium, calcium, potassium, and critically, lithium and rare earth elements17. Advanced nanofiltration systems, bipolar membrane electrodialysis, membrane crystallization, and selective adsorption technologies are being deployed to extract these vital minerals before any liquid is discharged17. A profound systemic synergy emerges from this technology: the mass adoption of water hydrolysis for power and transportation will necessitate massive battery storage architectures and electric vehicle manufacturing, both of which require immense volumes of lithium and rare earth metals. By implementing ZLD and brine mining, the hydrogen economy can simultaneously eliminate marine pollution and domesticate a secure, circular supply chain for the critical minerals required for the broader energy transition17.

6. Secondary Side Effect II: Automobile Fuel Cells and the Hydrological Cycle

A persistent question regarding the mass adoption of hydrogen as an automobile fuel is the fate of the water once the fuel is consumed. Fuel cell electric vehicles (FCEVs) generate electricity through an electrochemical reaction between stored hydrogen gas and atmospheric oxygen, bypassing the inefficiency of combustion. The only byproducts of this reaction are electrical current, warm air, and pure water vapor21.

6.1 Impact on the Global Water Cycle

At a planetary scale, the mass emission of water vapor from millions of hydrogen fuel cells has zero adverse effect on the global hydrological cycle25. The Earth's water cycle is a massive biogeochemical system driven by immense solar energy inputs and latent heat transfers10. The global ocean evaporates roughly 86% of all atmospheric moisture, dwarfing any anthropogenic vapor emissions10. More importantly, the hydrogen economy operates as a closed-loop hydrological system. The liquid water consumed during the initial electrolysis process is temporarily stored as chemical energy in the form of hydrogen gas. When that hydrogen is later run through a fuel cell on a highway, the exact stoichiometric volume of water originally split at the power plant is returned to the atmosphere as vapor6. Hydrogen energy is essentially a thermodynamic mechanism for shifting water geographically and temporally; it does not create or destroy water mass. In fact, if the vapor emitted by FCEVs or stationary fuel cells is condensed, it can be entirely recuperated and recycled back into the electrolysis process, further closing the loop4.

6.2 Urban Microclimates and Public Health

A highly localized side effect arises when assessing dense urban environments where millions of FCEVs might operate simultaneously. Because water vapor is a potent greenhouse gas that traps latent heat, concerns have been raised regarding whether urban tailpipe emissions could alter local relative humidity, exacerbate urban heat island effects, or increase the frequency of localized fog events30. Extensive atmospheric modeling indicates that converting an entire national vehicle fleet to hydrogen fuel cells would hardly affect tropospheric water vapor concentrations, even in densely populated metropolitan zones25. The physical amount of water emitted per mile by a hydrogen fuel cell vehicle is roughly equivalent to the volume of water vapor already emitted by a conventional internal combustion engine (ICE) combusting gasoline31. The combustion of hydrocarbon fuels naturally yields a molar ratio of [Figure omitted from source export] to [Figure omitted from source export] of approximately 0.93, meaning modern cities are already acclimated to massive vehicular water vapor fluxes31. The primary side effect of mass FCEV adoption in urban centers is overwhelmingly positive: the total elimination of toxic tailpipe emissions. Replacing ICE vehicles with FCEVs removes the chemical precursors to urban smog, ground-level ozone, and acid rain. Epidemiological modeling suggests that a full transition to hydrogen vehicles in a nation like the United States would save between 3,700 and 6,400 lives annually by preventing respiratory and cardiovascular diseases caused by particulate matter and localized nitrogen oxide (NOx) pollution25.

7. Secondary Side Effect III: The Global Warming Potential of Hydrogen Leakage

While hydrogen combustion and fuel cell utilization produce zero carbon dioxide, the mass adoption of hydrogen introduces a highly complex, invisible side effect: the climate impact of fugitive hydrogen emissions. As a molecule, hydrogen is the smallest and lightest element in the universe, making it notoriously difficult to contain. Throughout the production, compression, transportation, and storage lifecycle, trace amounts of hydrogen gas will inevitably leak into the atmosphere28. While hydrogen itself does not absorb infrared radiation and is not a direct greenhouse gas, there is a strong and growing scientific consensus that it acts as a potent indirect greenhouse gas in the troposphere33. When fugitive hydrogen leaks into the atmosphere, it reacts with hydroxyl radicals (OH). Hydroxyl radicals act as the atmosphere's primary "detergent," responsible for breaking down atmospheric methane ([Figure omitted from source export]), a highly potent greenhouse gas33. Because hydrogen readily consumes these hydroxyl radicals, it effectively extends the atmospheric lifetime of methane. Furthermore, the oxidation of leaked hydrogen in the troposphere leads to the formation of ground-level ozone and increases stratospheric water vapor, both of which exert a warming effect on the climate34. Recent scientific assessments evaluate hydrogen's Global Warming Potential (GWP) as significantly higher than previously understood. Studies estimate the GWP of hydrogen to be 11 ± 5 over a 100-year time horizon (GWP100) and 33 ± 13 over a 20-year time horizon (GWP20)34. The uncertainty in these figures is primarily attributed to the variable rate at which hydrogen is naturally removed from the atmosphere by microbial activity in soils34. This high GWP represents a critical systemic vulnerability. If the global hydrogen infrastructure—pipelines, liquefaction plants, and vehicle fueling stations—suffers from high leakage rates, the indirect warming effect of the fugitive hydrogen could offset a significant portion of the climate benefits gained by displacing fossil fuels. The European Commission and the Joint Research Centre (JRC) have identified this regulatory gap as an immediate risk to achieving climate objectives, necessitating the rapid development of stringent leakage monitoring technologies and maximum allowable leakage rates in upcoming legislative initiatives33.

8. Secondary Side Effect IV: The Iridium Supply Bottleneck

While water constraints are technologically solvable via desalination, a much more severe and immediate side effect of scaling water hydrolysis is the immense stress placed on critical mineral supply chains. The most profound bottleneck to the global green hydrogen economy is the extreme physical scarcity of platinum group metals (PGMs), specifically iridium.

8.1 The Chemistry and Constraints of PEM Electrolysis

Proton Exchange Membrane (PEM) electrolyzers are currently the preferred technology for coupling with renewable energy. They offer rapid response times, a compact physical footprint, and the unique ability to handle the intermittent voltage fluctuations inherent to solar and wind power35. However, the internal operating environment of a PEM electrolyzer is highly acidic and operates under severe oxidative stress38. At the anode, where the oxygen evolution reaction (OER) occurs, the only known materials capable of withstanding this corrosive environment while maintaining high catalytic activity are iridium and its oxides (e.g., [Figure omitted from source export])38. At the cathode, platinum is utilized to drive the hydrogen evolution reaction (HER)38.

8.2 The Iridium Deficit

Iridium is one of the rarest elements in the Earth's crust. It is not mined independently; rather, it is recovered exclusively as a minor byproduct of platinum and palladium extraction, overwhelmingly concentrated in South Africa's Bushveld Igneous Complex39. Global annual production of iridium is strictly limited to approximately 7 to 9 metric tons38. Because it is a byproduct of a chemically intensive and highly energy-demanding refining process, the iridium supply is structurally inelastic. Mining conglomerates cannot simply "ramp up" iridium production in response to hydrogen demand without simultaneously flooding the market with massive, uneconomical quantities of excess platinum40. Under standard conventional manufacturing practices, PEM electrolyzers require 1 to 2 milligrams of iridium per square centimeter ([Figure omitted from source export]) of catalyst-coated membrane36. At this standard loading rate, manufacturing just one gigawatt (GW) of PEM electrolyzer capacity requires roughly 400 to 700 kilograms of iridium37. If the global hydrogen economy requires scaling up to the thousands of gigawatts of capacity dictated by 2050 climate models (ranging from 1,400 GW to over 7,800 GW globally), current iridium loading rates would physically consume the entire global supply many times over, effectively halting the energy transition in its tracks37. The International Energy Agency (IEA) has explicitly identified this supply bottleneck as one of the most critical barriers to scaling green hydrogen42.

8.3 Technological Mitigation and Material Substitution

To prevent a total supply chain collapse, the industry must develop and commercialize extreme loading reduction technologies. Materials science breakthroughs involving single-atom catalysts, nanostructured porous supports, and ruthenium-iridium mixed oxides are currently attempting to drop iridium requirements by 90% to 95%, targeting a threshold of \<0.1 [Figure omitted from source export]38. By replacing pure iridium with ruthenium-iridium oxide compounds, manufacturers can maintain catalytic stability in acidic environments while reducing precious metal costs by up to 80%39. If these sub-milligram loading innovations fail to reach commercial scale, the industry will be forced to pivot away from PEM technology, heavily favoring Alkaline water electrolysis. Alkaline systems utilize a liquid electrolyte and rely on highly abundant, inexpensive catalysts like nickel and iron (requiring roughly 800 tons of nickel per GW)37. While alkaline systems brilliantly circumvent the iridium bottleneck, they present their own side effects: they are traditionally less responsive to the rapid fluctuations of intermittent renewables and require a significantly larger physical footprint, necessitating compromises in systemic grid design and land use38.

9. Secondary Side Effect V: Macro-Energy Infrastructure Demands

The final major systemic side effect of mass water hydrolysis is the staggering volume of new electrical generation infrastructure required to power the transition. Water is an inherently stable molecule; breaking the covalent atomic bonds between hydrogen and oxygen requires an immense input of electrical energy. Producing just 1 kilogram of hydrogen via electrolysis requires between 50 and 65 kWh of electricity9. If global demand reaches the extreme scenario of 2.3 Gt of hydrogen per year to completely supplant fossil fuels, the energy required strictly to power the electrolyzers would equal approximately 126,500 terawatt-hours (TWh)9. To contextualize this figure, the total global electricity generation across all sources (coal, gas, nuclear, and renewables) in 2022 was roughly 29,000 TWh9. Therefore, a mass transition to green hydrogen for global fuel and power would require building a clean electrical grid roughly four to five times larger than the entire existing planetary infrastructure9. The true environmental and physical impacts of the hydrogen economy will not stem from the depletion of water resources. Rather, the impact will manifest in the unprecedented wave of land-use changes, the massive mining operations required for copper and aluminum transmission lines, and the industrial manufacturing of millions of solar panels and wind turbines required to generate hundreds of thousands of terawatt-hours of new, zero-carbon electricity.

10. Conclusion

The widespread apprehension that a global green hydrogen economy will deplete the planet's water supply represents a fundamental misunderstanding of hydrological scale. Even under the most aggressive transition models envisioning total global decarbonization, mass water hydrolysis will consume less than 1.5 parts per million of the Earth's available freshwater, an amount vastly overshadowed by global agricultural demands and legacy fossil fuel water withdrawals. Because green hydrogen will precipitate the decommissioning of highly water-intensive petroleum extraction, refinery operations, and thermoelectric cooling towers, the ultimate macro-level effect will be a massive net conservation of global water resources. However, the localized constraints and systemic side effects of mass hydrolysis are highly complex and dictate stringent engineering pathways. The primary side effects and required mitigations include:

Ultimately, water is not a fatal flaw for the hydrogen economy; it is a design parameter. The success of the transition relies not on protecting the global water volume—which remains perfectly conserved in the atmospheric cycle via fuel cell tailpipe emissions—but on successfully navigating the vast industrial side effects. Decoupling electrolyzer supply chains from rare earth bottlenecks, safeguarding marine ecology from desalination waste, preventing fugitive gas emissions, and financing the greatest expansion of electrical infrastructure in human history remain the true hurdles to a hydrogen-powered planet.

Works cited

1. Growth no more stagnation. Time for joint decision-making \- Yakov and Partners, https://yakovpartners.com/publications/energy-balance-2050/

2. Energy forecast by the middle of the century | Avenston, https://avenston.com/en/insights/energy-forecast-by-2050/

3. IEA, Net Zero by 2050.pdf \- Department of Energy, https://www.energy.gov/sites/default/files/2021-12/IEA,%20Net%20Zero%20by%202050.pdf

4. The Water Question in Green Hydrogen Production, https://hydrogenera.eu/tpost/yih4iuto41-the-water-question-in-green-hydrogen-pro

5. Hydrogen Reality Check: Distilling Green Hydrogen's Water Consumption \- RMI, https://rmi.org/resources/hydrogen-reality-check-distilling-green-hydrogens-water-consumption/

6. Does the Green Hydrogen Economy Have a Water Problem? | ACS Energy Letters, https://pubs.acs.org/doi/10.1021/acsenergylett.1c01375

7. Quenching the Thirst for Water in Hydrogen Production \- Tetra Tech, https://www.tetratech.com/insights/quenching-the-thirst-for-water-in-hydrogen-production/

8. Water Footprint of Waste-to-Hydrogen Production in the GCC: A Comparative Pathway Analysis and Governance Framework \- MDPI, https://www.mdpi.com/2073-4441/18/11/1320

9. unknown\_url

10. Understanding the Importance of Hydrological Cycle on Earth \- Rainy, https://www.rainyfilters.com/about-us/blogs/hydrological-cycle

11. The Water Cycle \- NASA Science, https://science.nasa.gov/earth/earth-observatory/the-water-cycle/

12. 4 Ways to Lower Your Water Footprint | Seametrics, https://seametrics.com/water-footprint/

13. Water Intensity of Transportation | Environmental Science & Technology \- ACS Publications, https://pubs.acs.org/doi/10.1021/es800367m

14. The Water Intensity of the Plugged-In Automotive Economy | Request PDF \- ResearchGate, https://www.researchgate.net/publication/5246570\_The\_Water\_Intensity\_of\_the\_Plugged-In\_Automotive\_Economy

15. Ethanol as Fuel: A Bridge to Nowhere — NCEA \- National Center for Energy Analytics, https://energyanalytics.org/research/ethanol-as-fuel-a-bridge-to-nowhere

16. Evaluating Freshwater, Desalinated Water, and Treated Brine as Water Feed for Hydrogen Production in Arid Regions \- MDPI, https://www.mdpi.com/1996-1073/18/15/4085

17. In Seawater, Researchers See an Untapped Bounty of Critical Metals \- e360-Yale, https://e360.yale.edu/features/desalination-saltwater-brine-mining

18. GreeN-H2 Namibia \- Dechema, https://dechema.de/green\_h2\_feasability\_study/\_/report%20seawater%20brine%20treatment%20and%20disposal%20in%20Namibia%20(1).pdf

19. Desalination at a Turning Point: Breakthrough Innovations Driving Sustainable Water Production | EcoMENA, https://www.ecomena.org/desalination-breakthrough-innovations/

20. Seawater Refinary: A Pathway for Sustainable Metal Recovery and Green Hydrogen Production \- JOURNAL OF BIOENGINEERING, TECHNOLOGIES AND HEALTH, https://jbth.com.br/index.php/JBTH/article/download/418/354/

21. How Hydrogen Fuel Cell Technology is Revolutionizing Transport \- Addcomposite, https://www.addcomposites.com/post/how-hydrogen-fuel-cell-technology-is-revolutionizing-transport

22. Fuel Cell Electric Vehicles \- Alternative Fuels Data Center \- Department of Energy, https://afdc.energy.gov/vehicles/fuel-cell

23. Hydrogen & Fuel Cell Vehicles \- Drive Clean Indiana, https://drivecleanindiana.org/fuels-vehicles/hydrogen/

24. Hydrogen Fuel Cell Electric Cars | DriveClean, https://driveclean.ca.gov/hydrogen-fuel-cell

25. Cleaning the air and improving health with hydrogen fuel-cell vehicles \- PubMed, https://pubmed.ncbi.nlm.nih.gov/15976300/

26. (PDF) Hydrogen cars and water vapor \- Academia.edu, https://www.academia.edu/31918280/Hydrogen\_cars\_and\_water\_vapor

27. Water cycle \- Wikipedia, https://en.wikipedia.org/wiki/Water\_cycle

28. Hydrogen energy could help our climate — depending on its source, https://www.snexplores.org/article/hydrogen-fuel-clean-energy-source-climate

29. Water Recuperation from Hydrogen Fuel Cell during Aerial Mission \- PSE Community.org, https://psecommunity.org/wp-content/plugins/wpor/includes/file/2302/LAPSE-2023.9869-1v1.pdf

30. Hydrogen Energy Systems and Renewable Energy Sources \- Encyclopedia.pub, https://encyclopedia.pub/entry/54027

31. Switching to a U.S. hydrogen fuel cell vehicle fleet: The resultant change in emissions, energy use, and greenhouse gases \- Stanford University, https://web.stanford.edu/group/efmh/jacobson/Articles/I/JPowerSources2005.pdf

32. Issue with hydrogen fuel cells: water emission : r/electricvehicles \- Reddit, https://www.reddit.com/r/electricvehicles/comments/zbwdbj/issue\_with\_hydrogen\_fuel\_cells\_water\_emission/

33. (English version) Question for written answer E-002566/25 to the Commission Sara Matthieu (Verts/ALE) (25 June 2025\) Subject \- European Parliament, https://www.europarl.europa.eu/RegData/questions/reponses\_qe/2025/002566/P10\_RE(2025)002566\_EN.pdf

34. Estimates of emissions from hydrogen transportation fueling infrastructure and vehicles, https://www.tandfonline.com/doi/full/10.1080/10962247.2025.2495811

35. Proton Exchange Membrane (PEM) Water Electrolysis: Cell-Level Considerations for Gigawatt-Scale Deployment \- ACS Publications, https://pubs.acs.org/doi/10.1021/acs.chemrev.3c00904

36. VSPARTICLE and Plug Power achieve breakthrough tech for iridium barrier, paving way to the production of $1/kg green hydrogen, https://vsparticle.com/about/media-blogs/vsparticle-and-plug-power-achieve-breakthrough-tech-for-iridium

37. Are There Enough Critical Minerals for Hydrogen Electrolyzers? \- The Breakthrough Institute, https://thebreakthrough.org/issues/energy/are-there-enough-critical-minerals-for-hydrogen-electrolyzers

38. Green hydrogen catalyst materials 2026: PEM & alkaline | PatSnap, https://www.patsnap.com/resources/blog/articles/green-hydrogen-catalyst-materials-2026-pem-alkaline/

39. Iridium & Platinum Catalysts for PEM Electrolysis \- Heraeus Precious Metals, https://www.heraeus-precious-metals.com/en/products-solutions/category/hydrogen-systems/hydrogen-generation/

40. Global Iridium Supply Geology, Concentration, and Strategic Risk \- Phoenix Refining, https://www.phoenixrefining.com/blog/global-iridium-supply-geology-concentration-and-strategic-risk

41. PEM Electrolyzer Stack Market Research Report 2033 \- Dataintelo, https://dataintelo.com/report/pem-electrolyzer-stack-market

42. How \- Smoltek, https://www.smoltek.com/smoltek-hydrogen/about/how/

43. Why Iridium Supply Can't Just Increase | Phoenix Refining, https://www.phoenixrefining.com/blog/why-iridium-supply-can-t-just-increase