Where Did We Go Wrong with Hydrogen?

Where Did We Go Wrong with Hydrogen? From the Oil Crisis to Thermodynamics, Carbon Recycling - and Learning from Nature An open engineering discussion by Clean Energy and Water Technologies (CEWT) The story of hydrogen as an energy solution did not begin with hydrogen. It began with oil. The oil crises of the 1970s exposed a fundamental vulnerability in the modern industrial economy. The world had become deeply dependent on petroleum - not merely as a commodity, but as the energy foundation for transportation, industry, and economic development. What could replace oil? That question has occupied scientists, engineers, industry and policymakers for more than half a century. Today there is another reason to revisit it. Enormous financial, scientific and engineering resources have been committed worldwide to renewable energy, hydrogen production, electrolysers, storage, transportation, fuel cells, carbon capture and associated infrastructure. These investments have been made for an important purpose: to reduce greenhouse-gas emissions while maintaining the energy and industrial systems on which modern civilization depends. Yet the climate problem remains. Human societies continue to face substantial economic and social consequences from climate-related hazards. Are we obtaining the maximum possible decarbonization from the enormous resources being committed to the energy transition? This article is not an argument against hydrogen, nor an attempt to promote one technology at the expense of another. It is intended as an open engineering discussion. Let us return to first principles: What does chemistry tell us? What does thermodynamics permit? What can engineering practically achieve? And what does the complete system ultimately cost? Before Hydrogen, Look at the Hydrocarbon Consider one of the simplest hydrocarbons - methane: CH₄ Its combustion is familiar: CH₄ + 2O₂ → CO₂ + 2H₂O + energy The molecule contains two important elements: carbon and hydrogen. Both can undergo oxidation reactions that release energy: C + O₂ → CO₂ + energy 2H₂ + O₂ → 2H₂O + energy But carbon and hydrogen are not physically or chemically equivalent. Under ordinary conditions, solid carbon is generally much less reactive than molecular hydrogen. Hydrogen is an extremely light gas, diffuses rapidly, and can form combustible mixtures with air. Carbon is certainly not inert - carbonaceous dusts, for example, can present serious combustion hazards - but its physical behavior is fundamentally different from gaseous hydrogen. More importantly for our discussion, their oxidation products are different. C → CO → CO₂ Carbon monoxide remains chemically useful and combustible: 2CO + O₂ → 2CO₂ + energy At CO₂, however, carbon is already in a highly oxidized state. We cannot simply burn CO₂ again and obtain further combustion energy. That observation becomes important later. Carbon Was Not Originally the Problem Carbon-containing fuels helped create modern industrial civilization because they are extraordinarily useful. They can be energy dense, transportable and storable. Hydrocarbons became fundamental to transportation, electricity generation, heating, chemical manufacture and heavy industry. The problem emerged from the scale and direction of the carbon flow. Extract → Process → Use → Oxidize → Emit Carbon stored underground over geological timescales was extracted and oxidized, with much of it eventually transferred into the atmosphere as CO₂. The carbon atom itself had not disappeared. We had changed its chemical state - and then largely treated the resulting CO₂ as waste. Climate Change Changed the Question The search for alternative energy therefore acquired another objective. How do we maintain modern energy and industrial systems while substantially reducing greenhouse-gas emissions? Hydrogen appeared particularly attractive. Oxidize carbon and we can produce CO₂. Oxidize hydrogen and the principal reaction product is water. Could we remove carbon from the energy equation and build much of the future energy system around hydrogen? Before answering that question, however, we should remember what hydrogen was doing long before the idea of a hydrogen economy emerged. Hydrogen Was Chemistry Before It Became Energy Hydrogen has enormous industrial importance because of its chemical properties. It is a powerful participant in reduction chemistry. Consider iron-oxide reduction: Fe₂O₃ + 3H₂ → 2Fe + 3H₂O Hydrogen is not simply transporting energy here. It is participating directly in a redox reaction. Similarly: CO + 3H₂ → CH₄ + H₂O CO₂ + 4H₂ → CH₄ + 2H₂O Again, hydrogen is performing a chemical function. It provides reducing power. This distinction between hydrogen as a chemically reactive molecule and hydrogen as an energy carrier may be one of the most important distinctions in the entire discussion. From the Oil Crisis to the Hydrogen Economy The search for alternatives to petroleum encouraged a much broader role for hydrogen. Unlike petroleum, hydrogen did not necessarily have to be obtained from an oil field. It could be manufactured from other resources, stored and subsequently used. A conceptual transformation occurred. Hydrogen was no longer being considered only because of what it could do chemically. It was increasingly considered for what it could carry energetically. Hydrogen is generally an energy carrier, not a primary energy source. Molecular hydrogen normally has to be produced from hydrogen-containing compounds. Energy must therefore first be supplied to manufacture it. Grey, Blue and Green Hydrogen As decarbonization became increasingly important, hydrogen acquired its familiar colors. The hydrogen molecule itself remains H₂. What changes is principally the production pathway and treatment of associated emissions. Grey hydrogen is generally produced from fossil feedstocks without capturing the resulting CO₂. Blue hydrogen also uses fossil feedstocks but incorporates carbon capture intended to reduce associated emissions. Green hydrogen follows another pathway: 2H₂O → 2H₂ + O₂ with the electricity supplied from renewable sources. Sun/Wind → Electricity → H₂ Renewable electricity can therefore be transformed into a molecule that can potentially be stored, transported and used later. Applications were proposed across transportation, power generation, heating, shipping, steelmaking, energy storage and international energy trade. Individual hydrogen applications gradually expanded into a much larger vision: the hydrogen economy. Renewable Energy and Hydrogen Became Partners The expansion of wind and solar strengthened this vision. Renewable electricity is variable, while industrial economies require energy when it is needed. Renewable electricity → H₂ → storage → useful energy Investment followed. Electrolysers became larger. Hydrogen hubs were proposed. Storage and transportation systems were developed. Export projects appeared. Fuel-cell technologies continued to advance. Hydrogen was increasingly being asked to become a major component of the future energy system. The Fuel Cell If electricity can split water to produce hydrogen, electrochemistry can also move in the opposite direction. 2H₂ + O₂ → 2H₂O + electricity + heat Technically, this is impressive. Produce hydrogen from renewable electricity. Store it. Transport it if necessary. Then convert its chemical energy back into electricity without producing CO₂ at the point of use. But from a complete-system perspective, something interesting has happened: Electricity → H₂ → Electricity And this is where thermodynamics demands our attention. And Then Thermodynamics Intervened Let us start with a deliberately simple illustration: 100 units of renewable electricity Suppose an electrolyser converts approximately 70% of that electrical energy into the chemical energy of hydrogen: 100 Electricity → 70 Hydrogen The hydrogen may subsequently require purification, drying, compression or liquefaction, storage, transportation and dispensing. Suppose, simply for illustration, that 60-65 energy units remain available at the point of use. If that hydrogen is then converted back into electricity at approximately 50-60% efficiency, the overall sequence could become something of the order of: 100 → 70 → 60-65 → 30-39 These numbers are illustrative, not universal efficiencies. Actual performance depends on electrolyser technology, operating load, pressure, storage, transportation, final conversion technology and the defined system boundary. Every energy conversion has a thermodynamic consequence. Where the required service can be performed directly with electricity, converting electricity into hydrogen and subsequently converting hydrogen back into electricity introduces additional conversion losses and equipment. But that does not mean hydrogen has no role. It means we should identify where the additional functionality provided by hydrogen justifies those conversions. When the Molecule Itself Is Required Return to ironmaking: Fe₂O₃ + 3H₂ → 2Fe + 3H₂O Here hydrogen performs a chemical function. CO₂ + 4H₂ → CH₄ + 2H₂O Hydrogen supplies reducing power. Where does the hydrogen molecule perform something sufficiently valuable that direct electricity cannot conveniently provide? In some applications hydrogen may be an energy carrier. In others it is a feedstock. In others it is a reducing agent. Those applications should not automatically be treated as thermodynamically or economically equivalent. Thermodynamics Eventually Becomes Economics Energy losses do not occur in isolation. Every conversion requires equipment: electrolysers, compressors, storage systems, pipelines, liquefaction facilities where applicable, fuel cells or turbines, heat exchangers, electrical equipment, controls and maintenance. Capital has therefore been invested to create every conversion stage. Consequently, hydrogen economics cannot be determined simply from the cost of hydrogen leaving an electrolyser. We need to examine the complete system. What was the original energy input? How much useful output was finally produced? What infrastructure was required between them? What was its utilisation? What was the capital investment? What is the cost of the useful service ultimately delivered? This is why hydrogen should be evaluated application by application. But What If We Have Been Asking the Wrong Question About Carbon? For several decades, decarbonisation has understandably focused on replacing fossil carbon. Does carbon always have to be discarded after we oxidise it? C → CO → CO₂ CO₂ represents highly oxidised carbon. Chemistry does not, however, say that the carbon must remain there. If sufficient energy and an appropriate reducing agent are supplied, carbon can be moved back toward a reduced chemical state. One such reducing agent is H₂. CO₂ + 4H₂ → CH₄ + 2H₂O Now hydrogen is performing something fundamentally different from simply being converted back into electricity. It is changing the chemical state of carbon. And this brings us to nature. Nature Took a Different Path Nature has been cycling carbon for billions of years. Plants take carbon dioxide and water and, through the extraordinarily sophisticated biochemical machinery of photosynthesis, use incoming solar energy to produce carbohydrates. 6CO₂ + 6H₂O + solar energy → C₆H₁₂O₆ + 6O₂ Nature therefore takes oxidised carbon, water and incoming renewable energy and creates reduced carbon-containing compounds. Human industrial civilisation took a different pathway. We discovered hydrocarbons accumulated through natural and geological processes and became extraordinarily good at extracting their chemical energy: CH₄ + 2O₂ → CO₂ + 2H₂O + energy But our industrial system largely stopped at oxidation: Hydrocarbon → Energy → CO₂ → Atmosphere Nature operates through interconnected cycles. Human industry has largely operated through a linear carbon chain. Nature's Chemistry and Human Chemistry There is an important difference between the natural and synthetic processes. Nature does not operate a conventional chemical plant. Through biological evolution, living systems have developed enzymes, pigments, membranes and extraordinarily complex biochemical pathways capable of performing remarkable molecular transformations under relatively mild conditions. Humanity attempting to transform CO₂ industrially needs a different toolkit. We need energy. We need electrolysers to manufacture hydrogen. We need equipment to capture and separate CO₂. We need catalysts and reactors. We may require elevated temperatures and pressures. We need compressors, heat exchangers, process controls and safety systems. CO₂ + 4H₂ → CH₄ + 2H₂O Writing the reaction takes only a few seconds. Making it occur efficiently, continuously, safely and economically on an industrial scale is an engineering challenge. Humanity has become remarkably capable of manipulating nature. Perhaps we should become equally capable of learning from the principles by which nature operates. That does not mean trying to turn an industrial reactor into a leaf. It means recognising some of the principles natural systems demonstrate so effectively: use incoming energy, transform matter, recover materials, use the output of one process as the input to another, and cycle rather than continually consume and discard. Nature Produces Carbohydrates. Could Industry Regenerate Hydrocarbons? This leads to an intriguing comparison. CO₂ + H₂O + sunlight → reduced carbon compounds Industrial engineering could potentially establish another pathway. 2H₂O → 2H₂ + O₂ Using renewable electricity, followed by: CO₂ + 4H₂ → CH₄ + 2H₂O The products and mechanisms are fundamentally different. Photosynthesis produces carbohydrates through sophisticated biological chemistry. Methanation produces a hydrocarbon through catalytic chemistry. We should therefore not describe industrial methanation as artificial photosynthesis. But the underlying system principle is interestingly similar: Oxidised carbon + water + renewable energy → reduced carbon compound Nature produces carbohydrates. Humanity could deliberately regenerate hydrocarbons. Perhaps the lesson is not that carbon must disappear. Perhaps carbon should cease to be treated as disposable. From a Carbon Chain to a Carbon Cycle Extract carbon → use → CO₂ → release What if we could increasingly move toward: Reduced carbon → use → CO/CO₂ → capture → reduction → reduced carbon There is no creation of energy here. Returning CO₂ to a reduced carbon compound requires an external energy input. Renewable electricity can supply that energy, with hydrogen providing the reducing power. This is the reasoning that led us at Clean Energy and Water Technologies to investigate Carbon Recycling Technology - CRT. Carbon Recycling Technology Instead of treating CO and CO₂ only as wastes to be stored or released, can renewable hydrogen be used to return them to a useful reduced carbon molecule and repeatedly recycle that carbon within an industrial system? CH₄ → industrial use → CO/CO₂ → capture → reduction with H₂ → CH₄ → ... Hydrogen retains the role in which its chemistry is particularly valuable: a reducing agent. Renewable electricity remains important. Electrolysis remains important. Hydrogen infrastructure remains relevant. Carbon capture remains important. Existing industrial assets may remain useful. But rather than considering these technologies as independent solutions, CRT asks whether they can become components of one integrated carbon, hydrogen and energy system. This principle is particularly relevant to steelmaking. Carbon itself remains relevant to steel and metallurgical processes; the objective becomes controlling its source and destination and investigating whether process carbon can be recovered and recycled rather than continually emitted. Earlier CEWT work has examined recovering CO and CO₂ from steelmaking gases and converting those carbon oxides through hydrogen-assisted methanation into substitute methane gas for reuse. From Fossil-Origin Carbon to Regenerated Synthetic Hydrocarbon CRT does not assume that the world's existing hydrocarbon infrastructure disappears at the beginning of the transition. The process can initially start with a hydrocarbon of fossil origin. That establishes carbon within the process. After the hydrocarbon is used, however, the objective is to avoid treating its carbon as disposable. Instead, the carbon is recovered principally as CO and CO₂ and retained within the process boundary as far as technically practical. Renewable hydrogen can then reduce those recovered carbon oxides: CO + 3H₂ → CH₄ + H₂O CO₂ + 4H₂ → CH₄ + 2H₂O The methane produced through this regeneration step is a synthetic hydrocarbon. Fossil-origin hydrocarbon at initiation ↓ Recover and retain its carbon ↓ Recovered carbon + renewable H₂ ↓ Regenerated synthetic hydrocarbon ↓ Use → recover carbon → regenerate → repeat Chemically, methane remains methane: CH₄. A carbon atom does not carry a label identifying it as fossil or synthetic. What changes is the carbon pathway. In the conventional system: New fossil carbon → CH₄ → CO₂ → atmosphere In the proposed recycling system: CH₄ → CO/CO₂ → capture → CH₄ → CO/CO₂ → capture → ... The aim is therefore not to keep extracting fresh fossil carbon for every cycle. The aim is to retain the original carbon inventory as far as practicable and supply renewable hydrogen to regenerate the hydrocarbon. A Transition That Uses What We Have Already Built The world has already invested enormous resources in renewable electricity. It has also invested heavily in electrolysers, hydrogen production and related technologies. At the same time, enormous industrial infrastructure already exists around gaseous hydrocarbons - pipelines, boilers, process heaters, turbines, furnaces, compressors, storage and associated equipment. Must these systems necessarily compete with each other? CRT explores whether they can instead be integrated. Renewable electricity produces hydrogen. Hydrogen supplies reducing power. Captured CO and CO₂ provide the carbon. Methanation regenerates synthetic methane. Compatible existing infrastructure can potentially continue to use that methane. The carbon is then recovered and recycled again. The transition therefore becomes less about existing hydrocarbon infrastructure versus renewable infrastructure and more about using renewable energy and hydrogen to progressively change the origin and circulation of the molecules moving through that infrastructure. This could potentially preserve some of the value of infrastructure already built while simultaneously creating productive demand for renewable electricity and renewable hydrogen. Whether that advantage is realised must be demonstrated through actual engineering and economics. And Do Not Forget the Oxygen 2H₂O → 2H₂ + O₂ For every kilogram of hydrogen produced, approximately eight kilograms of oxygen are simultaneously generated. In an integrated industrial process, oxygen need not automatically be treated as an unwanted by-product. Where oxygen is required - for example, in certain steelmaking or oxy-combustion applications - it may have process value. Methanation is also exothermic. Its heat should not automatically be rejected if it can generate steam or satisfy another process duty. Water should similarly be examined for recovery and recycling. Do not optimise the electrolyser, carbon-capture unit, methanator, power plant and industrial process independently. Optimise the complete system. Account for every carbon atom. Account for hydrogen. Account for oxygen. Account for water. Account for heat. Then calculate the economics. CRT Must Pass the Same Test If we question hydrogen pathways using thermodynamics and economics, intellectual consistency requires CRT to face the same examination. CRT must demonstrate its carbon, hydrogen, oxygen, water and energy balances. It must quantify carbon-capture efficiency, hydrogen demand, electrolyser electricity consumption, synthetic methane production, oxygen utilisation, heat recovery and unavoidable losses. Then comes economics. Renewable electricity has a cost. Electrolysers require capital. Carbon capture and separation consume energy and require equipment. Methanation requires reactors and catalysts. Compression requires power. Equipment requires maintenance. The value of recovered heat, oxygen, water and recycled products must be considered alongside those costs. Most importantly, the carbon boundary must be explicit. No practical industrial carbon loop should be assumed to be perfectly closed. Purges, incomplete capture, leakage and other process losses may require carbon makeup. If that makeup comes from fossil sources, it must be counted. Captured carbon is not automatically avoided CO₂. Recycled carbon is not automatically zero emissions. Those conclusions must emerge from measured or rigorously calculated mass and energy balances. That is the standard against which CRT should be tested. So, Where Did We Go Wrong with Hydrogen? Perhaps, after following the argument this far, even the title deserves reconsideration. Maybe we did not go wrong with hydrogen at all. Hydrogen is a molecule. It has simply continued to obey chemistry and thermodynamics regardless of what humanity expected from it. Perhaps the more useful question is whether we sometimes asked: How can hydrogen replace fossil fuels? before asking: Where does hydrogen's chemistry provide the greatest system value? In some applications, the answer may indeed be as an energy carrier. In others, direct electrification may be more efficient. In ironmaking, hydrogen can function as a reducing agent. In chemical manufacture, it is an essential feedstock. And in carbon recycling, hydrogen may offer something particularly interesting: the reducing power required to transform captured oxidised carbon back into a useful molecule. This does not diminish hydrogen's importance. It may make its role more precise. Perhaps We Should Learn Again from Nature Humanity has become remarkably capable of transforming matter and controlling energy. But perhaps the next stage of industrial development is not simply learning how to manipulate nature more effectively. Perhaps it is learning how to design industrial systems according to some of the principles nature has demonstrated for billions of years. Nature does not operate a linear carbon economy. It cycles carbon. It uses incoming renewable energy to drive those transformations. Humanity cannot simply copy the biological machinery that accomplishes this so elegantly. We must use the tools available to engineering: renewable electricity, chemistry, hydrogen, catalysts, electrolysers, reactors, separation technology, heat integration and process control. Use energy. Transform matter. Recover it. Cycle it again. That is the intellectual pathway that led us to explore Carbon Recycling Technology. CRT is not presented here as the final answer. It is a proposition that must continue to be tested against chemistry, thermodynamics, engineering, and economics. Engineers, scientists, economists, researchers and industrial practitioners should challenge the assumptions, examine the reactions, test the mass and energy balances, question the economics and propose better alternatives. After enormous global investment in the energy transition, and while the consequences of climate change continue, our objective should not be to defend any particular technology. It should be to discover what actually works. Nature had billions of years to develop systems that cycle carbon. Humanity does not have billions of years to address climate change. Perhaps our task is not simply to eliminate carbon, but to stop treating it as disposable. Nature cycles carbon. Perhaps industrial civilisation should learn to do the same.