Can the hydrogen economy concept be the solution to the future energy crisis?

ABSTRACT

The Hydrogen Economy concept is being proposed as a means of reducing and eventually decarbonising the world’s energy use. It looks to hydrogen as being a replacement for methane (natural gas) and generally as a way of removing all fossil fuels from the energy supply. The concept, however, has at least four flaws, as follows: (1) hydrogen has significantly different properties to methane; (2) hydrogen has properties that create significant hazards; (3) hydrogen has a very small initiation (activation) energy; and (4) liquid hydrogen cannot readily replace liquefied natural gas (LNG). Hydrogen’s hazards will prevent it from being accepted in a societal sense. To the question ‘Can the Hydrogen Economy concept be the solution to the future energy crisis?’, the answer is ‘no’. Hydrogen has and will have a role in world energy but that role will be limited to industry. For the future we need an advanced electric economy.

KEYWORDS:

• Hydrogen Economy
• Hydrogen
• hazard
• reliability
• power dispatchability

1. Introduction

Hydrogen has considerably less energy on a volume/volume basis than methane; however, it produces no direct carbon emissions. So an economy with hydrogen as the means of producing, transporting, storing, reticulating and using energy would be a carbon less economy. A major question is where would you get a hydrogen supply that could meet demand with no carbon release?

Only water and energy are produced by the simple chemical reaction at the core of the H-E:

(1) $2H2+O2\to 2H2O+ENERGY\mathrm{\Delta }{H}^{\circ }-484kJ/mol$(1)

Figure 1. A basic representation of H-E.

Figure 2. The Stages of the Hydrogen Economy Progression Production: H2 Gathering, Transport, Storage, Transport (post Storage), Reticulation, and Use.

Figure 3. For Hydrogen Fuel Cell Electric Vehicles (HFCEVs) the emissions will be different. A feature of the operation of H-E is the swapping of energy between chemical energy (H2 gas and battery), electricity and mechanical energy.

Figure 4. Molten Catalyst Methane (hydrocarbon) cracking column.

Figure 5. The Fire/Explosion Triangle.

Figure 6. (a). LH2 by sea. This is still in the demonstration stage. The challenges will be very much to do with materials (steel, other metals composites and flexible tubing), plant (couplings, pumps and compressors, and heat exchangers) and innovative design. (b). LH2 ‘carriers’ by sea. Hydrogen can be incorporated into ammonia or a ‘cyclic hydrocarbon’ producing naphthalene, and then recovered at the destination port. Ammonia will only deliver 18% of its load as H2, and naphthalene 6% of its load as H2. This author believes that neither of those options appear to be financially feasible.

Figure 7. Adjusted natural hydrogen analyses for multiple natural gas wells.

Figure 8. The spalling of a uranium atom.

Figure 9. The energy for splitting water.

Figure 10. (a). Type 1 Anticlinal Gas Trap. (b). A Type 2 Evaporite Gas Trap.

Note the faulting (F). The plastic evaporites will seal structural faulting. The traps are not absolute in that they slow the flux of gas through the strata allowing for build up of hydrogen and helium.

Figure 11. Gas separations with hydrogen being separated either in or before the helium plant.

The concept of H-E was proposed by Ulf Bossel and Baldur Elaisson in January 2003 (Bossel and Elaisson 2003), in an AFDC published report, ‘Energy and the Hydrogen Economy’. Bossel and Elaisson recognised the challenges of getting hydrogen into a packaged form where it could be transported from a production site to a use location. Two choices of transport they considered were compressed gas and cryogenic liquid, neither of these options being comparable to natural gas transport in terms of costs and technical challenges.

Bossel and Elaisson (Bossel and Elaisson 2003) estimated that the ‘energy consumption of a (hydrogen) liquefaction plant could not drop much below 30% of the higher heating value of the liquified hydrogen’. So using a process that relies on liquefying, as is used in turning natural gas into LNG, is not valid when applied to hydrogen. They went on to state ‘[p]ipelines that transport hydrogen are inefficient and suffer from diffusion losses, brittleness of pipeline materials and seal leaks’. That is a valid point. There are, however, 700 miles of hydrogen pipeline already in existence (Melaina, Antonia, and Penev 2013), with the U.S. Office of Energy Efficiency and Renewable Energy’s Hydrogen and Fuel Cell Technologies Office page on ‘Hydrogen Pipelines’ referring to ‘almost 1,600 miles’ (OEE&RE 2021); so we know that hydrogen carrying pipelines exist and are probably being built or extended.

To understand what hydrogen may be able to provide it is useful to have a comparison of energy content between hydrogen and methane (natural gas).

2. Properties of hydrogen and methane (natural gas)

Hydrogen has been equated by proponents of H-E as being generally similar to Natural Gas (NG) – Methane. There are system losses with both gases during transport and storage and both can be liquefied using cryogenic technology. Hydrogen has been described by Crabtree G, Dresselhaus M and Buchanan M (Crabtree, Dresselhaus, and Buchanan 2004) as an energy carrier but it can also be a chemical precursor, as is methane.

In practice however, hydrogen and methane are very different. In a highly compressed state hydrogen, say at 25 MPa, has an expansion ratio at of around 1:240 and when liquefied the ratio is 1:848, so liquid H2 is very condensed. Further properties are presented in Table 1.

Table 1. Energy Density (Lower Heating Value – LHV).

Fuel	Specific Energy/Energy Density
Hydrogen	10⋅8 MJ/m^3 at 20°C @ 1 Bar
	120⋅0 MJ/kg at 20°C @ 1 Bar
	8⋅5 MJ/L Liquid <20 K
Methane – NG	35⋅8 MJ/m^3 at 15°C @ 1 Bar
	50⋅0 MJ/kg at 15°C @ 1 Bar
	21 MJ/L Liquid <111⋅65 K

Acknowledgement for hydrogen properties data. Miriam Ricci, Gordon Newsholme, Paul Bellaby and Rob Flynn have produced a symposium paper titled ‘Hydrogen: too dangerous to base our future upon?’ Symposium Series No. 151, Crown Copyright 2006. https://www.icheme.org/media/9792/xix-paper-04.pdf The authors are thanked for their contribution to the debate.

There is great variation in the components of Natural Gas: some resources are almost entirely methane, some are mainly carbon dioxide and/or nitrogen. An example of a ‘good’ NG is methane 88 · 8%, ethane 7 · 8%, propane 0 · 2%, CO2 1 · 9%, N2 1 · 3% and LHV SE 35 MJ/m³. This gas is a dry gas (low C2+ hydrocarbons) and meets the pipeline standard for CO2 content (<2%CO2); with a reduction in CO2 to less than 50 ppm it would be suitable for LNG. N.B. For domestic use this gas could be blended with hydrogen up to 15% H2.

From the volumetric specific energies (MJ/m³) a system that uses methane to move energy will be over three times more efficient than one that uses hydrogen: this fact is a major challenge for the Hydrogen Economy concept. The hazards associated with the H-E concept are another major hurdle that will be addressed later in this paper.

3. The meaning of hydrogen economy

H-E proponents often use a graphic, such as Figure 1, in the form of a rosette to show/demonstrate what they consider Hydrogen Economy means. A simplified rosette (from what was first used by the US NERL as a graphic in Oct 2011 and adopted by WIKI as an explanation of H-E (Ruth 2011)) without detailed graphics of say transport, production etc is shown adjacent. An important inclusion is Systems Integration that will be required since practically the whole energy system will be changed by the full acceptance of H-E.

Many schematic representations have been produced. They show the sequential production (with agglomeration of sources), the transport and storage, and use of hydrogen; Crabtree G et al. (Crabtree, Dresselhaus, and Buchanan 2004) produced a basic schematic which has been expanded and edited in Figures 2 and 13.

The cardinal points in the progression (Figure 2) are:

• Production, making hydrogen by any available method that is economically feasible,

• Gathering and agglomerating all sources of H2,

• Transporting H2, possibly by different means pre and post storage, whilst respecting its innate hazards,

• Storage, a crucial and hopefully leak free stage,

• Reticulation, the sending out of H2 to customers (a sensitive stage where community has a say),

• Using H2 in industry and commerce, but not in urban situations, and

• Hydrogen-fed Fuel Cell Electric Vehicles (HFCEVs), a special sub-case of use requiring very extensive (and expensive) hydrogen reticulation systems using pipelines or road tankers Figure 3.

For every H-E project the above stages would need a full Environmental, Social and Governance (ESG) analysis as well as a full safety audit. If Green Credits are to be earned when moving from a carbon economy to a hydrogen economy, then green credits auditing would also be required.

Production. The Hydrogen Economy will require access to vast quantities of hydrogen and those quantities would be far greater than the present demand for natural gas (NG). To meet expectations the hydrogen should be sourced without co-production of carbon dioxide (if CO2 is co-produced provision should be made for Carbon Capture and Sequestration – CCS). Using an electrolysis technology to reverse the hydrogen oxidation reaction produces hydrogen without carbon:

(2) $H2O+ENERGY\to H2+1/2O2$(2)

Using PEM (Proton Exchange Membrane), an advanced water hydrolysis technology, the above equation can be rewritten with the energy inputs shown. (Shiva Kumar and Himabindu 2019)

(3) $H_{2}O+Electricity(237\cdot 2kJ/mol)+Heat(48\cdot 6kJ/mol)\to H_2+1/2O_2$(3)

The total energy required by a PEM hydrolysis plant is 285⋅8 kJ/mol (0⋅08 kWh/mol). One mole of H₂ weighs ~ 2 grams. N.B. Reliable electrical energy would also be required for pipeline gas compressing, possibly liquefying, and then compressing hydrogen for storage. Hydrogen systems will be very energy demanding. Figure 6

Agglomerating the electrical outputs from multiple generation plants and devices with different and variable outputs will be challenging. Gathering the outputs of multiple hydrogen production plants will likewise be challenging. The PV cells, and batteries connected to those cells, will be producing DC power, which will be immediately available for electrolysis, whereas wind, hydro and biomass will likely be providing AC power that will need to be rectified. See Figure 11.

Transporting hydrogen by pipeline and road is already well established. However, it comes with significant hazards and losses of gas through permeation through steel and composite materials. Transport by ship is still at the early demonstration stage Figure 6a.

Reticulation, the dispatch of H2 to users and customers from a hub, will involve the negotiation of engineering, scheduling and supply management, business, and community relations issues. The engineering includes the supply to customers’ inlet nodes, metering, training of customers’ labour forces on the use of H2, and possibly the training of the health, environment and safety inspectorate. The scheduling will require liaison with customers to understand their supply and use scenarios and help them understand their need for an immediate stand-by supply and working with those customers on the likely cost of using H2 purchased from the hub. The biggest challenge could be to convince the populace that the potential hazards of H2 can be managed and that it is safe for the reticulation system to pass close to their premises.

Using hydrogen in industries other than ammonia production and oil refining will require education and training for staff, management and regulators. It was observed that when gas suppliers switched from coal gas to natural gas in the 1960s and 1970s, considerable effort in educating all interested parties was required. H2 will require a much greater effort.

Hydrogen as a vehicular fuel and energy carrier. Where hydrocarbons can be substituted by hydrogen, reductions in CO2, particulates and nitrogen oxides emissions to the atmosphere will occur. Where hydrogen is used in a combustion engine (reciprocating pistons or gas-turbine) particulates will be formed from lubricant combustion and emitted through the exhaust, and given the high temperatures of hydrogen flame, some nitrogen oxides will also be in the exhaust. In the vehicle fuel schematic below (Figure 3), a vehicle is being designed and built to utilise hydrogen as a fuel. Other proponents are working on supplementing natural gas with up to 20% hydrogen (St. John 2020). (N.B. This would not be useful in any system that required combustion to liberate energy and use heat transfer by radiance, since hydrogen burns with virtually no useful radiance and the methane is only marginally more radiant.) The concept of hydrogen as a supplementary fuel is looked upon as a partial decarbonising procedure (St. John 2020).

Here the fuel cells convert chemical energy to electrical energy, while the motor/generator can use electricity for locomotion or recoup mechanical energy as electricity to the battery. Convenient independent battery charging provides an additional energy input. This is useful in start up.

Dual fuelling, with hydrogen and electricity, is evident in hydrogen fuelled vehicles such as the Toyota Mirai. (All-New Mirai 2021)

4. A fueling demand comparison between HFCEVs and electric vehicles (EVs)

Electricity reticulation is available across very large parts of the globe for supplying electricity including recharging EVs, albeit that some electrical grids must be strengthened if EVs become a popular way of travelling. Reticulation of compressed H2 to large parts of the globe has barely started and may never exist outside a few wealthy regions such as California. At this juncture fuel cells fed by hydrogen are not going to be a major environmental saviour, whether or not they are part of motor vehicle technology.

5. The existing hydrogen industry

Ammonia is one of the most important basic chemical feeds to the chemical engineering industry. It is the key to the input of nitrogen into carbon, hydrogen and oxygen chemical systems, and is the source of nitrogen for amines, nitrates, nitrites and nitro and other organic and inorganic compounds and chemical groups. Since World War I nitrogen has been sourced from the atmosphere according to the exothermic equation:

(4) $\begin{array}{rl}& N_2+3H_2\to 2N{H}_3{H}^{\circ }-92kJ/mol\\ & Haber-BoschProcess\end{array}$(4)

In oil refining, hydrogen is used for hydrogenation of heavy oil constituents and sulphur removal from crude. Hydrogen used in ammonia production and oil refining is usually derived from steam reformed methane:

(5) $\begin{array}{l}C{H}_4+2H_{2}O\to 4H_2+C{O}_2\\ \left(\text{including}\text{water-shift}\right)\end{array}$(5)

Hydrogen is likely to have an increasing role in the iron/steel industries (and a lesser role in cement being only heat supply). Smelting with hydrogen is possible with the potential biomass sources of carbon providing for iron carbide (cementite) production. But how plentiful and how expensive will the biomass needed for the world’s steel production be and can it fully replace coke? Would carbon produced by methane splitting be suitable for low carbon smelting?

6. Comparative costing of the hydrogen economy and the existing carbon economy

A paper by Pinsky R et al, Comparative Review of Hydrogen Production Technologies for Nuclear Hybrid Energy Systems, 2020 (Pinsky et al.), provides proximate production costs for multiple hydrogen production technologies Pinsky R et al. (2020). These figures provide one aspect of a cost-benefit analysis that would be needed to progress the H-E past concept status.

7. Hazard analyses

H-E presents multiple hazards. Hazards associated with the physical, chemical, materials science and engineering nature of hydrogen can be qualitatively compared with those of natural gas (Ricci et al. 2006). A hazard of interest is the low electro-conductivity of hydrogen that can increase the propensity to generate electrostatic charges and produce sparks. On the positive side hydrogen has lower hazard for unventilated accumulations of hydrogen (hydrogen being so light that it tends to waft away), fires can likewise lift quickly into the atmosphere without seriously impinging on storage vessels and pipelines, and the hazard of asphyxiation is likewise reduced due to relative fast hydrogen dispersion (Ricci et al. 2006).

Did the engineers who undertook the Hazard Management of the Fukushima nuclear plants understand that their outer containment structures would allow for a build up of hydrogen? Were they aware of hydrogen’s broad flammability/explosive ranges with air, as well as it having a very small activation energy for ignition? Hydrogen that is released into confined spaces is a major hazard. The Fukushima hydrogen explosions set back the nuclear industry but also demonstrated the dangers of hydrogen. The memories of the exploding outer containment at Fukushima will be revived when there is another hydrogen fire/explosion. Undertaking Quantitative Risk (Hazard) Analyses will be at future stages of concept development through to project commissioning.

8. Another look at hazard and risk

Dr Peter M Sandman (circa 1993) developed the concept of Risk = Hazard + Outrage (Sandman 1993). Hazard with aspects of frequency, likelihood and severity can be measured. The level of outrage from a particular incident that may include political upheaval and loss of social acceptance is hard to predict. N.B. The advent of social media combined with ‘fake exaggerated news’ has made the blunting of outrage a greater challenge. Sandman’s approach and relevance will be discussed in the concluding pages.

Ingaldi and Klimecka-Tatar (Ingaldi and Klimecka-Tatar, 2020) discuss people’s attitudes to energy from hydrogen and the creation of controversies as ‘significant challenges for mobile [vehicle] technologies and daily life’, as that applies to hydrogen introduction. Their paper discusses the attitude of respondents [to a survey] that looked at the safety of hydrogen; respondents are ‘found to be not convinced that an adequate level of safety exists for energy derived from hydrogen, where safety can be understood to be technical’. The respondents also stated that ‘knowledge about hydrogen as an energy source, and its production safety and storage methods, is very low’. The respondents are aware of potential hazards and if coerced to accept hydrogen have the potential for outrage.

9. Nuclear energy and the response of the nuclear industry to the H-E

The World Nuclear Association, an international body in London with responsibility for overseeing 70% of the world’s nuclear power, has produced a white paper titled ‘Hydrogen Production and Uses’ (World Nuclear Association, 2021) that provides a wide perspective of where nuclear energy may go with respect to hydrogen production. Pinsky et al (2020) take a more focused approach in their paper, Comparative Review of Hydrogen Production Techniques for Nuclear Hybrid Energy Systems. Their contribution to the discussion is that nuclear power could provide electricity/energy for hydrogen production; even without economic analysis it can be assumed that hydrogen produced by fuel-cells being fed electricity from new nuclear power stations at this stage would produce expensive electricity, making electrolysis-based hydrogen production from nuclear energy also expensive.

On a basic hazard approach, the distance between nuclear power plants and hydrogen production facilities and transport systems should be considerable; a hazards analysis that takes into account international nuclear safety regulations would provide rules and regulations on distances and physical layouts.

If nuclear energy is a feasible contributor to H-E, why not simply use nuclear power generation to support an extended renewables/low carbon/electric economy (E-E)?

Low Carbon Hydrogen Sources: Options for the Renewable Energy Proponents

Blue Hydrogen, that being hydrogen produced along with carbon dioxide that is to be sent to Carbon Capture and Sequestration (CCS), has only a time limited role in H-E, as suggested in Figure 2. Sequestration, the ‘S’ in CCS, must be a near complete fate for the carbon, with leaks being kept within limits and gross leaks not tolerated. However, can ‘forever sequestration’ be guaranteed and policed?

It could be feasible to have a version of H-E that is almost solely dependent on methane and methane reforming. Such a strategy would involve a greatly increased search for methane resources. Major finds would mean endless opportunities for CCS. However, CCS opportunities at this scale would be unlikely to exist (Kindy 2021).

About 90% of the world’s hydrogen is produced from reformed natural gas and as of 2020, 70 million tonnes of hydrogen were produced per year (Ashcroft and Di Zanno 2021).²

10. Photocatalytic hydrogen (PCH) production: a low carbon hydrogen source

Some sources of ‘clean’ hydrogen are small and will probably remain small due to their innate low efficiency. Li and Li (2017) point to one such example: Photocatalytic Hydrogen (PCH) Production. Its efficiency is expressed as STH%. Solar-to-hydrogen (STH) efficiency..

(6) $STH\mathrm{\%}=\frac{outputenergyas{H}_{2}gas}{energyofincidentsolarlight}\times 100$(6)

Li and Li state that ‘[u]p to date [January 2017], the highest STH efficiency for PEC (photo-electric-catalysis) water splitting system as reported is ~2 · 5%’. There is a long way to go before PCH/PEC becomes a major supplier of hydrogen. The reactions for PEC are:

(7) $\begin{array}{rl}& 2H_{2}O+hv\to O_2+4H^{+}+4e^{-}\\ & \mathrm{a}\mathrm{n}\mathrm{d}\\ & 4H^{+}+4e^{-}\to 2H_2\end{array}$(7)

hv is Photonic Radiation.

11. An alternative H2 source: methane cracking/splitting

Methane (and other hydrocarbons) can be split according to the following endothermic equation:

(8) $CH4gas\to 2H2gas+Csolid\hspace{0.17em}\mathrm{\Delta }{H}^{\circ }=74\cdot 8\hspace{0.17em}kJ/mol$(8)

Cracking methane (and other H-Cs) has been proposed in the past by groups including Kvaerner (Lu et al. 2021). Dagle et al reviewed the concept to use Liquid Metal (tin or low melting temperature alloys) to crack (split) methane into hydrogen and solid carbon products (Dagle et al. 2017). The use of molten metal such as tin as a catalyst through which a stream of methane is passed avoids catalyst occlusion that has been the challenge in previous research. The process is carried out in a heated column as shown Figure 4.

The two products of the process should be pure hydrogen after separations and carbon after clean up (Msheik, Rodat, and Ananades 2021).

The aggregated value of the two products will be largely dependent on the value of the carbon, that is the value of the pure allotropes that are produced. Graphene, Buckminster-fullerenes and needle carbon have higher values than amorphous carbon and bulk hydrogen. The suitability of the carbon product for structural and chemical uses will be crucial in seeing Methane Cracking as a major industrial process.

12. The hazards of hydrogen

12.1. Managing hydrogen as a substance: hydrogen safety and hazard reduction

Hydrogen differs from methane in many ways, having a significantly higher hazard profile. The hazards are loss of health, commercial and industrial failure, and environmental and societal loss of amenity.

Looking at the Fire/Explosion Triangle for Flammable Gases (Figure 5) we find there is a wide explosive limit for air/hydrogen mixes, with Lower Explosion Limit of 4% and Upper Explosion Limit of 74% compared methane’s much tighter LEL/HEL difference 5% to 15%. Testing for hydrogen is more difficult and hazardous than for methane. Hydrogen being very light has a high dissipation rate in air if released to the atmosphere. However, the high hydrogen mixing rate and LEL/HEL makes it exceptionally hazardous whenever confined.

Some further hazards to consider:

•Hydrogen has a very low activation (ignition) energy of ~0 · 02 mJ, as compared to ~0 · 29 mJ for

methane, the latter for methane being fourteen times greater,¹

•The activation energy can be supplied as static electricity such that rapidly released compressed

hydrogen will always ignite,

•Hydrogen can permeate through steel and other confining materials causing increases in

brittleness,

•Hydrogen becomes a liquid at minus 20 · 28 K (Propane – LPG at 231 · 2 K and Methane 111 · 6 K),

•LH2 being a cryogenic fluid requires care in handling and has relatively high handling costs,

requiring specialist cryogenic infrastructure and a highly trained service team,

•Hydrogen has no odour and is difficult to odorise,

•Hydrogen burns with a clear, near invisible flame,

•Mixtures of H2 and air (or O2) are detonatable (a deflagration can become a detonation), and

•Hydrogen leaks are difficult to detect and hazardous to rectify.

Hydrogen has multiple hazards that must be managed if the Hydrogen Economy, as portrayed in Figure 2, is to be a reality.

Given the hazard profile, hydrogen introduction will incur higher insurance premiums and it will be more difficult to finance energy projects. Once they are aware of the hazards, communities likely will oppose hydrogen being introduced in their regions. Installing hydrogen reticulation grids to supply fuel for hydrogen vehicles and other uses will likely be opposed by community action groups. Hydrogen is a very difficult fuel to manage in comparison to other gaseous fuels in urban, commercial and small industrial applications. For these reasons hydrogen is a very challenging fuel around which to build an energy export/import industry.

12.2. Hydrogen as an export/import fuel

In 2020, Australia became the world’s largest exporter of LNG with exports worth $AU 49 billion. It is the nation’s fourth largest export and probably will be the third largest export once COVID diminishes education as an export earner.^3,4

LNG is a convenient and well understood cryogenic liquid. It has a Specific Energy of ~24 MJ/L (depending on composition) whilst Liquid Hydrogen (LH2) has an SE of 8 MJ/L. As a cryogenic liquid at 20 K, LH2 requires considerable energy to liquefy before loading and to regasify at the receiving port. The internal logistics gas demand is around 40% of the gas entering the liquifying plant.

13. Natural hydrogen

13.1. Mineral hydrogen extracted from natural gas

Hydrogen, as water, is a major component of the earth and also is part of the geology of the earth. Some of the hydrogen within the earth is tied up in hydrated minerals and is released in water–rock interactions involving iron. Klein, Bach and McCollom (Klein, Bach, and McCollom 2013) state ‘[h]ydrogen forms during the oxidation of ferrous iron in olivine and orthopyroxene to ferric iron in secondary minerals through reaction with water’. This can be represented by the general reaction:

(9) $2FeO+H_{2}O\left(aq\right)\to F{e}_2{O}_3+H_2$(9)

So hydrogen is produced by the oxidation of ferrous ions to ferric ions over geological time. Is this hydrogen stored in geological formations or does it migrate to the atmosphere and thence into space?

13.2. The relationship of hydrogen and helium

The following gas analyses are for two natural gas wells drilled in Central Australia and are interesting due to the presence of (a) very high helium content, (b) natural hydrogen presence (in one case very high and in the second only nuisance value) and (c) high nitrogen and moderate methane contents.

The gas analyses are very high in helium. So if the discovery is confirmed, both finds would be developed as Helium Resources. Well 1 has little fuel gas content; Well 2 is also poor in fuel gas. If the Well 1 hydrogen was recovered and mixed with the available hydrocarbons (H-Cs), that fuel could be used in an on-site captive power plant. The 0 · 03% hydrogen in Well 2 would be a contaminant that would have to be removed from the helium. Nitrogen could be a useful by-product from both wells.

The hydrogen content of the Well 1 find could potentially be removed from the bulk of the gas using adsorption technology (PSA) with either the use of the hydrogen as a component fuel gas (as stated above) or it could be flared. The feasibility of separation of the hydrogen would depend on the efficiency of the process in separating out hydrogen without losing significant helium. That could be a challenging task. The Well’s gas analyses demonstrate how variable the products of natural gas can be. What started as an exploration for hydrocarbons found potential value in a speciality gas, helium, and for Well 1 possibly hydrogen as well.

13.3. Other natural hydrogen finds

Recently there has been an increasing effort to ‘discover’ natural hydrogen. These efforts, that include collecting and documenting information on past finds, have brought considerable success in understanding what concentrations of hydrogen are possible in natural gas finds. Prinzhofera, Tahara and Diallob (Prinzhofera, Tahara, and Diallob 2018) have recorded the finds in Figure 7.

Of particular note is the Bougou 1 well (Mali) with an analysis of 97 · 4% H2, 1% N2 and less than 1% methane. Detailed estimates of that well’s resource size and extended productivity were not made. The natural hydrogen was used to power a regional village for over four years.

A major find with the gas analysis of Bougou 1 would be welcomed by gas explorers.

Finds such as those described in Figure 7 point to the need for petroleum explorers to undertake thorough sets of gas analyses of petroleum wells.

13.4. Radiolysis of water to produce H2 and He

In Figures 8 and 9 the process of radiolysis producing both hydrogen and helium are presented. The helium is an alpha particle that is spalt off a uranium or thorium atom or daughter atom.

The co-production of Hydrogen and Helium near simultaneously has recently been ‘rediscovered’ during the search for hydrogen sources.

The question of what are the relative migration (permeation) rates of the H2 molecules and the He atoms should be explored.

In a paper by Sophie Le Caer (Le Caer 2011), ionising radiation, including that radiation released on the production of an alpha (α) particle (a helium-4 atom) during the decay of a uranium or thorium atom, can produce hydrogen by water radiolysis.

(10) $N.B.1\cdot 6x{10}^{-13}Joules=1MeV$(10)

The co-production of He (a high value relatively rare mineral/atom) and H2 (a bulk relatively low value element) offers a new opportunity to gas and oil explorationists. There may be some difficulties with the separation of helium and hydrogen and that will be a challenge for petroleum industrial chemists.

13.5. Making a resource of ‘googles’ of individual decay/ionisation events

Hydrogen and helium are very small particles that once ‘liberated’ can permeate through almost any material. Once formed they migrate through the geological formations and then on reaching the atmosphere, continue their journey into space. Helium will go through the earth and its atmosphere unscathed whereas hydrogen may oxidise to water on the way.

That both hydrogen and helium can exist in the same strata where there is a sealing formation is indicated in Table 2. Sealing strata often include evaporites such as salt being laid down with tight shales in an expansive anticlinal structure (a Type 1 sealing structure) or in smaller (but often richer in helium) structural traps (a Type 2 structure) with massive salt/evaporites. The Qatar gasfields are examples of Type 1 traps and the US helium gasfields Type 2 traps. The smaller Type 2 system tends to be self-sealing if faulting occurs since the evaporites tend to be plastic under high pressures and temperatures.

Table 2. Analyses of NG Finds in Central Australia.

	Well 1	Well 2
Component	Mole %	Mole %
Helium	9	6 · 24
Natural Hydrogen	11	0 · 03
Nitrogen	61	43 · 87
Methane	13	33 · 49
Ethane	4	6 · 41
Other hydrocarbons	NA	3 · 41
Total	98	100 · 00

There may exist very large anticlinal formations that hold hydrogen (and helium) that have the potential for development.

If high hydrogen giant/very large Type 1 type traps exist, failures of explorers to make finds over the last 60 years should be examined. Perhaps explorers did not analyse for hydrogen or perhaps they simply never explored those potential sites.

The finds of highly concentrated hydrogen bearing natural gas in Mali and Kansas (Figure 7) do not come with measured resources. The Bougou 1 well(s), Mali, may have supported local power generation for a relatively short production period but that resource appears to have little in common with what is suggested in Figure 10a. Perhaps additional exploration in Mali and Kansas (were the Kansas finds made whilst exploring for helium?) of Type 2, Figure 10b, style could find locally useful resources of hydrogen. That is to be tested.

14. Separating the hydrogen, helium, fuel gases and other gases such as nitrogen and carbon dioxide

It is known that hydrogen and helium co-exist with a mix of other gases, some of which are valuable and some not so. Hydrogen is an industrial bulk gas with an existing price related to the demand for ammonia and its use in oil refining. Helium has no conventional market but trades at fifteen or more times the price of NG (methane), a bulk gaseous fuel. The price of hydrogen will depend on the demand, with some ‘authorities’ suggesting that price doubling or trebling will be possible post COVID and once H-E starts to eventuate. As to exploring for natural hydrogen, this should be done as a sub-activity of NG exploration. If major finds of ‘concentrated’ natural hydrogen are made, then the exploration priorities can be changed.

The process sheet shown in Figure 11 would likely be more suitable to a Type 1 development. The helium (and hydrogen) separation plant that processes the tails-gas could be a relatively standard cryogenic unit. To a large extent recovering and processing natural hydrogen will be a new challenge and finding a market/destination for remote finds of natural hydrogen will create many a quandary, in that the transport of a hazardous gas will be expensive and carry risk. Natural hydrogen would need to be discovered in multi-trillion cubic feet (TCF) quantities to satisfy the demand side of H-E (see Figure 2).

Natural Hydrogen could, however, have some niche applications as exemplified in the following hypothetical case:

A NG find in the Andaman Sea is found to have 10% natural hydrogen. The off-takers of the gas do not want natural hydrogen in their gas, so are happy to allow a third party to build a gas separation plant onshore. The separated hydrogen will be sent to an adjacent ammonia plant. The ammonia plant owners and operators are happy to have a zero-carbon ammonia production facility.

It is highly probable that there will be additional demand for hydrogen, even if only relatively small portions of the H-E actually come into being. Global hydrogen demand was ‘around 90 Mt H2 in 2020, having grown 50% since the turn of the millennium’, according to the IEA. (Global Hydrogen Review 2021) Hydrogen use in heavy industry outside ammonia production and oil refining will grow, with one possibility being Directly Reduced Iron. However, most of this demand for hydrogen will continue to be met from reforming natural gas.

The options for low (or nil) carbon hydrogen production will be limited due to cost, with hydrolysis being an example. There will be an ever-increasing demand for electricity from industry, commerce and communities which are aspiring to lifestyle improvements. Diverting electricity to hydrogen production will need to be justified to receive social acceptance. Failures in supply due to diversion will not be tolerated.

15. Guaranteed power dispatchability

Guaranteed power dispatchability is what communities have come to expect and will be looking for if the H-E is introduced. For industry power dispatchability is a non-negotiable expectation. The value of dispatchability is discussed in the NEM literature (National Energy Market 2021).

The introduction of the H-E will see the need for energy diversion from chemical fuels to electricity. In the near future electric vehicles (EVs), not hydrogen fuelled vehicles, will become common. (Battery Electric Vehicles (BEVs) versus Hydrogen Fuel Cell Electric Vehicles (HFCEVs) – BEVs win 2021) Although demand for non-electric ‘transport energy’ will still be there, and even though that includes hydrocarbons, dirty electricity (fossil fuel derived power) or intermittent green electricity, there will still be a need for increasing guaranteed dispatchable power delivered by efficient and secure power grids.

15.1. Other niche hydrogen production and utilisation scenarios

Research is being undertaken on what percentage of methane can be replaced by hydrogen in natural gas systems. Safety and technical compatibility must be understood as must the carbon footprint reduction.

Melaina, Antonia and Penev, of the US National Renewable Energy Laboratory (Melaina, Antonia, and Penev 2013) state in their report ‘[t]he implications of hydrogen blending vary with the concentration of hydrogen. Relatively low concentrations of hydrogen, 5%–15% by volume, appear to be feasible with very few modifications to existing pipeline systems or end-use appliances.’ This work is useful in that it may allow for the use of NG containing a ‘geologically feasible’ concentration of H2 to be used in specific applications off the NG grids. For example, raw NG that contains 7% H2 v/v may have 10% H2 after gas clean-up/removal of CO2 and N2. This mixture may be appropriate for commercial applications. (Melaina, Antonia, and Penev 2013).

Hydrolysis produces two products, hydrogen and oxygen. Oxygen has uses in sanitation, with its addition to sewage and wastewater, reducing the concentration of dangerous microbes. If oxygen is given a fair value, that cashflow will assist in supporting the use of electricity to produce hydrogen. It is noted that sanitation is not sterilisation: sterilisation requires ozone (O₃) which is very power consuming to produce.

In the upstream end of the petroleum industry the exploration for helium has accelerated from the 1970s. The current interest in natural hydrogen may well see very large finds of N-H. In parts of the world that are or can be covered by pipelines, pipeline transport of H2 seems appropriate between production nodes and reticulation hubs. Although H2 transport by pipeline is understood, it is costly because of materials, safety and community acceptance considerations.

Replacing LNG with LH2 in seaborne transport is probably not going to happen on a large scale. The energy losses during liquification, shipping and regasification will be too great to be financially sound whilst the maintenance of specially designed tankers will be costly. Using a tied solar PV plant to supply DC power to local electrolysis plants is a niche use, with methanol (Bowker 2019) or ammonia being products.

Figure 12. PV powered water electrolysis: a simplified view.

If Figure 12 were part of a remote HFCEV/EV fuelling station the bulk of plant would consist of a compressed hydrogen tank farm, battery bank and bowser assembly.

The filling points for compressed hydrogen (CH2) and power on the one hand and the tank farm and battery bank on the other hand would need to be well separated due to safety concerns. The combined hydrogen and power servo would have high CAPEX and OPEX, require high security and have a significant footprint.

16. Summing up the hydrogen economy concept

On first inspection the H-E concept has many positives.

With the exception of fossil fuels with CCS, there are no other references to carbon in Figure 2. CCS is questioned regarding its role as part of the Hydrogen Economy. The sequestration of large volumes of carbon dioxide ‘forever’ is a monumental task.

On reviewing the H-E proponents’ simple comparisons and assumptions, it is understood that they are suggesting:

• H2 could replace CH4,

• LH2 could replace LNG,

• the natural gas grid could be easily converted from methane to H2,

• the same level of hazard that applies to CH4/LNG would apply to H2/LH2,

• similar combustion properties exist for CH4 and H2 such that end-use appliances would need only modest modifications, and

• community acceptance of H2 would be similar to that experienced during the switch from town (coal) gas to natural gas in the 1960s/1970s.

This author believes that those comparisons and assumptions are misplaced, erroneous or just plain incorrect. In the first example hydrogen can never fully replace methane (and visa-versa) whilst in the third example the natural gas grid will be very difficult to convert to carry hydrogen. Researchers are trying to safely increase the percentage of hydrogen that can be blended with methane to greater than 15% (St. John 2020).

There is no way that the level of hazard that is found in methane and LNG will be the same as hydrogen/LH2, since the innate chemical and physical properties of the two gases are so very different. It has taken many years to understand what is required in safe LNG storage and transport.

The confidence the promoters of H-E are exhibiting must be challenged by physics, chemistry, materials science and engineering. Also society must also be given the opportunity to be educated about what is being proposed and then allowed to make up its collective mind.

17. The hazards, risks and social acceptance/rejection

Hazard and Risk should not the taken to be the same thing. Dr Peter M Sandman (Sandman 1993) produced the basis equation that: Risk = Hazard + Outrage. Hazards are measurable; the pot-hole is of measurable dimensions, its physical location is known (or soon will be) and its continued existence is ‘an accident waiting to happen’. Hazard has dimensions that can include, likelihood of a fall into it, the potential severity and injury from a fall, and the frequency of potential walkers to come across the pot-hole. If there is an accident/incident outrage may be generated; if nothing is done about the pot-hole in a reasonable time, social acceptance of the performance of the local authority will be jeopardised. Fukushima is having new high tsunami walls built and new levels of safety are being introduced in the management of Japan’s nuclear power plants; these measures were needed to allow limited nuclear power plants to restart.

Ingaldi M and Klimecka-Tatar D (Ingaldi and Klimecka-Tatar, 2020) discussed the ‘considerable controversy’ that hydrogen would incur ‘in many countries’. Their study looked at (social) acceptance in Poland, the Czech Republic and Slovakia of the proposed hydrogen economy.

Questions put in their survey were: ‘(is) Hydrogen energy safe for People’ and ‘(is) the use of hydrogen fuel safe’? The result of the survey was, ‘[t]he respondents are not convinced that an adequate level of safety exists for energy derived from hydrogen’. They suggested more education to convince the population that hydrogen is safe; the gist of the article was H-E is good, it only needs social acceptance.

Ricci et al (Ricci et al. 2006) delineated the Hazards of Hydrogen. They noted in their conclusion: ‘Hydrogen as energy carrier for the future has to be viewed as an element in a complex network of technologies ranging from generation of hydrogen by various means, through different forms of distribution, down to varied end uses. It will also form part of a “socio-technical system”, for there is a key human element to the safety of any technology’ and ‘[i]f part of the expectations is that hydrogen is safe or at least as safe in similar uses as the familiar fossil fuels of the present, the public could be unnerved by a significant accidental fire or explosion associated with hydrogen in the transition to a hydrogen economy.’ So H-E has to work with strong technical inputs ensuring very high safety whilst being able to answer the social uncertainty.

Ricci and colleagues point out that Industrial experience with hydrogen is frequently used to anticipate the nature of potential safety concerns arising from its use as an energy carrier and a vehicle fuel, and state that ‘Industrial production and use of hydrogen as a chemical has gone on for at least 50 years, is well understood’. Industrial production using hydrogen as a chemical input or fuel can be very positive.

18. Hydrogen’s potential sources and roles: some positive aspects

All is not negative with respect to hydrogen. On the production side commercial methane cracking to produce a carbon product and a hydrogen co-product is possible. If the demand for specific carbon allotropes, such as graphene, exists and the cracking process can produce those allotropes, then the cost of ‘non-carbon’ hydrogen could be reduced.

Natural hydrogen, if found in useful quantities and concentrations, may be the answer to securing hydrogen as a bulk commodity that can be used for power generation. Niche hydrogen production systems such as DC power from PV solar plants being used for hydrolysis, with the hydrogen product being used for ammonia making and with oxygen being made available for sanitation, are possible.

Pipeline transport of hydrogen between collection nodes, that are part of a natural hydrogen system, and a reticulation hub connected to heavy industry are possible and there are already hydrogen pipelines in existence.

19. An alternative to the H-E: nuclear energy

Figure 2 shows a hydro or pumped-hydro system with the energy held in water impoundments being used to produce hydrogen. Presently and in the future, pumped-hydro is used for ensuring baseload demand is met. In Figure 13 nuclear power has been added to increase the baseload supply and ensure power dispatchability and thus security. The preference for maintaining H2 supply is substituted for maintaining power supply.

There are relatively few options open for creating a new fuel economy, with the fuel also being an energy carrier. If all carriers (fuels) that contain carbon are ruled out, an Electric Economy (E-E) is the only choice. An E-E comes with significant existing infrastructure, some of which may need urgent upgrading. Regions that have an existing significant nuclear power capacity with pumped storage opportunities are limited and the E-E finance opportunities are very unevenly distributed over the globe. On the positive side an expanded Electric Economy does not come with a host of hazards like the proposed Hydrogen Economy.

Figure 13. An Electric Economy (E-E) with nuclear generation.

Figure 13 shows what is essentially an electric generation and energy transport system. Nuclear energy is matched up with pumped-hydro since both can deliver baseload power with energy security. The traditional fossil fuels and H2 produced from fossil fuels can recede as nuclear capacity increases. Energy efficiency improvements will reduce carbon emissions and better methane management will further reduce emissions. Improvements in electricity transmission and distribution systems will also reduce greenhouse gas (GHG) production. Natural hydrogen, if available, can be used in supporting biomass in power generation.

19.1. The size and nature of new nuclear power plants (NPPs)

Many commentators are advocating large baseload Nuclear Power Plants, say 1200 MWe per unit and above, and others are advocating for Small Modular Reactors (SMRs), say ≤300 MWe each. A compromise would be pods of say 3–4 SMRs. The selection of reactor size will be dependent on demand, situation, and ‘9th of a kind’ plant cost. SMRs will, however, often win on project deliverability given their modular format.

The Eastern Australian Power Grid is not suitable for very large generation plants. By contrast US and European units can be larger since the grids are stronger and have higher population densities to service. It would be useful if the first of the SMRs were already operating as base-load (in-effect spinning reserve) to support the electricity grid of eastern Australia. For this to happen a major increase in the social acceptance of nuclear energy will be required and the availability of nuclear plant modular packages that are 5^th of-a-kind (or greater) will also be required. This discussion is for the future.

Nuclear energy is the only non-carbon baseload option that can maintain dispatchable power that will support renewable energy. The two energy forms are complementary.

19.2. Nuclear, hydrogen production and use, and social acceptance

Since the 1960s a social movement has developed opposed to the use of nuclear energy (Gamson and Modigliani 1989) and nuclear energy lost much social acceptance after the Three Mile Island, Windscale and Chernobyl nuclear accidents. However, in recent years sections of public and government opinion in the United States, United Kingdom, China and India have become more supportive to nuclear. That trend has continued to be true even after the 2011 Fukushima accident (Kugelmass 2020). It can be noted that the UK is progressing its replacement of nuclear power plants with new units such as Hinkley Point C, 3200 MWe (Tabuchi 2021).

The hydrogen economy is now encountering increasing scepticism and a heightened lack of social and institutional acceptance, as described by Tabuchi and researchers at the Australian National University (and the University of Queensland) (Beck et al. 2019). The ANU researchers state: ‘This public sentiment is crucial and highlights the public’s concern over climate change and the environment. It also foreshadows that there may be large-scale public opposition to hydrogen production methods that rely on fossil fuels and unproven CCS technologies’ (Beck et al. 2019).

Zaunbrecher et al (Zaunbrecher et al. 2016) found that, although there are supportive attitudes and trust in hydrogen storage in the populace, there are misconceptions. There is a lack of information and other concerns were mentioned. The presence of the ‘well-known NIMBY effect’ is causing close proximity decreasing acceptance. The conclusion of the paper states, ‘however, fear of risks (hydrogen related hazards), especially regarding hydrogen storage in residential areas, should be addressed adequately.’ The authors suggested that social acceptance of hydrogen (storage) will be achievable if there are adequate separations between communities and hydrogen facilities.

20. Conclusion

Figure 13 shows the progression of an Electric Economy that includes some nuclear energy inputs for guaranteeing power dispatchability with nuclear energy complementing renewables. The transport and reticulation sections of the progression have been revamped and losses have been minimised. The role of hydrogen will increase especially if the production of commercial natural hydrogen can be achieved. Electricity produced from renewable sources independently of major grids will be able to take advantage of battery storage. That electricity could be a homestead supply, a small industry supply or a small mini-grid for example, township supply.

The potential for natural hydrogen finds that have high hydrogen analyses is proven. The question is now whether those potential finds have the volumes of gas with good strata permeability that can make those finds commercial. The finds would likely need to be Type 1 accumulations for major grid connection. Potentially multiple Type 2 finds when agglomerated could be a source of hydrogen for a niche ammonia plant or remote petroleum refinery. N.B. The promoters of hydrogen have promoted natural hydrogen to Gold Hydrogen, so can an ammonia plant be directly connected to a gas well? See: Gold Hydrogen P/L www.goldhydrogen.com.au

In short, hydrogen as the basis of the Hydrogen Economy is not a solution to the oncoming energy crisis. If a non-carbon H2 supply that has the size to match the methane resource, can be created, then a major energy transfer system will have been created. Hydrogen will never totally replace methane as a fuel energy carrier. Electricity will increasingly be the main energy carrier, with methane as LNG and/or piped natural gas having a lesser but still significant role.

Complementary activities to reduce carbon emissions must include the conversion of fugitive methane (Global Warming Potential 23) to CO2 (GWP 1). Examples of opportunities are the conversion of ventilation air methane by combustion, the collection and use of agriculture biogas, and higher levels of aerobic digestion when processing human wastes. Oxygen produced by fuel cells could be used in methane oxidation, biogas conversion and enhanced aerobic digestion of wastes.

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Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

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Michael C Clarke

Dr Michael C Clarke, FIEAust, CPEng, FAusIMM, MPESA, RPEQ, has qualifications and experience in the fields of mining, chemical and environmental engineering. He has worked with gases for a significant part of his professional career, including the combustion of ventilation air methane, the recovery of helium from natural gas, carbon dioxide capture and sequestration, the hazards associated with hydrogen and the combustion of methane with increased radiance. Dr Clarke has been a research engineer, consulting engineer and academic. He has been a consultant to the Asian Development Bank and upstream petroleum companies and a consultant and energy research leader to waste-to-energy developers. He holds two research degrees: a MEngSc that looked at the ‘Biodegradation of Cyanide in Mine Tailings’ and a PhD that examined the ‘Use of Selective Flocculation in Recovering Coal Values from Coal Rejects’.

Notes

1. Acknowledgement for hydrogen properties data. Miriam Ricci, Gordon Newsholme, Paul Bellaby and Rob Flynn have produced a symposium paper titled ‘Hydrogen: too dangerous to base our future upon?’ Symposium Series No. 151, Crown Copyright 2006. https://www.icheme.org/media/9792/xix-paper-04.pdf The authors are thanked for their contribution to the debate.

2. Ashcroft N and Di Zanno P’s article, ‘Hydropower: a cost-effective source of energy for hydrogen production’ was published on 1 November 2021. This author does not agree with Ashcroft and Di Zanno’s conclusion that ‘hydro will be one of the world’s major suppliers of electricity for hydrogen production by 2050’. This author would argue that land and water for hydro will compete with land and water for agriculture, urban growth and amenity; that hydro is cyclic in terms of drought and flood cycles; and that suitable sites for hydro have already been taken for existing hydro.

3. As well as being an important industry for Australia, LNG is a very important fuel for East Asia and South Asia. Switching to natural gas has been used (and will be used) to reduce the use of coal in power generation and thus coal produced emissions.

4. Methanol is suggested as being an energy storage medium as well as being an intermediate chemical in producing di-methyl-ether and acetic acid. Methanol being produced in the following reaction: CO + 2H2 → CH3OH (Bowker 2019). A question: Where do the promoters find the green carbon monoxide to produce methanol? Partially reformed biomass may be one answer, but the cost of biomass is often high and subject to seasonal fluctuations in supply. Another question: Where does guaranteed (dedicated) water come from if the whole fuels and production complex is situated in a region prone to drought?