Hydrogen to Replace Natural Gas- By the Numbers

photo credit: energy.gov

Hydrogen to Replace Natural Gas- By the Numbers

UPDATED: April 6, 2023

There’s been a lot of talk recently about hydrogen as a replacement for natural gas. The scheme is to gradually add H2 to the natural gas grid, with the H2 being made from water using “excess” renewable electricity when it’s available. But ultimately, there are people who think we should have pure hydrogen supplied to our homes instead of natural gas, using the same piping and distribution network that we have now. In their minds, all we’d have to do is to re-jet all our boilers, furnaces, stove cooktops and ovens and we’ll be away to the races. No need to abandon all that expensive capital- we’ll just change the fuel! We’ll be burning colourless, odourless hydrogen, making only water vapour, and global warming will be one step closer to being solved.

Sounds great! Where do I sign?

Hold on- not so fast!

In case you prefer video to reading (I read far faster than I can watch anything, but to each their own!) Rosemary Barnes did an excellent video interview with me that used excellent graphics to get my points across- and asked excellent probative questions too. Well worth a watch- and the detail is here in the article you’ve already clicked on if you want to understand the issue more completely.

Replacing Gas With Hydrogen is An Inefficient Use of Energy

The first and most obvious criticism of this scheme is efficiency. It doesn’t matter if you start with natural gas or electricity, the best you can do is to convert about 70% of the feed energy (lower heating value (LHV) of methane, or kWh of electricity) into LHV of product hydrogen. Best case. If the alternative is to use natural gas or electricity directly, hydrogen brings nothing but loss to that equation.

Obviously the whole idea here is to eliminate the fossil greenhouse gas (GHG) emissions associated with the burning that’s happening at your end of their pipe. Hydrogen offers the option to do that. You can start with bio-methane from anaerobic digestion, so the CO2 you emit when you make hydrogen is just part of the natural carbon cycle. Or you can capture all or part of the CO2 produced when making hydrogen from fossil natural gas at the hydrogen plant, or by pyrolyzing the methane and selling carbon as a byproduct for uses other than burning, or you can avoid the CO2 entirely by making the electricity you feed your electrolyzer from wind or solar, nuclear, hydro, geothermal etc. These are all ways by which you could end up with a fossil GHG emission-free fuel for your burner- ideally that is, assuming you could afford it.

You could of course feed the grid with methane from biogas instead- but while I’m convinced biogas will be an important fuel for those fuel uses we really do need in a post-fossil future, nobody should try to convince you that there will be enough biogas EVER to just replace existing natural gas supplies- or even a small fraction of those supplies. So if you want to keep your burners, and not emit fossil GHGs, hydrogen seems like your only option. And that’s exactly what the natural gas industry is telling governments all over the world.

Of course, these gas companies and electrolyzer suppliers are not giving their advice without self-interest in mind. They are starting from the position that they need to stay in business, and you need to keep your burners- fair enough! The obvious alternative is to replace your burners directly with electricity and cut out the lossy hydrogen middleman, but that would leave them out of business. For home heating, and even for domestic hot water, a heat pump will not only save you the 30% conversion loss to hydrogen, it will also give you about 3 kWh worth of heat for every kWh worth of electricity you feed. Far, far more efficient. But not cheap- the heat pump is going to cost you quite a few dollars- and while renewable electricity is getting cheaper by the day, grid electricity still sells at a large multiple of the cost of natural gas per unit of energy- because carbon taxes are inadequate, and because in some places, fossil fuels still power the grid.

For your cooktop, an induction heater will give you even better performance than a flame- you may have to throw out a few of your old aluminum pots and pans, but otherwise you’ll likely be very happy with that change. And your oven will do nicely with a plain old resistance heater- with much better temperature control.

Remind me what we need a fuel gas for again, exactly? I know only one answer to that- right now, natural gas is a very, very cheap fuel IF you ignore the fossil GHG emissions from both its production and distribution and its burning. Displacing natural gas use from home heating is going to be a tough struggle regardless how we do it- because the alternatives are going to cost more, at least initially.


Source: David Cebon, Hydrogen Science Coalition

Note that the figure above is almost accurate- the distribution losses for hydrogen are exaggerated a bit due to a misinterpretation of a piece of data in a peer-reviewed article by Ulf Bossell, but even so- the efficiency of heatpumps may not be 5-6x better than hydrogen, but it’s at least 4-5x better…

Hydrogen, on the other hand, isn’t a cheap fuel, period. And it should be obvious that it can NEVER be as cheap as either the natural gas or the electricity from which it is made.

Hydrogen Distribution is Lossy and Expensive

Even assuming that you were so nostalgically attached to your gas appliances that you couldn’t part with them, the gas industry would still need to overcome some serious problems that aren’t being discussed, before hydrogen starts flowing through the natural gas grid.

If we’re going to make hydrogen, whether it’s “blue” hydrogen made from natural gas with carbon capture and storage, or “green” hydrogen made from water using renewable electricity, it still has to get from where it’s made to your house. And it’s not as simple as just changing what flows through the pipes.

Compression- the Deal Killer

To move any gas economically, it needs to be compressed. And it turns out this is the big problem with hydrogen distribution- it’s the reason that 85% of hydrogen produced in Europe, for instance, travels basically no distance to where it’s consumed, because it’s made right on the same site or right next door.

Natural gas is about 8.5 times as dense as hydrogen, and dense gases are easier (more energy efficient) to move than less dense ones. Hydrogen partially makes up for that fact by being more energy dense per unit mass- about 3 times as much as natural gas. But, sadly, the work (mechanical energy) needed to drive a compressor is related linearly to the number of moles of gas we compress, rather than to their mass or volume per se. It also depends, more weakly and in a more complex way, on the ratio of specific heats of the gas- which, as it turns out, makes a minor difference (in favour of natural gas) which increases with increasing compression ratio. But when we compare the LHV of hydrogen per mole to the LHV of natural gas per mole, we find that natural gas is about 2.9 times as energy dense in molar units. Another way to put it is that it takes about three times as much energy to compress a MJ’s worth of heat energy if you supply it as hydrogen than if you supply it as natural gas. And this, folks, at least in part, explains why we don’t move hydrogen around much by pipeline. Instead, we move natural gas to where hydrogen is needed, and build a hydrogen plant there. (see the end of the article for the proof)

That 3x increase in the work of compression not only costs energy, it would also cost a gas utility big money, since it would mean that every compressor in their network would need to be replaced with a new unit with 3x as much power, and also physically larger- with 3x the suction displacement. And since hydrogen is so notoriously leaky, the hydrogen volumetric flowrate is higher for a given heat flow in the pipe line etc., the compressors would need to be totally different machines- considerably more expensive ones.

Hydrogen is, already, round numbers, about 37% best case in cycle efficiency when starting and ending with electricity. Whereas natural gas and electricity are roughly the same cost and efficiency to distribute on a per unit energy basis, hydrogen is going to cost about 3x what natural gas costs in lost energy, just to move the gas. And since the downstream equipment is only 50-60% efficient at producing electricity again, you’re going to have to move roughly twice as MUCH hydrogen energy to destination to do the same job as if you moved electricity instead. That’s forgetting about the extra capital cost that would also need to be spent.

Pressure Drop in Piping- A Wash

You’d think that you’d suffer an additional penalty moving hydrogen through piping once you’d gotten it up to the desired pressure- that was certainly my first impression. But as it turns out, the answer to that question is quite complex, and it depends on what conditions you run the calculations at. Hydrogen is less dense, less viscous, and more energy dense per unit mass than natural gas. But when you run the pressure drop calculations at the sorts of velocities and pressure drops used in pipelines which carry gases long distances (where pressure drops are on the order of 5 psi per mile of pipe, rather than the 5 psi per 100 ft of pipe that might be typical in a chemical plant’s piping), hydrogen and natural gas come out nearly even at a given rate of LHV heat delivered per hour down a pipe of given size. That does change at different points in the distribution system, and to a 1st approximation, the average works out to an existing gas pipe being able to carry about 90% of the energy n the form of hydrogen that it could carry if it were fed the average natural gas it was designed for. The velocity will be about three times higher, but the density is 1/8.5x as much, and together with the modestly lower viscosity, the factors nearly cancel one another out. However, since every kWh of energy lost due to friction in the pipeline has to come from a compressor, that still means that hydrogen costs about 3x as much per unit of energy to move from source to destination in a pipeline.

“Line Pack”- What’s That? Another Problem…

As I promise my readers, I EDIT my articles when they teach me new things or point out my mistakes. And a knowledgeable connection brought to my attention this rather major problem that is a result of hydrogen’s lower energy density per unit volume. “Line pack” is the name given to the amount of natural gas stored in the piping distribution system itself. And unless we increase the pressure of the distribution system- which we cannot do without new pipe- we will lose that storage. A typical gas system apparently can handle about 3-4 hours of average demand just using stored gas in the lines. Pure hydrogen, being 1/3 as dense in energy per unit volume, would reduce that to ~ 1 hour. That could mean a giant difference in distribution system reliability, the frequency and duration of outages, and the ability of the grid as it exists to handle variations in demand- the big spike when everybody gets home, cranks up their furnaces or boilers and turns on their cooktops for instance.

I’m already aware that sometimes, subdivisions out-grow the rate at which the gas utilities can install new lines to them. Accordingly, some utilities evaporate liquid natural gas from tanks into points downstream of the “bottleneck” in order to keep the furnaces and cooktops humming through peak hours. Doing that with hydrogen would be very expensive and very dangerous, given that liquid hydrogen takes about 40% of the energy IN the hydrogen just to liquefy it, boils at 24 Kelvin (24 degrees above absolute zero- liquid methane boils at a balmy 112 Kelvin or -161 C)- and as a liquid it is still only 71 kg/m3- methane is about 420 kg/m3 in comparison as a liquid.

Piping and Equipment

If you don’t heat it up too much, hydrogen is quite safe to carry in mild steel piping- even up to fairly significant pressures. The much talked about “hydrogen embrittlement” isn’t a factor in relation to hydrogen gas handling for soft mild steel or low alloy steel piping such as what is used in most chemical plant piping.

However, natural gas pipelines- particularly the pipelines carrying natural gas long distances or underwater- are not made from mild steels. They’re made from harder, strong steels- and those steels are, according to many reports, susceptible to hydrogen embrittlement or other hydrogen related damage mechanisms, particularly in their welds and heat affected zones- even at fairly modest pressures and temperatures.

According to credible reports written by natural gas distribution utilities themselves, such as this excellent one:


-most of the high and medium pressure natural gas distribution system would need to be totally replaced to handle pure hydrogen. (see p.12 of that reference, where it says this in as many words- and these guys, who own the pipes, should know best!) That’s a massive cost- especially to spend on a change to a fuel which might be better replaced with electricity anyway.

Note that hydrogen damage and hydrogen embrittlement are complex metallurgical topics, and that nascent hydrogen (hydrogen atoms generated by electrochemical action such as during corrosion) causes damage that molecular hydrogen cannot until a combination of high pressure and high temperature make that possible. But the reports about H2 compatibility problems with pipelines used for natural gas is quite well demonstrated, by people who know this issue far better than I do.

Here’s another reference, from AIGA standard 087/20:

From Standard AIGA-087/20 (Asian Industrial Gases Association) Section 4.2.1- Metals

“… For high pressure applications, carbon steel shall be used with caution. Carbon steels with high-carbon content and high-strength, low-alloy carbon steels are susceptible to embrittlement and crack propagation. The use of carbon or alloy steels requires control of tensile strength, heat treatment, microstructure, and surface finish as well as initial and periodic examination for inclusions and crack-like defects when in cyclic service”

And another, from Sandia National Laboratories:

A webinar I attended (September 21, 2022) on the platform “Mission-Hydrogen”, confirmed these concerns. (A video recording of the webinar and of the presenter’s slides is available).  The lecturer was Dr. Milos Djukic of the University of Belgrade, a senior fellow of the European Structural Integrity Society, whose summary paper on the issues related to hydrogen damage and embrittlement mechanisms in steels and alloys has been cited over 100 times.  In the talk, Dr. Djukic confirmed that 1-5% H2 is enough to cause worries about hydrogen assisted fatigue crack growth, that fatigue can be accelerated by more than 10 times (indeed Dr. Djukic confirms the rate may increase up to 30 times), and fracture resistance can be reduced by more than 50%, and that all the normal high yield stress API grades of pipeline steel are susceptible.  Dr. Djukic concluded in his talk as follows (emphasis is his):

“It is widely believed that existing gas pipelines that are retrofitted for transportation of natural gas-H2, CH4-H2 and N2-H2 gas mixtures, and repurposed for 100% H2 transport, are viable options and safe for long term future usage.  However, despite the fact that gaseous H2 transport via existing gas pipelines is a low-cost option for delivering large volumes of H2, there is a serious threat of hydrogen damage and catastrophic failure, particularly for old-aged gas pipelines, after future long-term H service. “

UPDATE April 2023: a recent study paid for by German gas and water association DVGW proves, by careful measurement, that the materials used in gas pipelines- even low yield strength versions- suffer from accelerated fatigue cracking and reduced fracture toughness, even in some cases at fairly low hydrogen partial pressures. However the study claims that it’s OK, because the cracking doesn’t happen faster and the fatigue resistance doesn’t drop sufficiently to fall outside the limits of dedicated hydrogen piping design code ASME B31.12- a code that fossil gas pipelines are NOT designed and fabricated to.

Under the hydrogen design code, the design pressure of an existing fossil gas line would need to be de-rated to perhaps 1/2 to as little as 1/3 of its original rating if it were switched to carry hydrogen. That’s going to have a very large impact on the energy carrying capacity of those lines, likely necessitating either twinning or replacement of any transmission line switched to hydrogen. And it stands to reason that “twinning” would need to be in the cards anyway, as in any realistic transition scenario there will be a time when a transmission system would need to supply both hydrogen AND fossil gas to its customers. Hmmm…the notion that you can re-use this infrastructure meaningfully is looking less and less promising the more we look into it!


The low pressure distribution system is mostly made up of low carbon steel and HDPE pipe, and you can run hydrogen through that easily enough.

(UPDATE: even HDPE may have some problems with hydrogen, per NREL’s recent report (10/2022): see https://www.nrel.gov/docs/fy23osti/81704.pdf)

However, piping designed not to leak natural gas can leak a lot of hydrogen due to hydrogen’s low density and high diffusivity. Intact HDPE piping and the seals and other “soft goods” used in the distribution system are quite permeable to hydrogen. And, sadly, stenching agents such as the thiols (mercaptans) used in natural gas to help detect leaks, may be used in hydrogen for burning, but not with hydrogen to be used to feed PEM fuelcells such as those used in vehicles. The catalysts in those fuelcells are extremely sensitive to sulphur compounds like that. Given hydrogen’s extremely wide explosive range- any mixture between 4% and 75% hydrogen in air is explosive- and its low ignition energy- the lack of a stenching agent to help you detect leaks seems a very challenging problem for distribution of this fuel to homes and businesses.

Hydrogen/Natural Gas Mixtures

The initial projects all try to smooth over these problems by mixing a little H2 into natural gas instead of making the big leap to pure hydrogen. And when you hear about “replacing 20% of natural gas with hydrogen”, you’d think that would make a big difference!

Think again.

A 20% mixture of H2 in natural gas is a 20% mixture by volume. That mixture has only 86% of the energy of an average natural gas, meaning that you’d have to burn 14% more volume of gas to make the same number of joules or BTU of heat. The savings in GHG emissions are nowhere nearly 20%- they’re closer to 7% just looking at the burning (assuming perfectly carbon free green hydrogen), and less than that when you consider the compression and pressure loss noted above. Such a reduction would already cause heat content sensitive users to scream, so forget about going to 30% H2! For a given amount of energy delivered, a 20% mixture of hydrogen in natural gas would take 13% more energy to compress and would lose about 10% more pressure per unit length of pipe than if you were to stick with natural gas- because the gas has to flow faster, and yet isn’t sufficiently lower in density to compensate. Those factors would eat some of your GHG emission savings. And while industrial users would be protected- they pay per BTU or joule of LHV or HHV they are delivered by the gas company- some users could be shortchanged since they pay per unit volume instead.

comparison between gas and H2 from Eng w Rosie

(Image Credit: Rosemary Barnes, from her Engineering With Rosie video, link previously provided)

Of course, to get ANY meaningful reduction in GHG emissions, you need to use “green” hydrogen (made by electrolysis using fossil-free energy). That doesn’t exist meaningfully in the market at present- it is too expensive. So what is brought to the rescue? So-called “blue” hydrogen, made the normal way, from fossils, but with carbon capture and storage (CCS). Sadly, that approach makes only muddy blackish-blue, bruise-coloured hydrogen at best, as this paper by Howarth and Jacobson published in Environmental Science and Engineering makes clear. Fossil advocates have pooh-poohed the paper because it uses methane emissions higher than they’d like to admit to, and because it uses the 20 yr time horizon greenhouse potential of methane relative to CO2 which is 86x CO2. But even if you use the sensitivity analysis in the paper to trim back the estimated methane leakage, and you imagine that all “blue” hydrogen production will use new oxy-blown autothermal reformers so carbon capture can be more complete, “blue” hydrogen appears to be a very poor strategy for decarbonization. It is, in contrast, an excellent strategy in the view of the fossil fuel industry, because their objective is to stay in business, not to decarbonize anything really.

But What About “Hard to Decarbonize Industries”?

Another excuse we hear for the need for hydrogen to replace natural gas is for “high temperature industrial heating”. For some reason, people just seem to assume that because we run some equipment right now by burning fuels, we cannot instead use electricity. The examples of steel and cement-making are frequently brought up, but there are many others.

Here I have to bring in what I do for a living. I design and build pilot plants, which are prototype units to test new chemical processes. These plants can vary from tiny lab units to quite large facilities that would look to the average person like any other real chemical plant. But the one thing that a pilot plant will almost entirely without exception be missing is any fired equipment. There are exceptions, but aside from the function of disposing of waste streams of combustible materials, every function that is accomplished on a commercial chemical plant using fired equipment, is done using electricity instead on a pilot plant. Why is that?

Many reasons:

1) Electricity is far safer and easier to control than fire, particularly at the small scale. Electric heating provides rapid, accurate control and reduces hot spots, reduces risks to materials of construction etc.

2) Electricity costs more than fuel as a heat source, but the energy cost of a pilot plant is seldom the most important factor to its operators.

3) Fired heaters generally need air emissions permits and may require stack gas testing- costs which the pilot plant avoids by using electric heating.

4) To heat a stream to high temperatures using a burner, you are left with a high temperature flue gas exiting the unit. Chemical plants make use of that hot flue gas to heat up numerous other streams to keep it from going to waste- or use it to make steam to drive equipment or keep things hot. On a pilot plant, it is just not worth the trouble of doing that kind of heat integration

5) Fired equipment is more expensive than electrically heated equipment

6) When you need the highest temperatures, sometimes electric heating is the only feasible option.

In steelmaking, the real need for hydrogen isn’t for heating at all- electric arc furnaces for steelmaking are already quite popular. Hydrogen is needed to replace the chemical reductant carbon monoxide made from coal coke, which is used to reduce iron oxide to iron metal. There are direct electrochemical reduction methods also under development, so it’s possible we could also make steel without using hydrogen at all.

In many other applications, electric heating could easily be used to eliminate the need to burn fuels. It would however require modification to major pieces of equipment, which might have a considerable cost. But if the alternative is to spend a multiple of that cost on hydrogen made FROM electricity, that savings can pay for quite a bit of capital.

In fact, if approached with a fresh sheet of paper and without a firebox on your head, most applications in industrial heating currently served with fire for cost reasons (because fuels are cheaper, as long as you can dump fossil CO2 to the atmosphere), could easily be converted to electric heating instead.

All we really need is to price fossil carbon emissions at a rate high enough- and durably enough- to make the associated capital investments worthwhile in economic terms for the affected industries.

Hydrogen Toxic Emissions

You will frequently hear the old trope that when you burn hydrogen, you get nothing but water! While that IS true if you “burn” hydrogen catalytically in a low temperature fuelcell, it is NOT true in general terms.

Burning ANYTHING in air results in nitrogen oxides (NOx) being generated by reaction between oxygen and nitrogen in the air. The higher the combustion temperature, the more NOx you generate. And the more H2 you add to a natural gas mixture, the higher the resulting free air combustion temperature will be- and hence, the higher the NOx emissions will be.

NOx consists of two important nitrogen oxides and one transient species. NO2 is the dangerous brownish gas which is toxic, produces “acid rain”, and is a photochemical smog precursor. It is however quite water soluble (hence the acid rain) and so it isn’t environmentally persistent.

N2O (nitrous oxide) isn’t toxic- it’s used as an anaesthetic and it may even be produced in our own bodies. It is however a powerful, persistent GHG with a 100 yr greenhouse potential of 300x that of CO2.

Industrial combustion equipment burning hydrogen or H2-rich mixtures can be fitted with selective catalytic reduction (SCR) units, which react NOx with hydrogen to produce N2 and water again. Not so with home appliances though- it is fundamentally impossible with things like cooktops for obvious reasons, and it is economically impractical with devices like furnaces, rooftop heating units, hot water heaters and heating boilers too.

This issue seems to be conveniently forgotten. Natural gas burning in homes is already a major source of indoor air pollution and apparently also a major cause of juvenile asthma. Hydrogen will make that worse, not better, relative to natural gas.

Flame Visibility

Don’t let the stupid “hydrogen olympics” fool you. Hydrogen flames are rich in the UV and emit very limited amount of visible light. They are visible only at night, unless the H2 is contaminated with something. The Olympic flame was contaminated deliberately with sodium carbonate, giving it the eerie orange glow from the spectral emission lines of sodium.

Hydrogen for Seasonal Energy Storage

Another argument that I frequently hear is that because of the double whammy of greater energy need for heating and lower solar power production in winter, we’ll need hydrogen to make up the shortfall. We’ll need to make vast quantities of hydrogen in summer, and store it in salt caverns until winter. While stored fuels of some kind are likely a useful part of an emergency response plan in any post-fossil fuelled future, it is to me a non sequitur that just because it’s possible to use hydrogen for this purpose, that doing so would actually make energetic or economic sense. Methane, whether from biogas or even fossil natural gas, seems a more logical choice as a gas to store, given that we already have strategic and emergency stores of natural gas in place. And we could just as easily store up a year’s worth of biogas methane as we could find a way to make hydrogen in excess in summer.

Green hydrogen’s chief economic problem as an energy storage medium is the cost of electrolyzers and storage equipment- and as we’ve seen in this paper, distribution cost isn’t going to be as low as some expect either. Multiplying the low capacity factor of a wind or solar production unit by another seasonal capacity factor of say 0.5 or less, doesn’t add up to a low capital cost per kg of hydrogen stored. This stored fuel would be very expensive indeed, even if the power itself were quite cheap.

Why Are We Doing This Again?

NREL’s document issued in October 2022 about hydrogen blending (see https://www.nrel.gov/docs/fy23osti/81704.pdf) contains a very good summary of the challenges involved in replacing fossil gas with hydrogen, including this excellent table:

In summary, it seems to me quite clear that hydrogen’s role as a replacement for natural gas has more to do with a need for gas production and distribution companies to stay in business by having something to sell, than any real GHG emissions benefit or significant technical need. And if they want to make the necessary investments entirely on their own nickel, to provide truly green or even “blue” hydrogen via an upgraded network to replace natural gas, perhaps that’s OK with me. Sadly, it seems quite clear that their caps are in hand, reaching out to the public sector to fund the necessary infrastructure investments. Personally, my thinking is that this would be throwing good money after bad.

DISCLAIMER: these are my personal opinions, informed by my knowledge and practice of chemical engineering over the past 30 yrs. My opinions are my own, and are not to be confused with those of former employers or current or former clients. I am motivated only by a sincere desire to get us off fossil fuels and by so doing, eliminate fossil GHG and toxic emissions associated with burning them, for as low a cost and impact on society as we can manage. Every article I write is likely to make one or another of my customers angry- you can rest assured of that!

I have made my best effort to be accurate in what I’ve said, doing my own confirmatory calculations. I can provide background on those to anyone who asks. But I’m human, and hence prone to error. I also don’t for a moment claim to know everything there is to know about this subject matter, which is where some people have spent their entire careers. If you can show me where I’ve gone wrong in my analysis or calculations, with references or dependable examples, I’ll gratefully edit my piece to reflect these new learnings on my part.


Here’s the abbreviated logic behind why it takes 3x as much compressor energy to move a given amount of H2 LHV as to move the same number of J or BTU of natural gas LHV.

Where a and b are constants, different for each gas, but only a little different between H2 and natural gas, and r is the compression ratio i.e. P2/P1, P1 is the initial absolute pressure and V1 is the initial volume, the work of adiabatic compression is given by a formula of the following form:

W = a P1V1 (1-r(1/r)^b)

Per the ideal gas law, P1V1 = nRT1, where n is the number of moles of gas, R is the ideal gas constant, and T1 is the initial temperature.

Taking gases 1 and 2 of nearly equal values of a and b (to avoid getting results which vary with r), and taking them at the same initial pressure, volume and temperature, it can be shown that:

W1/W2 = ~ n1/n2

Hydrogen has a molar LHV of 240 kJ/mol, and a middle of the road natural gas might have a LHV of 695 kJ/mol. The work ratio is therefore ~2.9:1 for hydrogen versus natural gas, if we were to move a constant number of kJ of LHV per compression stroke, or per unit time.

The actual values of a and b (related to the Cp/Cv ratio) for H2 and natural gas at commercially significant compression ratios adjust this 2.9:1 ratio to about 3:1.

What is #hopium?

Rene Magritte, “The Treachery of Images” 1929

First of all, #hopium isn’t my original idea. I would attribute the use of the term to the person who I first heard use it, but sadly I’ve forgotten. The moment I heard it, I knew this was the ideal description of a problem I’d been seeing in numerous areas of our attempt to decarbonize our economy. I now use it as a hashtag when I identify its use, when I see it.

Hopium is a merging of the words “hope” and “opium”. When I use it, I mean the conversion of our hope into a drug that compromises our ability to analyze and make good judgments about new technology.

Hopium is the fuel of “green-wishing”, without which, green-washing wouldn’t be possible. Greenwishing is wishful thinking which has us conclude, without a basis in fact, without the necessary weighing of benefits against disadvantages, that a particular new thing is going to be our decarbonization salvation. And greenwishing is at epidemic proportions. We’ve spent the past 30 yrs basically hoping that engineers like me will come up with some “deus ex machina” solution to the AGW risk, which will allow us to go on living the exact same way we’ve been living, with no compromises, no extra costs, no carbon taxes so we stop treating the atmosphere like a free public sewer.

On hope: I’m with the great German author Goethe, who famously said, “In all things, hope is preferable to despair.” I qualify Goethe’s comment though, by saying that in order for hope to be worthy of us, our hope can’t be contrary to the most basic laws of the universe. False hope which can be demonstrated clearly to be false is more than merely a distraction- it’s a tool used by hucksters to separate us, and our governments, from our money.

Deus ex machina- god from the machine- by DALL-E

The “opium” aspect is largely a result of either our ignorance of physical laws and of basic science, or our ridiculous willingness to set them aside when it sounds like it would make a good story or would solve our problems.


The delivery mechanism of hopium is marketing hyperbole. It isn’t just limited to the telling of lies or the spreading of misinformation that would lead to the false conclusion that something bad is actually good. It is the exaggeration of claims and neglecting to mention the limitations within which a technology, new or old, is of use- and where it goes off into the ditch and becomes a liability. It is telling the truth with head nodding “yes”, without telling any of the truth with head nodding “no” that we need to fully understand the issues.

While it’s natural for people selling things to put a positive spin on their product or service, what drives me to drink (and it’s not a far drive most days!) is when JOURNALISTS do this. When journalists fail to even ask the questions necessary to establish whether what they’ve been given is just a sales pitch or a realistic alternative. Of course that’s a big part of the problem right there- the loss of real journalism in the Internet era. Writers become salespeople whose job is to generate “clicks”, not to inform the public.

While I use the #hopium hashtag most often in relation to the so-called “hydrogen economy” predicated on the use of hydrogen as a fuel, it is by no means restricted just to hydrogen. Rather intense hopium slinging is rife in relation to battery development. In fact, it has long been so- Edison said as much:

“Edison warned that chasing the perfect battery is a fool’s journey: “a catchpenny, a sensation, a mechanism for swindling the public by stock companies,” he wrote. Working on the latest, greatest battery brings out a man’s “latent capacity for lying.”

(This brilliant article by my connection @Copeland Kell says it better than I could!)

And in case you need a recipe on how to do this, there’s one provided in a peer-reviewed journal article!


But hopium is also rife in relation to carbon capture and storage schemes and particularly the foolishness known as “direct air capture”. If you’re interested in this, you can’t do better than @Michael Barnard’s brilliant take-down of Carbon Engineering, who Michael aptly refers to as “Chevron’s Figleaf”

Small modular nuclear reactors, especially the thorium ones, are another clear example. They rely on an ignorance of the PAST of nuclear power, and of the most elementary engineering economics. They are extraordinarily unlikely to EVER make cheap kWh.


In the most delicious irony, Hopium is also the chosen name of a French hydrogen fuelcell car company – fuelcell cars being to me the epitome of a bad idea which has been known for decades to be a bad idea, and yet hope for it springs eternal- and public money keeps being poured down this particular black hole long after its best before date.

What did Hopium choose to call its first car model? The Machina, of course. You can’t make sh*t up better than this…

I often say that I have a high tolerance to hopium because I was once a hopium addict myself. I was a true believer in hydrogen, until I spent a couple years working directly on a project trying to make small reformers and other equipment for making hydrogen to supply fuelcells. It was intense study and practice with the material which woke me up to what others have known about it for a considerable period of time.

What’s the antidote to hopium? Information and analysis done by disinterested parties. I try my best to be part of that. And when I believe firmly that a technology has promise and is a good solution, I do try my best to establish the limits within which that conclusion is accurate. Electric vehicles being just one such for-instance. My first article about energy and decarbonization matters was in fact written to take on a #hopium fuelled fallacy popular in the EV media at the time.

I also co-wrote with James Carter a series of articles which were quite popular with readers but not with the media outlet who chose to publish it…they like telling happier stories I guess.

How can you help to combat the #hopium epidemic? Well, sharing my articles is a help! Nobody is paying me to write them, and they are not written in response to personal or professional financial interest. My employer disavows all connection with my efforts, even when it sometimes brings them business, because it also brings out people who try to silence me by means OF my employer. They would prefer me to shut up about this stuff! But I have the opportunity to speak out and at this point in my career, I see that as a responsibility.

I advise you as my sister did: keep an open mind, but not so open that your brain falls out of your head. And be cautious and skeptical rather than being automatically negative- that can have you buying into nirvana fallacy arguments against things which really could be effective to help us with decarbonization. And work on solutions- real solutions, rather than easy ones. Here’s my suite of solutions- I mis-numbered them so there’s one left for

And lastly, be wary of anything anyone asks you to eat, smoke or drink…

And be wary about my alter-ego. You can tell him not only by what he says, but by his beard of bees…

Distilled Thoughts On Hydrogen

All my concerns about hydrogen #hopium, in one convenient place!

Hydrogen is being sold as if it were the “Swiss Army knife” of the energy transition. Useful for every energy purpose under the sun. Sadly, hydrogen is rather like THIS Swiss Army knife, the Wenger 16999 Giant. It costs $1400, weighs 7 pounds, and is a suboptimal tool for just about every purpose!

The Wenger 16999 Giant (the Wenger brand is discontinued- owned by Victorinox)

Why do you hate hydrogen so much? I DON’T HATE HYDROGEN! I think it’s a dumb thing to use as a fuel, or as a way to store electricity. That’s all.

I also think it’s part of a bait and switch scam being put forward by the fossil fuel industry. And what about the electrolyzer and fuelcell companies, the technical gas suppliers, natural gas utilities and the renewable electricity companies that are pushing hydrogen for energy uses? They’re just the fossil fuel industry’s “useful idiots” in this regard.


If you prefer to listen rather than read, I appeared as a guest on the Redefining Energy Podcast, with hosts Laurent Segalen and Gerard Reid: episodes 19 and 44


…or my participation in a recent Reuters Renewables debate event, attended by about 3000

This article gives links to my articles which give my opinions about hydrogen in depth, with some links to articles by others which I’ve found helpful and accurate.

Hydrogen For Transport

Not for cars and light trucks. The idea seems appealing, but the devil is in the details if you look at this more than casually.


When you look at two cars with the same range that you can actually buy, it turns out that my best case round-trip efficiency estimate- 37%- is too optimistic. The hydrogen fuelcell car uses 3.2x as much energy and costs over 5.4x as much per mile driven.


What about trucks? Ships? Trains? Aircraft?

For trucks- I agree with James Carter- they’re going EV. EVs will do the work from the short range end of the duty, and biofuels will take the longer range, remote/rural delivery market for logistical reasons. Hydrogen has no market left in the middle in my opinion.

Trains: same deal.

Aircraft? Forget about jet aircraft powered by hydrogen. We’ll use biofuels for them, or we’ll convert hydrogen and CO2 to e-fuels if we can’t find enough biofuels. And if we do that, we’ll cry buckets of tears over the cost, because inefficiency means high cost.

(Note that the figures provided by Transport and Environment over-state the efficiency of hydrogen and of the engines used in the e-fuels cases- but in jets, a turbofan is likely about as efficient as a fuelcell in terms of thermodynamic work per unit of fuel LHV fed. The point of the figure is to show the penalty you pay by converting hydrogen and CO2 to an e-fuel- the original T&E chart over-stated that efficiency significantly)

Ships? There’s no way in my view that the very bottom-feeders of the transport energy market- used to burning basically liquid coal (petroleum residuum-derived bunker fuel with 3.5% sulphur, laden with metals and belching out GHGs without a care in the world) are going to switch to hydrogen, much less ammonia, with its whopping 11-19% round-trip efficiency.



Fundamentally, why do we burn things? To make heat, of course!

Right now, we burn things to make heat to make electricity. Hence, it is cheaper to heat things using whatever we’re burning to make electricity, than it is to use electricity. Even with a coefficient of performance for a heat pump, so we can pump 3 joules of heat for every joule of electricity we feed, it’s still cheaper to skip the electrical middleman and use the fuel directly, saving all that capital and all those energy losses.


Accordingly, hydrogen- made from a fuel (methane), is not used as a fuel. Methane is the cheaper option, obviously!

In the future, we’re going to start with electricity made from wind, solar, geothermal etc. And thence, it will be cheaper to use electricity directly to make heat, rather than losing 30% bare minimum of our electricity to make a fuel (hydrogen) from it first. By cutting out the molecular middleman, we’ll save energy and capital. It will be cheaper to heat using electricity.

I know it’s backwards to the way you’re thinking now. But it’s not wrong.

Replacing comfort heating use of natural gas with hydrogen is fraught with difficulties.


Hydrogen takes 3x as much energy to move than natural gas, which takes about as much energy to move as electricity. But per unit exergy moved, electricity wins, hands down. Those thinking it’s easier to move hydrogen than electricity are fooling themselves. And those who think that re-using the natural gas grid just makes sense, despite the problems mentioned in my article above, are suffering from the sunk cost fallacy- and are buying a bill of goods from the fossil fuel industry. When the alternative is to go out of business, people imagine all sorts of things might make sense if it allows them to stay in business.

Hydrogen as Energy Storage

We’re going to need to store electricity from wind and solar- that is obvious.

We’re also going to need to store some energy in molecules, for those weeks in the winter when the solar panels are covered in snow, and a high pressure area has set in and wind has dropped to nothing.

It is, however, a non-sequitur to conclude that therefore we must make those molecules from electricity! It’s possible, but it is by no means the only option nor the most sensible one.


…But…Green Hydrogen is Going to Be So Cheap!

No, sorry folks, it isn’t.

The reality is, black hydrogen is much cheaper. And if you don’t carbon tax the hell out of black hydrogen, that’s what you’re going to get.

Replacing black hydrogen has to be our focus- our priority- for any green hydrogen we make. But sadly, blue (CCS) hydrogen is likely to be cheaper. Increasing carbon taxes are going to turn black hydrogen into muddy black-blue hydrogen, as the existing users of steam methane reformers (SMRs) gradually start to capture and bury the easy portion of the CO2 coming from their gas purification trains- the portion they’re simply dumping into the atmosphere for free at the moment.


There is no green hydrogen to speak of right now. Why not? Because nobody can afford it. It costs a multiple of the cost of blue hydrogen, which costs a multiple of the cost of black hydrogen.

The reality is, you can’t afford either the electricity, or the capital, to make green hydrogen. The limit cases are instructive: imagine you can get electricity for 2 cents per kWh- sounds great, right? H2 production all in is about 55 kWh/kg. That’s $1.10 per kg just to buy the electricity- nothing left for capital or other operating costs. And yet, that’s the current price in the US gulf coast, for wholesale hydrogen internal to an ammonia plant like this one- brand new, being constructed in Texas City- using Air Products’ largest black hydrogen SMR.


At the other end, let’s imagine you get your electricity for free! But you only get it for free at 45% capacity factor- which by the way would be the entire output of an offshore wind park- about as good as you can possibly get for renewable electricity (solar here in Ontario for instance is only 16% capacity factor…)

If you had 1 MW worth of electrolyzer, you could make about 200 kg of H2 per day at 45% capacity factor. If you could sell it all for $1.50/kg, and you could do that for 20 yrs, and whoever gave you the money didn’t care about earning a return on their investment, you could pay about $2.1 million for your electrolyzer set-up- the electrolyzer, water treatment, storage tanks, buildings etc.- assuming you didn’t have any other operating costs (you will have). And…sadly…that’s about what an electrolyzer costs right now, installed. And no, your electrolyzer will not last more than 20 yrs either.

Will the capital costs get better? Sure! With scale, the electrolyzer will get cheaper per MW, as people start mass producing them. And as you make your project bigger, the cost of the associated stuff as a proportion of the total project cost will drop to- to an extent, not infinitely.

But the fundamental problem here is that a) electricity is never free b) cheap electricity is never available 24/7, so it always has a poor capacity factor and c) electrolyzers are not only not free, they are very expensive and only part of the cost of a hydrogen production facility.

Can you improve the capacity factor by using batteries? If you do, your cost per kWh increases a lot- and that dispatchable electricity in the battery is worth a lot more to the grid than you could possibly make by making hydrogen from it.

Can you improve the capacity factor by making your electrolyzer smaller than the capacity of your wind/solar park? Yes, but then the cost per kWh of your feed electricity increases because you’re using your wind/solar facility less efficiently, throwing away a bunch of its kWh. And I thought that concern over wasting that surplus electricity was the whole reason we were making hydrogen from it!?!?

John Poljak has done a good job running the numbers. And the numbers don’t lie. Getting hydrogen to the scale necessary to compete with blue much less black hydrogen is going to take tens to hundreds of billions of dollars of money that is better spent doing something which would actually decarbonize our economy.


UPDATE: John’s most recent paper makes it even clearer- the claims being made by green hydrogen proponents of ultra-low costs per kg of H2 are “aspirational” and very hard to justify in the near term. They require a sequence of miracles to come true.


Why Does This Make You So Angry, Paul?

We’ve known these things for a long time. Nothing has changed, really. Renewable electricity is more available, popular, and cheaper than ever. But nothing about hydrogen has changed. 120 megatonnes of the stuff was made last year, and 98.5% of it was made from fossils, without carbon capture. It’s a technical gas, used as a chemical reagent. It is not used as a fuel or energy carrier right now, at all. And that’s for good reasons associated with economics that come right from the basic thermodynamics.

What we have is interested parties muddying the waters, selling governments a bill of goods- and believe me, those parties intend to issue an invoice when that bill of goods has been sold! And that’s leading us toward an end that I think is absolutely the wrong way to go: it’s leading us toward a re-creation of the fossil fuel paradigm, selling us a fossil fuel with a thick obscuring coat of greenwash. That’s not in the interest of solving the crushing problem of anthropogenic global warming:


Where Does Hydrogen Make Sense?

We need to solve the decarbonization problem OF hydrogen, first. Hydrogen is a valuable (120 million tonne per year) commodity CHEMICAL – a valuable reducing agent and feedstock to innumerable processes- most notably ammonia as already mentioned. That’s a 40 million tonne market, essential for human life, almost entirely supplied by BLACK hydrogen right now. Fix those problems FIRST, before dreaming of having any excess to waste as an inefficient, ineffective heating or comfort fuel!!!

Here’s my version of @Michael Liebreich’s hydrogen merit order ladder. I’ve added coloured circles to the applications where I think there are better solutions THAN hydrogen. Only the ones in black make sense to me in terms of long-term decarbonization, assuming we solve the problem OF hydrogen by finding ways to afford to not make it from methane or coal with CO2 emissions to the atmosphere- virtually the only way we actually make hydrogen today.

If Not Hydrogen, Then What?

Here’s my suite of solutions. The only use I have for green hydrogen is as a replacement for black hydrogen- very important so we can keep eating.


There are a few uses for H2 to replace difficult industrial applications too. Reducing iron ore to iron metal is one example- it is already a significant user of hydrogen and more projects are being planned and piloted as we speak. But there, hydrogen is not being used as a fuel per se- it is being used as a chemical reducing agent to replace carbon monoxide made from coal coke. The reaction between iron oxide and hydrogen is actually slightly endothermic. The heat can be supplied with electricity- in fact arc furnaces are already widely used to make steel from steel scrap.

In summary: the hydrogen economy is a bill of goods, being sold to you. You may not see the invoice for that bill of goods, but the fossil fuel industry has it ready and waiting for you, or your government, to pay it- once you’ve taken the green hydrogen bait.

DISCLAIMER: everything I say here, and in each of these articles, is my own opinion. I come by it honestly, after having worked with and made hydrogen and syngas for 30 yrs. If I’ve said something in error, please by all means correct me! Point out why what I’ve said is wrong, with references, and I’ll happily correct it. If you disagree with me, disagree with me in the comments and we’ll have a lively discussion- but go ad hominem and I’ll block you.