Hydrogen: a primer

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What is it, how do we make it, and what is it good for

Recently a reader (I have a Reader!) wanted to know more about hydrogen. I provided a quick answer, offering to dig a little deeper if useful. So here goes. There will be a bit of basic chemistry which I hope I have simplified sufficiently. Ultimately every bit of analysis here relates to energy: where does it come from, what does it cost, and what are the greenhouse gas emission implications; and generating energy often involves the chemistry of combustion. After all, 75% of total world greenhouse gas emissions are related to energy production and use.

Hydrogen is the name of an atom, with the symbol H, as well as the name of a molecule made up of two hydrogen atoms, H2. Similarly, two oxygen atoms O pair up to make an oxygen molecule O2. Hydrogen, like a lot of things, will burn in an oxygen atmosphere. The chemists call this process “oxidation”, because the stuff being burned is broken up into smaller units which combine with the oxygen in the air. Combustion, or oxidation, releases a lot of heat, which is why it is useful. So oxidising hydrogen looks like this:

2 H₂ + O₂ → 2 H₂O

This simply says that 2 molecules of hydrogen H₂, containing a total of 4 atoms of hydrogen, combine with a molecule of oxygen O₂, containing two atoms of oxygen, to make two molecules of H₂O, also known as water. (Both sides of this equation contain four hydrogen atoms and two oxygen atoms, so it is balanced – we haven’t created or destroyed any atoms. This is a basic concept called conservation of mass.)

The interesting thing about this is that there is no carbon anywhere in the process, so there is no opportunity to oxidise carbon to carbon dioxide (CO₂); the only emission is water vapour. (Combustion in air, which contains nitrogen as well as oxygen, is a bit more complicated, but we’ll leave that aspect for another day.) From a greenhouse gas perspective, this appears to be a winner: heat without CO₂ generation.

But the real question is where the hydrogen comes from. Production and transportation of hydrogen both require energy, potentially creating a GHG impact.

Hydrogen: how is it made

There are several ways of obtaining hydrogen, which isn’t just lying around – it tends to react with oxygen pretty quickly and turn to water. It is also a key part of fossil fuels. The two major approaches to making pure hydrogen molecules are to break up the water molecule that we just made above, or to break up a hydrocarbon molecule of some sort. We’ll start with the hydrocarbon path.

Natural gas is the simplest hydrocarbon, being made up of a carbon atom and 4 hydrogen atoms: CH₄. This molecule is also known as methane. Separating hydrogen from methane is done with two reactions, the first called steam reforming (see the Wikipedia article for more information, click here):

CH₄ + H₂O → CO + 3 H₂

In this reaction, methane and water (in the form of steam) combine to generate one molecule of carbon monoxide (CO) and three hydrogen molecules. The carbon monoxide is a nuisance, so more water is added (this is called the water gas shift reaction):

CO + H₂O → CO₂ + H₂

So overall we’ve used two water molecules and a methane molecule to make four hydrogen molecules and one molecule of carbon dioxide (CO₂). While the chemists will scream that this is not an accurate representation of what happens at the molecular level, the following illustrates the overall combined mass balance of the two reactions:

CH₄ + 2 H₂O → CO₂ + 4 H₂

If you are burning hydrogen made using this way, your tailpipe or smokestack emissions may consist only of water vapour, but you have generated greenhouse gas emissions (one carbon dioxide emitted for every four hydrogen molecules generated) somewhere else.

It is worth noting that similar processes can be applied to most carbon-containing materials, such as wood chips, oil, coal, etc. (For those interested, look up gasification and the Fischer-Tropsch process.) If the material comes from plants, for example wood chips, the process is presumed to be greenhouse gas neutral, as the CO₂ emitted is presumed to have been pulled out of the air when the plant grew; the assumption is that we are not putting new carbon (from fossil sources) into the atmosphere, but simply returning carbon to the atmosphere that was there until the seedling took root. This assumption comes with a certain amount of hand waving and deserves a deeper dive in a future article.

It is also worth noting that unlike combustion, which generates heat, this reaction, like baking a cake, requires heat: there is an energy cost to this approach.

The proponents of this approach counter the GHG argument by proposing a technology called carbon capture, use and sequestration (CCUS) to redirect the CO2 back into the ground. But this technology is an expensive energy hog which doesn’t remove 100% of the carbon dioxide in a gas stream, and which remains to be proven at large scale. The whole objective needs to be a smarter use of energy, and using lots of energy to make more energy is problematic in my view, especially if it isn’t a zero-carbon approach. We also need technologies that work now, as time is getting very short.

The second path involves reversing the combustion process described above. If that process created heat, i.e. energy, reversing it needs energy. Typically this involves a process called electrolysis (you can also look this up on Wikipedia, click here) which requires a lot of electricity. The result is the generation of molecules of oxygen and hydrogen which need to be separated to prevent them combining again:

2 H₂0 →2 H₂ + O₂

This approach generates no carbon dioxide, as long as the power is not generated with fossil fuels; if power is fossil-based, once again we have simply shifted the emissions elsewhere.

Hydrogen: How would we use it if we had a lot of it

Hydrogen is a very dilute gas and needs to be compressed to very high pressures in order to get a reasonable amount of energy into a reasonable sized reservoir, such as a vehicle fuel tank. So beyond the energy required to make it, there is the energy required to compress it.

Furthermore, it is highly explosive. Oxidation as described above happens very quickly and can make a huge mess if there is enough hydrogen available. Think of your barbecue propane tank on steroids, or Google “Hindenburg disaster” for a preview. So safe handling is a major issue. For this reason, I think using hydrogen to fuel vehicles is a major disaster looking for an opportunity to happen; Hollywood movies notwithstanding, a ruptured gasoline tank burns nice and hot but a ruptured pressurised hydrogen tank can fling hot, flaming shrapnel over distances of hundreds of metres, potentially killing or injuring many random bystanders.

Hydrogen is used in the production of a range of petrochemicals and fertilisers. These are non-combustion processes and generate no GHGs, except in the production of any energy required to run the reactions in question; they take place in large industrial sites where occupational health and safety (OH&S) procedures for dealing with high pressure flammable gasses are in place, so we’ll leave these for another day. But I will point out that this will be a problem eventually as the hydrogen used in these processes typically arises as a byproduct of oil refinery operations: if we stop burning gasoline and diesel, which we should, this source of hydrogen may disappear. So these users may eventually need to find new hydrogen sources.

Hydrogen could replace fossil fuels in a variety of industrial processes such as steel or cement making. If these large industrial users have access to green power (hydro, solar or wind), hydrogen production onsite from water begins to make sense. The hydrogen would then be used onsite, with no pipeline or tanker transport required, in situations where industrial-grade OH&S procedures are in place to prevent an explosion.

It has been suggested that hydrogen could be distributed via the existing natural gas pipeline network to homes and factories across the continent, but this requires assurance that every single inch of pipe in the network is made of steel grades that resist hydrogen embrittlement, a condition where hydrogen attacks and weakens steel. And when I say every inch, I mean right to the burner tip in every gas appliance connected to the grid, whether domestic, institutional, commercial or industrial. To my mind, this creates an unacceptable risk to the public unless a local green hydrogen production facility is paired with new pipelines to new developments. 

Hydrogen’s place in a Net Zero world

So there you have it: Hydrogen is best used on large industrial sites, where it can be made onsite from water using green electricity. Onsite storage and use can be regulated through OHSA or other regulatory bodies to eliminate safety risks to the public. The benefits are decarbonising large industrial processes for which there aren’t really any immediately obvious substitutions available today.

Hydrogen use in vehicles is possible but the safety issues are huge. The same is true if we try to put hydrogen into the existing natural gas pipeline network.

Hydrogen from natural gas raises uncomfortable questions around fugitive methane emissions, carbon capture at less than 100% levels, and high levels of complexity, cost and energy demand. In particular, the cost per tonne of CO₂ abated, the so-called carbon index, should be a guide: Could those dollars and energy resources be better invested elsewhere, with greater levels of GHG reductions per dollar spent? And the technology is not yet proven at large scales; arguably we don’t have the time to sit around and hope it all works.

I hope I’ve answered my Reader’s questions; and I would be happy to try to answer yours too! Please write, especially if you feel this outline has been excessively or insufficiently simplistic.

2050: More actual real things you (yes, you) can do today

Note: This was also posted on my new Substack page (click here). Please bookmark that page as I may eventually stop posting here.

It is easy to look at the problem of climate change from a citizen’s perspective and throw up your hands in despair, because it appears there is little we can do given the scale of the problem, or because of the perception (perhaps justified) that corporate interests are driving decisions, not citizen’s concerns. But small local efforts add up quickly when taken up by enough people. In this post I hope to provide some positive approaches we can all take.

The first step is to vote, and to research politician’s platforms thoroughly prior to doing so. I have mentioned Mark Jaccard’s book (click here for the free digital version) and my first suggestion is to read it. He cuts though a lot of the obfuscation and gets down to the basic facts. 

The next step is to start to look at changes in your lifestyle that might be beneficial to the planet without being painful to you. Agriculture represents a part of the problem, and eating less meat will help the climate (and perhaps your health as well), but three quarters of the problem is due to the production and use of energy. And everything we do in our industrialised society has an energy impact.

For over 21 years I commuted 65 kilometres daily to work and back. A rough back-of-the-envelope calculation shows this generated about 4 tonnes of CO₂ per year, a piddling amount when compared to global energy emissions of about 8.5 billion tonnes (8.5 Gt CO₂) from transportation sources in 2020. Today there are options: buy an electric vehicle, take public transit (at the time I could beat public transit on my bicycle), or work from home for some or all of the time. (Cycling a 65 km round trip in urban situations with lots of stoplights added up to close to 3 hours on the road daily, once time for the shower at the office was included. I did it a few times a month, but it was not a daily solution, and was a non-starter in winter weather.) 

Next, let’s look at the grocery store, where I will try not to look like a hippy-dippy, crunchy-granola type wearing socks in my Birkenstocks.

I live in Eastern Canada, a location known for its winters. When I see lettuce on the shelves in February, I guess there has been some energy used to transport it here from somewhere warm, like California. Hopefully that truck will be electrified shortly, and in any case we should not be depriving ourselves of lettuce. But consider mineral or sparkling water shipped from France or Italy in a bottle, frequently made of glass. Yes, marine transport is cheap, but do we not have water in North America? In fact, our property taxes pay for safe and abundant municipal tap water, and any further concerns about the level of safety can be dealt with using a simple replaceable filter at much lower cost. And even if that filter comes from China, the embedded energy of a new filter every few months is presumably a lot lower than for several 750 mL water-filled glass bottles every week. 

Moving on, one also finds imported jams, pickles, etc., on the shelf next to local brands. This 250 mL jar of imported cherry jam weighs in at 579 grams off the shelf, but the empty jar weighs 217 grams with the lid, which works out to 37.5% of the total shipped weight excluding the inevitable carboard box. Every aisle should raise similar concerns or questions.

Outside the grocery store, Chinese goods are cheap, but the energy costs to get them here are significant, not to mention that the low price comes from offshoring well-paid local jobs to low-paid overseas jobs. My own view has always been to buy the best you can afford and look after it; it will last you much longer and cost less over the long run. “Cheap” is actually “expensive”.

At home, we all use energy for heating and cooling. Small steps, such as changing thermostat settings by a degree or two, combined with wearing a sweater and slippers in the winter, can have an impact. If the budget doesn’t allow for more efficient windows or doors, installing or repairing weatherstripping to reduce leaks will still make a difference. Incandescent bulbs use 8 to 10 times more energy than modern LED bulbs, which additionally last 10 times as long before failing. Shutting off the computer or entertainment system when not in use saves more energy than allowing it to go to sleep mode. And while most appliances today are reasonably energy efficient, running energy hogs such as washers, dryers and dishwashers outside peak hours lessens the load on the grid and reduces the investments needed to build new generating capacity. (Peak hours are usually defined as weekdays, 6:00-9:00 and 16:00-20:00, when people are home cooking.)

In a cold climate, however, the bulk of your energy bill is going to be heating. Where I live, the temperature difference in winter between outside and a comfortable inside environment can be as much as 40 or 50 degrees Centigrade; in a hot climate the temperature difference in summer can be 20 degrees or more. (Both depend, obviously, on your thermostat setting). Larger energy efficiency steps include improving insulation any time you are redoing a wall, either from the inside (such as kitchen renovations) our outside (new siding or bricks). Staying with the building envelope, savings from properly insulated basements, attics and modern windows and doors can add up quickly.

Moving inside, heat pumps are typically three times as energy efficient as gas or electric heating and can additionally provide air conditioning in the summer if you don’t already have it. (In the last 10 years, air conditioning in my neck of the woods has gone from a nice-to-have technology to something we can no longer do without.) These are available in ductless form for older homes without forced air, or as an insert to replace a burner or electric element in a forced air system.

Thinking further out there, housing in my neighborhood consists mainly of 100-year old three-story walk-up flats with flat roofs. A very rough first pass shows that the 1000 square foot roof on my building, if carpeted with solar panels, could provide, on average, one third of the building’s power use annually, or enough for roughly one of the three flats. This would need to be paired with local battery storage backed up with a grid connection. It would be expensive, but prices for batteries are dropping along with those for solar panels; meanwhile government incentives (including incentives for the grid operator to allow individual generating capacity to connect to the grid) will be essential. See the recommendation to vote, above, because this would be a huge step to reducing climate change as well as dependence on large generating stations and the necessary transmission lines and transformers.

Of course I am talking here of energy efficiency, not cost efficiency; relative prices for natural gas and electric power are highly local and may serve to slow or accelerate the move to greater electrification. Government carrots (incentives) and sticks (carbon costing of some type) will be essential to get the more expensive but ultimately more effective solutions implemented faster.

And if, through all this, you are saving electricity generated in a hydroelectric station, this can all be justified by the fact you are freeing up power to electrify the vehicle fleet while minimising the need for new dams.  

Moving on to recycling, the industrialised West obviously sends too much stuff to landfill. Recycling can be an option, but recycling comes with energy consumption and, particularly in the case of paper, water use. In the late 1990’s I edited monographs on the topic of energy and water use in pulp and paper processes, including recycling processes, and I would be happy to provide information as needed. So the act of disposing of something, whether a broken toaster or the packaging your groceries or goods came in, also has energy implications. Far better to prioritise repair, recover and reuse before recycling; products that are designed with end-of-life in mind at the start are key to the concept of a circular economy and will become more common as circularity becomes more accepted. Take the time to seek these products out as they become more available.

Finally, going beyond recycling, we have composting and biodegradability. While nice on paper, both lead to CO₂ emissions as the organic portion of the raw material decomposes. Use this for food scraps, not “biodegradable” plastic forks.

I realise that much of what I have described here applies to people who own their home and have some financial capacity to invest in goods, services and technologies that might not pay off for a number of years, as well as the ability to pay for healthy foods and high-quality goods which tend to be more expensive. The decisions described here can be difficult if you are having trouble paying the mortgage or buying basic groceries; tenants are at the mercy of a landlord when it comes to investment in energy systems. The social systems needed to generate decent living conditions for all are well documented by a large number of other bloggers on Substack and elsewhere, and are just outside the scope of this blog. Meanwhile you can plan your vote while being mindful of the energy impacts of everyday decisions.

Write to discuss!

 

2050: Things you can do now, and why you should do them now.

Note: This was also posted on my new Substack page (click here). Please bookmark that page as I may eventually stop posting here.

The last two or three posts have been heavy on the data, and being a nerd, I was intending to dive a little deeper into the numbers in this post. But I realised I have probably presented enough information in the last few posts to wrap this up with some advice and guidance for citizens (spoiler alert: VOTE!) and governments, backed by high-level facts and information.

So what does the literate but non-scientific citizen in a democracy need to take from all this as we all head to elections over the next few years?

The IEA report described in this series of posts promotes the idea that technology will save us, so we won’t have to change our habits, much.

But the problem is that several of the technologies required are unproven, expensive energy hogs. If any one of them doesn’t pan out, we may have to change our habits to a much more significant degree, in a much bigger hurry than anticipated now. This in turn requires convincing governments and politicians that citizens will support these painful changes. And the time available may be shorter than we thought, if recent floods across the US South, Europe and elsewhere are any indication of how quickly things are changing; people caught up in these disasters have indeed had to change their habits much more suddenly and drastically than anyone expected.

Figure 2.32 in the IEA report (click here) shows gigatonnes of CO₂ abated, sorted by technology, and further shows the state of readiness of these technologies. The objective is to eliminate 460 Gt CO₂ of cumulative emissions over the next 25 years. The good news is that 292 Gt CO₂ can be eliminated using technologies that are available and commercial today, with the only constraint being how fast we can implement them: these are solar and wind power, electric cars, and heat pumps.

The less good news is that most of the remaining technologies are at demonstration or prototype scale today. Technologies at the demonstration stage include electric trucks (arguably just about commercial as I have seen electric delivery vehicles from IKEA and others on my city’s streets); carbon capture (CCUS) for the production of cement, legacy fossil fuel energy, steel, and chemicals; and liquid biofuels via the Fischer-Tropsch pathway (a subject for another day). These technologies are expected to abate about 79 Gt CO₂.

Technologies at the prototype stage are expected to abate 60 Gt: biofuels or bioenergy with CCUS where there is a “double counting” allowed if the biomass is regrown; steel production including electrified primary steel, shipping, and direct air capture (DACCS). DACCS in particular is expected to take out 12.5 Gt, even though it is still at the prototype stage and is, furthermore, among the costliest approaches in terms of dollars per tonne removed. I am sure the costs will drop as it is scaled up, but again the issue is whether we can afford to wait that long.

Another pathway is hydrogen, made from water using green electricity. But the electrical energy needed for hydrogen by 2050 (Figure 2.16) is a staggering 12,314 TWh, more than building heat, cooking, light duty vehicles and heavy-duty trucks combined (11,156 TWh). By way of comparison, energy use for my 100 m² apartment in a 1920’s vintage rowhouse, with heating and cooling entirely by electricity, was 12,724 kWh in the 12 months ended November 6, 2024. Hydrogen generation is thus predicted to be a billion times (1,000,000,000 times) larger than this. (I had to go back to the data to be sure I hadn’t accidentally added a few zeros here.) The justification for spending so much of our precious green power, close to 40% of total wind and solar power in 2050, on hydrogen generation needs to be made much more clearly.

So what will increased societal change look like?

First, it is all very well to say we will replace all cars with electric cars. But urban gridlock isn’t going to allow for all those cars, regardless of energy source. While citizens in smaller communities will still need individually-owned private vehicles, congested urban cores need massively improved all-electric public transit systems (rapid rail systems supported by local trams and busses) which make better use of the available electrical power. Between cities, high-speed rail, well integrated with urban transportation infrastructure, will be more effective than short-haul aviation. Meanwhile, if you can, drive less, take public transit or a car-sharing service, walk or cycle.

Second, the current housing shortage across the industrialised world is not going to get better without billions of square metres of new residential floor space. In turn this is going to mean smaller homes in the industrialised world. Approximately a third of the new urban population will be in Africa, where residential space per capita needs to grow; but in the industrialised world it is no longer sensible to pave over good agricultural land so families of three or four can live in suburban homes built on 60’ by 120’ lots (670 m²). While I am not advocating 36 m² per capita, I think there is room to increase space efficiencies which will lead to reduced heating and cooling loads per capita. And apartments or townhouses, with fewer outside walls exposed to the elements, require less energy per square metre than the classic standalone bungalow or split-level home which is exposed on all sides. So are you planning a move? Consider an urban space with easy access via non-carbon mobility approaches to essentials such as employment, parks, schools, churches and shopping.

And while on the topic of your current or future home, investments in heat pumps and better insulation, windows and doors will improve your carbon footprint and save you money in the long run. The problem is the savings will take a long time to pay back the costs, given today’s electricity prices. This is an easy fix that requires government subsidies and incentives to move forward more quickly, fixes that should be implemented because they are relatively cheap per tonne of CO₂ abated, but meanwhile when shopping for home improvements, it might make sense to upgrade to the more climate-friendly solution.

Finally, there is the issue of nuclear power. If your over-riding concern is carbon and climate change, then nuclear holds a lot of promise. But the issues remain, mainly that a small accident leaves a huge mess behind, witness Chernobyl and Fukushima. Building these huge plants is also very expensive and very time consuming, and the cost of power generated is much higher than with other options. Should we be spending so much time and money here, for a costly and dangerous solution? A vigorous debate is needed.

Essentially this all describes many large European and Asian cities today. So it is all possible, if governments take the steps needed. Voters are the ones who will convince the politicians.

So if you are worried about the world your children and grandchildren will inherit, push back when you hear about the latest and greatest technological saviour just over the horizon, and look to local solutions where you can make a change, even a small one, in the short term. Small improvements made early will add up over the years and may be better than a large improvement in 2048 or 2052; a bird in the hand is worth two in the bush. 

I recall thinking, when Katrina destroyed New Orleans, that surely that was the incentive needed for the industrialised world to start changing tack. Here was a climate disaster in the heart of the USA! I was obviously hopelessly naïve in this; the question is how many Hurricane Helenes or videos of torrents carrying houses and cars downriver will it take to change the public mood. I remain cautiously optimistic.

Reference: International Energy Agency (2021), Net Zero by 2050, IEA, Paris: Net Zero by 2050 Scenario - Data product - IEA. License: Creative Commons Attribution CC BY-NC-SA 3.0 IGO.