Hydrogen Stocks: What Is Inside the Hydrogen and Fuel Cell Theme

The theme applies one test: does a meaningful part of the business depend on hydrogen? In practice that means making fuel cells, building the electrolyzers that split water into hydrogen, or producing, transporting, and selling hydrogen at industrial scale.

The word doing the work is meaningful. Hydrogen touches an enormous amount of the industrial economy, so a looser test collapses immediately. Refiners are the largest hydrogen consumers in the world and are not hydrogen stocks, because they buy it as an input and cheaper hydrogen simply improves their margins. Utilities that could one day blend hydrogen into a gas network are not hydrogen stocks either. Drop the materiality requirement and the theme quietly becomes a list of energy and chemicals companies with a hydrogen anecdote attached, which is the failure mode of most thematic screens.

The second structural choice is that the theme spans layers rather than picking one, and here that choice is unusually consequential. A hydrogen theme built only from pure-plays would contain no company with a profitable hydrogen business, which describes the story rather than the industry. A theme built only from incumbents would be a diluted industrial gas position wearing a clean-energy label. Holding both means the roster contains an existing cash-generative trade sitting next to a bet on a future one, and those two do not succeed or fail at the same time. For the general idea, see thematic investing.

Hydrogen is described by color, and the colors are not a branding exercise. They are the economics, and they are the single most useful thing to understand before reading the roster below.

• Grey hydrogen is made from natural gas, usually by steam-reforming methane. It is the overwhelming majority of what the world actually produces and consumes today, and it is what refineries and fertilizer plants have been buying for decades. It is cheap, which is exactly why it dominates.
• Blue hydrogen is the same process with carbon capture attached. It reduces emissions and adds cost, so it exists where policy or a customer is willing to pay for the difference.
• Green hydrogen is made by running electricity through an electrolyzer to split water. If the electricity is renewable, the hydrogen carries almost no emissions. It is also, at present, more expensive than grey hydrogen, which is why most green projects rely on subsidy, tax credits, or a mandate to reach a buyer at all.

That is the theme in one paragraph. The hydrogen the world consumes is grey and cheap. The hydrogen the theme is a bet on is green and is not yet cost-competitive without support. Almost everything that has gone wrong for the pure-play names traces back to that gap staying open longer than expected, and almost everything that has gone right for the incumbents traces back to the fact that they sell the cheap kind today and can add the clean kind when a customer pays for it. Reading the constituents below without that distinction makes the theme look like eight companies doing the same thing. They are not.

Hydrogen is not a new product waiting to be commercialized. Refineries have used it for decades to strip sulfur out of fuels, and fertilizer plants use it to make ammonia, and they buy it by the pipeline and the tanker from a small group of industrial gas companies. That trade is large, contracted, and profitable today. It is also almost entirely grey hydrogen, made from natural gas, because that is the cheapest way to produce it. This layer is in the theme because it is the only part of the theme where hydrogen is an existing business rather than a projected one, and because these companies are the ones with the plants, the pipelines, the liquefiers, and the customer relationships that any clean-hydrogen buildout has to run through.

How this layer relates to the rest. This layer is the theme's floor and its competition at the same time. It supplies the hydrogen the fuel-cell layer consumes, and it is the incumbent that the green-hydrogen developers have to either displace or sell into. The asymmetry is the point: if clean-hydrogen policy support slows, these companies keep selling grey hydrogen to refiners and fertilizer plants exactly as before. No other layer of the theme has that fallback.

An electrolyzer splits water into hydrogen and oxygen using electricity. Run it on renewable power and the hydrogen is green, produced without the natural gas the incumbents currently rely on. This layer builds those machines and, in some cases, builds and operates the production plants that use them. It is where the theme's thesis actually lives, because green hydrogen is the only version of hydrogen that is new. It is also, so far, the layer with the widest gap between the size of the story and the size of the realized business: order books here move with subsidy announcements and mandates rather than with a cost advantage, because the cost advantage does not yet exist.

How this layer relates to the rest. This layer only wins when green hydrogen approaches the cost of grey. Until then its customers are buying on policy support, which means a change of government, a delayed tax credit, or a missed mandate resets demand in a way that does not happen to a refinery's standing hydrogen order. It supplies the clean molecules the fuel-cell layer needs to have an environmental case at all, and it is trying to take share from the very incumbents that sit above it in this theme.

A fuel cell runs the reaction in the other direction, combining hydrogen with oxygen to produce electricity, with water as the main byproduct. This is the demand side of the theme, and it is decided application by application rather than all at once. In each case hydrogen has to beat something specific on total cost of ownership: batteries and overhead wires in buses and trucks, diesel gensets and grid connections in stationary power, grid electricity in data centers. That is why adoption here has been uneven rather than absent. Where hydrogen's advantages of refueling speed, weight, and duty cycle matter, it wins pockets. Where they do not, it loses to cheaper incumbents, and no amount of policy support changes the arithmetic for long.

How this layer relates to the rest. This layer is downstream of both the others: it needs the industrial gas layer to physically deliver hydrogen, and it needs the electrolyzer layer to make that hydrogen clean enough for the environmental case to hold. It also contains the theme's most uncomfortable fact. The most commercially successful equipment in this layer today is fuel-cell hardware frequently running on natural gas rather than hydrogen, which means part of what looks like realized hydrogen demand is really demand for fast, firm, on-site power that happens to be sold by hydrogen companies.

Read top to bottom, the theme is a dependency chain with a cost problem in the middle of it. The industrial gas layer already produces hydrogen at scale and sells it profitably, mostly grey. The electrolyzer layer is trying to produce a cleaner substitute that currently costs more. The fuel-cell layer is trying to create demand for hydrogen in applications where it must beat batteries, diesel, or a grid connection. Each layer needs the one before it, and only the first is indifferent to whether the other two ever work.

That asymmetry is worth stating plainly rather than softening. The pure-play fuel-cell and electrolyzer companies have been listed for years, several of them for a very long time, have raised and consumed enormous amounts of capital, and have largely not reached sustained profitability. Over the same period, the companies quietly earning money from hydrogen have been the industrial gas incumbents, whose hydrogen business predates the theme by decades and was never a clean-energy story at all. This is not a prediction about what happens next. It is the record so far, and a roster that hides it is not describing hydrogen honestly.

The practical consequence is that the eight names do not move for one reason. Industrial production, gas prices, and long-term contract renewals drive LIN and AIQUY. Clean-hydrogen policy and project economics drive APD and PLUG. Application-level adoption, and lately the scramble for fast on-site data-center power, drives BE and FCEL, while BLDP tracks the far slower arithmetic of hydrogen in buses and trucks. A subsidy withdrawal hits the middle layer hardest and leaves the incumbents largely intact. A data-center power boom lifts part of the application layer while doing nothing for green hydrogen economics. Understanding which lever moves which constituent is more useful than any ranking of the eight.

A membership test is only credible if it excludes things. These are the names people most often expect to find here, and the specific reason each one does not qualify.

• Natural gas producers and LNG operators. Most hydrogen made in the world today comes from natural gas, so gas producers are the upstream input to the hydrogen business as it currently exists. That makes them the opposite of a green-hydrogen bet rather than an expression of one: cheap gas is what keeps grey hydrogen cheap and green hydrogen uncompetitive. They belong in the natural gas theme, where being the incumbent fuel is the thesis rather than the obstacle.
• Solar, wind, and renewable power producers. Green hydrogen is made with electricity, so renewable generators are a supplier to the theme rather than a member of it. Their revenue comes from selling power, and it comes whether or not that power ever goes into an electrolyzer. They sit in the clean energy theme, where the exposure they offer is the point rather than a second-order effect.
• Refiners and fertilizer producers. These are the largest consumers of hydrogen on earth, which sounds like a strong qualification until you look at the direction of the exposure. They buy hydrogen as an input cost, so cheaper hydrogen improves their margins. Their share prices track crack spreads and crop economics, not hydrogen adoption, so they fail a test that asks whether hydrogen capability drives the revenue.
• Global automakers with fuel-cell programs. Several of the largest car companies have built hydrogen vehicles and sold them in small numbers for years. The programs are real, and they are a rounding error inside businesses that make their money on internal-combustion and battery-electric vehicles. The inclusion test asks for material exposure, and a research program inside a mass-market automaker is not it.
• Hydrogen truck and vehicle startups. This corner of the theme has been the most punishing, with several high-profile ventures failing to reach commercial scale or surviving only after restructuring. The theme covers heavy mobility through a component supplier instead, which is exposed to the same adoption question without depending on any single vehicle program reaching production.

The first two are worth dwelling on, because they show the test working rather than being applied loosely. Natural gas producers sit in the natural gas theme because cheap gas is what makes grey hydrogen cheap, so owning them as hydrogen exposure means owning the incumbent that green hydrogen has to undercut. Solar and wind names sit in the clean energy theme because they sell electricity and get paid whether or not any of it ever reaches an electrolyzer. Both are genuinely connected to hydrogen. Neither is a hydrogen bet, and a theme that included them would be describing adjacency rather than exposure.

The same eight names, grouped by the layer they occupy rather than ranked, so the shape of the theme is visible at a glance.

Three of the 8 are profitable industrial gas incumbents and one more is a profitable diversified industrial. That balance is the theme's central design decision, not an accident of what happened to be listed, and it is what stops the roster from being eight variations of the same pre-profit bet.

The passive route is a thematic fund, and it answers a different question. A dedicated hydrogen fund such as HDRO holds whatever its index defines as hydrogen, at weights you do not control, and in practice those indexes lean heavily toward the pure-play equipment makers because those are the companies that look most like hydrogen companies. That is the opposite of the balance this theme is built around. The dedicated fund universe is also small and has shrunk as interest in the theme faded, which is itself a piece of information about how the last few years went. Our best hydrogen ETFs guide compares the fund options in more detail.

A theme inverts the trade. You know exactly which eight names you own, which layer each one represents, and what weight each carries, including how much sits in profitable incumbents versus pre-profit developers, and you accept that eight names is a narrower roster than a fund holds. Neither is automatically better. The fund is the simpler instrument, the theme is the more deliberate one, and plenty of people hold a broad fund as a core with a small thematic tilt beside it.

A list of eight names is an input, not a portfolio. What turns one into the other is structure: which layers you want exposure to, what weight each name carries, and whether the concentration you end up with was chosen or inherited.

• Decide the layer mix first, then the names. The split between profitable incumbents and pre-profit developers changes the character of the position far more than swapping one fuel-cell company for another.
• Set target weights that sum to 100. Equal weighting across eight names is a choice, and so is anchoring on the industrial gas layer. Both are defensible. Not deciding is what leaves you concentrated by accident after one name runs.
• Frame it against the S&P 500. A narrow thematic position should be judged against a broad benchmark, because the extra concentration has to be buying you something.
• Size it before you buy. Several constituents are pre-profit, dilutive, and dependent on policy support. Set the position size while you are calm rather than after a subsidy headline.
• Revisit as weights move. Thematic positions drift fast when the constituents have this much dispersion between them, and this roster has more dispersion than most.

This is what Walnut is built for. You describe the thesis, the AI assistant proposes constituents and weights you can edit, the portfolio tracks as one performance line against the S&P 500, and you place trades you approve yourself at your own broker. Walnut is informational and does not tell you which stocks to buy.

For the companion view of which hydrogen names are most widely held and discussed, see best hydrogen stocks. For the broader theme these constituents sit beside, see best clean energy stocks.

The hydrogen and fuel cell theme is eight companies across three layers, and the layering carries the whole argument. Linde, Air Products, and Air Liquide already produce and sell hydrogen profitably, mostly the grey kind made from natural gas. Plug Power and Cummins represent the electrolyzer bet on green hydrogen, one as a pure-play staking everything on it and one as a diversified industrial that can afford to wait or walk away. Bloom Energy, Ballard, and FuelCell Energy are the demand side, winning applications one at a time where hydrogen beats the alternative.

Understood as a flat list of eight hydrogen stocks, the theme looks like a single bet on a clean fuel. Read honestly, it is a bet on a cost gap closing, held alongside companies that make money whether it closes or not, and the record so far is that the gap has been more stubborn than the narrative implied. That is the structure you are deciding whether to own. Nothing here is a recommendation, and Walnut is not an investment adviser.