Unless we have been living in a cave for the last few years, it is near impossible to ignore the flood of news in the popular press about the benefits of a hydrogen-fuelled economy.
Much has been written about how clean and environmentally-friendly hydrogen is as a fuel source and as an alternative to the current pollutive uses it is employed in.
‘Look, no emissions’
At first blush, the benefits of hydrogen are obvious. When combusted in engines it produces only water as a by-product. As a form of energy, it is compact and powerful. The energy content of hydrogen is better by far than its competitors (e.g. natural gas, diesel, gasoline) on an energy per unit weight basis.
What is far less often mentioned in reporting on hydrogen is that almost all (98–99%) of hydrogen we use is currently produced via steam reforming of methane (CH4), the main component found in natural gas. The process involves passing superheated steam to react with methane under pressure, a process both energy- and carbon-intensive.
Depending on the plant design, the process needs high temperature (750–1,100°C) and pressures (20– 25 bar) and is highly inefficient in terms of greenhouse gasses (CO2) emitted. Pembina Institute, a Canadian think tank, reports in a 2020 assessment, that for each kilogram of “clean” hydrogen produced, about 11–12kg of unclean carbon dioxide is also produced via the same process that made the hydrogen in the first place. No prizes for guessing where all that CO2 is going.
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This intensely polluting process called “grey hydrogen” is the dominant technology for the foreseeable future as researchers and companies work towards greener alternatives that produce less CO2 as a direct and necessary by-product.
Uses
What the current clean and green narrative also fails to mention is that almost all major current uses of hydrogen produced today are not so squeaky clean. According to IEA data, worldwide production of hydrogen was 115 million tons globally of which 70Mt (metric tonnes) was produced via dedicated production predominantly from natural gas (71%) and coal (27%).
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This production resulted in about 830 Mt of CO2 emissions, around 2.2% of the global energy-related total. The main uses of this hydrogen were in refining (38Mt), ammonia production (31Mt, used in particular for fertilisers production) and methanol (12Mt, used mostly as a fuel additive and for plastics production).
Oil use both as a fuel and as a feedstock into other industries like chemicals and plastics will not likely go away in the medium (~20-year) term. Neither will ammonia, whose main use is in the production of fertiliser, necessary to maintain crop yields to feed a hungry world.
Yes, there have been attempts to ban or at least make the use of commercial fertilisers prohibitive, but that will unlikely make its use any less prevalent because of the pressures of maintaining and even increasing crop yield. Recent attempts to ban the use of fertiliser in India, for example, has led to a run-up in the black market prices of the same.
And despite the ravages of Covid on the global economy, global steel production is still estimated to rise from 1799 million tons in 2020 to about 1900 million tons in 2021 according to estimates from the Economist Intelligence Unit (EIU). It will be increasingly hard to call any of these activities “green” in any meaningful way.
Alternatives
There is of course the narrative that hydrogen production can be made cleaner if we assume that the production process is itself free from nasty side effects like CO2 as a necessary and significant by-product. To support that narrative, so-called “green hydrogen” is proposed.
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Green hydrogen is produced by electrolysis of water in which zero-carbon electricity (assumed to have negligible cost from, say, solar and wind) is used to split water into hydrogen and oxygen. The electrolysis process itself uses methods at a much higher cost per unit output compared to dirtier methods of producing hydrogen.
There has, again, been the headline-grabbing projects announced to make the production of hydrogen “environment friendly” in efforts to promote green hydrogen. In 2016, three Swedish companies — LKAB, SSAB and Vattenfall — announced plans for a fossil-free steel production plant that uses hydrogen instead of coal for direct reduction of iron ore combined with an electrically-powered arc furnace.
The key assumption is that instead of the conventional route, hydrogen is produced from the electrolysis of water by use of renewable electricity (the assumed “green hydrogen”).
This, however, begs the question of why renewable electricity was not used directly instead of taking the intermediate step of making hydrogen, which is not currently an efficient process.
Depending on the operating conditions, current technology needed to convert power to hydrogen and back to power has a round-trip efficiency of 18–46%, according to scientific journal Nature Energy.
Other researchers estimate about 30–35% giving pause to the decision to use electricity to produce hydrogen that will then be converted to power, instead of using electricity directly.
Costs
Real-world estimates of the cost of producing hydrogen at scale are hard to come by. A 2012 detailed study by the US Department of Energy National Laboratory in Idaho came up with a detailed life cycle cost of US$2.68/kg ($3.60/kg) assuming economies of scale at 50,000 kg/day plant, an extremely optimistic scenario given current plant size are orders of magnitude smaller.
A more recent cost assessment of green hydrogen production at Columbia University in 2021 finds average cost levels of US$6–12/kg, and more importantly, remains high without subsidies. This is because electricity is the major cost component of production (50–70%) even where the production location is abundant with significant renewable resources.
Actions
In practice, other uncomfortable truths remain on the long road to a credible hydrogen future.
However, there is some emerging data that makes the transition possible. Momentum is building for green hydrogen because worldwide, the costs of both wind and solar are falling as the scale of deployment measured by cumulative megawatts generated builds.
This pushes down the cost of producing electricity from these sources making the low-cost assumption of green hydrogen increasingly feasible, albeit over a long time. Energy consultants Wood Mackenzie estimates that 253MW of green hydrogen projects have been deployed between 2000 to end of 2019.
According to their model, an additional 3205MW will come onstream by 2025, representing almost a 13-fold increase over six years (2019–2025). If the model predictions are realised by 2025, the scale and the pace of mass deployment will begin to have an effect driving down hydrogen cost.
This, in turn, will make the claim of green hydrogen a viable economic alternative to the current dirty backstory it labours under. The World Economic Forum warned last year in its Global Risks Report (16th edition) that: “Climate action failure” is the most impactful and second most likely long-term risk identified in the Global Risks Perception Survey (GRPS).
Whatever the costs, we will do well to act now than later.
Tang Weng Fai is a former journalist who also worked in a technology incubator
