IELTS Reading 115: The Hope and Hard Truth of Green Hydrogen

Adapted from Science / IEA Global Hydrogen Review 2025 (Jan 2025). IELTS Reading Section 3 difficulty, approximately 1,050 words. Source: https://www.science.org/content/article/will-new-generation-water-splitting-devices-help-green-hydrogen-replace-fossil-fuels

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Reading Passage

A. When engineers look for a fuel that can carry energy from the windiest desert to the farthest factory, hydrogen has an obvious appeal. It is the lightest element on Earth, it burns without carbon dioxide, and the only waste product from using it in a fuel cell is water. Most hydrogen produced today, however, is anything but clean: it is made from natural gas or coal in a process that releases carbon into the atmosphere. "Green" hydrogen is the promised alternative — hydrogen split from water by running renewable electricity through a device called an electrolyser. In theory, the whole chain runs on sunshine and wind, leaving no climate footprint. The molecule is meant to do the jobs that electricity alone struggles with: powering steel furnaces, fuelling heavy lorries, storing summer sunshine for a dark winter. For a decade, governments and investors have poured money into it as the missing piece of a decarbonised economy. Yet by 2025 the gap between the promise and the production line had become impossible to ignore. The molecule was meant to store energy that solar and wind could not — summer sunshine kept for a dark winter, offshore wind turned into a fuel a ship could burn at sea. Those uses are real, but the journey from a laboratory electrolyser to a refinery's tanker has proved longer, and pricier, than the glossy projections of the early 2020s suggested.

B. The first obstacle is simply physical. Splitting water into hydrogen and oxygen is not free; every electrolyser wastes some of the electricity fed into it as heat, and real systems convert only about sixty to eighty per cent of input energy into hydrogen, well below the theoretical maximum. On top of that, the best low-temperature electrolysers depend on rare materials. The fastest-growing design, known as a proton-exchange membrane machine, needs iridium — one of the rarest metals on the planet — to coat its electrodes, and its delicate membranes degrade faster when the current swings up and down. That sensitivity is a serious problem, because green hydrogen is meant to run on wind and solar, whose output fluctuates from minute to minute. Ask a PEM electrolyser to follow a gusty wind farm, and the very flexibility it needs becomes the thing that wears it out. Older alkaline electrolysers are cheaper and sturdier but less efficient, forcing engineers to choose between robustness and speed. Neither design yet reconciles the two, and that unresolved trade-off sits at the heart of every business plan for a green hydrogen plant.

C. The scale of what is required is humbling. If hydrogen were to supply three hundred million tonnes a year — the kind of volume needed to displace a meaningful slice of fossil fuels — the electrolysers alone would demand more than a terawatt of cheap renewable electricity. That is more solar and wind capacity than the entire world has installed at present, built from scratch and dedicated to splitting water. Then there is the molecule itself. Hydrogen is the smallest of all gases, which makes it fiendishly hard to contain: it leaks through seals, it embrittles steel pipelines, and it resists being chilled and compressed into the dense form that long-distance transport needs. Moving it cheaply would require an entirely new network of dedicated pipelines and storage caverns, a piece of infrastructure that almost nowhere yet possesses. Without that network, green hydrogen must be made where it is used, tying each project to a single customer and a single site. A steelworks may host its own electrolyser; a fueling station cannot yet pipe hydrogen across a continent the way natural gas flows today.

D. The result, by the middle of 2025, was a reckoning. A wave of announcements in 2020 and 2021 had promised gigafactories and export terminals on every continent. As developers ran the numbers, many of those projects collapsed. In July 2025 alone, more than ten billion dollars of planned green hydrogen facilities were cancelled across six major economies, wiping out roughly a million tonnes of intended annual capacity. The International Energy Agency's review for 2025 reported that low-emissions hydrogen did grow by ten per cent in 2024 and was on course to reach a million tonnes the following year — a real gain, but still under one per cent of global hydrogen production. High costs, uncertain demand, weak regulation and slow infrastructure, the agency concluded, were holding the field back. Electricity alone accounts for sixty to seventy per cent of the cost of green hydrogen, and without rock-bottom power prices the product cannot yet compete with grey hydrogen made from fossil gas. When the power price is high, electrolysing water is simply a more expensive way to buy fuel.

E. None of this means green hydrogen is dead, only that it is narrowing. The likeliest future is not a universal fuel carried everywhere but a niche used where electricity genuinely cannot reach — high-temperature industry, long-duration storage, shipping fuels that cannot be electrified. Researchers are meanwhile chasing new ways around the material bottlenecks: developing cheaper catalysts that avoid iridium, making membranes that survive fluctuating currents, and testing electrolysers that run directly on seawater or at high temperature. The honest lesson of the cancelled projects is that a molecule's theoretical cleanliness is not enough; it must also be cheap, storable and demand-ready. A blue-print on a slide does not pump fuel, and a headline about a "hydrogen valley" means little until a customer signs a long-term contract. Hydrogen may yet become a cornerstone of a decarbonised world, but the version that succeeds will almost certainly be smaller, slower and more carefully matched to specific hard-to-electrify tasks than the heady visions of a few years ago.

Questions 1-4

Choose the correct heading for paragraphs B, C, D and E from the list of headings below.

List of Headings i. Why splitting water is harder than it looks ii. How much renewable power the world has installed today iii. The scale and storage problem nobody mentions iv. The 2025 reckoning: cancelled projects and stubborn costs v. A narrower, more realistic future for the fuel vi. The history of the natural gas industry vii. Why hydrogen burns without oxygen

1. Paragraph B: ____
2. Paragraph C: ____
3. Paragraph D: ____
4. Paragraph E: ____

Questions 5-8

Choose the correct letter, A, B, C or D.

5. What is "green" hydrogen? A. Hydrogen produced from natural gas. B. Hydrogen split from water using renewable electricity. C. A fossil fuel recovered from coal. D. A colouring agent added to fuel.

6. Why is the dependence on iridium a problem? A. Iridium is one of the rarest metals and PEM membranes degrade under fluctuating currents. B. Iridium makes the hydrogen turn green. C. Iridium is too heavy to transport. D. Iridium causes water pollution.

7. What challenge does hydrogen's small size create? A. It is too large to fit through pipes. B. It leaks through seals, embrittles steel and resists compression. C. It cannot be burned at all. D. It turns into oxygen instantly.

8. What did the 2025 project cancellations reveal? A. Green hydrogen had become the cheapest fuel worldwide. B. Many projects failed because costs, demand and infrastructure did not stack up. C. Renewable electricity had become free. D. Governments banned hydrogen entirely.

Questions 9-13

Do the following statements agree with the claims of the writer?

Write:

• TRUE if the statement agrees with the information
• FALSE if the statement contradicts the information
• NOT GIVEN if there is no information on this

9. Real electrolyser systems convert about sixty to eighty per cent of input energy into hydrogen.
10. Low-emissions hydrogen already accounts for more than half of global production.
11. Electricity accounts for sixty to seventy per cent of the cost of green hydrogen.
12. Alkaline electrolysers are both cheaper and more efficient than PEM machines.
13. Green hydrogen is expected to completely replace all petrol by 2030.

Questions 14-15

Complete the summary below using NO MORE THAN TWO WORDS from the passage.

Hydrogen is the smallest of all gases, which makes it hard to contain: it (14) __________ through seals and makes steel pipelines brittle, so cheap long-distance delivery would require a new network of dedicated pipelines and storage (15) __________.

Answers & Explanations

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