Episode 08 of the Renewable Energy Mall & Engineering Review examines green hydrogen from first principles — and the analysis is structured around a single number that the technology's public discourse handles with remarkable inconsistency: the round-trip efficiency of the power-to-hydrogen-to-power pathway, which currently sits between 25 and 40 percent depending on electrolyser technology and reconversion method.
This figure is not a flaw awaiting resolution. It is the thermodynamic character of hydrogen as an energy carrier — a consequence of conversion losses at each step in the value chain that no foreseeable technology improvement will eliminate. Electrolysis at 65–75% efficiency. Compression and storage at a further 5–8% loss. Reconversion via fuel cell at 55–65% or via gas turbine at 40–55%. The compound result is that approximately 60–75% of the renewable electricity used to produce green hydrogen is irrecoverably lost before it reaches the end application. Lithium-ion batteries return 85–95% of input electricity. Pumped hydro returns 70–85%. Understanding this gap is the prerequisite for honest use case analysis.
The electrolyser technology landscape is covered in detail. Alkaline electrolysis — the commercial baseline at approximately $700–1,000/kW, 60–70% efficiency, and mature manufacturing — handles baseload production reliably but responds poorly to variable renewable generation. PEM electrolysis at $1,200–1,500/kW and 65–75% efficiency handles dynamic operation well but carries platinum-group metal catalyst requirements that introduce potential supply chain constraints at gigawatt scale. Solid oxide electrolysis at 80–90% efficiency when integrated with high-temperature heat sources remains pre-commercial, with electrode durability under thermal cycling as the unresolved technical constraint.
The learning curve section examines the optimistic case for cost reduction — electrolyser learning rates estimated at 13–18% per doubling of cumulative production, compared to solar PV's roughly 24% — and identifies where the analogy holds and where it diverges. Global installed electrolyser capacity in 2024 is approximately 1 GW. Solar PV had already undergone substantial industrial scaling through consumer electronics before the energy transition accelerated its trajectory. Electrolysers have not. The dramatic cost reductions projected for 2030 are plausible; they depend on deployment volumes that are not yet committed and manufacturing scale-up that has not yet occurred.
The use case analysis is the analytical core of the episode. Green ammonia production — decarbonising the Haber-Bosch process that feeds approximately half the world's population — emerges as the strongest near-term application: large existing hydrogen demand, direct substitution pathway, and immediate off-take markets in agriculture and as a shipping fuel and hydrogen carrier. Green steel via direct reduced iron is the second most credible near-term deployment, with SSAB, ArcelorMittal, and ThyssenKrupp all at advanced pilot or commercial scale. Seasonal grid storage is identified as the strongest long-term grid application — the only technology capable of economically bridging multi-week low-renewable periods — but the economics do not support commercial deployment at scale before the mid-2030s given current delivered hydrogen costs.
Applications identified as economically weak: home heating, where heat pump efficiency of 300–400% versus hydrogen boiler effective efficiency below 50% represents a 6–8× disadvantage that no policy mechanism can rationalise; personal transport, where battery EV wheel-to-energy efficiency of roughly 3× FCEV has driven a 500:1 market preference; and short-duration grid storage, where the efficiency disadvantage relative to lithium-ion is simply not offset by any technical property hydrogen offers at sub-72-hour durations.
The Africa assessment addresses four markets in detail. Namibia's Hyphen project, targeting 300,000 tonnes of green ammonia per year, is the continent's most ambitious export programme — with exceptional resource quality and a realistic 2030–2032 production timeline if financing closes. South Africa's Northern Cape resources are world-class, but the domestic grid crisis — extended load-shedding consuming residential and commercial demand — creates a political and economic tension between export hydrogen programmes and domestic energy security that the national strategy does not resolve. Morocco, with Atlantic corridor wind resource, existing undersea cable infrastructure, a domestic phosphate fertiliser industry providing immediate off-take, and geographic proximity to European markets, is the most commercially credible near-term export programme on the continent. Egypt's Suez Canal Economic Zone position and existing LNG infrastructure are strategic assets; the 600,000-tonne export ambition requires financing commitments that are not yet in place.
The structural finding for African green hydrogen is the transport cost gap. Production at $1.50–2.50/kg in best African sites is competitive with fossil hydrogen on a production cost basis. Shipping to Europe — as ammonia or liquid hydrogen — adds $1–2/kg, producing a delivered price of $2.50–4.50/kg. European domestic green hydrogen production, as electrolyser costs fall through the 2020s, approaches $2.50–3.50/kg by 2030. The window of African production cost advantage is narrower than the export strategies assume. The more robustly founded strategic case for most of the continent is domestic industrial use: green ammonia for African agriculture reducing import dependency, green steel for African manufacturing building industrial value chains, green hydrogen for African refining and chemicals capturing value on the continent rather than exporting a commodity at a transport premium.
The episode concludes with a structured assessment of what green hydrogen can realistically deliver by 2035 — not as a prediction, but as a calibration of which applications will have moved from demonstration to commercial scale versus which remain dependent on cost reductions and infrastructure investment that are still speculative.
📖 Read the full analysis on Medium → https://medium.com/@donfackfortune/green-hydrogen-the-most-debated-technology-in-the-energy-transition-honestly-assessed-369568f983c2
📩 Read on Substack → https://open.substack.com/pub/donfackfortune/p/green-hydrogen-the-most-debated-technology?r=7ivxz0&utm_campaign=post&utm_medium=web&showWelcomeOnShare=true
REM — Renewable Energy Mall & Engineering Review | Episode 08 Authored by Donfack Fortune — Mechanical Engineer & Energy Systems Analyst 🏢 Follow REM: https://www.linkedin.com/company/112016019
