Hydrogen (H2) is the most abundant element in the universe and carries the promise of clean energy: it burns (or powers fuel cells) producing only water as a byproduct. But hydrogen doesn't exist freely in nature—it must be produced, and how it's produced determines whether it's truly "green" or simply shifting emissions elsewhere. Grey hydrogen (95% of current hydrogen) is produced from methane gas through steam reforming: it produces 9-12 kg of CO2 per kg of H2 produced. Green hydrogen is produced through water electrolysis powered by renewable energy (wind or solar): zero direct emissions. Current cost is the main obstacle: €4-8 per kg versus €1-2 per kg for grey hydrogen.

The green hydrogen value chain: production, transport, use

Production via electrolysis: electrolyzers (PEM, alkaline, SOEC technologies) break down the H2O molecule into H2 and O2 using electricity. Current efficiency: 60-80% (for every kWh of input electricity, you get 0.6-0.8 kWh of hydrogen). PEM electrolyzers (Polymer Electrolyte Membrane) are best suited for pairing with renewables due to their flexibility and rapid response. Transport and storage: hydrogen has very low volumetric energy density. To transport it, you must either compress it at high pressure (350-700 bar: energy-intensive), liquefy it at -253°C (energy-intensive), or convert it to ammonia (NH3: denser, easier to transport, but requires reconversion). Losses along the chain: compression, transport, and decompression consume 20-30% of hydrogen's energy. This means the "well-to-wheel" efficiency of green hydrogen in vehicles is 25-35%, compared to 75-90% for battery BEVs: a significant gap for applications where batteries work well (cars, urban buses).

Where green hydrogen makes sense: real applications

Green hydrogen makes sense in applications where batteries aren't practical: Heavy industry: steel production (through direct reduction with H2 instead of coke: DRI-H2), cement production, chemicals (ammonia for fertilizers, methanol, plastics): these are sectors difficult to electrify directly, and where green hydrogen offers a realistic decarbonization pathway. In Sweden, HYBRIT (a joint venture of SSAB, LKAB, and Vattenfall) produced the first batches of green steel with hydrogen in 2021. Heavy long-distance transport: trucks, trains, ships, and aircraft on long routes where battery limitations (weight, charging times) are more problematic. In Japan, hydrogen locomotives are already operational. In Europe, fuel cell trucks from Hyundai and Toyota are in deployment phase. Seasonal energy storage: converting excess renewables into hydrogen during overproduction periods (summer with abundant solar) to reconvert it to electricity with fuel cells or turbines in winter. This offsets conversion inefficiency with the value of seasonal dispatch.

Current state and prospects: where we really are

The European Hydrogen Strategy (2020) sets ambitious targets: 40 GW of electrolyzers in Europe by 2030, producing 10 million tonnes of green hydrogen. Target cost: below €1.50/kg by 2030 (cost parity with grey hydrogen). The REPowerEU update (2022) increased targets to 20 million tonnes of renewable hydrogen by 2030. In Italy, the National Recovery and Resilience Plan (PNRR) allocates approximately €3.64 billion for hydrogen, focusing on renewable production, distribution networks, and industrial applications. Current reality: green hydrogen covers less than 1% of global hydrogen consumption. The cost gap remains significant. Delays in electrolyzer construction and infrastructure development are systematic. More realistic projections (IEA, 2023) indicate that green hydrogen will play a significant role in global energy no earlier than 2030-2035, with full industrial maturity around 2040-2050.

The colors of hydrogen: a quick guide

The hydrogen market uses a color-coding system to classify production methods. Grey: methane gas reforming without CO2 capture. 95% of current hydrogen. Blue: gas reforming with CO2 capture and storage (CCS). Reduces emissions by 60-90% compared to grey but requires CCS infrastructure that's not yet widespread. Green: electrolysis with renewable energy. Zero direct emissions. The target of the energy transition. Pink: electrolysis with nuclear energy. Zero direct emissions, without renewable variability. Debated in Europe. Turquoise: methane pyrolysis (produces H2 and solid carbon instead of CO2). Emerging technology, not yet at industrial scale. Yellow: electrolysis with grid electricity mix (variable emissions based on renewable share in the mix). For consumers or investors: only green and pink (in certain contexts) can be considered truly "clean" in the long term.

Hydrogen in Italy: key projects

Italy has a strategic geographic position to become a European green hydrogen hub: proximity to North Africa (great solar and wind potential), existing pipeline networks (partially convertible for hydrogen transport), and the industrial hub of the North (strong demand for heavy industry energy). Key ongoing projects: H2 Mezzogiorno (ENI and SNAM): green hydrogen production in Sicily and Puglia from solar on marginal agricultural land. SoutH2 Corridor: planned pipeline from Algeria to Germany through Tunisia, Sicily, and northern Italy. Hydrogen Valley in Taranto (Ilva/Arcelor Mittal): study for converting the blast furnace to green hydrogen. Port of Civitavecchia: hub for importing liquid hydrogen from the Mediterranean. These projects are in planning or study phase: implementation depends on reducing electrolyzer costs and availability of low-cost renewable electricity.

Criticisms of green hydrogen: reasons for skepticism

Not all experts are equally enthusiastic about green hydrogen. Main criticisms: low systemic efficiency (electricity → hydrogen → electricity: overall efficiency 25-35% versus 90% for direct electricity use with batteries or heat pumps), methane losses in blue hydrogen (CCS is not 100% efficient, and methane losses during gas production can negate the climate advantage), distracting attention (emphasis on hydrogen as a future solution can reduce investment in already available and economical solutions like solar, wind, heat pumps, and electric vehicles), greenwashing risk (some companies use the green hydrogen narrative to justify continued short-term gas use). Expert consensus is that green hydrogen is essential for certain sectors, but it's not the solution for all sectors where more efficient alternatives exist.