# Hydrogen: Production route

Grey, blue or green: how the colours really differ

Source page: https://www.materialinsights.org/chemicals/hydrogen/routes/

What this tab covers How it is made: the main production routes or, for product families, the main product types and technologies, compared on share of supply, inputs per tonne, plant scale, yield, co-products and unit cost.

Hydrogen is made by breaking apart a hydrocarbon or water. Steam methane reforming of natural gas is the cheapest route almost everywhere gas is available. China relies on coal gasification. Refineries also get hydrogen as a by-product of naphtha reforming, and chlor-alkali plants vent or sell by-product hydrogen. Low-emissions routes either capture the CO2 from reforming (blue) or split water with renewable power (green). Electrolysis needs about 50-55 kWh per kg, so its cost is set by power price and electrolyser use.

#### Routes compared

| Route | Share of supply | Inputs per tonne | Typical scale | Yield | Co-products | Unit cost |
|---|---|---|---|---|---|---|
| **Steam methane reforming (SMR) and autothermal reforming (ATR)** | about two-thirds of world hydrogen (indicative, basis: IEA GHR 2025, 290 bcm of gas used) | about 0.15-0.17 MMBtu of gas per kg H2 including fuel (indicative) | refinery and ammonia SMRs typically 50-500 t H2 a day (indicative) | about 70-75% energy efficiency on LHV basis (indicative) | about 9-10 kg CO2 per kg H2, half of it as a concentrated stream that can be captured | about $1.0/kg at US gas of $3.3/MMBtu and about $2.1/kg in India on LNG (JMK Research 2025) |
| **Coal gasification** | about one-fifth of world hydrogen (indicative, basis: IEA GHR 2025, 90 Mtce of coal) | about 7-8 kg coal per kg H2 (indicative) | Chinese coal-chemical complexes of several hundred kt H2 a year (indicative) | about 55-60% energy efficiency (indicative) | about 20-25 kg CO2 per kg H2, slag, sulphur | about $1-2/kg with cheap domestic coal (indicative) |
| **By-product hydrogen (naphtha reforming, chlor-alkali, steam cracking)** | most of the remaining sixth (indicative) | not applicable: co-product | set by the host unit | not applicable | this is the by-product | near zero marginal cost; valued at fuel or SMR replacement value |
| **Water electrolysis (alkaline, PEM, solid oxide)** | under 1% (2 GW installed in 2024) | about 50-55 MWh electricity and 9-15 t water per t H2 (indicative) | largest projects 100 MW-2 GW; IOCL Panipat contract 10 kt a year | about 60-70% LHV efficiency (indicative) | 8 t oxygen per t H2 | India tenders $4.4-4.6/kg (2025); electrolyser installed cost $2,000-2,600/kW outside China, $600-1,200/kW in China (IEA 2024) |
| **Reforming with carbon capture (blue hydrogen)** | under 1% | as SMR plus power for capture and compression | world-scale ATR projects about 1 Mt ammonia a year, e.g. CF/JERA/Mitsui Blue Point | slightly lower than unabated SMR | captured CO2 for storage or EOR | about $0.5-1/kg above grey (indicative) |

#### How each route works
**Steam methane reforming (SMR) and autothermal reforming (ATR)**

Methane and steam react over a nickel catalyst at about 850 C to give syngas, then a shift reactor converts CO to CO2 and more hydrogen. Pressure swing adsorption purifies it. Fuel gas heats the reformer, so about a third of the gas is burned rather than converted.

Cheapest and proven; high CO2 and exposed to gas price swings.
 IEA GHR 2025; JMK Research (May 2025); efficiency and gas use indicative **Coal gasification**

Coal is gasified with oxygen and steam to syngas, cleaned of sulphur and shifted to hydrogen. Used mainly in China for ammonia, methanol and coal-to-chemicals. Needs a large air separation unit for oxygen.

Energy security for coal-rich countries; roughly double the CO2 of gas.
 IEA GHR 2025 (coal use); intensity and cost indicative **By-product hydrogen (naphtha reforming, chlor-alkali, steam cracking)**

Catalytic reformers that make high-octane petrol release hydrogen, which the refinery reuses in its hydrotreaters. Chlor-alkali cells make about 0.03 t of hydrogen per tonne of chlorine.

Cheap but cannot be scaled on its own.
 IEA GHR (indicative) **Water electrolysis (alkaline, PEM, solid oxide)**

Electricity splits water into hydrogen and oxygen. Alkaline cells are cheapest; PEM responds faster to variable solar and wind. Output cost depends on power price and hours of use.

Near-zero emissions with clean power; two to four times the cost of grey hydrogen.
 IEA GHR 2025; JMK Research (May 2025); PTI via The Week (Sep 2025) **Reforming with carbon capture (blue hydrogen)**

ATR or SMR plants capture the concentrated CO2 from the shift step and, with ATR, from flue gas too. Capture rates of 90%+ are claimed for new ATR designs.

Cheapest low-carbon route where gas and CO2 storage exist; upstream methane leaks remain.
 CF Industries 2025 results; cost indicative Unit economics are indicative ranges from the sources named; costs move with feedstock and energy prices, plant size and region.

## Other sections

- [Summary](https://www.materialinsights.org/chemicals/hydrogen/index.md)
- [Overview](https://www.materialinsights.org/chemicals/hydrogen/overview/index.md)
- [Correlation](https://www.materialinsights.org/chemicals/hydrogen/correlation/index.md)
- [Production](https://www.materialinsights.org/chemicals/hydrogen/production/index.md)
- [Feedstocks](https://www.materialinsights.org/chemicals/hydrogen/feedstocks/index.md)
- [Cycles](https://www.materialinsights.org/chemicals/hydrogen/cycles/index.md)
- [Trading](https://www.materialinsights.org/chemicals/hydrogen/trading/index.md)
- [Movement](https://www.materialinsights.org/chemicals/hydrogen/movement/index.md)
- [Regulation](https://www.materialinsights.org/chemicals/hydrogen/regulation/index.md)
- [Characteristics](https://www.materialinsights.org/chemicals/hydrogen/characteristics/index.md)
- [Emissions](https://www.materialinsights.org/chemicals/hydrogen/emissions/index.md)
- [Relationships](https://www.materialinsights.org/chemicals/hydrogen/links/index.md)