Hydrogen by technology


Hydrogen can be produced using 4 broad process groups: thermal, electrolytic, biological, and solar-driven. Within each group, multiple forms of technology have been developed. For the map, we have divided the dataset into these groups. The database and map are intended to be evergreen. As the hydrogen sector develops, the PE Media Network data and maps team will be adding more projects. Most of the current projects indicated on the map fall into the Thermal and Electrolytic process groups.

Thermal processes for hydrogen production typically involve steam reforming, a high-temperature process in which steam reacts with a hydrocarbon fuel to produce hydrogen. Many hydrocarbon fuels can be reformed to produce hydrogen, including natural gas, diesel, renewable liquid fuels, gasified coal, or gasified biomass. According to the IEA, Hydrogen is almost entirely supplied from natural gas and coal today.

Water can be separated into oxygen and hydrogen through a process called electrolysis. Electrolytic processes take place in an electrolyser, which functions much like a fuel cell in reverse. Instead of using the energy of a hydrogen molecule like a fuel cell, an electrolyser creates hydrogen from water molecules.

Biological processes use microbes, such as bacteria and microalgae, to produce hydrogen. In microbial biomass conversion, the microbes break down organic matter like biomass or wastewater to produce hydrogen, while in photobiological processes the microbes use sunlight as their energy source.

Solar-driven processes use light as the agent for hydrogen production. Solar-driven processes include photobiology, photoelectrochemical reactions and solar thermochemical reactions. Photobiological processes use the natural photosynthetic activity of bacteria and green algae to produce hydrogen. Photoelectrochemical processes use specialised semiconductors to separate water into hydrogen and oxygen. Solar thermochemical hydrogen production uses concentrated solar power to drive water splitting reactions, often along with other species such as metal oxides.

What's in the map

Field Description
Project Name of the project
Technology group The group into which the technology type falls into
Technology type Type or process method employed
Technology type abbreviation Common abbreviation for technology type
Description Brief description of the project
End-use product Principle product produced. Usually, hydrogen (H2) or methane (CH4)
Hydrogen end user - Power Supply of electricity to the electricity grid with a gas turbine or fuel cell
Hydrogen end user - Grid injection Injection in natural gas or pure hydrogen grids
Hydrogen end user - Mobility Used in vehicles (road, off-road, rail, maritime or aviation)
Hydrogen end user - Industry heat Industrial applications such as refineries, steel plants or high temperature heat
Hydrogen end user - Heat/power (CHP) Heat and power via CHPs, for example in fuel cells or turbines
Hydrogen end user - Domestic heat Direct use in building for water and space heating
Hydrogen end user - Chemicals Production of (intermediate) chemicals, such as methanol, ammonia (for fertiliser or chemical products) or final chemical products.
Methane end user - Grid injection Grid injection as end user sector
Methane end user - Mobility Used vehicles (road, off-road, rail, maritime or aviation)
Synfuels end user - Mobility Used vehicles (road, off-road, rail, maritime or aviation)
Status Phase of project
Sub-status Additional stage of the project
Start date Date at which the project started or is expected to start
Project particpants The project operator, promotor and /or shareholders

H2 Technology graphs

Based upon data from the map above

Total number of projects by technology type

Excluding unknowns

Data shown illustrates total number of projects with a known technology type or process
Abbreviations Description
ALK Alkaline electrolysis
APC Amine Post Combustion
AM Augmented McLyzer
ATR Autothermal Reforming
Bio-pyro Biogas pyrolysis
BioR Biogas reforming
BioG Biomass gasification
BG Bitumen gasification
CCGT Combine-Cycle Gas Turbine
CCS Carbon Capture & Storage
CCUS Carbon Capture, Utilisation & Storage
CG Coal gasification
DAC Direct Air Capture
DS Direct Separation
HEE Hygenic Earth Energy
HTSE High Temperature Steam Electrolysis [Nuclear]
IS Iodine-sulfur
LTE Low Temperature Electrolysis
MS-PG Membrane separation from purge gas
MP Methane Pyrolysis
MF Microbial fermentation
MH Modern Hydrolysis
MCCS Modular Carbon Capture and Storage
MOLSIV Molecular Sieve
NG Natural Gas
OAC Ocean Air Capture
PCC Post Combustion Capture
PCG Petroleum coke gasification
PC+NAS Post-Combustion+Non-Aqueous Solvent (NAS)
PEG Plasma Enhanced Gasification [Recycled Waste]
PEM Polymer Electrolyte Membrane Electrolysis
POX Pressure Oxidation
Pre-C Pre-Combustion
PtX Power to X
S Separation
SMR Steam Methane Reforming
SOEC Solid Oxide Electrolyser Cell

Total number of projects

By region

Data shown illustrates total number of projects from the above graphic split by region

Total number of projects

By country

Data shown illustrates total number of projects from the above graphic split by country

Technology types

Low temperature electrolysis (LTE)


The electrolysis process uses electricity to split water into Hydrogen and Oxygen molecules. A typical electrolyser cell consists of two electrodes (cathode and anode) and a conducting electrolyte. The functioning of different types of electrolysers differs depending on the electrolyte material, as explained below. Low-temperature electrolysis refers to electrolysis at operating temperatures below approximately 300 °C and typically use Alkaline water electrolysis (AWE) cells or Polymer electrolyte membrane (PEM) cells.

Alkaline water electrolysis (AWE)


Alkaline water electrolysers employ alkaline liquid (usually aqueous KOH or NaOH) electrolytes which readily conduct electricity. In AWE cells, water dissociation and hydrogen generation occurs at cathode and hydroxyl ions (OH-) transfer through the porous diaphragm producing water and oxygen at the anode. These cells use inexpensive metals as electrode material and produce hydrogen of purity up to 99.9% at approximately 70-80% efficiency but operate best at low current densities. Alkaline electrolysis is a mature technology where significant advances with respect to electrode and separating diaphragm materials have improved the cost, efficiency, and durability of the cells.

Polymer electrolyte membrane electrolysis (PEM)


Polymer electrolyte membrane (PEM) electrolysers use a solid ion-conducting membrane as the electrolyte instead of a liquid. In PEM cells, water dissociation occurs at the anode and protons migrate selectively through the membrane generating hydrogen at the cathode. This type of electrolysis has advantages such as smaller footprint, high current density, higher efficiency, low (20-80 °C) temperature operation, higher dynamic operation, and higher hydrogen purity. PEM cells, however, uses high activity noble metal electrocatalysts which makes them more expensive than AWE cells.

High temperature steam electrolysis (HTSE)


High-temperature steam electrolysis employs high temperature (750-1000 °C) for electrolysis of water. It utilizes inexpensive thermal energy from nuclear reactors to convert water to steam and the dissociation reaction proceeds in vapor phase producing Hydrogen. The energy demand for electrolysis in vapor phase is lower thus consuming nearly 35% lower electricity compared to LTE. The overall efficiency for HTSE is therefore higher than LTE. In HTSE, high temperature electrolysis of steam at the cathode produces hydrogen molecules and oxygen ions which migrate through the solid oxide electrolyte to form oxygen molecules at anode. HTSE cells are also called Solid Oxide Electrolyser Cells (SOEC).

Power to X (PtX)


Besides being stored in batteries, electricity may be stored by converting it to another form of energy, including hydrogen. Power-to-X describes the process of converting power generated from various renewable sources to other forms of energy carriers for use in other sectors or for storage and then re-conversion to power when needed.
The X in the terminology can refer to one of the following: power-to-ammonia, power-to-chemicals, power-to-fuel, power-to-gas, power-to-hydrogen, power-to-liquid, power-to-methane, power-to-food, power-to-power, and power-to-syngas. For example – power-to-hydrogen refers to the process of using electricity to split water and produce hydrogen through electrolysis. Similarly, power-to-gas refers to converting renewable grid energy to gaseous carriers such as hydrogen or methane.

Autothermal reforming (ATR)


Autothermal reforming is a process for generating hydrogen and carbon dioxide by partial combustion of a gaseous hydrocarbon feed followed by catalytic reforming in the presence of steam. The process supports a variety of feeds such as natural gas, refinery off-gas, tail gas, light ends or naphtha. ATR often combines partial oxidation and steam reforming in a single reactor for a combined reforming process. Despite higher capital cost for oxygen plant, this technology is popular for higher hydrogen production, lower operating temperature, less coking, easier start-up, and fast response times.

Steam methane reforming (SMR)


Steam reforming or steam methane reforming is a mature and widely used technology that uses high temperature (700-1000 °C) steam to produce hydrogen from a methane source such as natural gas. In SMR, methane reacts with high pressure steam in presence of a catalyst to yield hydrogen (H2), carbon monoxide (CO), and carbon dioxide (CO2). This is followed by the water-gas shift reaction where CO and steam react in presence of a catalyst to produce more hydrogen and CO2. The product H2 is separated and further purified using pressure swing adsorption (PSA). A variety of feedstock such as gasoline, LPG, naphtha, refinery off-gas, ethanol or propane may be used for SMR. Feed flexibility, low operating cost and existing infrastructure make steam reforming the most common method for producing hydrogen today.



Gasification is a non-combustion process that converts solid organic biomass or fossil fuel based carbonaceous material such as coal to hydrogen, carbon dioxide and carbon monoxide using controlled amount of steam and oxygen at high temperatures. . The carbon monoxide then reacts with water via the water gas shift reaction producing more hydrogen and carbon dioxide. Hydrogen is usually separated and concentrated from the effluent gas stream through adsorption or membrane separation.

Direct air capture (DAC)


Direct air capture, as the name suggests, is a technology to capture CO2 directly from the atmosphere. It involves contacting atmospheric air with a chemical solution which reacts with the CO2 in the air to trap it in the form of a salt. The CO2 depleted air is recycled back to the atmosphere while the trapped CO2 is separated, concentrated, stripped via calcination, and compressed to be utilized or stored as pure CO2.

Carbon capture & Storage (CCS)

Carbon capture and storage (CCS) is the process of capturing the carbon dioxide (CO2) formed from burning of fossil fuels in industrial processes, power plants etc. and storing it so that it is not emitted to the atmosphere. Employing CCS involves three main steps – capture, transportation, and storage. Various technologies may be used for CO2 capture at source and may be categorized as 1) post-combustion carbon capture – capturing CO2 from exhaust/flue gases, 2) pre-combustion carbon capture – separating CO2 from gasified fuel, and 3) oxy-fuel combustion systems –burning fuel in an oxygen rich environment producing concentrated stream of easily separable CO2. The captured CO2 is usually compressed into a liquid for transportation before being stored in underground geological reservoirs. Current CCS technologies can capture 90% and above of the CO2, thus avoiding emission to the atmosphere. The term sequestration is often used to indicate long term storage of the captured carbon in underground reservoirs.

Carbon capture, Utilisation & Storage (CCUS)

Carbon capture, utilisation, and storage (CCUS), refers to the CCS process explained above and adds the concept of ‘utilization’ of the CO2 for making useful products or for applications other than underground storage. One primary use of captured CO2 is to inject CO2 and water in oilfields to improve yields, known as Enhanced Oil recovery (EOR), while sequestering the CO2 underground. Other CO2-utilization technologies of interest include: CO2 conversion to fuels via methanol, methane, alkanes and syngas; CO2 as feedstock for chemicals such as organic polycarbonates, inorganic resins, or agrochemicals such as urea; CO2 mineralization for non-geologic storage; and the use of carbon to fabricate materials for construction or commercial products.