How do they produce green hydrogen via solar energy?

Hydrogen (H₂) energy is a promising source of clean and renewable energy that has the potential to reduce greenhouse gas emissions and mitigate climate change. Hydrogen can be produced through a variety of methods, including the steam methane reforming (SMR) of natural gas, the electrolysis of water, and the gasification of biomass.

Over 95% of the world’s hydrogen (over 60 million tons) is currently produced by steam methane reforming (SMR) process. However, the SMR process requires substantial energy input and emits a significant amount of CO₂, i.e. 5.5 kg of CO₂ per kilogram of hydrogen produced.

Electrolysis produces H₂ that does not result in CO₂ emission. Hydrogen production through electrolysis is sustainable if the electricity is generated from renewable sources such as hydropower, solar, and wind. Such produced hydrogen is called green hydrogen. However, the energy efficiency of electrolysis is low. The industrial production of 1 kilogram of H₂ from 9 kilograms of water requires approximately 55 kilowatt-hours of electricity when the most efficient alkaline or PEM electrolysis processes are used.

Several companies are developing technologies that use solar energy to produce green hydrogen beyond electrolysis.


Synhelion develops a solar receiver-reactor that uses concentrated solar energy in a solar tower configuration and reticulated porous ceria redox material to convert CO₂ and water into syngas with a desirable molar ratio of H₂ and CO. The syngas is then used to synthesize  kerosene via the established Fischer-Tropsch synthesis process.

Synhelion feature

Synhelion has raised a total of $45.8M in funding over 4 rounds. Their latest funding was raised on Dec 15, 2022 from a Series C round.

Synhelion is funded by 9 investors. AMAG Group and Cemex Ventures are the most recent investors.

Gianluca Ambrosetti and Philipp Furler are CEOs.

Fusion Fuel

Fusion Fuel has developed a hydrogen generation device composed of micro PEM electrolyzers (HEVO) coupled directly with highly efficient, multiple-junction solar cells. The device collects and concentrates sunlight, converts concentrated sunlight into both electricity by the solar cell and thermal energy harvested by a heat exchanger. Thereby, the device utilizes the electric and thermal energy to produce green hydrogen at a cost-competitive price.

Fusion Fuel feature

Fusion Fuel has raised a total of $52.3M in funding over 2 rounds, a Post-IPO Equity round and a Grant round. Their latest funding was raised on Dec 7, 2022 from a Grant round.

Fusion Fuel is registered under the ticker NASDAQ:HTOO.

Fusion Fuel is funded by Portugal´s Recovery and Resilience Plan.

André Antunes is Director.


SunHydrogen develops more stable and efficient photochemical diodes, also known as photoelectrosynthetically active heterostructures (PAHs), for hydrogen production. SunHydrogen develops methods for fabricating PAHs devices that are capable of producing hydrogen on a commercial scale.

SunHydrogen feature

SunHydrogen has raised a total of $11.1M in funding over 2 Post-IPO Equity rounds. Their latest Post-IPO Equity round was raised on Dec 7, 2020.

SunHydrogen is registered under the ticker OTCPINK:HYSR.

SunHydrogen is funded by TRITON FUNDS LLC.

Tim Young is CEO.

Syzygy Plasmonics

Syzygy Plasmonics designs and commercializes photocatalyst reactors that use renewable energy-powered light sources and plasmonic photocatalyst beds to drive chemical reactions at a low temperature. This light-driven chemical reactor allows the construction of the reactor with relatively inexpensive materials, such as glass or aluminum, and extends the lifespan of reactor components. In addition, Syzygy Plasmonics’s reactors are small and can  be installed on-site to produce only the required amount of gas, eliminating the need for liquifying, transporting, and re-gasifying the liquid.

Syzygy Plasmonics feature

Syzygy Plasmonics has raised a total of $106M in funding over 6 rounds. Their latest funding was raised on Nov 16, 2022 from a Series C round.

Syzygy Plasmonics is funded by 13 investors. Saudi Aramco Energy Ventures and The Engine are the most recent investors.

Trevor Best is CEO.

NX Fuels

NX Fuels develops one-step photochemical water splitting technology based on arrays of magnesium (Mg)-doped InGaN nanowires with favorable surface band bending. The Mg dopants reduce hole depletion and an electron accumulation in a near-surface region of the InGaN nanowires, resulting in a more balanced redox reaction for water splitting, thereby enhancing the photocatalytic efficiency and stability of the InGaN nanowires.

NX Fuels feature

In October 2022, NX Fuels was granted $60,000 by The U.S. Department of Energy (DOE) for developing its photochemical water splitting technology.

Saemin Choi is CEO.

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