Low-carbon hydrogen refers to hydrogen that is produced using processes that emit significantly fewer greenhouse gases (GHGs) compared to conventional methods. Unlike grey hydrogen, which is made from fossil fuels with high CO₂ emissions, low-carbon hydrogen includes both green and blue hydrogen, depending on the production method and the extent of carbon emissions mitigation.
As a versatile energy carrier, low-carbon hydrogen plays a critical role in the global transition to a cleaner energy system, particularly in decarbonizing industry, transport, power generation, and heat production.
What is Low-Carbon Hydrogen?
Hydrogen is the most abundant element in the universe, but it does not naturally exist in its pure form on Earth. It must be extracted from compounds like water (H₂O) or natural gas (CH₄). The carbon intensity of hydrogen depends on the energy source and method used for its production.
Low-carbon hydrogen typically includes:
- Green hydrogen: Produced via electrolysis of water using renewable electricity (from solar, wind, hydro, etc.), resulting in zero direct emissions.
- Blue hydrogen: Produced from natural gas using steam methane reforming (SMR) or auto-thermal reforming (ATR), with carbon capture and storage (CCS) applied to prevent CO₂ emissions from reaching the atmosphere.
- Turquoise hydrogen: Produced via methane pyrolysis, which generates solid carbon instead of CO₂, offering a low-emission alternative when powered by clean energy.
To qualify as low carbon, the hydrogen must achieve a minimum GHG emissions reduction—typically 70–90% lower than conventional grey hydrogen—based on lifecycle analysis.
How is it produced?
- Electrolysis (Green Hydrogen)
Electricity is used to split water into hydrogen and oxygen using an electrolyzer. If the electricity comes from renewable sources, the result is green, zero-carbon hydrogen. - Steam Methane Reforming + CCS (Blue Hydrogen)
Natural gas is reacted with steam to produce hydrogen and CO₂. With carbon capture technologies, up to 90% of the CO₂ can be stored underground or reused, reducing overall emissions. - Methane Pyrolysis (Turquoise Hydrogen)
Methane is thermally split into hydrogen and solid carbon without generating CO₂. If powered with clean electricity, this method can be near-zero-emission.
Applications of Low-Carbon Hydrogen
Low-carbon hydrogen can be used across various sectors:
- Industry: Decarbonizing high-temperature processes in steel, cement, glass, and chemical production.
- Mobility: Fuel for hydrogen fuel cell electric vehicles (FCEVs), especially in heavy-duty transport like trucks, trains, and buses.
- Power generation: Used in gas turbines or fuel cells for electricity, either standalone or blended with natural gas.
- Heating: As a clean-burning fuel for residential and district heating systems.
- Energy storage: Converts surplus renewable electricity into storable hydrogen for long-term grid balancing (Power-to-Gas).
Benefits of Low-Carbon Hydrogen
- GHG emissions reduction: Provides a clean energy alternative for sectors where electrification is challenging.
- Energy system flexibility: Acts as a bridge between electricity and other energy carriers through sector coupling.
- Fuel diversity and security: Diversifies energy sources and enhances resilience against supply disruptions.
- Industrial competitiveness: Opens up opportunities for sustainable product innovation and green export markets.
- Supports circular economy: Blue hydrogen with CCS and turquoise hydrogen with solid carbon can complement waste and CO₂ management strategies.
Challenges
Despite its potential, low-carbon hydrogen faces several challenges:
- High production costs: Green hydrogen remains more expensive than grey or blue hydrogen due to electrolyzer and renewable energy costs.
- Infrastructure gaps: Widespread use requires new pipelines, storage facilities, and refueling stations.
- Carbon capture reliability: For blue hydrogen, the effectiveness of CCS technologies is crucial for real emissions reductions.
- Certification and tracking: Standards are still evolving to define and verify what qualifies as “low-carbon” hydrogen under different regulatory schemes.
- Availability of renewable electricity: The growth of green hydrogen depends on expanding global renewable energy capacity.
