- Turquoise hydrogen is an emerging form of hydrogen production that offers a potential low-emission alternative to conventional methods by using a process known as methane pyrolysis. In this thermochemical reaction, methane (CH₄)—the primary component of natural gas—is split into hydrogen gas (H₂) and solid carbon (C) at high temperatures (typically above 1,000°C), usually in the absence of oxygen. The reaction is represented as:
- CH₄ → C + 2H₂
- What sets turquoise hydrogen apart is its unique carbon byproduct. Unlike grey hydrogen (which releases CO₂) or blue hydrogen (which attempts to capture and store CO₂), turquoise hydrogen produces solid carbon that can be captured, stored, or utilized more easily and safely, avoiding the technical and environmental challenges of carbon capture and storage (CCS). This makes turquoise hydrogen an attractive bridge technology between fossil-fuel-based hydrogen and fully renewable green hydrogen.
- The process of methane pyrolysis can be powered by renewable electricity (such as through plasma torches or electrically heated reactors), further reducing its carbon footprint. However, if fossil-based electricity is used, the overall environmental benefit can be diminished. The sustainability of turquoise hydrogen therefore depends largely on the source of both the methane and the energy used to drive the reaction. To be considered a low-carbon or carbon-neutral process, it should use low-leakage, responsibly sourced natural gas and clean electricity.
- The solid carbon produced has potential commercial applications in various industries. It can be used to manufacture carbon black (used in tires and inks), graphite, construction materials, or even in advanced carbon composites and battery anodes. If markets for solid carbon are expanded and stabilized, this could make turquoise hydrogen economically competitive, as the carbon byproduct becomes a valuable co-product rather than a waste.
- Currently, turquoise hydrogen is still in the early stages of development, with several pilot and demonstration projects underway. Companies and research institutions are exploring scalable reactor designs, energy-efficient heating methods, and safe carbon handling. One of the main technical challenges is maintaining reactor stability and efficiency at the extreme temperatures required, while managing the build-up of solid carbon that could interfere with the process.
- Compared to other hydrogen production methods:
- Grey hydrogen is cheap but emits CO₂.
- Blue hydrogen reduces emissions through CCS but involves high infrastructure and energy costs.
- Green hydrogen is the cleanest but currently the most expensive and limited by renewable power availability.
- Turquoise hydrogen offers a middle ground, with the potential to be cleaner than blue hydrogen and cheaper than green hydrogen, provided methane leaks and carbon disposal are well-managed.
