Green vs blue hydrogen: What’s the difference?

As energy producers look to transition to more environmentally friendly fuels, hydrogen is emerging as a key player—but not all hydrogen is equally low in carbon emissions. This blog explores the different methods of hydrogen production, with a particular focus on green and blue hydrogen for their prominent roles in the energy landscape.

The colors of hydrogen production

Hydrogen can be produced through various methods, each represented by a different color on the spectrum (note: the color bears no relation to the actual hue of the final product). From grey hydrogen derived from natural gas to green hydrogen produced using renewable electricity, color coding highlights the environmental impact of each production method. Another variant, pink hydrogen, is created using nuclear energy. However, green and blue hydrogen are at the forefront of the industry's efforts to reduce carbon footprints, so we will focus on these two, particularly for applications like hydrogen-fueled gas turbines.

What is green hydrogen?

Green hydrogen is produced by a process called electrolysis, where water is split into hydrogen and oxygen using electricity from renewable energy sources like wind, solar, or hydropower. This method can produce zero carbon emissions, making it the least carbon-intense form of hydrogen available. As the world looks to decarbonize, green hydrogen is being hailed as a key solution.

What is blue hydrogen?

Blue hydrogen is produced from natural gas through a process called steam methane reforming (SMR). SMR mixes natural gas with very hot steam in the presence of a catalyst, where a chemical reaction creates hydrogen and carbon monoxide. Additional water is added to the mixture converting the carbon monoxide to carbon dioxide and creating more hydrogen. Carbon emissions generated during this process are captured and stored, rather than being released into the atmosphere. This makes blue hydrogen a lower-carbon alternative to traditional grey hydrogen where the emissions are not captured, though it still produces some carbon emissions when compared to green hydrogen. Blue hydrogen can serve as a transitional fuel, helping bridge the gap between our current reliance on fossil fuels and a future powered by renewable energy, with hydrogen-fueled turbines playing a supporting role.

Green vs blue hydrogen:

When comparing green hydrogen vs blue hydrogen, several differences stand out:

• Production method: Green hydrogen is produced from water using electrolysis powered by renewable energy, while blue hydrogen is generated from natural gas with carbon capture and storage (CCS) technology.
• Environmental impact: Green hydrogen production has minimal carbon footprint, whereas blue hydrogen, although less carbon intense than traditional methods, still involves some emissions due to natural gas usage.
• Energy sources: Green hydrogen relies entirely on renewable energy, making it more sustainable, while blue hydrogen depends on fossil fuels, which can limit its long-term viability.
• Cost & scalability: Green hydrogen is currently more expensive and less scalable due to the lack of renewable energy resources and the cost of electrolysis technology. In contrast, blue hydrogen benefits from established natural gas infrastructure, making it more cost-effective and scalable in the near term.