The key difference between grey blue and green hydrogen is that grey hydrogen is the hydrogen gas produced using fossil fuels, and blue hydrogen is the hydrogen gas that is produced using non-renewable energy whereas green hydrogen is hydrogen gas that is produced using renewable energy.
Hydrogen gas is a colourless, odourless and relatively unreactive gas. This gas was artificially produced for the first time in the early 16th century through the reaction between acids and metals. Henry Cavendish was the first scientist to discover the hydrogen gas. Today, hydrogen gas is referred to as grey, blue or green hydrogen depending on the source of production of this gas.
CONTENTS
1. Overview and Key Difference
2. What is Grey Hydrogen
3. What is Blue Hydrogen
4. What is Green Hydrogen
5. Side by Side Comparison – Grey Blue vs Green Hydrogen in Tabular Form
6. Summary
What is Grey Hydrogen?
Grey hydrogen is the hydrogen gas that is generated via the combustion of fossil fuels such as natural gas. This type of hydrogen gas usually accounts for about 95% of the hydrogen gas that is produced worldwide today.
Generally, hydrogen atoms do not exist in nature on their own. Hydrogen tends to latch on to oxygen and carbon atoms in chemical compounds such as water (H2O molecule), carbohydrates (sugar, biomass), hydrocarbons (oil, natural gas, biogas), etc. In order to separate hydrogen from these compounds, a supply of energy is required. For example, we need to supply electrical energy to separate hydrogen from water via splitting the water molecule through electrolysis. If we use electricity produced from fossil fuels (with the presence of carbon emission), then the hydrogen gas that generates through this process is “dirty”; we call it grey hydrogen. However, if we use clean electricity (with zero carbon emission), then the generated hydrogen is green hydrogen. During the generation of grey hydrogen, byproducts such as carbon dioxide, which is a greenhouse gas, are formed.
Grey hydrogen production is common since it is a cheap way to produce hydrogen and has an easy operation method. Moreover, it requires less equipment and comparatively less space. Nevertheless, the production of grey hydrogen is strongly unacceptable due to the production of greenhouse gases.
What is Blue Hydrogen?
Blue hydrogen is the hydrogen gas that is generated from non-renewable energy sources such as nuclear energy. This type of hydrogen gas meets the low carbon threshold. This type of hydrogen generation is considered as “fairly clean”. During blue hydrogen gas generation, carbon emission is prevented by capturing and storing carbon. The processes used in this generation usually captures about 90% of carbon; thus, the method has low to moderate carbon intensity.
What is Green Hydrogen?
Green hydrogen is the hydrogen gas that is generated using renewable energy such as solar energy and wind energy. This type of hydrogen gas only meets the low carbon threshold. In other words, this type of hydrogen forms when we use clean energy sources to separate hydrogen from other compounds such as water molecules. The clean sources of energy include wind, solar energy, hydropower, nuclear energy, etc.
This type of hydrogen production is considered as the gold standard because it produces zero emission of greenhouse gases.
What is the Difference Between Grey Blue and Green Hydrogen?
Hydrogen gas is a dimolecular substance having the chemical formula H2. The key difference between grey blue and green hydrogen is that grey hydrogen is the hydrogen gas produced using fossil fuels, and blue hydrogen is the hydrogen gas that is produced using non-renewable energy whereas green hydrogen is hydrogen gas that is produced using renewable energy.
Below infographic shows more details of the difference between grey blue and green hydrogen.
Summary – Grey Blue vs Green Hydrogen
Hydrogen gas is named as grey, blue or green hydrogen depending on the source of production of this gas. The key difference between grey blue and green hydrogen is that grey hydrogen is the hydrogen gas produced using fossil fuels, and blue hydrogen is the hydrogen gas that is produced using non-renewable energy whereas green hydrogen is hydrogen gas that is produced using renewable energy.
Reference:
1. “Hydrogen – Future Energy, Here Today.” Woodside, Available here.
Image Courtesy:
1. “Landscape, emissions, chimney” (CC0) via Pikist
2. “Solar panel, solar energy, windräder, renewable energy, green power, energy revolution, solarpark, voltaic, clouds, autumn sky” (CC0) via Pxfuel