Hydrogen is the most abundant element on earth, made up of oxygen and water. It is also a relatively clean fuel source with no carbon emissions. When burned, hydrogen only produces water. However, for hydrogen to truly be a clean fuel source, its production methods need to be free of carbon emissions as well. Hydrogen is classified using a color system that indicates how clean its production process is. The color system, from cleanest to least clean is as follows: green hydrogen, blue hydrogen, grey hydrogen and brown hydrogen. This article focuses on the two cleanest versions of hydrogen, blue and green. The differences between the two are outlined below.
What is blue hydrogen?
Blue hydrogen is produced using fossil fuels. During the production process natural gas is split into hydrogen and CO2. This process utilizes either Steam Methane Reforming (SMR) or Auto Thermal Reforming (ATR). Carbon Capture Usage and Storage (CCUS) is employed to capture and store greenhouse gases produced during this process, which lessens blue hydrogen’s negative environmental impact.
Blue hydrogen’s applications include energy storage, electricity generation, and a fuel source for vehicles and heating buildings. Blue hydrogen’s benefits, when compared to other fuel sources, are that it is a relatively low-carbon one. However despite its efforts to be clean or come across as such, blue hydrogen is still harmful to the environment.
What is green hydrogen?
Green hydrogen is the cleanest form of hydrogen produced, with no carbon emissions released during production. The hydrogen production process utilizes an electrolyzer and the electrolysis of water, which splits water molecules into hydrogen and oxygen. This process is powered by electricity, and In order for hydrogen to be considered green the electricity used must come from a clean power source. Clean power sources include renewable energy technologies such as wind, geothermal or solar.
Green hydrogen’s current applications include energy storage; fuel for various transportation sectors, including air, marine and road; and to generate electricity and drinking water. Green hydrogen has many benefits. It is sustainable, easy to store for later use, and easy to transform into electricity tor gas. Its drawbacks include high cost, high required energy consumption and safety issues. However, there are ways to overcome these drawbacks. For example, the high cost of green hydrogen is associated with the high cost of the renewable power sources required to produce the hydrogen. This high cost can be offset with energy project financing options.
There are many similarities between blue and green hydrogen. They have the same chemical structure, and can even be used in many of the same applications. However, understanding the differences between the two is important to understanding when, how and if each should be utilized.
1. Environmental impact
Different environmental impacts are the direct result of each type of hydrogen’s production method. Blue hydrogen’s use of fossil fuels and SMR or ATR allows for carbon emissions to escape, even with CCUS in place. Green hydrogen’s use of electrolysis only produces water as a result, creating no negative environmental impact.
Blue and green hydrogen have different costs. Blue hydrogen currently costs less with estimates at around $1.50 per kg or less. Green hydrogen currently costs over two times that cost and shows no sign of going down without massive improvements in the electrolysis and a much cheaper (but still clean) electricity source.
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