Today’s living standard and sophisticated way of life require more units of energy to function. And with technological advancements, this need is expected to go further north in the coming years.
The latest update by the U.S. Energy Information Administration (EIA) has estimated an increase of around 50% in global energy consumption by 2050. Though this increase is expected to have a good contribution from renewable energy sources, a major portion would come from conventional fossil fuels like crude oil, natural gas and coal, thus exacerbating global climate change.
Achieving the worldwide goal of net zero emissions by 2050 requires many decarbonising methods. Carbon-free hydrogen has emerged as one such area with a high possibility of decarbonisation.
Which hydrogen holds the potential to decarbonisation
The colour of hydrogen represents the process that is used in its production. Hydrogen is a clean energy source that leaves no air residue and only emits water vapour on combustion. It is also the most abundant element in our universe, but rarely exists in free form as a gas. Therefore, hydrogen needs to be produced from various sources, which determines its colour as explained below:
- Black and Brown hydrogen: It refers to the hydrogen produced by the black (bituminous) or brown (lignite) coal through the “partial oxidation” method. This process produces methane and carbon dioxide, both major greenhouse gases, thus making this type of hydrogen the most damaging to the environment.
- Grey Hydrogen: This hydrogen is produced by “steam reforming” and uses natural gas or methane as the raw material. The emissions produced from this process are smaller than that produced from “partial oxidation”, and hence it’s not as damaging as compared to Black and Brown hydrogen.
- Blue Hydrogen: This type of hydrogen requires the same steam reforming process; however, the carbon generated in the process is captured and stored in the subsurface (sequestered) through carbon capture and storage (CSS). It produces almost carbon-neutral hydrogen as this technique can catch 80-90% of the carbon produced from the steam reforming process.
- Green hydrogen refers to the hydrogen produced from the “electrolysis of salt and mineral-rich water”. Electrolysis requires energy, which during the production of green hydrogen is obtained from renewable sources, making this process carbon neutral with no residue or emissions. It also provides a process of storing renewable energy in hydrogen fuel during their peak cycle hours. But due to its high cost of operation, it only serves 0.1% of the overall hydrogen production market. With technological enhancements and reduced cost of electricity production for the renewable sector, we can expect a rise in green hydrogen production.
- Turquoise hydrogen: This type of hydrogen is produced by the process of “methane pyrolysis”, which produces solid carbon as a by-product. This solid carbon can be used as a nutrient for enhancing soil fertility. The production of solid carbon nearly nullifies the possibility of gas entering the atmosphere, thereby making this process almost carbon neutral or with a very low carbon production potential. Turquoise hydrogen production is still in the development phase.
- Pink hydrogen: If water electrolysis in green hydrogen production uses nuclear energy as an energy source, we can refer to the produced hydrogen as pink hydrogen.
Why is the world focusing on green hydrogen?
Green hydrogen holds the promise to help meet global energy demand as well as contribute to climate action goals. Produced by using renewably generated electricity, green hydrogen is produced through the electrolysis of water. It is easy to store and transport.
Green hydrogen, which may serve as an alternative to conventional fuels, can aid many hard-to-decarbonise and energy-intensive sectors to achieve their targets of net zero carbon emissions. Some of these sectors are chemicals, steel, shipping, and aviation.
Challenges to green hydrogen transition
- Based on the current renewable energy scenarios, green hydrogen costs twice or thrice that of blue hydrogen.
- Unavailability or low production of renewable energy sources in many regions also limits the production of green hydrogen.
Strategies to reduce the cost of green hydrogen
As per the International Renewable Energy Agency (IRENA), green energy producers can follow a few strategies to reduce their cost and bring it down to the blue hydrogen’s level.
Some of these methodologies are:
- Modifying electrolyser design and construction (increasing the plant’s capacity to 20 MW from 1 MW) can reduce the cost to one-third of the current production cost.
- Scaling up the process to gigawatt-scale by improving procurement strategy will also help to bring down the cost of green energy production.
- Improvement in the power supply system is also expected to enhance the process of green hydrogen production.