Green Hydrogen

In News

The government is planning to blend 15 per cent green hydrogen with piped natural gas (PNG) for domestic, commercial and industrial consumption. 

About

• The move is in line with India’s ambitious target of reducing greenhouse emissions and becoming carbon neutral by 2070.
• This initiative will be part of the government’s National Hydrogen Energy Mission aimed at generating hydrogen from green power sources.

Government’s plans

• The government will bring green hydrogen under renewable purchase obligation (RPO).
  • It means that bulk buyers such as Discoms and captive users have to buy a certain proportion of renewable energy (RE) out of their total power requirement. 
• A similar mechanism will be created for hydrogen and it will be called hydrogen purchase obligation (HPO).
  • The HPO will cover industries like oil refineries and fertiliser plants, which use grey hydrogen. 
  • The idea is to create demand for green hydrogen. 
  • HPO is likely to come from 2023.
• Government plans to float bids for manufacturing green hydrogen, which will be supplied to fertiliser units and petroleum refineries. 
• Similarly, the plan is also to supply green hydrogen for PNG. 
• The government will offer free transmission (of power) for this like in the case of Renewable Energy. 
  • The objective is to blend 15 per cent green hydrogen with PNG, as it is technically viable. Beyond this, the gas pipeline would have to be refurbished.

About Hydrogen

• Hydrogen is the lightest element. 
• It is the simplest and smallest element in the periodic table. No matter how it is produced, it ends up with the same carbon-free molecule. 
  • However, the pathways to produce it are very diverse, and so are the emissions of greenhouse gases like carbon dioxide (CO2) and methane (CH4).

• At standard conditions, hydrogen is a gas of diatomic molecules having the formula H2. 
• Properties 
  • It is colourless, odourless, tasteless, non-toxic, and highly combustible. 
  • Hydrogen is the most abundant chemical substance in the universe, constituting roughly 75% of all normal matter.
  • Hydrogen fuel is a zero-emission fuel burned with oxygen. It can be used in fuel cells or internal combustion engines. It is also used as a fuel for spacecraft propulsion.

Image Courtesy: Britannica 

• Different Types of Hydrogen 
  • Green hydrogen: It is defined as hydrogen produced by splitting water into hydrogen and oxygen using renewable electricity. 
    • This is a very different pathway compared to both grey and blue.
  • Grey hydrogen: It is traditionally produced from methane (CH₄), split with steam into CO₂ – the main culprit for climate change – and H₂, hydrogen. 
    • Grey hydrogen has increasingly been produced also from coal, with significantly higher CO₂ emissions per unit of hydrogen produced, so much that is often called brown or black hydrogen instead of grey. 
    • It is produced at an industrial scale today, with associated emissions comparable to the combined emissions of the UK and Indonesia. 
    • It has no energy transition value, quite the opposite.
  • Blue hydrogen 
    • It follows the same process as grey, with the additional technologies necessary to capture the CO₂ produced when hydrogen is split from methane (or from coal) and store for the long term. 
    • It is not one colour but rather a very broad gradation, as not 100% of the CO₂ produced can be captured, and not all means of storing it are equally effective in the long term. 
    • The main point is that by capturing a large part of the CO₂ , the climate impact of hydrogen production can be reduced significantly.

Image Courtesy: wef

Advantages of hydro energy

• Flexible carrier: Hydrogen is a flexible energy carrier and can be used for many energy applications like the integration of renewables and transportation. 
• Fewer emissions: It is produced using RE and electrolysis to split water and is distinct from grey hydrogen, which is produced from methane and releases greenhouse gases. 
• The byproduct is also environmentally friendly: Energy can be extracted from hydrogen through combustion or through fuel cells, which emit only water as a by-product.
• Global dominance increasing: Several countries in Europe and North America are experimenting with mixing green hydrogen with PNG. For instance, in the UK, power utilities are blending hydrogen into pipelines to fuel power plants, industrial applications and to serve homes. The mixing is around 15-20% in some networks. Besides, there are various pilot projects on hydrogen blending with PNG being tested in countries like the Netherlands, Germany, France, Australia, South Korea and Japan.

Disadvantages

• Increased leakage risks: According to a study by the US Energy Department’s National Renewable Energy Laboratory (NREL) in 2013, “How it (hydrogen) affects the pipelines it travels in and appliances that use it. 
  • On the pipeline front, hydrogen embrittlement can weaken metal or polyethylene pipes and increase leakage risks, particularly in high-pressure pipes”.
• Brittle: Hydrogen embrittlement is a situation when the metal (pipeline) becomes brittle due to the diffusion of hydrogen into the material. The extent of embrittlement depends on the amount of hydrogen and the material’s microstructure. 

Other Challenges

• Highly Flammable: Its flammability and its lightness mean that hydrogen, like other fuels, needs to be properly handled. Compared to gasoline, natural gas, and propane, hydrogen is more flammable in the air. 
• Lack of Infrastructure: Because hydrogen is so much less dense than gasoline, it is difficult to transport. It either needs to be cooled to -253?C to liquefy it, or it needs to be compressed to 700 times atmospheric pressure so it can be delivered as a compressed gas. 
  • There is not enough infrastructure to accommodate the widespread use of hydrogen.
• Requires modifications: To distribute pure hydrogen, natural gas pipelines would require major alterations to avoid potential embrittlement of the metal pipes, or completely separate hydrogen pipelines would need to be constructed.
• Constraints in Fuel Cells: Fuel cell technology has been constrained by the high cost of fuel cells because platinum, which is expensive, is used at the anode and cathode as a catalyst to split hydrogen. 
  • A challenge for fuel cell electric vehicles has been how to store enough, to 13 kilograms of compressed hydrogen gas, in the vehicle to achieve the conventional driving range of 300 miles. 

Suggestions

• The Center on Global Energy Policy recommended that policymakers take a colourblind approach to planning and analysis to determine whether blue or green hydrogen production best suited their geography, rather than picking a pathway before understanding the associated costs and challenges.

Sources: BL