Hydrogen holds the title of being the universe’s most plentiful element. However, it’s rare to find hydrogen in its pure, elemental form. Hydrogen is found combined with other elements, like oxygen, forming compounds such as water (H2O).
An interesting process called electrolysis can split water into its base elements – oxygen and hydrogen, by passing an electric current through it. If the electricity used in this process is sourced from renewable energy like wind or solar, the resulting hydrogen is known as ‘green hydrogen’.
The colour names given to hydrogen types indicate the energy source used in its production. For example, hydrogen made using coal is referred to as ‘brown hydrogen’.
What Is Green Hydrogen And How Is It Produced?
- Green hydrogen refers to a type of fuel that is generated from hydrogen, which is universal, light, and highly reactive.
- The creation process is known as electrolysis, where an electric charge is used to split hydrogen from oxygen in water.
- This electricity must come from renewable sources to ensure that the process is carbon-free, meaning no carbon dioxide emissions.
- The procedure of green hydrogen production involves disassembling water molecules into their components – oxygen and hydrogen. This is achieved if the electricity used for this separation is harnessed from renewable resources.
How It Is Produced
- Electrolysis requires water with salts and minerals for electrical conductivity.
- Two electrodes are submerged in water and linked to a power source, where a direct current is then applied.
- The process separates hydrogen and oxygen since the electrodes pull in ions of the opposite charge.
- An oxidation-reduction reaction takes place during electrolysis due to the influence of the electricity.
The International Energy Agency (IEA) suggests that using green hydrogen could prevent the emission of 830 million tonnes of CO2 each year. This is the amount currently produced when making this gas with fossil fuels. Similarly, the complete replacement of all grey hydrogen worldwide would necessitate an additional 3,000 TWh/year generated from new renewable sources. This amount is equivalent to the current energy demand of Europe.
Advantages And Disadvantages Of Green Hydrogen
Green hydrogen is an eco-friendly energy resource with several pros and cons.
- One of its key benefits is that it’s entirely sustainable, producing no pollutants during combustion or creation.
- It’s simple to store, making it usable for other functions at a later date.
- It’s versatile and can be converted into electricity or synthetic gas for various uses.
On the downside, green hydrogen has a few drawbacks.
- Firstly, it’s costly to produce due to the high expense of renewable energy sources used in its electrolysis process.
- Secondly, its production consumes more energy compared to other fuels.
- Lastly, hydrogen’s high volatility and flammability necessitate extensive safety measures to prevent leaks and explosions.
Understanding The Differences: Green Hydrogen vs. Grey Hydrogen vs. Blue Hydrogen
Hydrogen is the tiniest and most basic element we find on the periodic table. Regardless of how it is made, it always results in the same molecule free from carbon. Yet, the ways to produce it vary greatly. These varying methods also result in different levels of greenhouse gas emissions, such as carbon dioxide (CO2) and methane (CH4).
You may hear hydrogen technologies being referred to as ‘grey’, ‘blue’, or ‘green’. This actually refers to how the hydrogen is made. When hydrogen burns, it releases only water – but making it can create a lot of carbon.
Hydrogen can be grey, blue, green, and even pink, yellow, or turquoise based on how it’s produced. Among these, only green hydrogen is made in a way that doesn’t contribute to climate change. This makes it essential to achieve a net-zero carbon footprint by 2050.
Green Hydrogen
- Green hydrogen is a type of hydrogen that is derived from water.
- The process involves breaking down water molecules.
- The electricity used in this process is sourced from renewable energy.
- This method of production distinguishes it from other types of hydrogen, namely grey or blue hydrogen.
Also Read | National Green Hydrogen Mission
Grey Hydrogen
- Grey hydrogen is typically derived from methane (CH4).
- The methane is steam-split into carbon dioxide (CO2) and hydrogen (H2).
- An increasing amount of grey hydrogen is now being produced from coal.
- Hydrogen production from coal results in even more CO2 emissions per unit.
- Because of the high emission levels, this type of hydrogen is often referred to as brown or black.
- The emissions from this hydrogen production method are considerable, equating to the total emissions of the United Kingdom and Indonesia combined.
- Grey hydrogen is produced on an industrial scale today.
- However, it does not aid in the transition towards cleaner energy sources – rather, it exacerbates the problem.
Blue Hydrogen
- Blue hydrogen involves the same procedure as the grey variety with some additional steps.
- The extra steps involve capturing the CO2 produced when hydrogen is separated from methane or coal.
- This captured CO2 is then stored for long durations.
- Blue hydrogen isn’t just one shade but varies significantly because not all CO2 emissions can be captured.
- Similarly, not all storage methods are equally effective for the long term.
- However, by capturing a large portion of CO2, the environmental impact of hydrogen production can be significantly reduced.
Turquoise Hydrogen
- Turquoise hydrogen is a potential new category in the ‘hydrogen taxonomy rainbow.’
- This type of hydrogen is produced via methane pyrolysis, a technology still in the pilot stage.
- The method promises high capture rates between 90 to 95% and effective long-term storage of CO2 in a solid form.
- This could potentially surpass the blue hydrogen in efficiency, warranting its unique classification.
- However, while methane pyrolysis remains in the pilot stage, green hydrogen is experiencing rapid growth, driven by two essential technologies: renewable power sources, such as solar PV and wind (among others), and electrolysis.
Green Hydrogen As Clean Energy
- Hydrogen is an advanced source of energy due to its high energy content per weight, which is why it is a preferred choice for rocket fuel.
- Particularly, green hydrogen is one of the purest energy sources with virtually no emissions.
- Green hydrogen can be utilised in fuel cells for vehicles or in energy-intensive industries like those producing fertilisers and steel.
- Globally, nations are focusing on building green hydrogen capacity as it provides energy security and aids in reducing carbon emissions.
- Green hydrogen plays a pivotal role in our transition towards greener energy.
- However, this transition isn’t immediate. The world needs to augment the deployment of renewable electricity to decarbonise power systems.
- The next step involves accelerating the electrification of the energy sector to take advantage of low-cost renewable electricity.
- Finally, sectors, such as heavy industry, shipping, and aviation , need to be decarbonised fast using green hydrogen.
- It’s worth noting that the current hydrogen production is mainly grey hydrogen, which has high CO2 and methane emissions.
- Priority should be to decarbonise the existing hydrogen demand, for instance, by swapping natural gas-derived ammonia with green ammonia.
Impact Of Green Hydrogen
Green hydrogen is gaining traction worldwide, with countries such as the USA, Russia, China, France, Germany and India leading the way; Japan is even striving towards becoming a fully hydrogen-powered economy. Let’s break down how green hydrogen will influence our future:
Powering And Hydrating The Future
Green hydrogen can generate electricity and produce drinking water simultaneously. This is achieved when hydrogen reacts with oxygen in a fuel cell, a technique effectively employed during space missions for sustainable water and power supply.
Storing Energy Efficiently
Green hydrogen can be compressed and stored in tanks for extended periods, making it a long-lasting energy source. These tanks are lighter and easier to manage than lithium-ion batteries, adding to their appeal.
Revolutionising Transportation
The adaptability of hydrogen makes it an excellent fuel option for sectors hard to decarbonise, like heavy transport, aviation, and maritime transport. Several initiatives, including the EU-backed Hycarus and Cryoplane, aim to implement hydrogen in passenger aircraft, marking promising steps towards a greener future.
Looking Ahead
Green hydrogen production currently poses a challenge due to its high costs. Yet, as the world continues to decarbonize and renewable energy becomes more affordable, these concerns will fade. Renewable energy is now the least expensive electricity source in many regions.
Green hydrogen production through electrolysis needs to become more widespread and less costly. The great news is that unlike other potential clean energy solutions such as CCS and methane pyrolysis, electrolysis is readily available in the market today. It can be easily sourced from a variety of international suppliers at this time.