Green Hydrogen
Green Hydrogen
Introduction to Hydrogen
We know that Hydrogen is
a colourless and odourless gas. Now a
days, this gas is becoming popular as clean and convenient burning fuel. This
colourless and odourless gas can be stored as liquid or a compressed gas. It is
very versatile in nature. Because of which it can be used for everything, from
the production of plastics and fertilizers to powering cars’ internal
combustion engines.
Hydrogen has to be
extracted by a chemical process from its other compounds as there are no
deposits of natural hydrogen on earth. The vast majority (around 95% of the
word’s hydrogen) is produced using fossil fuels, either by using natural gas
(through a process known as SMR i.e., steam methane reforming) or using a coal
gasification process. But these methods are not the clean ways to produce
hydrogen. The clean way to produce hydrogen is
through a process called electrolysis. We know that water is made up of
hydrogen and oxygen atom. When in the process of electrolysis, an electric
current is passed through water, it splits water into hydrogen and oxygen.
Types
of Hydrogen
1. Grey
Hydrogen
2. Blue
Hydrogen
3. Green
Hydrogen
What is Green Hydrogen?
Even
if we refer it as green hydrogen, it is a non-toxic colourless gas. It’s the most abundant element – it’s estimated that 90%
of all atoms are hydrogen atoms, comprising around three-quarters of the total
mass in the universe.
As mentioned above, electrolysis is the clean
way to produce hydrogen. When in the process of electrolysis, an electric
current is passed through water, it splits water into hydrogen and oxygen. To
generate electricity, if we use renewable or clean energy for electrolysis of
water then the generated hydrogen is called as green hydrogen. And most
importantly, no harmful emissions are produced in this process.
Hydrogen
Technology
Hydrogen
is an ideal, highly efficient, renewable, clean, and sustainable energy carrier
produced by electrolysis of water and thermochemical water splitting. Hydrogen
possesses a high energy yield of 122 kJ g−1 , which is 2.75 times higher than
that of hydrocarbon fuels. Technologies utilized during the progress of
hydrogen generation, hydrogen storage, hydrogen transportation, and hydrogen
application are collectively referred as hydrogen technology, which is a
complex of multiple techniques. Hydrogen technologies are under active research
in many countries, such as the US, Germany, China, Japan, Korea, and Singapore
to challenge the long-term energy availability issues, and they propose a
number of energy strategies to structure their national energy consumption and
development to meeting their sustainability goals as well as the growing energy
demand.
Hydrogen Generation:
Hydrogen production is the basis for large-scale commercialization of hydrogen. At present, various hydrogen production technologies such as water electrolysis, methanol reforming, water gas, ammonia decomposition, and chlor-alkali industrial tail gas treatment have been used on a large scale. Water electrolysis is considered as the most promising and environmentally friendly means to generate hydrogen. Fuel cells can convert the energy in H2 into electricity, while there are some systems that convert different power into hydrogen, and then provide reaction gas for the fuel cell to generate electricity. Photo electrocatalytic (PEC) systems are widely used to produce renewable energy, based on photoanodes where H2 is transported to generate electricity.
Hydrogen Storage:
Generally speaking, hydrogen can be compressed (CH2), liquefied (LH2), or incorporated into specific storage materials (usually solid or liquid) for its later utilization in turbines, engines, high-efficiency fuel cells, or for chemicals to release its high power. Although hydrogen has many irreplaceable advantages, it still faces a great challenge in terms storage with safety, durability, and high efficiency. At present, there are three typical categories for hydrogen storage: storage in solid hydrides, gaseous storage, and liquid storage. Gaseous high-pressure hydrogen storage has the disadvantages of low hydrogen storage density and high pressure conditions, high requirements on the material of the storage device, easy leakage, and high storage cost. Metal hydride hydrogen storage has higher hydrogen storage density, better safety, and higher volume, making metal hydride more suitable for vehicle fuel cells, nickel metal hydride batteries, etc. Stored in an underground cavern or in a pressurized tank, or physically adsorbed in metals and high-surface-area adsorbents, hydrogen can be stored by physical or chemical methods. There are two reactions of dissociative chemisorption and electrochemical decomposition of water between metal and hydrogen, as shown below.
Hydrogen Transportation:
Hydrogen delivery methods are classified into three categories according to the different states of H2 during delivery: compressed gas hydrogen transportation (CGH2), liquid hydrogen (LH2) transportation, solid hydrogen (SH2) transportation. Pipelines and trucks are the most widely used means for H2 transportation.
Importance of
Green Hydrogen
As we are working towards
a clean and healthy environment, our capability to create large quantities of
green hydrogen will play a vital in making an alternative to fossil fuels. Now
a days electric cars are becoming very popular. If the demand of EVs increases,
the demand for electricity to charge them will also increase. Because of that,
for our sustainable future, we should rethink about our strategy for production
of electricity. We can handle this
increased demand by using a green hydrogen.
By-Products of
Green Hydrogen
As mentioned earlier,
there are no harmful emissions produced in the process of generating green
hydrogen through the electrolysis of water. Because of that green hydrogen can
be considered as the clean energy source. In this process of generating green
hydrogen the only by-product is water vapours.
Impact of Green Hydrogen
Hydrogen as a fuel might
sound unreal for few of us. But in some of the countries like US, France,
Russia, Germany, China Hydrogen as a fuel is a reality. Impacts of green
hydrogen are explained below:
1. Drinking water and Electricity Generator:
As we know, we can generate electricity by reacting hydrogen and oxygen in fuel cell. And the by-products of this process are water and electricity. This process can be very useful on space missions as we can provide water and electricity to crew in sustainable manner.
2. Energy Storage:
We can store energy for longer period of time in compressed hydrogen tanks. These tanks are lighter than the lithium-ion batteries because of that they are easier to handle than the batteries made up of lithium ion.
3. Transport and mobility:
As
we know, hydrogen is very versatile. Because of its great versatility, it can
be used in those consumption niches that are very difficult to decarbonize for
e.g. heavy transport and aviation.
How Green Hydrogen can be dominating the renewable energy industry?
Among all the renewable
energy sources, Green hydrogen is an extremely promising renewable energy
source and as such, we won’t stop hearing about it any time soon. It creates very innovative opportunities
because of which it can play a key role in the world’s transition to
sustainable energy sources.
Advantages of
using Green Hydrogen Energy
1.
Sustainable: Green hydrogen can be sustainable if produced
responsibly. Also, hydrogen can be used to decarbonise energy production in
future.
2.
Flexible: Green hydrogen can be used
immediately after production or we can also store it for the future use.
3.
Domestic and Commercial: green hydrogen
can also be used for domestic needs. We can also use it as a transport fuel. In
factories green hydrogen can be used to nullify the carbon use from
manufacturing processes.
4.
As we have mentioned earlier green
hydrogen is produced from the electrolysis of water, it can be created wherever
there is electricity and water.
5.
To power anything that uses electricity
for e.g. electric vehicles and other electronic devices, green hydrogen can be
used with fuel cells.
Disadvantages
of using Green Hydrogen energy
1. High Cost: Renewable energy sources which are used for electrolysis of water to
produce green hydrogen are more expensive because of which obtaining green
hydrogen is becoming more expensive.
2. High energy consumption: Energy required for generating green hydrogen
is much more than other fuels.
3. Safety issues: As we know, hydrogen is
highly volatile and flammable element. Therefore, to prevent leakage and
explosions we need to take extensive safety measures.
Challenges for Green Hydrogen
1. Technology:
As discussed
above, electrolysis is used to generate the green hydrogen. For that purpose,
we need larger electrolysers than we have seen or used till now.
2. Transportation and Storage:
For the transportation and storing purpose of green hydrogen, very
high pressure and high temperature is required.
3. Cost:
The prices of green
hydrogen per kilogram has to reduce to a benchmark of $2/kg. According to some
reports, $1/kg is achievable by 2050.
4. Electricity:
We need a huge amount of electricity to generate green hydrogen.
Is Hydrogen
Safe?
Hydrogen is recognized as an unsafe
energy source for its higher flame temperature and explosion energy, wider
ignition limits, and high diffusion coefficient. However, hydrogen-driven vehicles
are found to be less dangerous than petrol vehicles, because the latter
typically leak highly hazardous flammable gas, whereas the former cannot damage
anything with their minor heat radiation, unless it is placed in flame
immediately upon leakage.
Its flammability and its lightness mean that hydrogen, like
other fuels, needs to be properly handled. Many fuels are flammable. Compared
to gasoline, natural gas, and propane, hydrogen is more flammable in the air.
However, low concentrations of hydrogen have similar flammability potential as
other fuels. Since hydrogen is so light—about 57 times lighter than gasoline
fumes—it can quickly disperse into the atmosphere, which is a positive safety
feature.
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. Currently, hydrogen is transported through dedicated pipelines, in low-temperature liquid tanker trucks, in tube trailers that carry gaseous hydrogen, or by rail or barge
Why India’s
clean energy future lies with Green Hydrogen and not Blue?
The Government of India has already announced its plans to launch a National
Hydrogen Energy Mission (NHEM). With an installed RE capacity of 105GW and a target of 500 GW by 2030, hydrogen production through the
renewable energy (RE) mix is possible. Scaling of RE projects across the
country would also facilitate green hydrogen production through electrolysis.
India being a agri-based economy hydrogen production through electrolysis can
be complemented with the abundant biomass available in the country. Efficient
waste management practices can also be adopted by tapping into the
country’s 170,000 tonnes of daily municipal solid waste generation.
The NHEM is
expected to drive production, supply, and distribution of hydrogen as a clean
fuel for multiple sectors
Conclusion
Green Hydrogen can be used to reduce carbon emissions in applications that are otherwise difficult to decarbonize. Even though Green Hydrogen has many advantages over other energy sources, it will not be the largest energy economy. Because of inevitable energy losses when converting electricity to hydrogen, it is most productive to directly use electricity when possible. However, hydrogen is conveniently suited to decarbonize applications which renewable electricity cannot. Therefore, academic and industrial efforts should target green hydrogen not as the sole solution to decarbonization nor as an infeasible idea to cast aside, but instead as the linchpin economy that works with electrification and other technologies to make possible a society supported entirely by renewable energy.
Authors:
Adwait Gaikwad
Aryan Khandekar
Soham Babar
Sakshi Bade
Vivek Bagul
Comments
Post a Comment