About next generation energy hydrogen

We will introduce “hydrogen”, the next generation of energy that is carbon neutral. Hydrogen is divided into three types: “green hydrogen”, “blue hydrogen” and “grey hydrogen”, each of which has a different production method. We will also explain each method of manufacture, physical properties as elements, storage/transportation methods, and methods of use. And I will also introduce why it is the next generation dominant energy source.

Electrolysis of Water to Produce Green Hydrogen

When using hydrogen, it is important to “produce hydrogen” anyway. The easiest way is to “electrolyze water”. Maybe you did in grade school science. Fill the beaker with water and electrodes in water. When a battery is connected to the electrodes and energized, the following reactions occur in the water and in each electrode.
At the cathode, H+ and electrons combine to produce hydrogen gas, while the anode produces oxygen. Still, this approach is fine for school science experiments, but to produce hydrogen industrially, efficient mechanisms suitable for large-scale production must be prepared. That is “polymer electrolyte membrane (PEM) electrolysis”.
In this method, a polymer semipermeable membrane that allows the passage of hydrogen ions is sandwiched between an anode and a cathode. When water is poured into the device’s anode, hydrogen ions produced by electrolysis move through a semipermeable membrane to the cathode, where they become molecular hydrogen. On the other hand, oxygen ions cannot pass through the semipermeable membrane and become oxygen molecules at the anode.
Also in alkaline water electrolysis, you create hydrogen and oxygen by separating the anode and cathode through a separator through which only hydroxide ions can pass. In addition, there are industrial methods such as high-temperature steam electrolysis.
By performing these processes on a large scale, large quantities of hydrogen can be obtained. In the process, a significant amount of oxygen is also produced (half the volume of hydrogen produced), so that it would have no adverse environmental impact if released into the atmosphere. However, electrolysis requires a lot of electricity, so carbon-free hydrogen can be produced if it is produced with electricity that does not use fossil fuels, such as wind turbines and solar panels.
You can get “green hydrogen” by electrolyzing water using clean energy.

There is also a hydrogen generator for large-scale production of this green hydrogen. By using PEM in the electrolyzer section, hydrogen can be produced continuously.

Blue Hydrogen Made from Fossil Fuels

So, what are other ways to make hydrogen? Hydrogen exists in fossil fuels such as natural gas and coal as substances other than water. For example, consider methane (CH4), the main component of natural gas. There are four hydrogen atoms here. You can get hydrogen by taking this hydrogen out.
One of these is a process called “steam methane reforming” that uses steam. The chemical formula of this method is as follows.
As you can see, carbon monoxide and hydrogen can be extracted from a single methane molecule.
In this way, hydrogen can be produced through processes such as “steam reforming” and “pyrolysis” of natural gas and coal. “Blue hydrogen” refers to hydrogen produced in this way.
In this case, however, carbon monoxide and carbon dioxide are produced as by-products. So you have to recycle them before they are released into the atmosphere. The by-product carbon dioxide, if not recovered, becomes hydrogen gas, known as “grey hydrogen”.

What Kind of Element Is Hydrogen?

Hydrogen has an atomic number of 1 and is the first element on the periodic table.
The number of atoms is the largest in the universe, accounting for about 90% of all elements in the universe. The smallest atom consisting of a proton and an electron is the hydrogen atom.
Hydrogen has two isotopes with neutrons attached to the nucleus. One neutron-bonded “deuterium” and two neutron-bonded “tritium”. These are also materials for fusion power generation.
Inside a star like the sun, nuclear fusion from hydrogen to helium is taking place, which is the energy source for the star to shine.
However, hydrogen rarely exists as a gas on Earth. Hydrogen forms compounds with other elements such as water, methane, ammonia and ethanol. Since hydrogen is a light element, as the temperature rises, the movement speed of hydrogen molecules increases, and escapes from the gravity of the earth to outer space.

How to Use Hydrogen? Use by Combustion

Then, how is “hydrogen”, which has attracted worldwide attention as a next-generation energy source, used? It is used in two main ways: “combustion” and “fuel cell”. Let’s start with the use of “burn”.
There are two main types of combustion used.
The first is as rocket fuel. Japan’s H-IIA rocket uses hydrogen gas “liquid hydrogen” and “liquid oxygen” which is also in a cryogenic state as fuel. These two are combined, and the heat energy generated at that time accelerates the injection of the water molecules generated, flying into space. However, because it is a technically difficult engine, except for Japan, only the United States, Europe, Russia, China and India have successfully combined this fuel.
The second is power generation. Gas turbine power generation also uses the method of combining hydrogen and oxygen to generate energy. In other words, it’s a method that looks at the thermal energy produced by hydrogen. In thermal power plants, the heat from burning coal, oil and natural gas produces steam that drives turbines. If hydrogen is used as a heat source, the power plant will be carbon neutral.

How to Use Hydrogen? Used as A Fuel Cell

Another way to use hydrogen is as a fuel cell, which converts hydrogen directly into electricity. In particular, Toyota has drawn attention in Japan by touting hydrogen-fueled vehicles instead of electric vehicles (EVs) as an alternative to gasoline vehicles as part of its global warming countermeasures.
Specifically, we are doing the reverse procedure when we introduce the manufacturing method of “green hydrogen”. The chemical formula is as follows.
Hydrogen can generate water (hot water or steam) while generating electricity, and it can be evaluated because it does not impose a burden on the environment. On the other hand, this method has a relatively low power generation efficiency of 30-40%, and requires platinum as a catalyst, thus requiring increased costs.
Currently, we are using polymer electrolyte fuel cells (PEFC) and phosphoric acid fuel cells (PAFC). In particular, fuel cell vehicles use PEFC, so it can be expected to spread in the future.

Is Hydrogen Storage and Transportation Safe?

By now, we think you understand how hydrogen gas is made and used. So how do you store this hydrogen? How do you get it where you need it? What about security at that time? We’ll explain.
In fact, hydrogen is also a very dangerous element. At the beginning of the 20th century, we used hydrogen as a gas to float balloons, balloons, and airships in the sky because it was very light. However, on May 6, 1937, in New Jersey, USA, the “airship Hindenburg explosion” occurred.
Since the accident, it has been widely recognized that hydrogen gas is dangerous. Especially when it catches fire, it will explode violently with oxygen. Therefore, “keep away from oxygen” or “keep away from heat” is essential.
After taking these measures, we came up with a shipping method.
Hydrogen is a gas at room temperature, so even though it’s still a gas, it’s very bulky. The first method is to apply high pressure and compress like a cylinder when making carbonated drinks. Prepare a special high-pressure tank and store it under high-pressure conditions such as 45Mpa.
Toyota, which develops fuel cell vehicles (FCV), is developing a resin high-pressure hydrogen tank that can withstand 70 MPa pressure.
Another method is to cool down to -253°C to make liquid hydrogen, and store and transport it in special heat-insulated tanks. Like LNG (liquefied natural gas) when natural gas is imported from abroad, hydrogen is liquefied during transportation, reducing its volume to 1/800 of its gaseous state. In 2020, we completed the world’s first liquid hydrogen carrier. However, this approach is not suitable for fuel cell vehicles because it requires a lot of energy to cool.
There is a method of storing and shipping in tanks like this, but we are also developing other methods of hydrogen storage.
The storage method is to use hydrogen storage alloys. Hydrogen has the property of penetrating metals and deteriorating them. This is a development tip that was developed in the United States in the 1960′s. J.J. Reilly et al. Experiments have shown that hydrogen can be stored and released using an alloy of magnesium and vanadium.
After that, he successfully developed a substance, such as palladium, which can absorb hydrogen 935 times its own volume.
The advantage of using this alloy is that it can prevent hydrogen leakage accidents (mainly explosion accidents). Therefore, it can be safely stored and transported. However, if you are not careful and leave it in the wrong environment, hydrogen storage alloys can release hydrogen gas over time. Well, even a small spark can cause an explosion accident, so be careful.
It also has the disadvantage that repeated hydrogen absorption and desorption lead to embrittlement and reduce the hydrogen absorption rate.
The other is to use pipes. There is a condition that it must be non-compressed and low pressure to prevent embrittlement of the pipes, but the advantage is that existing gas pipes can be used. Tokyo Gas carried out construction work on the Harumi FLAG, using city gas pipelines to supply hydrogen to fuel cells.

Future Society Created by Hydrogen Energy

Finally, let’s consider the role hydrogen can play in society.
More importantly we want to promote a carbon-free society, we use hydrogen to generate electricity instead of as heat energy.
Instead of large thermal power plants, some households have introduced systems such as ENE-FARM, which use hydrogen obtained by reforming natural gas to generate the required electricity. However, the question of what to do with the by-products of the reforming process remains.

In the future, if the circulation of hydrogen itself increases, such as increasing the number of hydrogen refueling stations, it will be possible to use electricity without emitting carbon dioxide. Electricity produces green hydrogen, of course, so it uses electricity generated from sunlight or wind. The power used for electrolysis should be the power to suppress the amount of power generation or to charge the rechargeable battery when there is surplus power from natural energy. In other words, the hydrogen is in the same position as the rechargeable battery. If this happens, it will eventually be possible to reduce thermal power generation. The day when the internal combustion engine disappears from cars is fast approaching.

Hydrogen can also be obtained through another route. In fact, hydrogen is still a by-product of the production of caustic soda. Among other things, it is a by-product of coke production in ironmaking. If you put this hydrogen in the distribution, you’ll be able to get multiple sources. Hydrogen gas produced in this way is also supplied by hydrogen stations.

Let’s look further into the future. The amount of energy lost is also an issue with the method of transmission that uses wires to supply power. Therefore, in the future, we will use the hydrogen delivered by pipelines, just like the carbonic acid tanks used in making carbonated drinks, and buy a hydrogen tank at home to generate electricity for every household. Mobile devices that run on hydrogen batteries are becoming commonplace. It will be interesting to see such a future.