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Hydrogen Energy Definition

Hydrogen fueling station

Hydrogen is today the most abundant element in the known universe, and this is the reason why we consider hydrogen energy a renewable resource that can replace the dirty fossil fuels in a not so far future.

Burning cleaner than other fuels, hydrogen is also considered a clean source of power that besides energy releases mostly water as by-product.

Hydrogen Energy Definition

Hydrogen energy is a clean and renewable source of power that releases no harmful emissions into the atmosphere when we burn hydrogen with oxygen.

However, if hydrogen is burned in air that contains mostly nitrogen, a small amount of various oxides of nitrogen will be released.

Even so, the amount of harmful emissions released when burning hydrogen in air is way smaller than the amount of harmful emissions released while burning fossil fuels.

Hydrogen Uses

Hydrogen is used today in the industry to refine petroleum, treat metals, produce fertilizers, process food, etc., but hydrogen for energy is mainly used as fuel for space rockets (liquid hydrogen) and in fuel cells that power the electrical systems of spacecraft.

Hydrogen powered fuel cells can be used in a wide variety of applications because they can be used as a power source for laptops, cell phones and other gadgets, but also for several military applications.

Large hydrogen fuel cells can be used as clean sources of power in remote areas that are not connected to the grid and also for buildings in the case of a blackout or other emergency.

Lately, hydrogen fuel cells have become popular among green vehicles because combining hydrogen with oxygen in the fuel cell to produce electricity will create a vehicle with zero-emissions that will be two to three times more efficient than a regular vehicle with internal combustion engine that uses gasoline as fuel.

Large hydrogen fuel cells can be used as clean sources of power in remote areas that are not connected to the grid and also for buildings in the case of a blackout or another emergency.

Hydrogen Energy in Fuel Cells

Hydrogen is the simplest element among all the elements of the periodic table because the hydrogen atom consists of only one proton and one electron.

Despite its abundance and simplicity, hydrogen does not occur naturally as a gas on our planet, it always appears in combination with other elements such as oxygen in water (H2O), in hydrocarbons such as gasoline, natural gas, propane, methane, and in other organic matter.

Using hydrogen as an energy source involves extracting processes that need to be efficient.

In the U.S., hydrogen is mainly produced through a process called steam reforming, which is the process of combining high temperature steam with natural gas (CH4) to extract the hydrogen.

CH4 + H2O + heat = CO + 3H2

Steam reforming is the most common method used by the industry to extract hydrogen and because involves high temperature in the extraction process, is considered highly inefficient.

Hydrogen produced through steam reforming has less energy than the natural gas used to extract the hydrogen.

Hydrogen is also produced through electrolysis, which means that hydrogen is separated from water using an electric current.

Electrolysis process

The electric current used in the electrolysis process can be produced from renewable resources such as solar and wind power, but the electrolysis process requires more energy than steam reforming, which reduces the efficiency even more.

The process called polymer exchange membrane electrolysis (PEM electrolysis) for hydrogen extraction is more efficient than the previous methods described above, and another advantage is produced by the fact that using this type of electrolysis, hydrogen can be produced on-site.

Because many companies have decided to create green vehicles using hydrogen fuel cells we need not only to produce hydrogen, but also to store it, which is another challenge due to the costs involved.

Hydrogen has extremely low density as a gas or in liquid form, and this is the reason why we need to increase its density.

We can do this in two different ways:

1. Compressing hydrogen

We can compress the hydrogen at a pressure of 790 atmospheres (which consumes about 13% of the hydrogen energy) to store hydrogen.

2. Turning the hydrogen gas into liquid state

The advantage produced by the hydrogen liquefaction is created by the fact that a cryogenic hydrogen tank will be much lighter than a tank that holds pressurized hydrogen.

However, to liquefy hydrogen, we need to reduce its temperature down to -253°C, which means an efficiency loss of 40%.

Pressurization seems to be a better choice because the energy loss in this case is only 13%.

Once hydrogen is produced and compressed or liquefied, we need to transport it to the end-user location, which can be a vehicle refueling station.

Transporting hydrogen is not cheap, so even if the production facility is large and produces hydrogen at a lower price due to its massive production capacity, the fact that the delivery point is pretty far away from the facility will increase the price of the hydrogen due to its high transportation costs.

In the case of the distributed production facilities, hydrogen will be produced on-site, so the delivery costs will be low, while the production costs of hydrogen will be high due to the fact that hydrogen is produced in small scale.

To increase the network of refueling stations for hydrogen, small-scale on-site hydrogen production facilities have been installed at several refueling pumps.

The Difference Between Hydrogen Fuel Cell Vehicles and Electric Cars

What would you choose? an electric car or a vehicle powered by hydrogen fuel cells?

Let’s compare them to see the differences.

Both these green vehicles rely on electric motors which require electricity to work.

An electric car uses its large and heavy lithium-ion battery to provide energy to the motors, while a fuel cell vehicle will use hydrogen to produce power for its electric motors.

Hydrogen is a clean fuel, but the electricity used to charge the battery of the electric vehicle could be clean (produced by renewables) or dirty (produced by burning fossil fuels).

Electric vehicles using Lithium-ion batteries

Electric vehicles rely on the old lithium-ion technology for batteries, which means a large and heavy battery that will become even heavier if we want to increase the range of the vehicle.

However, due the high energy density of the hydrogen and its lightweight nature, compressed hydrogen and fuel cells can extended the range of the vehicle without adding much weight to the vehicle.

A hydrogen fuel cell vehicle can be refueled in about 5 minutes, but an electric vehicle requires more than 3 hours to fully recharge.

An on-site facility for hydrogen production will use off-peak electricity (clean, dirty or combined) to produce the clean fuel, and if we refuel our hydrogen fuel cell vehicle there, we will pay about $85 for a full tank, which will ensure a range of about 300 miles (480 km).

The price per kilometer here reaches the level of 17.7 cents per each km (which is way more expensive than recharging the battery of the Tesla Model 3).

The price is higher for using hydrogen fuel cells, but hydrogen is a very abundant resource, is also clean, and pollution can occur only when we produce the hydrogen (the energy involved in the process could be clean or dirty).

Both these vehicles (electric cars and hydrogen fuel cell vehicles) are equally clean, but in order to replace all the polluting vehicles on the road today we need to improve the battery technology, and seriously increase the recharging network stations for electric cars and also the refueling stations for hydrogen.


Everything that is clean and renewable is very welcome in the today’s society, while anything that is related to fossil fuels represents the past and will be around only for a few more decades.

Article written by:

I write about the renewable energy sector, electric cars and climate change issues. I love nature and good food, so I travel all over the world to see new places and meet new people. Magda Savin

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