O vodíku - Národná vodíková asociácia

Why hydrogen?

The basic prerequisite for the application of hydrogen in all affected sectors is the transition to a low-emission or emission-free economy. The European Union itself has set itself the goal of achieving complete climate neutrality by 2050, i.e. capturing and storing the same amount of greenhouse gas emissions as will be released into the atmosphere.

The very fact of the development of renewable energy sources in all member states then creates space for the stabilization of their unpredictable electricity production. In this case, hydrogen will play the role of an energy carrier, which is particularly suitable for seasonal accumulation and some mobility applications.

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What is hydrogen?

Hydrogen is the lightest gaseous chemical element, which makes up two-thirds of all cosmic matter. It is estimated to make up more than 30% of the total mass of the Sun. It is the third most abundant element on Earth, yet it hardly ever occurs as a single molecule because it is highly reactive and immediately forms compounds.

Hydrogen is ubiquitous, whether in the form of water, natural gas, or methanol. Being the simplest and lightest element, it disperses into the air very quickly upon release. When hydrogen leaks, it does not pollute the environment in any way. It is an emission-free substance that is non-toxic and has no odor. Hydrogen is flammable but does not support combustion, burning with a colorless flame.

What energy properties does hydrogen have?

Hydrogen is a very energy-rich fuel (33 kWh/kg) and is thus currently a direct competitor especially to battery technologies. In a direct comparison of hydrogen with batteries, today the leader in the field of battery technology is the automobile company Tesla, whose batteries reach an energy density of 250-260 Wh/kg. Read more

What is the history of hydrogen use?

Hydrogen is a gas known to the world for a long time, it was discovered in 1776 by the British scientist Henry Cavendish. Unfortunately, at the time of its discovery, hydrogen did not find wider application in industry, mainly due to the advent of cheaper fossil fuels in the 19th and 20th centuries. When you say the word "hydrogen", everyone naturally thinks of the Hindenburg airship disaster. Despite the fact that "exploding" hydrogen is still described as the culprit, the disaster was caused by an electrical discharge that ignited the highly flammable material from which the ship's hull was made. Read more

What is the use of hydrogen?

Hydrogen is a carrier (storage) of energy. It is widely used in transport, energy and industry. In the future, hydrogen is to serve as one of the energy carriers for the application of the so-called sector coupling, or the concept of sector integration. Read more

In energy, hydrogen can be used as energy storage. Due to the fact that hydrogen stores a large amount of energy (approx. 33 kWh/kg) and can easily be stored in large quantities, hydrogen is an ideal medium for seasonal energy accumulation (in the order of TWh). Read more

In transport, hydrogen is the main competitor of battery electric vehicles (BEVs). Hydrogen cars (FCEVs) have a longer range (600 km and more), a short filling time (approx. 5 minutes), they work better in cold conditions, when there are significantly smaller losses of range, and at the same time they have lower consumption at higher speeds. Read more

In industry, hydrogen can replace fossil fuels. In the steel industry, it can be used to reduce iron, for example. Today, hydrogen is primarily used for the production of ammonia, which is subsequently used mainly in the production and processing of fertilizers. Read more

How is hydrogen produced?

96% of all hydrogen produced today comes from fossil fuels. Only 4% is produced using water electrolysis. However, this ratio should change in the next decade in favor of emission-free production using the above-mentioned electrolysis of water.

Currently, it is reported that 96% of all world hydrogen production comes from fossil fuels, mainly in the so-called steam reforming of natural gas. It is the cheapest current hydrogen production technology. Steam reforming is a chemical process in which steam with a temperature of 750-950 °C is fed to methane. Read more

The mixture of methane and steam subsequently reacts to form hydrogen, carbon monoxide and a smaller proportion of carbon dioxide. Subsequently, carbon monoxide reacts with additional water vapor to form hydrogen and carbon dioxide. The overall efficiency of this process is around 75%. However, it creates a large amount of CO2, up to 9-12 kg of CO2 is produced per 1 kg of hydrogen produced. Hydrogen produced in this way is called gray.

A transitional method of hydrogen production can be a combination of already known technologies, namely steam reforming of natural gas with CCS (Carbon Capture Storage). In this variant, the generated CO2 emissions are captured using CCS or CCU (Carbon Capture Utilization) technology, and the produced hydrogen is practically emission-free (emissions reduced by up to 95%). Hydrogen produced in this way is called blue.

In the future, the most supported method of hydrogen production in the European Union is the production of hydrogen by electrolysis of water using electricity from renewable energy sources. Unfortunately, today the production of hydrogen with the use of electricity reaches approximately 4% of the share of all production worldwide. In addition, most of this hydrogen is a by-product of the production of chlorine by the technology of salt solution electrolysis - ie. white hydrogen (formed as a byproduct of other chemical reactions).

If hydrogen is produced by electrolysis of water and the electricity used comes from renewable sources, this hydrogen is called green. Green hydrogen is emission-free and has the greatest potential in terms of limiting greenhouse gas emissions. During the electrolysis of water, the chemical bond between hydrogen and oxygen is split in the solution to form gaseous hydrogen and oxygen. Currently, the overall efficiency is around 50-60%, depending on the use of electrolyser technology. About 9 liters of water and about 50 kWh of electricity are needed to produce 1 kg of hydrogen.

There are still other methods of hydrogen production that can be found in the professional literature. Currently, there is talk of the potential for hydrogen production in newly developed nuclear reactors of the fourth generation with the help of high-temperature electrolysis of water vapor on cells with solid oxides.

In addition, hydrogen is further classified into other "colors" based on the source from which it is produced. We can thus further discover brown hydrogen (produced by gasification of coal) or turquoise hydrogen (produced from natural gas, but the by-product is solid carbon).

How is hydrogen produced in the Slovak Republic and what is the potential for the production of green hydrogen here?

Due to its specific position in the heart of Europe, the Slovak Republic has relatively little potential for the production of so-called green hydrogen.

The coefficient of utilization (approx. slightly above 20%) of wind power plants is lower in our country than in neighboring coastal states, where strong and stable winds blow on the coasts (approx. above 30%). Currently, there is no large electrolyser in the Slovak Republic that is intended for the production of green hydrogen on a commercial basis. Read more

What is water electrolysis?

Electrolysis is a process in which a direct current of electricity breaks the chemical bond between hydrogen and oxygen in an aqueous solution.

2 H2O → 2 H2 + O2

How much water is used in electrolysis?

For the production of 1 kg of hydrogen and 8 kg of oxygen, 8.92 liters of demineralized water are needed, i.e. water stripped of all present minerals (even purer than distilled water) Read more

What types of electrolyzers do we have?

Currently, three types of electrolyzers are most often discussed, which are advanced enough to saturate the market demand. These are electrolyzers using alkaline electrolysis, PEM electrolysis and high-temperature electrolysis taking place in fuel cells with solid oxides. Read more

What kind of water can be used in electrolysis?

The water required for the production of very pure hydrogen must be demineralized, i.e. free of all dissolved substances and impurities. However, it can be obtained from practically any water source. Read more

Hydrogen storage

How can hydrogen be stored?

Currently, the most promising and also the most commercially advanced technology for hydrogen storage is hydrogen compression in the gaseous state. The hydrogen stored in this way tends to escape due to the very small size of the molecule. Read more

Application of hydrogen in mobility

What are fuel cells?

Fuel cells in electric cars are basically small electricity generators that get their energy from a direct electrochemical reaction between oxygen and hydrogen. Hydrogen is stored in a tank from which it is fed into the fuel cell. There it reacts with oxygen and thus produces electricity. The product of this electrochemical reaction is only distilled water. Read more

How do fuel cells work in electric cars?

A fuel cell is similar in structure to batteries. In the fuel cell we find an anode, a cathode and a membrane with a catalyst. Hydrogen enters the system on the anode side and oxygen on the cathode side. Read more

How does a battery electric car differ from a fuel cell car?

A fuel cell vehicle (FCEV) is also an electric vehicle. The car includes a battery, an electric motor and a fuel cell together with a hydrogen tank. Read more

How is a hydrogen electric car refueled?

Refueling takes place at filling stations. The whole process is very similar to refueling traditional fossil fuels. After connecting the filling gun to the tank valve, you push the lever and the whole system takes care of the rest of the work. Filling the tanks takes 5 minutes and will give the car full capacity. Read more

How many filling stations do we have in Slovakia?

On February 18, 2022, representatives of Messer Tatragas opened to the public the first hydrogen filling station operated in the leased premises of Slovnaft. The capacity of the tank is 5 to 6 kg of hydrogen, 1 kg of hydrogen is sold for 21.6 euros, and a car can be refueled in approximately 2 to 3 minutes. This device currently pumps to a relatively low pressure of 200 bars, but in general, passenger vehicles can be filled up to 700 bars, where the range is around 600 to 700 km. Read more

How does a hydrogen electric car work in cold weather?

The advantage is the reliability of the entire system in cold weather. Compared to battery accumulators, fuel cells are not subject to degradation during cold weather. Read more

Can't the waste water in the hydrogen electric car system freeze?

Fuel cell systems and water drainage are currently designed so that water cannot freeze in the entire system of the car. Read more

Is battery electromobility a better solution for transport than fuel cells?

It depends on who you ask and what type of transport we are talking about. Hydrogen and batteries are two complementary technologies that complement each other. Why?

1Long-distance freight transport:

Hydrogen currently offers greater potential for transporting goods over longer distances. Despite the hypothetical technological evolution of batteries (batteries with a solid electrolyte), it is unlikely that within ten years it will be possible to recharge the batteries with such an amount of energy that it would be possible to use the increased capacity for a range of over 1000 km without major problems. In addition, current batteries are very heavy, and even with a doubling of the energy density from the current 260 Wh per 1 kg battery to 500 Wh per 1 kg, you would still need a battery with a minimum capacity of 1.5 MW for a long-distance transport over 1000 km, a battery weighing 3 tons. Recharging such a significant amount of electricity is also a problem. How much power would the chargers need to recharge 1.5 MW overnight between shifts? With the hypothetical idea of 20 such trucks standing in the parking lot in a row, we reach numbers that make it possible to build not only a more powerful substation, but also a small power plant near such chargers. For that reason alone, it is appropriate to consider changing electricity to another, easily storable energy carrier that can be produced continuously from renewable energy sources. We can also deliver hydrogen to the truck significantly faster and we would not endanger the stability of the transmission system during recharging/refuelling. Thus, hydrogen currently offers greater potential for transporting goods over longer distances.

2Freight transport in cities:

In cities, on the other hand, battery electromobility can play a more significant role due to its high efficiency and low costs. The batteries are great for city traffic, where operators don't need a long range. The advantage of the whole solution is additionally supported by low operating costs and high efficiency thanks to energy recovery and low transport speeds.

3Passenger car transport:

The market for BEVs (battery electric vehicles) is currently a relatively developed market. In addition, significant progress is made every year towards achieving the driving characteristics of internal combustion cars (range, charging speed). BEVs are the ideal solution for standard daily driving and charging at home. Today, BEVs offer a decent range of around 400 km, are highly efficient and locally emission-free. In particular, there will not be an equal competitor for BEVs in suburban transport at present or in the near future. Fuel cell passenger vehicles (FCEVs), on the other hand, cannot compete with BEVs in some areas, although their application is possible, especially considering their specific characteristics. They offer a longer and more stable range, even at higher speeds, especially on highways, their characteristics are similar to internal combustion engines in terms of range. FCEVs can also be a suitable alternative for drivers who live in densely populated areas without adequate recharging options at home. However, the development of FCEVs is currently hindered by high procurement costs and insufficient infrastructure of filling stations, which are also significantly more expensive compared to the construction of charging stations.

4Bus service:

For urban transport with distances in the order of tens of kilometers, the most efficient solution is a battery bus, similar to the case of urban freight transport. Hydrogen buses have greater potential, especially in intercity and long-distance transport, because they offer a more stable and longer range.

5Train transport:

Hydrogen has the potential to replace diesel train transport in parts of the country where electrified railways do not exist. Pilot projects are already operating all over the world, namely in France, which plans to test hydrogen trains from 2023. Similar to Slovakia, where hydrogen trains could run mainly on the Nové Zámky - Prievidza line.

How heavy are hydrogen storage tanks in cars?

Hypothetically storing 4.2 kg of compressed hydrogen at a pressure of 700 bar requires a tank in cars that weighs around 135 kg. Read more

Couldn't hydrogen be liquefied and then refueled like standard gasoline?

This solution is extremely energy inefficient. Liquid hydrogen must be kept at a temperature of -253 °C, and if these conditions are not met, the hydrogen evaporates. Read more

Is hydrogen safe?

All fuels contain a high concentration of energy and can therefore be dangerous under certain conditions. However, hydrogen can be considered as safe or even safer than any other fuel. Read more

Hydrogen economy

How much does it cost to produce 1 kg of hydrogen?

The price mainly depends on the production method. For the production of green hydrogen, it is also necessary to take into account the different price in individual parts of the world, depending on how much it costs to produce electricity from renewable energy sources. The price of hydrogen production varies in the following numbers:

Steam reforming of natural gas	1,5 - 2,5 €/kg
Coal gasification	1,8 - 2,5 €/kg
Electrolysis of water	5 - 8 €/kg

How much does 1 kg of hydrogen cost at filling stations?

For the end user, the price of hydrogen for 1 kg is currently set at 12.85 euros in Germany (where the most filling stations are located). Converting to kilometers and using an average consumption of 1 kg per 100 km, 1 km in a hydrogen electric car will cost you ~ 0.1285 EUR. Read more

How will the price come down in the next 10 years?

The hydrogen economy will not be sufficiently developed without the help of state subsidies. To reduce the price, it is necessary to invest in production. In the coming years, support for low-emission and zero-emission (green hydrogen) will prevail in Europe, the aim is to build 40 GW of electrolysers within the EU by 2030 and support the construction of another 40 GW of electrolysers outside the borders to increase imports. Read more