What is hydrogen? Types, production and uses

Hydrogen (H₂) is the most abundant element in the universe and one of the most heavily used intermediates in the chemical industry. Today, the vast majority of hydrogen produced is consumed not as an energy carrier but as a chemical feedstock — in ammonia and methanol production and in refinery processes. The energy transition debate stands to change this picture.

What is hydrogen?

Hydrogen is a colorless, odorless gas that is much lighter than air and highly flammable. Its energy content per unit mass is higher than that of any known fuel, but its energy content per unit volume is low. This contradiction is at the heart of storage and transport: high pressure (350–700 bar), cryogenic liquefaction (−253°C), or binding to a carrier such as ammonia or methanol.

In the industry, hydrogen is referred to by colors according to its production method. These colors do not denote a chemical difference but a carbon footprint label — the molecule is identical in every case.

How is it produced?

On the electrolysis side, three technologies are competing: alkaline (mature, low cost), PEM (fast response, suited to variable renewable power) and solid oxide (high efficiency, high temperature, still at the scale-up stage).

Where is it used?

• Ammonia production: the single largest use of hydrogen; the foundation of the fertilizer chain.
• Methanol production: the starting point for formaldehyde, acetic acid and numerous derivatives.
• Refining: hydrocracking and hydrodesulfurization — removing sulfur from fuel.
• Food: hydrogenation of vegetable oils.
• Metallurgy: direct reduction of iron ore — the most concrete route to reducing carbon emissions in steel.
• Electronics and glass: protective atmosphere.
• Transport: fuel-cell heavy vehicles, ships and trains — still at limited scale.

The Turkish market and production

In Turkey today, the overwhelming majority of hydrogen consumed is produced and consumed on-site: refineries, fertilizer plants and petrochemical complexes produce their own hydrogen. The independent commercial hydrogen market consists mainly of cylinder and tank deliveries by industrial gas companies.

The country's high solar and wind potential keeps the debate over export-oriented investment in green hydrogen and its derivative products (green ammonia, e-methanol) alive. The determining variables are: electrolyzer investment cost, the unit price of renewable electricity, the impact of the Carbon Border Adjustment Mechanism on export-oriented industry, and transmission/storage infrastructure. Developments on these topics can be followed in the news items below.

Technical properties

Two rows in the table sum up the entire hydrogen economy: the highest energy density by mass, the lowest by volume. This is why hydrogen's cost does not end at production; compression, storage and distribution typically make up a significant share of the total delivered cost. In material selection, hydrogen embrittlement (the loss of toughness in certain steels under hydrogen exposure) is a fundamental design constraint.

Points to consider when evaluating a project

• Look at the delivered cost, not the production cost. Compression, storage and transport make up a larger line item than production in most projects.
• Calculate the capacity factor. An electrolyzer investment pays off based on how many hours a year it operates; an intermittent renewable source directly reduces this figure.
• Define the buyer from the outset. Green hydrogen projects are difficult to finance without a long-term offtake agreement.
• Choose the certification scheme early. The scheme accepted by the export market affects plant design and measurement infrastructure.
• Review material compatibility. Whether existing pipes and equipment are suitable for hydrogen service is a separate engineering study.

Frequently asked questions

Is there a product difference between green hydrogen and gray hydrogen?

There is no difference at the molecular level; both are pure H₂. The difference lies in the CO₂ released during production, and this difference is documented through certification. For a buyer, what matters is how the product will be reflected in the carbon footprint calculation — particularly for exports.

Why is hydrogen expensive?

For green hydrogen, most of the cost comes from the price of electricity and the amortization of the electrolyzer investment. Compression, storage and distribution add to this. For gray hydrogen, cost is largely tied to the price of natural gas; as carbon pricing rises, the gap between the two narrows.

Can hydrogen be transported through the natural gas network?

Limited-ratio blending is being tested in many networks. However, hydrogen can embrittle steel, can create compatibility issues with existing meters and burners, and because its energy content by volume is low, the same pipe cannot carry the same amount of energy. Pure hydrogen generally requires dedicated lines.

Is hydrogen safe?

Its risks are known and manageable. It has a very wide flammability range and low ignition energy; on the other hand, because it is much lighter than air, it rises and disperses rapidly in the event of a leak, unlike liquid fuels, which pool on the ground. What matters is ventilation, leak detection and material selection.

What are the first targets for industrial transition to hydrogen?

Areas where electrification is difficult: replacing existing gray hydrogen in ammonia and methanol production, refinery hydrogen, direct reduced iron, and process heat requiring high temperatures. Hydrogen is already used in these areas; what will change is the production method.