Hydrogen Gas: Properties, comparisons, and its key role in a cleaner industry 

Takeaways 

• Hydrogen exists in solid, liquid, and gas states, but is primarily used as a gas in industry. 

• Hydrogen gas offers high energy per mass and zero-carbon combustion but is challenging to store and transport. 

• Compared to methane, propane, and butene, hydrogen is cleaner but less energy-dense by volume. 

• Industries use hydrogen gas in refining, chemicals, metallurgy, energy storage, and transportation. 

• Hydrogen can be produced via electrolysis, steam methane reforming, biomass gasification, and other methods. 

• Hydrogen gas supports emission reduction in sectors like steel, transport, and energy storage. 

• Infrastructure for hydrogen—especially storage and transport—requires strategic investment. 

What Are the States of Hydrogen? 

Hydrogen, the lightest and most abundant element in the universe, exists in three states: solid, liquid, and gas. Each state has specific uses based on the conditions under which it's most stable. 
 

• Gas: At standard temperature and pressure, hydrogen exists as a diatomic gas (H₂). It's non-toxic, colorless, and odorless. This is the state most commonly used across industries due to ease of generation and immediate usability in pipelines and processes. 
   

• Liquid: Hydrogen gas condenses into a liquid at a very low temperature of -253°C. Liquid hydrogen is used in aerospace, where high energy density is needed. The low temperature required to maintain this state makes it expensive to store and transport, though advancements in cryogenic technology are addressing some challenges. 
   

• Solid: Under extreme pressure and low temperatures, hydrogen can exist as a solid. While not widely used industrially, solid hydrogen is of scientific interest and could have niche applications in space or materials science. 

Knowing the properties of hydrogen in these states helps determine how and where it's best applied in practice. 

To learn more about physical properties and conditions, read Stargate Hydrogen’s article on liquid hydrogen. 

More about the Hydrogen Gas 

Hydrogen gas is the gaseous molecular form of hydrogen, normally written as H₂.  

Each molecule contains two hydrogen atoms bonded together. At typical ambient conditions, pure hydrogen is a colourless and odourless gas. 

Hydrogen is the lightest element, and H₂ is the lightest molecular gas. Its low molecular mass gives hydrogen gas several properties that matter in industrial engineering, including very low density, high gravimetric energy content and rapid upward dispersion when released in open or suitably ventilated spaces. 

Hydrogen is already an established industrial material rather than simply a prospective energy carrier. Global hydrogen demand surpassed 100 million tonnes in 2025, according to the International Energy Agency (IEA), and traditional uses in industry and refining continued to account for most demand. 

Comparing Hydrogen Gas with Methane, Propane, and Butene 

Hydrogen gas competes with hydrocarbon gases in many industrial settings. Let’s compare key performance indicators relevant to R&D and procurement teams: 

Considerations about comparing hydrogen gas 

• Hydrogen’s key advantage is its zero-carbon emissions when combusted. This makes it attractive for decarbonization initiatives. 
• Its disadvantage lies in volumetric energy: more space is needed to store the same amount of energy compared to hydrocarbons. 
• Infrastructure and handling safety are major concerns. Hydrogen is more flammable and leaks more easily than heavier gases. 

For further reading on technical comparisons, see this post on hydrogen storage solutions. 

Where Is Hydrogen Gas Used in Industry? 

Hydrogen gas is primarily used as an industrial feedstock and process gas. Major applications include petroleum refining, ammonia and methanol production, iron and steel processing, hydrogenation and a range of chemical and manufacturing processes. 

The IEA reports that established applications such as refining, ammonia, methanol, and fossil-based direct-reduced iron account for the overwhelming majority of hydrogen demand. 

Oil Refining 

Refineries consume industrial hydrogen gas in processes including hydrotreating and hydrocracking. 

Hydrotreating uses hydrogen to remove contaminants such as sulphur from refinery streams. Hydrocracking combines catalytic processing with hydrogen to convert heavier hydrocarbon fractions into lighter products. Hydrogen availability, purity, and pressure can therefore be closely linked to refinery throughput and product specifications. 

More about how Hydrogen is used in Oil Refineries here: https://stargatehydrogen.com/hydrogen-for-oil-refineries/

Ammonia and Fertiliser Production 

Ammonia production is one of the world's largest uses of hydrogen gas. 

In the Haber-Bosch process, hydrogen reacts with nitrogen to form ammonia: 

N₂ + 3H₂ → 2NH₃ 

Ammonia is subsequently used in fertilisers and numerous chemical processes. Changing the method used to produce the hydrogen feedstock can therefore change the emissions profile associated with ammonia production. 

More about how Hydrogen is used for ammonia production here:  https://stargatehydrogen.com/hydrogen-for-ammonia-production/

Methanol and Hydrogen-Derived Fuels 

Hydrogen is also a feedstock for methanol production. Depending on the process, hydrogen reacts with carbon monoxide and/or carbon dioxide as part of methanol synthesis. 

Hydrogen produced using low-emissions electricity can also be combined with captured or biogenic carbon to make synthetic hydrocarbons and other hydrogen-derived fuels. The environmental outcome depends on the complete production pathway, including electricity and carbon sources. 

More about how Hydrogen is used for e-fuels production here: https://stargatehydrogen.com/hydrogen-for-e-fuels-production/

Iron and Steel 

Hydrogen can be used as a reducing agent in certain direct reduced iron processes, where its role is to remove oxygen from iron ore. 

When hydrogen replaces carbon-based reducing agents, the chemistry of the reduction step can reduce direct CO₂ formation. The overall emissions outcome still depends on hydrogen production, electricity supply and the rest of the steelmaking process. 

More about how Hydrogen is used for steel production here: https://stargatehydrogen.com/hydrogen-for-steel-production/

Hydrogenation and Chemical Processing 

Hydrogenation involves adding hydrogen to chemical compounds, often using a catalyst. It is used in sectors ranging from chemicals and petrochemicals to food processing. 

Industrial users may require tightly controlled hydrogen purity, pressure and flow because impurities or supply variations can affect catalysts and product quality. 

More about how Hydrogen is used for hydrogenation here: https://stargatehydrogen.com/hydrogen-for-hydrogenation/

Hydrogen Gas in Energy Storage 

Beyond combustion or industrial feedstock, hydrogen gas is increasingly used in energy storage systems. Here’s how: 

• Power-to-Gas: Excess renewable electricity (e.g., from solar or wind) is used to electrolyze water into hydrogen. That hydrogen can then be stored for long periods. 
• Seasonal Storage: Unlike batteries, hydrogen can be stored for months with minimal losses, making it useful for balancing seasonal energy fluctuations. 
• Fuel Cells for Grid Support: Stored hydrogen can be converted back to electricity during peak demand using stationary fuel cells. 

This energy buffering role is key for industries aiming to stabilize their operations while integrating renewables. 

Learn more in this post on hydrogen storage solutions. 

Hydrogen Gas Production Methods 

Hydrogen gas production separates hydrogen from hydrogen-containing compounds such as natural gas, coal, biomass or water. Hydrogen is an energy carrier and industrial feedstock, not a primary energy source that is normally available as free H₂ in nature. 

Current global production remains dominated by fossil fuels. The IEA reports that low-emissions hydrogen still accounts for only a small share of global hydrogen supply. The way hydrogen gas is produced directly affects its cost and sustainability. Here's a closer look: 

1. Steam Methane Reforming (SMR) 

• Still the most common method. 
• Efficient but emits significant CO₂ unless paired with carbon capture. 

2. Electrolysis 

• Uses electricity to split water. 
• Can be fully green if powered by renewable energy. 
   

Technologies include:  

• Alkaline Electrolysers: Proven, cost-effective, longest lifespan and most reliable
• PEM Electrolysers: High efficiency, faster response, small form factor.  
• Solid Oxide: Operates at high temperatures, promising higher efficiencies and integration with heat-intensive processes. 

3. Biomass Gasification 

• Converts organic waste into hydrogen-rich gas. 
• Useful in circular economy strategies. 
• No greenhouse gas emissions thanks to being closed carbon cycle. 

4. Photocatalysis and Emerging Technologies 

• Research is ongoing into sunlight-driven direct hydrogen generation, but not yet commercial. 

For technical insights on production, check Hydrogen Production 101 by Stargate Hydrogen. 

Hydrogen Infrastructure Challenges 

Despite its benefits, hydrogen gas presents logistical hurdles: 

• Storage: Due to its low density, hydrogen must be compressed or liquefied. This increases costs and complexity. 

• Transport: Existing pipelines are not always compatible due to hydrogen embrittlement. Blending with natural gas is one option, but pure hydrogen distribution needs dedicated infrastructure. 

• Safety Protocols: Hydrogen is more flammable and leaks easily due to its small molecule size. Leak detection, ventilation, and training are all necessary. 

Companies looking to use hydrogen gas need to assess not just the fuel source, but also the infrastructure readiness of their facilities. 

For more on these challenges, read Stargate Hydrogen’s post on hydrogen system design. 

On-Site vs Delivered Hydrogen Gas 

Hydrogen gas can either be produced at the point of use or produced elsewhere and transported to the industrial site. Neither approach is inherently preferable for every facility. 

Delivered hydrogen can arrive as compressed gas, cryogenic liquid or through a pipeline where suitable infrastructure exists. On-site hydrogen production generates hydrogen at or close to the process consuming it. The decision requires an assessment of the complete hydrogen supply system. 

Hydrogen Demand 

The required flow rate and consumption profile are fundamental. A facility consuming hydrogen continuously at industrial scale faces different economics from a site with small or intermittent demand. Engineers should examine average demand, peaks, turndown requirements and anticipated future consumption. 

Electricity Supply 

For on-site hydrogen production by electrolysis, electricity price, availability and carbon intensity can strongly affect both economics and emissions. 

Renewable electricity does not necessarily have to be physically adjacent to the electrolyser, but the project's electrical architecture and the rules governing claims about renewable or low-emissions hydrogen need to be considered. 

Water Supply and Quality 

Electrolysis consumes water as a reactant and requires feed water that meets the electrolyser system's quality requirements. Water treatment and cooling requirements also need to be included in plant design. 

Required Hydrogen Purity and Pressure 

The downstream application defines hydrogen specifications. 

An ammonia plant, refinery, hydrogenation process and fuel-cell installation can have different requirements. Purification, drying and compression therefore need to be evaluated as part of the hydrogen production system rather than after the electrolyser has been selected. 

Reliability and Storage 

On-site production does not automatically remove the need for hydrogen gas storage. 

Buffer storage may be required to separate hydrogen production from process demand, handle short interruptions or maintain downstream operations during maintenance. Some sites may also need backup hydrogen supply or redundancy in production equipment. 

Site Integration 

Available space, electrical infrastructure, cooling, water, hazardous-area classification, ventilation, vent routing, oxygen management and connection to the consuming process can all influence project feasibility. 

For EPC and industrial project teams, this is why a useful comparison is often the total delivered cost and operational performance of hydrogen at the required point of use, rather than the nominal production cost of H₂ alone. 

How Hydrogen Gas Helps Reduce Carbon Emissions 

One of hydrogen’s strongest benefits is the absence of carbon emissions during combustion. This makes it attractive for industries under pressure to decarbonize: 

• Steel Industry: Projects in Europe are piloting hydrogen instead of coal for ore reduction, significantly lowering CO₂ output and increasing steel quality 

• Heavy Transport: Hydrogen fuel cells are viable where battery solutions fall short due to exponentially increasing weight or charging time constraints. 

• Chemical Sector: Green hydrogen replaces fossil-derived feedstock in ammonia and methanol production, reducing lifecycle emissions. 

• Power Grid: Acts as long-term energy storage for intermittent renewables, reducing the need for coal or gas peaker plants. 

As regulatory frameworks tighten and carbon pricing spreads, hydrogen gas offers a realistic path to compliance and sustainability. 

For examples and use cases, see Stargate Hydrogen’s article on green hydrogen production. 

Frequently Asked Questions About Hydrogen Gas 

What Is Hydrogen Gas? 

Hydrogen gas is molecular hydrogen, H₂. It consists of two bonded hydrogen atoms and is a colourless, odourless gas under normal ambient conditions. It is widely used as an industrial feedstock and process gas. 

What Is Hydrogen Gas Used For? 

Major hydrogen gas uses include petroleum refining, ammonia and fertiliser production, methanol synthesis, hydrogenation and some iron and steel processes. Hydrogen is also used in electronics, controlled atmospheres, fuel cells and energy applications. 

How Is Hydrogen Gas Produced? 

Hydrogen gas can be produced through natural gas reforming, coal gasification, biomass and waste-based processes, and water electrolysis. Most global hydrogen production still comes from fossil fuels without carbon capture. 

How Does Electrolysis Produce Hydrogen? 

Electrolysis applies electrical energy to split water into hydrogen and oxygen. The overall reaction is 2H₂O → 2H₂ + O₂. The lifecycle emissions associated with hydrogen production by electrolysis depend strongly on the source of electricity. 

Is Hydrogen Gas Flammable? 

Yes. Hydrogen gas is highly flammable and has a broad flammability range in air, commonly cited as approximately 4 to 75% by volume under normal conditions. Industrial installations use engineered measures such as ventilation, gas detection, pressure relief, appropriate materials and process controls to manage this property. 

Is Hydrogen Gas Toxic? 

Hydrogen itself is not considered toxic. However, a large hydrogen release can displace oxygen in an enclosed space, creating an asphyxiation hazard. Its flammability also makes leak prevention and detection essential. 

Can Hydrogen Be Produced On-Site? 

Yes. On-site hydrogen production can use an electrolyser to produce hydrogen from water and electricity directly at or near the point of consumption. Whether this is preferable to delivered hydrogen depends on demand, electricity, water, required purity and pressure, storage, reliability, infrastructure and economics. 

Final Thoughts 

Hydrogen gas is moving from niche applications to center stage in industrial strategies. Its unique energy properties, clean combustion, and versatility make it an important consideration for any company evaluating long-term decarbonization goals. But it’s not a plug-and-play solution. Each use case demands thoughtful planning—especially when it comes to production, storage, and infrastructure. 

Want to evaluate if hydrogen gas fits your technical roadmap? Contact Stargate Hydrogen's specialists for a detailed consultation.