Hydrogen knowledge

Hydrogen is the lightest and most common element in the universe. It is a colourless, odourless gas that can be used as an energy source. Unlike many other chemical substances, hydrogen is non-toxic and poses no immediate danger if released into the environment. However, hydrogen can be dangerous in enclosed spaces as it can displace oxygen, leading to asphyxiation. In the event of a leak in an enclosed space, there is also a risk of explosion as hydrogen is highly flammable. Good ventilation and leak monitoring are therefore crucial to ensure safety. 

Hydrogen has a high gravimetric energy density (33.3 kWh/kg; petrol: 12 kWh/kg), which makes it an efficient energy carrier. Its volumetric energy density (2.8 kWh/m3 ; petrol 9,000 kWh/kg), on the other hand, is very low. It must therefore be compressed, liquefied or chemically bound for practical use - which requires a great deal of energy and technology. Suitable transport carriers for hydrogen are, for example, ammonia and methanol, which can transport many times more hydrogen than pure hydrogen.

These carriers, known as hydrogen derivatives, can be used to store and transport large amounts of energy, which is particularly advantageous for mobile applications such as vehicles. On the other hand, they also make hydrogen attractive for importing clean energy from global sources on a large scale. This means that the location of hydrogen production using solar energy (e.g. electrolysis in the global south) and the time and place of use can be flexibly organised and decoupled from each other.

It burns with oxygen to produce pure water. This essentially produces clean water vapour and thus helps to avoid climate-damaging fossil fuel emissions locally.

Hydrogen is highly flammable and can form explosive mixtures with oxygen. This property requires special precautions during storage and handling. However, hydrogen is no more dangerous than other flammable gases such as natural gas or propane if it is handled under controlled conditions. It is technically very manageable and has been used in various industries for many years.

Hydrogen as an energy carrier can contribute to a significant reduction in greenhouse gas emissions if it is produced from renewable sources, but production from fossil fuels can still cause CO2 emissions.

As a molecule itself, it has the following effects:

• Rapid diffusion: hydrogen is the lightest element and diffuses very quickly into the atmosphere. In the event of a leak, hydrogen disperses rapidly and rises quickly due to its low density. This reduces the risk of accumulation in areas close to the ground, which is an advantage compared to heavier gases such as propane or natural gas.
• Reactivity: Hydrogen is highly flammable and can form explosive mixtures when combined with oxygen. In the event of a leak, there is a risk of fire or explosion, especially in closed or poorly ventilated rooms. Good ventilation and leak monitoring are therefore crucial.
• Environmentally friendly: In contrast to fossil fuels, hydrogen does not cause any direct environmental pollution such as oil or petrol in the event of a leak. There are no toxic residues or soil contamination.
• No greenhouse gas effect: Hydrogen itself is not a greenhouse gas. In the event of a leak, hydrogen does not contribute directly to global warming. However, it is important to consider the entire production chain, as the production of hydrogen from fossil fuels can cause CO2 emissions if no CO2 capture takes place.

Fuel cells: Hydrogen is used in fuel cells to generate electricity. This is particularly relevant for mobility, which is to be operated emission-free. However, stationary fuel cells for power generation are also an application. Keyword safety: There are often concerns about safety, as hydrogen is a highly flammable and volatile gas. Here are some points that emphasise the safety of hydrogen systems:

• Modern safety standards: Hydrogen vehicles and fuel cells are designed and tested to rigorous safety standards. These standards ensure that the systems function safely even under extreme conditions.
• Robust tanks: Hydrogen is stored in specially developed pressurised tanks that are extremely resistant and meet high safety requirements. These tanks are designed to remain intact in the event of an accident.
• Leak detection: Hydrogen-powered vehicles are equipped with advanced leak detection systems that react immediately to hydrogen leaks and initiate appropriate safety measures.
• Rapid diffusion: Hydrogen is very light and diffuses quickly into the atmosphere, which reduces the risk of accumulation and thus the risk of explosion.
• Proven technology: Hydrogen and fuel cells have been used for decades in various applications, from aerospace to industry, and have proven to be safe and reliable.

Direct reduction in the steel sector: Hydrogen can be used as a reducing agent in steel production to replace the use of coal and significantly reduce CO2 emissions.

Chemical industry: Hydrogen is an important raw material in the chemical industry, where it is used to produce ammonia, methanol and other chemicals.

Energy production: Hydrogen can be burnt in adapted gas turbines or mixtures with natural gas, for example. This makes it a flexible and low-emission energy source. However, efficiency losses are high (electricity is converted into → H₂ is burnt and (re)converted into → electricity). Hydrogen as a fuel is not completely emission-free either. Depending on the process, different levels of NOₓ emissions can be produced. This is why hydrogen is more useful as a backup solution or in special applications, not as a permanent solution for energy generation.

Storage of renewable energy: Hydrogen can be used as a storage medium for surplus renewable energy by extracting it from water through electrolysis. This energy can later be converted back into electricity if the demand for electricity cannot be met by renewable sources such as wind and PV.

Generation of process heat: In industry, hydrogen can be added proportionally to the burners. This means that hydrogen can be used in energy-intensive sectors until there is a complete switch to hydrogen.

Hydrogen can be produced by electrolysis of water, steam reforming of natural gas or by thermochemical processes. If renewable energy (e.g. wind, solar or hydroelectric power) is used in hydrogen electrolysis, this is referred to as green hydrogen. In most other production processes, it is therefore important to capture the CO2 produced and store it permanently in order to obtain sustainable hydrogen.

The colour theory describes the origin of hydrogen: green hydrogen is produced from renewable energies, blue hydrogen from fossil fuels with CO2 capture, and grey hydrogen from fossil fuels without CO2 capture. Here is an overview of all the "colours":

Green hydrogen:

• Production: water (H2O) is split into hydrogen (H2) and oxygen (O2) by electrolysis using electricity from renewable energy sources such as wind, solar or hydroelectric power.
• CO2 emissions: No direct CO2 emissions as the energy sources are renewable.

Blue hydrogen:

• Production: From fossil fuels, usually natural gas, by so-called steam reforming. The resulting CO2 is captured and stored (see Carbon Capture and Storage [CCS]).
• CO2 emissions: CO2 emissions are reduced as the CO2 is captured and stored, but not completely eliminated.

Grey hydrogen:

• Production: From fossil fuels, usually natural gas, by vapour reforming without CO2 capture.
• CO2 emissions: High CO2 emissions, as the CO2 is not captured.

Turquoise hydrogen:

• Production: By methane pyrolysis, in which natural gas is broken down into hydrogen and solid carbon.
• CO2 emissions: No direct CO2 emissions, as the carbon is in solid form and is not released as CO2.

Brown or black hydrogen:

• Production: From coal by gasification or other processes. Does not take place on an industrial scale.
• CO2 emissions: Very high CO2 emissions, as coal is a carbon-rich fuel and there is no CO2 capture.

Red hydrogen

• Production: Hydrogen is produced by thermochemical processes using nuclear energy. The heat from nuclear reactors is used to split water into hydrogen and oxygen.
• CO2 emissions: The production of red hydrogen is almost CO2-free, as the energy source nuclear power does not cause any direct CO2 emissions. However, there are environmental concerns regarding the disposal of radioactive waste and the safety of nuclear power plants.

White hydrogen:

• Production: White hydrogen refers to naturally occurring hydrogen that exists in geological formations without human intervention. It is therefore not produced by industrial processes. White hydrogen is a promising energy carrier due to its potentially CO2-free production. Despite its potential, the commercial utilisation and distribution of white hydrogen is currently limited. This is mainly due to the difficulty of developing it, a lack of infrastructure, little research and development and regulatory and economic challenges.
• CO2 emissions: As white hydrogen is naturally occurring and not produced by industrial processes, there are no direct CO2 emissions associated with its production. The challenge lies in the (cost-efficient) development and utilisation of these natural deposits.

Hydrogen derivatives are chemical compounds that are produced from hydrogen or contain hydrogen as an essential component. These derivatives are often used to store, transport or utilise hydrogen in various industrial processes, as they transport larger quantities of hydrogen per unit volume than pure hydrogen itself. The most common derivatives include ammonia and methanol, which are used as a means of transporting hydrogen or as raw materials in the chemical industry.

Fuel cells, hydrogen combustion engines (with significantly reduced emissions compared to operation with fossil fuels) and hydrogen turbines are some of the technologies that can be used to utilise hydrogen as an energy source. In green steel production, it is used as a CO2-free fuel instead of coal/coke. It is also used to produce ammonia (e.g. fertiliser industry), methanol (fuel or chemical industry) or as a coolant.

The main players include energy companies, technology developers, governments, investors, operators and end users from various sectors. The value chain in the H2 market is essentially energy production (for the production of hydrogen), hydrogen production, storage, transport and application.

Hydrogen is seen as a key component of the energy transition, as it can contribute to the decarbonisation of industry and transport and supports the integration of renewable energies.

Green hydrogen is currently generally more expensive than grey or blue hydrogen, as the production costs for renewable energies are higher. No reliable price information is available for the other colours, as the technologies are still being developed, or are not widely used, or have not yet been commercially developed.

Hydrogen must be able to compete with fossil fuels in terms of price, which requires a reduction in production costs through technological advances and economies of scale. The price of hydrogen today can vary greatly depending on the production method and market conditions. In general, the price of hydrogen in Germany has been between 5-6 euros in the industry and 8-15 euros per kilogram at HRS (Hydrogen Refuelling Stations) in recent years, with green hydrogen tending to be more expensive than grey or blue hydrogen. In order to be competitive, especially compared to fossil fuels, the aim is to reduce the cost of green hydrogen to around 2 to 3 euros per kilogramme (6 euros at refuelling stations). This requires technological progress and economies of scale in production and infrastructure, which must be further strengthened by incentivising manufacturers and users.

In addition, subsidy programmes should be reactivated and relaunched to make investment in hydrogen more attractive. Furthermore, green electricity must become cheaper, as the price of electricity is the most important cost factor in electrolysis. This will enable the necessary infrastructure to be built in time for the ramp-up and hydrogen can then outcompete fossil fuels, which have necessarily become more expensive due to CO2 certificates.

Investments in hydrogen are worthwhile as the technology is mature and demand is increasing. In the long term, hydrogen investments make sense as it will become part of the future energy landscape (worldwide). Interesting areas are production, storage, transport and application in industry and transport.

Hydrogen is a very volatile and highly flammable medium and requires special tanks and infrastructure for safe transport and storage, which entails additional costs and technical challenges.

Sector coupling refers to the integration and networking of different energy sectors - such as electricity, heat and mobility - in order to increase efficiency and maximise the use of renewable energy. Through sector coupling, hydrogen is used as an energy carrier to store surplus renewable energy and utilise it in other sectors when needed. This enables a flexible and sustainable energy supply by removing the boundaries between sectors and promoting holistic energy utilisation. Hydrogen plays a central role in sector coupling, as it acts as a link between electricity generation, industrial utilisation and mobility.

Germany plays a leading role in the hydrogen market, both in terms of the development of technologies and the political framework conditions:

1. Import/export: Germany is endeavouring to build a hydrogen economy based on both domestic production and imports. Due to limited domestic renewable energy capacity, Germany is expected to import 70% of hydrogen from countries with abundant renewable resources. At the same time, Germany is investing in the development of export capacities for hydrogen technologies and expertise.
2. Policy framework: Germany has introduced several initiatives and laws to promote the hydrogen economy. These include the Hydrogen Acceleration Act, which aims to accelerate the development and deployment of hydrogen technologies. This law is intended to support investment in infrastructure, research and development and create incentives for industry to utilise hydrogen as an energy source.

If you still have questions after this FAQ list that have not been answered here, or if you would like to go into more detail, please do not hesitate to contact us. Contact us: wasserstoff@hydrohub.de or directly Manuel Frinke (frinke@energy-engineers.de) or Friederike Ferdinand (ferdinand@energy-engineers.de)