Hydrogen: A tiny chemical with enormous importance for a successful energy transition

Just 0.000000031 mm small and yet with great potential – that is hydrogen. Green hydrogen in particular is regarded as THE energy carrier of the future. However, handling hydrogen is not without danger.

Experts in standardization are committed to making the use of hydrogen safe in different areas and for numerous applications, as well as to integrating hydrogen as a component of smart energy systems.

Hydrogen – Element No. 1

In the periodic table of the chemical elements, hydrogen is located at the top left under the atomic number 1 and the symbol H (lat: hydrogenium; English: "water producer"). Under everyday conditions, hydrogen is a colorless and odorless diatomic gas (H?). When hydrogen is reacted with oxygen (O?) in a controlled manner, it releases a lot of energy and some water, but no carbon dioxide (CO?).

At 120 kJ/g, the weight-based (gravimetric) energy density of hydrogen exceeds all electrical storage options known to us to date by at least two orders of magnitude. Surplus energy from renewable sources (e.g. wind power and photovoltaics) could therefore be stored on a large scale as hydrogen. All these properties make hydrogen highly interesting for the energy transition (BMWi 2020).

Large quantities of hydrogen are available on Earth. However, the deposits known to date consist almost exclusively of hydrogen in chemically bound form; for example water, hydrocarbons and minerals. Hydrogen must therefore be produced from chemical compounds using energy.

Production and costs

The most widely used process for the production of hydrogen is so-called "steam reforming". In this multi-stage process, hydrocarbons (above all natural gas) are reacted with steam at high pressure and temperature via catalysts. The result is hydrogen and carbon dioxide – the latter even in relatively high quantities. With production costs of €1.50/kg, this is the cheapest process for hydrogen production today (IEA).

Great hopes are placed on the production of hydrogen from water electrolysis using various processes (e.g. alkaline electrolysis (AEL) or polymere electrolyte membrane electrolysis (PEM)). In each case, water (H2O) is split into its components hydrogen and oxygen in an electrolyzer using electric current. Today with around ?€4/kg this production process is still rather expensive. However, the International Energy Agency (IEA) assumes that scaling effects and declining prices for electricity from renewable energies can reduce costs by 30 percent by the year 2030 (IEA 2019)*.

The colorful world of hydrogen

? DKE

The "color" or category assigned to hydrogen provides a basic indication of the energy source that was tapped to produce the hydrogen and thus allows conclusions to be drawn about its environmental compatibility.

In addition, other hydrogen production sequences are known of that have yet to be assigned a color. These include chemical processes in which hydrogen is produced as a by-product, e.g. chlor-alkali electrolysis or the plasmolysis of wastewater and plastic waste.

Green hydrogen

is obtained exclusively using energy from renewable energy sources (e.g. wind, hydropower, photovoltaics), typically through water electrolysis. Compared to other processes this production sequence results in significantly less emissions of climate-damaging substances. However, today the market share is correspondingly low.

Yellow hydrogen

is also produced through water electrolysis using the “electricity mix” as energy source; hence, the hydrogen production causes fluctuating emissions according to the energy mix of the electric grid.

Red hydrogen

is also obtained through water electrolysis, with the electrical energy obtained being provided purely by nuclear power. Sometimes reference is also made to pink, rose or violet hydrogen. The process is much debated, since on the one hand it does not cause direct CO? emissions, but on the other hand it is inextricably linked to the issue of nuclear power.

Brown and black hydrogen

are obtained through gasification, steam reforming or partial oxidation of lignite or hard coal. Both are similar to gray hydrogen, both in terms of low production costs and the extensive emission of climate-damaging substances.

Gray hydrogen

is obtained from fossil hydrocarbons, primarily by steam reforming of natural gas. The process is inexpensive, but also involves the emission of significant amounts of climate-damaging substances (especially CO?).

Blue hydrogen

is produced in the same way as gray hydrogen, but the CO? in the process waste gas is captured and deposited (carbon capture and storage, CCS) or alternatively used as a raw material for chemical processes (carbon capture and utilization, CCU). On the one hand, the process is being considered as a "low-CO?" transitional solution for the development of hydrogen production; on the other hand, it is being discussed because of the use of fossil fuels and the question of the final destination of the captured CO?.

Turquoise hydrogen

is obtained through pyrolysis of hydrocarbons. Instead of CO?, solid carbon is produced as a by-product. The necessary thermal energy is ideally obtained from renewable energy sources. Similar to blue hydrogen, this process is also discussed as a "low CO?" transitional, while the use of fossil energy sources and the final deposition of the carbon are regularly subjected to criticism.

Orange hydrogen

is obtained through fermentation and gasification of biomass or water electrolysis with electric current from waste-fired power plants. The process relies on the utilization of residual materials and waste from industry, agriculture, forestry and households; which, however, is associated with the emission of CO?.

Important raw material and energy carrier

While hydrogen is regarded as the energy carrier of the future, it is already an important raw material today. For example, global production of hydrogen in the year 2019 amounted to approximately 117 million tons (Statista 2019). The largest customers for purified hydrogen are the metal-working and chemical industries. In 2018, about 32 million tons of hydrogen were required for the synthesis of ammonia alone (Statista 2018).

Ammonia is a significant starting material for a wide range of pharmaceutical and cosmetic products, but most importantly for the production of fertilizers in agriculture. Through this chain, hydrogen is even an important factor in feeding the world's population.

In the future, hydrogen will also play an important role as an energy carrier and help reduce global greenhouse gas emissions. The gravimetric energy density, which is many times higher than that of lithium-ion batteries, makes the use of hydrogen particularly attractive wherever weight and payload are especially important, and where great ranges and low downtimes are needed (in aviation and heavy-duty transport). In addition to the direct combustion of hydrogen, the conversion of hydrogen back into electricity by means of fuel cells plays a particularly important role here. The VDE fact check Hydrogen in Mobility provides a very good overview of the possible applications in the mobility sector.?

However, fuel cell technology opens up a wide range of possible applications for hydrogen far beyond the mobility sector.

• Fuel cells could be used to replace diesel generators in remote areas (NOW).
• Fuel cell-based industrial trucks (e.g. forklifts), which are particularly suitable for indoor use in hygiene-critical areas, are already a reality.
• Already widespread in Japan, but still in its infancy in Europe: fuel cell heating systems. Through cogeneration of heat and power, these devices provide electrical power and use the resulting waste heat to provide useful heat, for example in the form of hot water. The energy yield (the combined electrical and thermal efficiency) can reach values close to 100 percent.

Experts in standardization make working with hydrogen safe

In electrotechnical standardization, the topic of hydrogen is becoming increasingly important, since electrical systems are operated, among other things, where hydrogen is produced, stored and processed. In addition, hydrogen is becoming increasingly important as an energy carrier for electrical equipment.

Thus at DKE numerous experts are active on various standardization committees that deal with aspects involving the safe use of hydrogen – on both a national and international scale. A selection of the national standardization committees at VDE DKE is presented below.

Safe operation of fuel cells with hydrogen as an energy carrier

Hydrogen has recently been attracting growing attention as an energy carrier. The DKE began to support this development at an early stage.

In 1999 the standardization committee DKE/K 384 – Fuel cells was founded which, among other things, is dedicated to the question of how fuel cells can be operated safely. Through this committee VDE DKE gives German industry a voice on the international stage when it comes to drafting uniform global standards for the safe operation of fuel cells.

A selection of the standards and project portfolio clearly shows how diverse the possible applications of fuel cells are and thus of hydrogen as well.

DIN EN IEC 62282-3-100 (VDE 0130-3-100)

Fuel cells can serve as a substitute for diesel generators in remote locations or provide emergency power in hospitals. The safety requirements for these stationary fuel cells, i.e. permanently fixed at a particular location, are described in this standard.

DIN EN 62282-6-101 (VDE 0130-6-101)

Fuel cells can also be built small enough to be suitable for powering mobile electronic devices such as laptops or cell phones. The standard defines safety requirements for these so-called "micro fuel cells" and the associated fuel cartridges.

DIN EN IEC 62282-4-202 (VDE 0130-4-202)

Fuel cells can also fly – at least in conjunction with a drone. Compared to Li-ion batteries, fuel cells make higher payloads and greater ranges possible as well as shorter downtimes. The standard is still being prepared and describes uniform test methods for the performance behavior of corresponding fuel cells.

DIN EN IEC 62282-8-301 (VDE 0130-8-301)

Fuel cells have a reverse gear, in technical terms also referred to as "reversible operation". So-called "solid oxide fuel cells" can absorb CO? in reversible operation and process it together with water and electric current to produce methane. Uniform test methods for this process are currently being developed and will be described in the standard as soon as available.

Safe use of hydrogen (explosion protection)

Hydrogen has long played an important role in industry, both as a reactant and as byproduct. Like gasoline, diesel and many other energy carriers, hydrogen can form explosive mixtures with air or oxygen – commonly referred to as "oxyhydrogen".

The DKE began early with its work on how hydrogen can be used safely. The result of this work is technical standards – agreements on minimum technical requirements in order to be able to achieve a certain level of safety.

For example, the standardization committee DKE/K 235 – Installation of electrical equipment in hazardous areas was founded as early as the beginning of 1973 and has been dealing with the topic of explosion protection ever since. The following standards in particular stand out in the field of explosion protection:

DIN EN 60079 (standard series)

Explosion protection is a multifaceted topic. Accordingly, the DIN EN 60079 series of standards deals with the many additional measures for the installation and safe operation of electrical systems in potentially explosive atmospheres.

DIN EN 60079-10-1 (VDE 0165-101)

As the risk of formation of an explosive atmosphere increases, so does the effort required to prevent the formation of an ignition source.

Potentially explosive atmospheres are thus divided into zones according to the existing risk potential, for each of which specific design and operational requirements apply. The standard provides assistance in assessing the risk of ignition and defining such zones.

DIN EN 60079-14 (VDE 0165-1)

As a rule, it makes sense to not operate electrical equipment in potentially explosive atmospheres.

However, following this principle with a reasonable amount of effort is not always possible. The standard deals with the principles for the selection and suitability of equipment for use in potentially explosive atmospheres and the installation of electrical systems in the same.

Integration of hydrogen into smart energy systems

Regenerative energy sources, for example sunlight and wind, represent a free but fluctuating energy supply.

The standardization committee DKE/K 901 – System Committee Smart Energy is dedicated, among other things, to the question of how the resource electricity can be dynamically and intelligently distributed. Smart energy systems make new market and grid functions possible along with linking all of the energy sources in every sector. This also includes the generation of hydrogen (power-to-gas).

The committee also coordinates the joint cooperation of standardization-relevant groups with the German Federal Ministry for Economic Affairs and Climate Action (BMWi) and the German Federal Office for Information Security (BSI).

IEC SRD 62913 (series of documents)

The series of documents provides an overview of different use cases, organized by topics such as energy markets, mobility and others.

IEC SRD 63199

This document reflects the status of the most important standards in the field of "Smart Energy Grids". It identifies items in need of standardization, their current status and the work required in order to achieve it.

Sources

* The Future of Hydrogen, Seizing today’s opportunities. Final Report. International Energy Agency, Juni 2019.

More information in the context of our theme week on hydrogen

• The age of hydrogen | LinkedIn