All about liquid hydrogen
Sustainability is a central issue in today’s society. Natural disasters, disturbing news reports, and the pressure from politicians demand that more and more industries make every effort to operate more sustainably.
In line with the European Green Deal, the European Climate Act also imposes the legally binding target of reducing greenhouse gas emissions by 55% in 2030 from the 1990 levels and achieving climate neutrality in the EU by 2050. To meet these targets, Action is called for today within many industries. It is resulting in a lot of research, discussion, and, fortunately, the development of promising renewable energy sources.
In this blog, we focus on hydrogen as an essential part of the current sustainability discussion. Hydrogen has enormous potential to serve as a sustainable energy carrier if adequately produced and used.
What exactly are the characteristics of this gas? What possibilities does hydrogen offer in terms of sustainability? What are essential applications, and which solutions does Demaco offer? We will discuss this and much more in this blog.
What is liquid hydrogen?
Hydrogen is the lightest gas in the universe. Under normal conditions, it is a chemical element with symbol H and atomic number 1, a colorless, odorless, and highly flammable gas. The gas does not occur on Earth in isolated form but is part of water. Hence, a lack of hydrogen will indeed not become an issue.
Hydrogen is used in both liquid and gaseous form. The gas has a density (kg.m-3) of 0.08988 and a boiling point of -252.9 ℃. At its boiling point, hydrogen condensates from gas to liquid.
Compared to most other gases, the boiling point of hydrogen is extremely low. Only helium with its boiling point at -268.9 ℃ has an even lower boiling point. The very low temperature combined with the high flammability of hydrogen makes it a relatively dangerous material. Stringent safety measures and advanced infrastructures are thus essential.
The history of liquid hydrogen
Hydrogen was first produced in 1671 by scientist Robert Boyle. He investigated the reaction of various metals by dipping them in acid. As the metals yielded their respective reactions with the acid, hydrogen was produced as a side effect.
It was, however, not until 1766 that hydrogen was identified for the first time by Henry Cavendish. He confirmed in a research paper that hydrogen was a separate element and went into further detail about the extreme flammability of this then newly discovered gas.
Cavendish also discovered that hydrogen gas forms water when combined with fire. This discovery led to the name that Antoine Lavoisier gave the gas a few years later: hydrogenium («hydro» and «genes» to be translated as «water-maker» or «water-former»).
The hydrogen production did not really take off until William Nicholson and Sir Anthony Carlisle discovered a process to produce hydrogen in 1800. The electrolysis method amounts to applying electric current to water, thus producing hydrogen and oxygen gas.
At that time, hydrogen was exclusively gaseous. Only decades later, several scientists worldwide started their experiments on liquefying gas. One of these researchers was Kamerlingh Onnes, a professor at Leiden University. He built a cold laboratory and competed diligently with other researchers to be the first to produce liquid hydrogen.
While Onnes was on the right track, Scottish physicist James Dewar was the first to succeed in turning hydrogen into a liquid. In 1898, he achieved a temperature of -252.9 ℃ for the first time. A few years later, in 1906, Onnes also successfully produced liquid hydrogen. He accomplished this in his cryogenic laboratory in Leiden, where at the time, the lowest temperatures worldwide were reached.
Meanwhile, research into the application of hydrogen also steadily continued. This resulted in the development of the first gas battery in 1945 and, shortly after that, research into the possibilities of hydrogen as an energy carrier in a fuel cell.
During the 1990s, the potential of hydrogen became increasingly apparent. Experiments on ships, trucks, and aircraft began, and the aerospace sector soon became a major user.
The sustainability benefits were also becoming more apparent. In 1970 John O’M. Bockris created the term «hydrogen economy. He described an economy in which renewable hydrogen would be the primary energy carrier, replacing our fossil fuels.
The advantages of liquid hydrogen
While Bockris’ hydrogen economy has not yet become reality, sustainable hydrogen is indeed in the spotlight. The sustainability benefits are significant:
- First, hydrogen is an omnipresent element. So even while there are currently challenges related to hydrogen production, there is no shortage of raw materials.
- Next to that, when produced and used in a sustainable way, hydrogen doesn’t adversely affect the environment. The only by-products are heat and water, which are easily reabsorbed into the atmosphere.
- Finally, the production of hydrogen does not require large areas of land, which for example, is the case for biofuel and hydropower.
In addition to sustainability, hydrogen has practical advantages. For example, it can efficiently store for a prolonged time the generated energy. This is in contrast to power generated from wind energy. This power has to be fed directly into the network and discharged in case it is filled to capacity.
But is hydrogen really as sustainable as many people think? This depends on the way it is produced. If renewable energy is used during the production process, hydrogen is indeed a very sustainable option.
Unfortunately, however, this is not yet the case in most cases. Only 5% of hydrogen is currently produced using sustainable energy; fossil fuels are still used in the rest of the cases. And while with good intentions, this production method doesn’t make hydrogen very sustainable at all.
The production of hydrogen
Because hydrogen does not exist on Earth in its pure form, it must be produced. There are three slightly different production processes based on the same principle.
To produce hydrogen, a feedstock that is brought into contact with a source of energy is required. Both the feedstock and the source of energy can differ. In practice, there are three different production processes:
Grey hydrogen is produced using fossil fuels (such as coal or natural gas) and steam. As a result, this form of hydrogen production is also called steam methane reforming. The advantage of this production method is that the costs are relatively low, and large-scale production is possible.
A significant disadvantage, however, is that CO2 is released during production. This, unfortunately, makes grey hydrogen harmful to the environment.
Currently, about 95% of hydrogen is produced by steam methane reforming. This is performed in large reformers, which split hydrocarbon into hydrogen and carbon.
The production of blue hydrogen is basically the same as that of grey hydrogen, with one difference. The vast amount of CO2 released during the production process is not absorbed into the air but captured or reused.
This makes blue hydrogen a lot more sustainable than grey hydrogen. However, capturing the C02 requires energy, reducing the final yield in total energy.
Green hydrogen production uses green energy and water. Using electrolysis, the water is converted into hydrogen and oxygen. This method of production does not release CO2, which makes green hydrogen the only genuinely sustainable hydrogen.
Large-scale production of green hydrogen would be a significant step forward in making fuel and energy more sustainable. Unfortunately, this is currently not the case because several factors make the production of green hydrogen problematic:
- The production of green hydrogen is very costly compared to that of grey hydrogen. Electrolysis technologies are expensive, and green energy is also (for now) more costly than grey electricity.
- Electrolysis consumes a relatively large amount of energy. Critics, therefore, ask whether it would not be more efficient to feed the used electricity directly into the energy network. With electrolysis, you actually have an efficiency of 70%. This means that 30% of the generated energy is lost in the process of making hydrogen.
- Electrolysis requires water. For which currently, mainly clean water is used, which could cause problems in countries with water shortages. However, research shows that seawater and wastewater can also be used for successful electrolysis. This offers possibilities for the future.
The reasons mentioned above imply that the production of green hydrogen is still slow to take off. For this reason, a substantial price drop and a lot of support from governments are needed to make the large-scale production of green hydrogen possible.
Storage and Transportation
While hydrogen is relatively widely used in gaseous form, storing and transporting gaseous hydrogen is challenging. Because of its extremely low density, hydrogen in gaseous form takes up a lot of volume at atmospheric pressure.
However, putting the gas under high pressure (350-700 bar tank pressure) or liquefying it solves this problem. In fact, in liquid form, the density of hydrogen increases as much as 800 times. This means that 800 times more hydrogen can be stored in the same tank or vessel.
What does this mean for the transport of hydrogen? Over short distances, hydrogen is often transported in liquid form in optimum insulated transfer lines, while for long-distance transport, large cryogenic tankers or trains are used. Hydrogen is also transported in its gaseous form by road or rail in high-pressure cylinders.
Like transportation, storing hydrogen is also made more manageable when it is in its liquid form or is kept at very high pressure. Therefore, gaseous hydrogen is usually stored in special tanks built to withstand and regulate this high pressure. Liquid hydrogen is also stored in large tanks or storage vessels. These are equipped with optimal (vacuum) insulation, minimizing energy losses.
The possibility of using existing natural gas infrastructures to transport hydrogen in the future is currently being investigated. This option seems feasible without too many modifications to the existing infrastructures, but again here, too high costs are involved. Another issue is that not every infrastructure is the same, and each one will have to be individually evaluated to assess the extent of the required adjustments.
The applications of liquid hydrogen
What exactly is hydrogen used for? Currently, liquid hydrogen is mainly used and explored in the following industries:
- The space industry, including as a propellant for space rockets. When combined with liquid oxygen (as an oxidizer), hydrogen can generate the tremendous power that is needed to launch a space rocket.
- The maritime industry shows increasing interest in hydrogen as a sustainable energy carrier (via fuel cells). In order to meet the EU’s targets on reducing CO2 emissions, a shift from fossil fuels to CO2-free fuel is mandatory for this industry.
- The aviation industry is working persistently on models for hydrogen-powered aircraft engines. The first pilot models are expected to be built around 2030, but the new aircraft models will not be put into service before 2040.
- The road transport sector, comprising both freight and passenger transportation. Some passenger cars and trucks have recently been developed that use hydrogen as an energy source. However, the use of hydrogen for freight traffic is not expected to take off before 2025. Trials of using hydrogen as a source of energy for internal combustion engines are also taking place.
- The Industrial sector, in which hydrogen serves as a fundamental raw material for ammonia and plastics production. Hydrogen is also used to make petroleum products and methanol.
- The energy sector, in which hydrogen can be used to both cool generators in power plants and stabilize the power grid. Hydrogen is stored and used in fuel cells, which provide a stable backup of energy resulting in optimal uptime.
While the above industries are currently the most prominent users of- and interested in- hydrogen, many other sectors utilize the versatile gas. For example, the food industry uses hydrogen to convert unsaturated fats into saturated oils and fats.
The industrial sector, among other things, also uses hydrogen to produce iron; hydrogen is used for so-called atomic hydrogen welding (AHW). The electronics industry uses hydrogen for various electronic components, and in the medical sector, hydrogen is used to make hydrogen peroxide (H2O2).
As mentioned earlier, in many industries, hydrogen is used in its gaseous form but stored and transported in liquid form. However, there are also several applications for liquid hydrogen:
- The aerospace industry is one of the major users of liquid hydrogen. As stated earlier, this industry uses liquid hydrogen to launch rockets.
- Currently, there is a growing interest in superconductivity (the state in which material has virtually no resistance when transporting electricity), in which liquid hydrogen plays an important role. This provides another potential use for the liquid gas.
- Lastly, the development of heavier trucks and extended-range ships is also considering the use of liquid hydrogen in the tanks.
The risks of liquid hydrogen
The use of hydrogen, whether in gas or liquid form, is not without risks. When hydrogen reacts with the right amount of oxygen gas, a massive amount of energy is released, causing an explosion. In addition, hydrogen has a relatively low combustion temperature and is therefore highly flammable.
Furthermore, because hydrogen is colorless and odorless, a leak in a system is hard to detect. Even a hydrogen flame is almost invisible, and therefore difficult to extinguish. Liquid hydrogen is also extremely cold (-252.9 ℃) and will cause freezing on contact. Finally, oxygen can condense if the hydrogen is insufficiently insulated, forming an increased fire hazard.
There is some debate as to how the above risks compare to other fuels. In fact, research shows that hydrogen poses a slightly higher fire risk than gasoline or natural gas. What this increased risk means for the future of hydrogen remains to be seen. However, all other fuels are not without their dangers either, and with the proper infrastructure and information, hydrogen can be managed well and safely.
Fortunately, hydrogen has been used in various industries for a long time, and infrastructures and security measures have improved significantly over the past few decades. Sophisticated sensors now exist that immediately indicate a leak from an infrastructure. Hydrogen tanks, pipelines, and applications are also subject to rigorous testing standards. This equipment is exposed to high pressure and extreme temperatures before it can be put into service.
With the proper infrastructure in place, hydrogen can be safely managed without any problems if the end-user also handles the gas responsibly. In this respect, providing correct information plays an important role. The better the user follows the instructions and is made aware of possible dangers, the smaller the risk will be.
Insulation for liquid hydrogen
Liquid hydrogen requires a higher quality of insulation than some other liquid gases. The main reason for this is the extremely low temperature of the gas. If, for example, hydrogen is transported through a transfer line with foam insulation, a small rupture in the foam may be the source of oxygen condensation due to the extreme cold emitted by the liquid hydrogen. A fire or explosion will ensue should this condensed oxygen come into contact with hydrogen or any other combustible material.
Fortunately, there is a form of insulation that provides optimal insulation. The vacuum technology method is the solution for safely transporting, storing, and using liquid hydrogen. Vacuum insulating is as much as 15 times better than other insulation materials (for example, PIR/PUR, or Foamglas, Armaflex, Perlite, and Misselon) and can be used for pipes as well as fittings, tanks, and cryogenic equipment.
Vacuum technology uses vacuum or high-vacuum to insulate transfer lines or systems optimally. A vacuum environment is created by encapsulating these lines or systems with a double wall and vacuumize the space between the two walls. The vacuum ensures that heat transfer cannot occur (since most molecules have been extracted) between the warm outside and the cold inside.
Vacuum insulation for hydrogen systems is not only safe but also meets the strict requirements for hydrogen infrastructures. For example, transfer lines for liquid hydrogen on ships are expected to be equipped with a double-containment for extra safety (should the process line have a leakage, the extra-containment will be in place). If the pipelines are provided with vacuum insulation, the vacuum tube also functions directly as a double-containment. As such, vacuum insulation kills two birds with one stone.
Demaco's solutions for liquid hydrogen
At Demaco, we believe in the future of green hydrogen. In fact, we are at the forefront of researching the best hydrogen infrastructures. For decades, we have experimented with prototypes, engaged in pioneering projects, and delivered proof of concept for advanced projects and products.
We work with major players in the hydrogen market and are affiliated with Hydrogen Europe. This association represents the interests of the hydrogen and fuel cell industry and, together with hundreds of companies and associations, is committed to the future of hydrogen in a zero-emission society. Through our collaboration with Hydrogen Europe, we not only closely follow all developments, but we are also actively involved in research and decision-making. This makes us and keeps us experts in the field of hydrogen.
Demaco is also a turnkey supplier for hydrogen projects around the world. We are involved from the first concept and offer support from the initial conceptual sketch, detailed design, engineering, production, delivery, assembly, supervision, commissioning, and finally, the maintenance and certification of the infrastructure and its equipment.
Naturally, all of our projects are carried out using the best materials, are thoroughly vacuum insulated, and follow strict engineering design standards concerning potential explosion hazards under atmospheric conditions (ATEX). As a result, we can minimize the mentioned risks related to hydrogen. In addition, Demaco is DNV-certified for shipboard applications.
Currently, we offer the hydrogen market the following products and solutions:
- A. Filling stations and loading bays for trucks
- B. Vacuum insulated loading arms for ships
- C. Vacuum insulated transfer lines between a tank or liquefier and the application onboard ships and on land.
- D. Vacuum insulated distribution boxes
- E. Hydrogen purifiers
- F. Small-scale hydrogen liquefiers
We are proud of the knowledge and experience we accumulated over the past decades. Because we have been working with hydrogen for such a long time, our methods, products, and infrastructures have been extensively tested and optimized. We are able to offer proven technology whenever a (new) customer comes to us for a solution.
There is still a long way to go before Bockris’ hydrogen economy will become reality. We, however, are ready!