Hydrogen the all-rounder

By Oliver Jesgulke and Volker Paulun
Use as a storage medium, as propulsion energy and as a carbon substitute in industrial applications: There are quite a few expectations pinned on hydrogen. Schaeffler’s hydrogen expert Dr. Stefan Gossens looks at current trends.
© Mercedes-Benz
H2 in commercial vehicles

Like many truck manufacturers, Daimler Trucks is pursuing fuel cell technology in the electrification of its vehicles, from urban distributors to international long-distance haulers. Pictured above are sketches of the GenH2 concept vehicle with a targeted range of 1,000 km (621 mi). Its mass production launch is planned for the middle of this decade.

In the commercial vehicle sector, hydrogen as a propulsion source has already become well-established. For instance, 50,000 forklift trucks worldwide now have a fuel cell on board. Most manufacturers such as Linde, Jungheinrich, Toyota and Still offer a hydrogen version of their forklifts and many large companies are gradually changing their intralogistics fleets as part of their transformation towards CO2-free manufacturing. The industry network Clean Intralogistics Net (CIN) supports this development and Schaeffler is on board as well. Together with other partnering companies, CIN is driving the market activation and market development of the fuel cell in intralogistics. With 77 production plants, Schaeffler is also a potential user of fuel cell powered forklifts. The network members represent the entire value chain, from manufacturers of forklifts and fuel cells to component and gas suppliers to users of the technology.

In the truck segment, there’s a lot of momentum towards hydrogen. Practically every manufacturer is currently working on hydrogen models and the first prototypes have already been deployed to fleets. Volvo and Mercedes recently entered into a joint venture for mass production of fuel cells. The advantage of commercial vehicles over passenger cars is that they travel according to pre-planned schedules and routes, so that the sparse filling station network is not as critical. Plus, due to the fact that commercial vehicles are typically on the road all the time, the operation of an IC engine with liquid hydrogen is conceivable as well. Consequently, the disadvantage of hydrogen evaporating when the vehicle is not being used for longer periods of time is clearly less critical than in the case of passenger cars.

Fuel cell technology is near-perfectly suited for use in garbage trucks because green hydrogen for their powertrains can be produced directly from biogenic waste at incineration plants. German vehicle manufacturer Faun is planning to launch mass production of such a garbage truck in 2021 featuring a hybrid powertrain with a fuel cell serving as a range extender for the battery-electric drive system.

Hydrogen the all-rounder© Schaeffler

Dr. Stefan Gossens, Innovation Program Manager for Energy Storage and Conversion at Schaeffler: “High performance, long range, fast refueling and lower weight compared to batteries: in commercial vehicles, hydrogen can display its strengths even more effectively than in passenger cars. The tens of thousands of forklifts existing by now have shown that the technology is also suitable for mass deployment in the field. Increasing use of hydrogen trucks would also boost the expansion of H2 fillings stations. Hyundai has projected that such a facility would be profitable if just 15 trucks would regularly fill their tanks there.”

H2 in passenger cars

The three tanks of the new Toyota Mirai have a hydrogen capacity of 5.6 kg (12.3 lb). The WLTP-based range is 650 km (404 mi), compared to the predecessor’s 500 (311). Another major stride compared to the predecessor was the reduction of the production time for a single fuel cell stack from 15 minutes to a few seconds.

A nice PR success for Toyota: The Japanese automaker delivered to the Pope as a gift a Mirai converted into a “Popemobile,” which made positive headlines and caused the Holy Father to be inducted into the exclusive club of hydrogen car users. Even 40 years after the German Aerospace Center (DLR) presented Europe’s first hydrogen passenger car (a modified BMW 5), this vehicle category is still a niche product, although there’s a lot speaking in favor of green hydrogen in automobiles: especially their long achievable range, fast refueling and, obviously, their emissions, which, ideally amount to nothing but water.

A sparse filling station network (of currently 140 stations in all of Europe, of which 76 are in Germany, according to the European Automobile Manufacturers’ Association (ACEA)), an offering of models that can be counted on the fingers of one hand and, above all, the high vehicle prices that are almost twice as high as those of comparable cars using IC engines, have been preventing any appreciable spreading of the technology so far. Toyota is confident that this is going to progressively change. While of the first Mirai generation 11,000 more or less hand-made units were produced in five years, this number is planned to increase to 30,000 mass-produced units of the successor – per year. Toyota’s competitor Hyundai is planning to sell 110,000 fuel cell vehicles by 2025, equating to one in six of its electric cars.

Dr. Stefan Gossens: “In terms of technology, Toyota, Hyundai and Honda are showing an impressive level of maturity. In terms of price, that’s not the case yet. The manufacturers currently competing in this segment are not generating any profit, but securing an advantage over the competition. Once the vehicle prices drop, which they did, for instance, by nearly 20 percent from the first to the second Mirai generation, it’s certainly possible that a market for hydrogen passenger cars will develop.”

Hydrogen the all-rounder

34 grams (1.2 oz)
of gaseous hydrogen are sufficient for propelling the hydrogen bike presented by Linde in 2015 across a distance of 100 kilometers (62 miles). Afterwards, the tank would be refilled in six minutes. At CES in Las Vegas in 2019, the French company Pragma Industries unveiled another hydrogen bike called Alpha 2.0 that’s primarily intended for use by fleet operators. Initial prototypes are on the road in the motorcycle segment as well. However, Schaeffler’s expert Dr. Stefan Gossens feels that the H2 bike market is an absolute niche. His conclusion: “There’s no potential there for hydrogen.”

© Airbus
H2 in rail, air and maritime transportation

ZEROe is an Airbus concept aircraft. Two hybrid hydrogen turbofan engines provide thrust for the blended-wing-body aircraft. The liquid hydrogen storage tanks are installed underneath the wings.

Although the rail sector has been working on hydrogen-powered trains for 20 years, the first production hydrogen fuel cell train – the Coradia iLint produced by the French manufacturer Alstom – has only been in service for two years in the Netherlands, Germany and Switzerland. Fuel cell trains can replace diesel-powered locomotives on routes that aren’t suitable for electrification. In maritime transportation, fuel cells could replace diesel engines as well. The first ferries using the technology are planned to be deployed in 2021, with the largest one of them measuring more than 80 meters (262 feet). The Swedish-Swiss ABB Group is working on a fuel cell buffer battery solution in the medium two-digit megawatt range that may even be usable on huge ocean liners. The DFDS shipping company is planning to develop a 23-MW fuel cell propulsion system for a liner serving the Oslo–Frederikshavn–Copenhagen route. The green hydrogen for it is supposed to be supplied by a large-scale electrolyzer that receives its electric power from a nearby wind farm. In the aviation sector, hydrogen is getting ready for take-off as well. This fall, Airbus announced that the company is planning to have an H2 jet airborne by 2035. In this case, the hydrogen will either be burned in a gas turbine and/or converted into electric power for electric motors in a fuel cell. The biggest challenge this entails is that a hydrogen tank for comparable range would have to be about four times as voluminous as a kerosene tank. This limits the utilization of this new technology to short and medium hauls of up to 3,700 kilometers (2,300 miles). For long hauls, scientists are working on hydrogen-based synthetic fuels that are intended to replace the currently used kerosene.

Dr. Stefan Gossens: “In this sector, regulatory requirements are forcing both manufacturers and operators to pursue CO2-free, or at least clearly reduced, mobility as well. In the rail sector, the fuel cell has already proved to be a viable alternative to the diesel engine that can be implemented quickly. However, I’m currently not seeing fuel cells actually being able to replace the huge ship diesel engines in the foreseeable future, but on ferries or smaller ships this is already a very realistic proposition. In aviation, my main hope is that it will boost the industrialization of synfuels by using green hydrogen that can also be utilized in other areas.”

Hydrogen the all-rounder

the 30-meter (98-foot) catamaran Energy Observer embarked on a six-year expedition at sea. A fuel cell makes the vessel energy self-sufficient. The required hydrogen is produced by an on-board electrolyzer, which in turn is supplied with electric power by deck-mounted solar cells.

H2 in industry

Per metric ton (1.10 short tons) of crude steel, 1.34 metric tons (1.48 short tons) of CO2 are produced on average. As a result, the steel industry causes roughly one third of all CO2 emissions within the industrial sector – so the utilization of green hydrogen in this area is correspondingly climate-friendly.

Hydrogen is already an important raw material for industrial purposes. It’s used not only for refining crude oil into kerosene, gasoline or diesel, or for producing fertilizers and chemical products, but also in iron and steel production. Today, however, so-called gray hydrogen is typically used for these purposes (see also box on page after next), during the production of which CO2 is released into the atmosphere. This is prevented by shifting to green hydrogen, in other words hydrogen that’s produced in carbon-neutral processes. In refineries, for instance, electrolyzers can use waste heat for the purpose of splitting off H2 molecules from water. In primary steel production, green hydrogen can be used instead of coal and natural gas for carbon-neutral direct reduction of iron ore into crude steel. In this case, waste heat can be used to reduce costs in hydrogen production. In the chemical industry, H2 is a key component for the production of ammonia or methanol and co-processed for many types of polymers. Shifting from gray to green hydrogen would massively reduce CO2 emissions in the chemical sector.

Dr. Stefan Gossens: “For industry, hydrogen from green electricity is practically the only way to achieve a climate-neutral use of resources. How­ever, this requires massive capital expenditures. At the moment, promising large-scale electrolyzers are appearing on the market, but they entail an enormous hunger for energy. We’re talking about many gigawatts here to make industry climate-neutral.”

84 %
efficiency in the production of green hydrogen is achieved by the world’s largest high-temperature electrolyzer (HTE) GrInHy2.0 operating at the steel plant of Salzgitter Flachstahl GmbH. At high temperatures (around 850 °C/1,560 °F), the reduction kinetics of the electrolysis process improves so that electric power consumption decreases. HTEs are particularly effective where waste heat from other processes can be supplied.

Producing, storing and transporting H2

The 116-meter (380-foot) long Suiso Frontier, the world’s first hydrogen tanker, transports 1,250 cubic meters (44,100 cubic feet) of H2. To liquefy it, it’s cooled down to –253 °C (–423 °F), which causes the volume to shrink to one eight-hundredth of the gaseous state. The liquid H2 is stored in double-walled vacuum tanks.

Hydrogen can only provide sustainable relief to the climate if it’s produced in green ways, in other words by using renewable energy sources. The energy chain with green hydrogen consists of the following stages: With electricity from renewable energy sources, hydrogen is produced by electrolysis in an emission-free process and subsequently used at the same or another location to provide energy, for instance, through a fuel cell or in production processes. The sources of the required green electricity (wind, sun, water) are largely located not only in Europe, North America or Asia, in other words the regions where energy is mostly consumed, but also in Africa, South America, Australia or the Middle East, among others. In such regions with favorable energy conditions, hydrogen can be produced in large quantities and subsequently transported regionally as well as globally. The greater the distance between the place of production and consumption the more important is transportation. As a material-based energy carrier, hydrogen has the advantage over electricity that it’s easier to store over longer periods of time and in larger quantities and can be transported with greater flexibility, for instance by ships. However, its transportation is far more complicated than that of natural gas or oil because hydrogen has the lowest atomic mass of all elements and therefore is the most volatile gas of all.

Another consequence of this is that, due to its low density, hydrogen, in its uncondensed state, requires large volumes: 33 kilograms (73 lb) of H2 would fill a balloon with a diameter of 13 meters (43 feet). Various physical-based and material-based methods can be used for transportation and storage. The physical-based ones include compressed storage (350 to 700 bar / 5,000 to 10,000 psi), liquefication at –253 °C (–423 °F), a combination of liquefication and pressure (cold and cryo-compressed hydrogen, CcH2) or cooling down to the melting point (–259 °C/–434 °F), at which hydrogen changes into a gel-like substance and its energy density increases once again. Currently, the energy consumed by these methods amounts to between 9 and just over 30 percent of the energy contained in hydrogen. Theoretically, 4 to 10 percent are attainable.

In the material-based storage method, hydrogen is linked to carrier materials and subsequently split off again. Most of these methods, which are energy-intensive as well, are still in development. They include metallic hybrid storage systems that, due to their high weight, tend to be more suitable for stationary use. Microporous adsorption materials which, in powder form, can achieve high volumetric storage densities are at the beginning of their development. The third version, which has seen the furthest development so far, is liquid organic hydrogen carriers (LOHC). The mixture that’s hydrated due to the addition of hydrogen has physical-chemical properties similar to those of diesel fuel and can be stored and transported accordingly. There are plans for converting such LOHCs directly inside a fuel cell. In this way, electric propulsion power could be generated directly on board of the vehicle. When carbon dioxide is added to green hydrogen, the result is methane (power-to-gas method). The methane in turn can be fed into existing natural gas grids and distributed. As a result, emissions by the CO2-intensive heating sector can be significantly reduced without incurring major infrastructural costs.

Dr. Stefan Gossens: “Generally, in order to take advantage of hydrogen’s enormous potential for a global energy transition, we have to drive its industrialization and establish a completely new industry – with new technologies, production facilities and supply chains. With our core competencies in materials, forming and surface technology, Schaeffler can make a major contribution to efficient large-volume production of key components such as electrolyzers and fuel cells.”

© iStock
H2 color theory

Green hydrogen – in other words hydrogen produced by means of renewable energies – will reduce emissions in a wide range of applications such as steel and concrete production, refineries, decentralized heat and energy generation and mobility.

Even though hydrogen is actually a colorless gas, it comes in all kinds of colors. Today, hydrogen is green, gray, blue and turquoise, because there’s a color etiquette based on what H2 is produced from: Green hydrogen is produced from water by means of electrolysis and the electric power this takes is generated by renewable energy sources such as the sun, wind or hydropower.

By contrast, gray hydrogen is produced from fossil fuels, typically natural gas that’s transformed into hydrogen and CO2 by application of heat – a process that’s also known as steam reformation. This has the disadvantage of the CO2 generated in the process being released into the atmosphere, plus the production of one metric ton (1.10 short tons) of hydrogen generates about ten metric tons (eleven short tons) of CO2.

Blue hydrogen is produced from natural gas as well. However, the CO2 is permanently stored in deep geological layers on land or under the seabed as solid or gaseous carbon. The advantage of the so-called carbon capture and storage (CCS) method is that the carbon dioxide is not released into the atmosphere. Blue is regarded as a transitional technology toward green hydrogen. However, the methods it involves are controversial because critics fear that it may entail huge environmental risks.

Turquoise hydrogen is a mix of blue and green hydrogen and produced by thermal fission of methane. Unlike in the case of blue hydrogen, the use of methane pyrolysis does not even produce any gaseous CO2, but carbon or carbon compounds. Again, the crucial factor is whether or not green electricity is used in this process. Conclusion: Ultimately, only the production of green hydrogen is a clean method for producing hydrogen from the environmental point of view. 

Dr. Stefan Gossens: “It’s unlikely that we’ll be able to produce all the green energy in places where it’s needed. There’s no way around imports for us and other EU countries, so we need to emphasize international cooperation.”