Hydrogen cooled well below zero poses particular challenges to the components used, especially the moving ones. The ball bearings of submersible pumps for pumping cryogenic media are examples of such heavily burdened parts. That is why NSK, a company originated in Tokyo, has developed self-lubricating deep groove ball bearings that work without the need to apply a separate lubricant.
Friction-reducing agents other than the pumped media are not used, which is normally tribologically unfavorable. Pumps designed for cryogenic applications have a double-row bearing arrangement of the pump shaft, where the inner and outer rings are made of special corrosion-resistant steel. The stainless steel NSK bearings have a wear-resistant cage made of self-lubricating fluoroplastic so that cryogenic gases such as GH2 (gaseous hydrogen) or LNG (liquefied natural gas) can be pumped at down to -200 °C.
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The European rolling bearing manufacturer NSK Europe Ltd. now offers a whole range of deep groove ball bearings specially designed for these unusual operating conditions – with shaft diameters from 30 to 100 mm. They tolerate very low temperatures as well as rotational speeds of up to 3,600 min-1 and are suitable for hydrogen refueling stations as well as for larger pumping stations.
At Hannover Messe 2022, the company H-Tec Systems, from Augsburg, introduced the Hydrogen Cube System (HCS) to a wide audience. The HCS generates green hydrogen via PEM electrolysis. The modular system is suitable for use in large multi-MW electrolysis plants within the energy-intensive manufacturing and chemical industries or to store surplus wind power.
The Cubes are available as a closed container solution for outdoor installation as well as an open one for indoor installation. They are equipped with 18 S450 PEM stacks as well as integrated process water treatment and power supply. The system can optionally be expanded with a fresh water or hydrogen purification unit or a heat recovery unit, the manufacturer states.
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Several 2-MW Cubes can be combined to form a multi-megawatt system. A plant to reach 50 MW in the long term can also be planned and designed in this way. The Cubes achieve, according to H-Tec Systems, a system efficiency of 74 percent. They have an integrated process water treatment and power supply system. An HCS with five units, so with 10 MW electrolysis capacity, can thus produce 4,500 kg of H2 per day. That makes 40 to 50 truck or bus tanks full. Through the modular construction, several units can be joined together as described and the entire plant can be centrally controlled and monitored.
The HCS is suited, according to H-Tec Systems, for various applications in industrial production such as for chemical plants, for fleet refueling of trucks or buses, or in steel production. Additionally, operators of renewable power plants have the option of using it as a power buffer. A specific example: According to the company’s own calculations, a 10-MW HCS could reduce the CO2 emissions in the steel production industry by 117 tonnes per day and 42,000 tonnes annually.
Because of increasing demand, the Augsburg-based company intends to further expand its production capacity. Together with large-scale plant manufacturer MAN Energy Solutions, with its direct access to the large-series production knowhow of Volkswagen, an automated factory for the production of the electrolysis stacks is to be completed by the end of 2023, H-Tec Systems states. Through this, a production capacity of 1,000 MW is to be achieved, depending on demand, by 2025 – and continuously expanded in the following years, according to the current plans.
In June 2022, automotive supplier Schaeffler together with Symbio – a Michelin and Faurecia company – established the joint venture Innoplate which plans to produce “the next generation” of bipolar plates. Benjamin Daniel, head of the fuel cell business unit at Schaeffler Automotive Technologies, explains the new options.
H2-international: Bipolar plates are considered a strategic component in a fuel cell system. At Schaeffler how do you tackle the challenges of their production? Which areas of expertise do you bring to this?
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Daniel: The ability to mass-produce components such as bipolar plates efficiently and economically is essential for the large-scale deployment of fuel cell systems. This industrialization is at the heart of Schaeffler’s strategy and is an important part of the 2025 road map. It allows an overall reduction in the cost of fuel cell stacks and systems. As a world-leading automotive and industrial supplier we have extensive expertise in precision forming and punching technology as well as a deep knowledge of the processes involved in the mass manufacturing of metal bipolar plates. We use this experience both for electrolysis and as a key element in fuel cell stacks. Schaeffler’s high degree of vertical integration with regard to forming technology and its sophisticated coating processes form the basis for a sound understanding of mass production processes for bipolar plates.
What role does your joint venture with Symbio play here?
Together we see enormous potential in the developing hydrogen economy. The establishment of this Franco-German project will also strengthen the European value chain for hydrogen-based mobility. By the end of the year we will be starting joint venture operations under the Innoplate brand and pushing the production of next-generation bipolar plates for the entire market for proton exchange membrane fuel cells. As a result, customers will benefit in future from increased performance, larger capacities and a lower price. In addition, the joint venture allows us to quickly enter the market with a leading fuel cell provider as a partner.
What’s the current situation and what will the next steps be?
At the moment we’re developing the manufacturing processes in our center of excellence for hydrogen technology in Herzogenaurach and are establishing production at the joint venture site in Haguenau in France. At first we want to make 4 million bipolar plates a year at the production site in Haguenau, with the aim of producing around 50 million plates annually by 2030. By that time we expect there to be 120 members of staff working in this area. The joint venture’s customers are Schaeffler and Symbio. Symbio has already received its first order as a major fuel cell system supplier from a leading vehicle manufacturer. It’s envisaged that the joint venture will produce the bipolar plates for the order.
In PEMECs (proton-exchange membrane electrolyzers) as well as PEMFCs (PEM fuel cells), chemical processes are taking place during operation that attack the surface of the material used and lead to corrosion in the medium or long term. Various studies show that because of internal corrosion processes in BPPs (bipolar plates) made of pure stainless steel, the, for example, target fuel cell service life of at least 10,000 operating hours in passenger cars is difficult to reach. Fuel cells for heavy-duty applications or for electrolyzers in continuous operation demand much longer lifetimes.
PVD (physical vapor deposition) coating, a technology used for decades for a variety of applications, presents a solution to this problem. “Through suitable coating of the two outer sides of BPPs, their corrosion behavior under long-term operation and thus their service life can be significantly optimized,” says Dr. Andreas Kraft, Director of Operations at PVT (Plasma und Vakuum Technik GmbH). According to him, this does not result in any loss of conductivity, but even rather an improvement towards a desired high conductance value. The company with headquarters in Bensheim, near Frankfurt am Main, has been operating in the field of ion- and plasma-assisted PVD coating of tools and components for more than 35 years.
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The coatings that are applied to the BPP, although very thin, constitute a major cost factor in the manufacture of the plates. “For a plate with a size of about 750 cm2, the cost of coating should end up well below 1 euro per plate,” stressed Kraft. Simultaneous coating of both sides of a BPP therefore requires a highly productive coating process as well as technology that gives reliable, reproducible results. This is why, according to the materials expert, the batch coating systems typically used in tool and component coating are uneconomical in terms of productivity and do not lead to the desired results.
“For a mass production of this sort, only so-called in-line systems come into consideration, in which substrates are coated on both sides with high throughput and without rotation,” stressed Kraft. In contrast to batch systems, these are multi-chamber setups in which the substrates are transported from chamber to chamber. The chambers are separated by large transfer valves, and the spatial and temporal separation allows various defined processing steps to occur. This design allows for a clean environment with consistent vacuum and processing conditions.
With the i-L 4.3500 in-line system developed by PVT, according to Kraft, 5 million BPPs of size 500 mm x 150 mm for fuel cells can be coated on both sides in the same consistent quality. The system is realized by the combination of four individual modules, with each forming a chamber, so that BPPs could simultaneously, at different positions, be fed in (into vacuum), coated under constant vacuum conditions, and finally discharged again (back into ambient conditions).
The PVT manager stressed that the coating costs per plate for a fuel cell BPP typically end up well below 1 euro. Depending on the process and coating materials used, the costs can even turn out significantly lower, according to Kraft.
The bipolar plate is one of the most used components in a fuel cell stack, alongside the gaskets and the membrane electrode assembly. This is why it’s important in the overall scheme of things to bring down their cost. Manufacturers, regardless of whether they produce metal or graphite solutions, are increasingly looking to automate and link up individual processes on the one hand and to optimize the products themselves on the other, for instance by further reducing sheet thicknesses. Already plans are afoot to scale up production and could result in several million bipolar plates being manufactured for use in over 100,000 stacks every year.
In a proton exchange membrane fuel cell, the bipolar plate is a key component. It accounts for up to 80 percent of stack weight and up to 65 percent of stack volume, hence its enormous importance in terms of the power density. It’s equally significant for the functioning of the fuel cell: The bipolar plate or BPP separates and distributes process gases and removes product water. Not only that, this component is responsible for performing the essential tasks of conveying the generated current and evenly distributing all media.
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BPPs are principally made from graphite carbon or metal. The various materials are associated with different properties and have different advantages for plate functionality. Because of low efficiency benefits and a lack of manufacturing processes for competitive metal BPPs, it is the graphite variant that has dominated in the past. However, graphite-based BPPs exhibit volumetric and gravimetric shortfalls compared with their metal counterparts, particularly when it comes to demanding applications. Plus, graphite is extremely brittle and can therefore break easily. Nevertheless, graphite plates are frequently deployed in stationary applications in which the volume of the structure is not a limiting factor.
On matters of cost, it’s metal plates that take the lead. “With the right production process the sheet thicknesses can be reduced down to 0.05 mm. Here, metal is at a completely different price level to graphite,” emphasizes German manufacturer CellForm. Given that several hundred plates are used in a single stack, the financial ramifications for the final application are huge. A further advantage of metal BPPs cited by CellForm is their positive impact on the cold-start capability of the fuel cell.
The company, based in Baienfurt in Baden-Württemberg, covers the entire manufacturing process for metal BPPs with a multistage forming process and subsequent laser welding. Commenting on working with metal, company representatives point out that the “extremely thin” sheet thicknesses are a particular challenge: Shaping such fine initial sheets and creating the highly precise and complex geometry of the channels can, due to physical constraints, quickly lead to fractures that would render the BPP unusable. On top of this come the stringent quality requirements with low margins for error which need to be met when producing in large volumes. “Only those who satisfy this requirement will be able to maintain their position in this growing and fiercely competitive market,” says the company.
These challenges, according to CellForm, are putting a certain degree of selective pressure on the manufacturing processes which are still under development. “Physical restrictions – such as heat generation – will limit how much these processes can make in future mass production,” states the manufacturer. This problem, it says, isn’t noticeable when dealing with small volumes, but will become increasingly evident in the years ahead as demand grows.
A full decarbonization of the European energy supply to achieve the 1.5 °C target from the Paris agreement is not a question of “if” but of “how”. In particular, the European Green Deal envisages climate neutrality by 2050 based on renewable energy sources (RES) as top priority of its political agenda for the coming decades [1]. What is more, the International Energy Agency (IEA) promotes a radical paradigm change of the global energy supply in favour of RES [2]. In Germany, a foregoing climate policy has been fortified by the federal German Constitutional Court’s groundbreaking verdict to introduce more stringent climate policies as a reaction to several constitutional complaints against failing climate policy. In the Netherlands, the local Den Haag Court of Justice has ruled that Shell shall amplify its CO2-emission reduction measures in its global operations [3] [4] [5].
Both the European Commission and the IEA underpin that hydrogen should gain a key role in the power sector as well as in all other energy sectors on the way towards zero CO2 emissions [1] [2]. Hydrogen can be easily stored in large quantities for long periods of time and used for re-electrification in corresponding power plants. In this way, it can contribute to integrate intermittent renewable power into the energy system [2].
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In this context, an important question referring to the optimal mix for hydrogen production has yet not been answered: from which energy sources and in which world regions shall (green) hydrogen be produced and what are relevant corresponding international strategies? From the German and European perspective, multiple hydrogen supply options could be chosen from as hydrogen is a universal energy carrier which can be produced by different and in the future more decentralised technologies around the globe [6] [7].
Multiple hydrogen production options
Following the official terminology of the European Commission concerning different production pathways [8], hydrogen is classified as “fossil-based H2” and “electricity-based H2”, distinguished by primary energy input (e.g. natural gas, mineral oil or electricity) and the respective key production technology. These two classes are subdivided into “low-carbon H2” (incl. “fossil-based H2” with carbon capture as well as “H2 from electrolysis with electricity from grid or nuclear electricity”) on the one side and “renewable or clean H2” through electrolysis with renewable electricity (REN-E) on the other side. In addition, the following terms are being used:
Green hydrogen (electrolysis based on renewable electricity or gasification of biomass),
Blue hydrogen (traditional process from fossil energy with carbon capture and storage – CCS),
Turquoise hydrogen (methane pyrolysis),
Yellow or red hydrogen (electrolysis based on nuclear electricity) and
Grey hydrogen (traditional processes without CCS or electrolysis based on grid electricity).
The structure of terms and the colour coding are depicted in Figure 1.
Traditional production technologies
The traditional hydrogen production technologies belong to the group of fossil-based processes, today typically dominating global bulk hydrogen production. Steam reforming of natural gas or methane (SMR) is the principal process technology (catalytic, endothermal) in (chemical) industry which requires steam as single additional feedstock and with highest efficiencies in large plants. Worldwide, about 2% of global coal and 6% of global natural gas consumption is used for hydrogen production, out of which 73 MtH2/a are converted to pure hydrogen and a further 42 MtH2/a blended with synthesis gases [6].
Another similar and widely applied industry process technology is dubbed partial oxidation of heavy fuel oil (POX), which requires oxygen as feedstock (non-catalytic for sulphur-containing fuels, exothermal). It is applied in locations where cheap heavy fuel oil (HFO) is available such as in oil refineries. By combining both processes through adjusting a stochiometric equilibrium of steam and oxygen feeds, the highly dynamic autothermal reformation process (ATR) has been developed for e.g. natural gas as feed at a somewhat reduced overall efficiency (65% instead of the up to 80% of SMR). Another advantage of this technology is that the resulting synthesis gas has high hydrogen contents.
Furthermore, the reaction is energy neutral, i.e. neither auxiliary thermal energy is required nor waste- or off-heat need to be considered, allowing a robust process design (Table 1). With the goal to substitute fossil by renewable energy according to emission reduction targets, SMR, POX and ATR will only contribute temporarily. Both regional and logistic aspects have to be considered in assessing an economic competitiveness of fossil hydrogen over time, and the degree to which CO2 can be taken out of the atmosphere at the given and measurable scale.
All fossil processes are characterised by highest efficiencies at large plant scales even though there is a small market for decentral yet less efficient methane steam reformers today. Nevertheless, the current hydrogen supply is dominated by the delivery (merchant hydrogen) or production of large hydrogen quantities onsite.
Tab. 1: Key data of the most relevant hydrogen production technologies
H2-class
Technology
TRL1 [1-9]
Costs
(2030) [€/kgH2]
Efficiency
(LHV2) [%]
CO2-emissions [gCO2/kWhH2]
Operating
temperature [°C]
Fossil-based H2
SMR
9
1.5 – 63
65 – 803
310 – 4003
700 – 800
POX
9
1.5
69
1,300
ATR
9
1.5
65
850 – 1,300
Pyrolysis4
3 – 7
2.5 – 7
30 – 60
190 – 230
600 – 1,600
Renewable
or clean H2
Gasification
of biomass
7
3 – 5.53
45 – 703
40 – 903,5
T-Bandwidth6
PEMEL
8 – 9
3 – 6.57
59 … 71
08
50 – 100
AEL
9
3 – 6.57
58 … 67
08
70 – 90
SOEL
5 -7
>80
08
700 – 900
1 TRL – Technology Readiness Level; 2 LHV – Lower heating value; 3 Depending on plant scale; 4 Bandwidth depending on technology; 5 For larger plants also depending on transport distances for biomass; 6 The reaction zone comprises a temperature bandwidth [10]; 7 Strongly dependent on electricity supply costs; 8 Only for full renewable electricity utilization
Pyrolysis, electrolysis and biomass-gasification
Another fossil energy based hydrogen production technology – undergoing commercialization since only recently – is the so called methane pyrolysis. It comprises a class of process technologies of its own, all having a high specific energy input in common. Possible concepts are the electric arc or microwave plasma processes (using direct electricity as energy input) or the energy contained in part of the methane feed to heat a (catalytic) moving reaction bed reactor at very high temperatures crushing the remaining methane share into its constituents hydrogen and carbon. On the one hand, an advantage of all pyrolysis based processes is solid carbon as final product instead of gaseous – and hence difficult to handle – CO2. If applied well, solid carbon can be re-utilized in a way that no CO2 is released to the atmosphere in any of the consecutive processes. On the other hand, the pyrolysis process is highly dynamic and difficult to control, i.e. it is not as robust as SMR. Finally, also the solid carbon markets are rather limited seen from an energy market scale perspective.
The key technology for green hydrogen production is electrolysis. It comprises a group of technologies, splitting water into its constituents hydrogen and oxygen using electricity as energy input. The proton exchange or membrane technology (PEMEL) applies solid proton conducting membranes whereas alkaline electrolysers (AEL) use caustic soda in an internal electrolyte circulation loop and as gas carrier. Both technologies are operated at low temperature in opposite to the high temperature or solid oxide electrolysis (SOEL) using a steam feed at up to 850°C. SOEL apply solid anode and cathode layers, plated on a gastight ceramic carrier substrate. The Anion-Exchange-Membrane Electrolysis (AEMEL) has begun to be offered in the market only recently and currently in small numbers. It promises however to be comparatively cost efficient as the use of Pt-group catalysts is avoided and at the same operational dynamics as PEM electrolysis.
Another relevant green hydrogen production pathway is the gasification of biomass or biogenic residues applying steam in an allothermic process (Güssing principle) [10]. As compared to low temperature AEL and PEMEL this technology has not been widely commercialized yet. Furthermore, its wide application is hampered by the limitation of available biomasses or (non-)organic residues in Europe.
Beyond hydrogen from electrolysis, it may also be produced through further green hydrogen production pathways (see Fig. 2). A thorough assessment of 10 process technologies found, however, that most of the alternative options are limited by either region specific advantages or are at a very early research or development stage
Other term widely used today is “by-product H2” The term is applied to (chemical) processes (e.g.in refineries) in which hydrogen is produced “inadvertently” and can be made readily available at low cost in large quantities. As today’s by-product hydrogen is generated through fossil based processes it is in principle also denoted as grey hydrogen, i.e. characterized by similar specific CO2 emission levels.
Depending either on production technology or customer specific quality requirements, the hydrogen delivered has to be purified by a set of gas cleaners designed to meet the relevant end-user needs by impurities, process layout and plant scale. Typically and according to recent agreements by European gas industry, this will comprise industry grade hydrogen in dedicated hydrogen transmission grids or fuel cell grade hydrogen with a very low level of hydrogen impurities
Natural hydrogen has been dubbed as “white” and is not industrially applied today. As its exploitable potentials are limited in view of the energy markets, white hydrogen from indigenous sources such as from Africa or Brazil is believed to have little impact on the development of future hydrogen energy markets, even though further analysis is being undertaken [11] [12] [13].
Power-to-X as major ingredient for renewable hydrogen production
Water electrolysis is the key process technology of all Power-to-X concepts which are the basis of green hydrogen supply. Power-to-X can be principally subdivided in different main pathway routes. The major concept is the one of Power-to-Gas (PtG) with its two options Power-to-Hydrogen (PtH2) and Power-to-Methane (PtCH4). Further Power-to-X concepts, extending the gas-focused energy world by other alternatives are: e.g. Power-to-Heat (PtH), Power-to-Liquids (PtL) as well as Power-to-Chemicals (PtCh). With the exemption of PtH, all concepts are unified by the common and central hydrogen molecule [14].
A major consequence is that electrolysis is seen as key technology for the future sustainable energy supply, with high electrical efficiency at all scales, large and small. This is the consequence of electrolysis being a surface-driven process for which only the balance-of-plant equipment’s efficiency does not scale linearly, and in contrast to volume-driven processes which are characterised by significantly increasing efficiencies towards larger process scales. The underlying argument is that today’s fossil or nuclear primary energies will be substituted by electrons as major primary energy source. Electrolytic hydrogen can thus contribute to seasonal energy storage at large scale and supplement the short-period local energy storage of electrons in mechanic-kinetic (e.g. flywheel) or mechanic-potential (pumped hydro storage) or electrochemical storage (e.g. batteries) systems. A side-effect is the substitution of a large number of aboveground electricity transmission lines with large specific footprint by cost efficient and publicly acceptable underground gas pipelines with a low specific footprint.
The CAPEX-dominated costs and resource-intense application of large-scale electricity transport and storage will thus be pushed towards OPEX-dominated costs, combined with the high energy-density gas transport/storage. With a view to water intensity, electrolysis consumes about 9 kg of water per kg of hydrogen, a factor asking for monitoring in the future. This poses no substantial challenge for central Europe (e.g. a long-term production of 100-400 TWhH2/a of hydrogen for the case of Germany would require the provision of ca. 27-108 Mt/a of water, equivalent to about 0.7-3.0% of all German drinking water needs today). In addition, it should be born in mind that water after thermal use in fuel cells becomes part of a natural water recirculation, even though locally uncoupled in case of large scale hydrogen imports.
International hydrogen production strategies
Several strategic considerations accompany the techno-economic aspects of introducing hydrogen into the energy system at large scale. In general, they strongly depend on regional framework conditions in different countries and specifically the individual strategic energy and industry policy targets, climate policy ambitions or availability of natural energy or material resources as well as societal development ambitions. Typically, these aspects are reflected in the national hydrogen strategies, being developed by different countries worldwide [15].
In view of the international context, the strategies to introduce hydrogen as energy carrier foresee two phases (Fig. 3). The first phase until 2030 typically comprises an activation of potential H2 markets. Being a transitional phase, all hydrogen colours will typically be allowed by policy makers for cost and capacity arguments. Just a few countries with specifically large renewable energy potentials such as Spain, Portugal, Ukraine, Chile or Morocco put their focus explicitly only on green hydrogen from the very beginning. In contrast, in e.g. Japan and South Korea also grey hydrogen will contribute to the H2 production mix due to cost reduction considerations (Japan) or yet less ambitious climate policy goals (e.g. South Korea), even if it is “only” imported as grey hydrogen in short term.
In other countries with a relevant natural gas production level or well-implemented gas infrastructure such as the Netherlands, the United Kingdom (UK), Norway or Russia blue hydrogen is believed to contribute in short- and medium-term. Some countries such as Germany, the European Union (EU) and Russia have developed a technology-neutral approach open for a large variety of different options. Nevertheless, Germany plans to install an electrolysis capacity of 10 GW by 2030, and the European Union of 40 GW, giving room for an early large share of green hydrogen [8] [16].
Fig. 3: Hydrogen colour preferences of selected national hydrogen strategies
Long-term focus on green hydrogen
In the long-time perspective after 2030, the global focus visibly shifts to the production and use of green hydrogen. In particular, Germany and the European Union including most EU Member States stick out visibly in their ambition to focus on green hydrogen from renewable sources, reflecting the European zero CO2 emission policy by 2050. In this way, an attempt is made to use the many advantages of green hydrogen and to achieve several energy policy goals at the same time. On the one hand, green hydrogen can be used effectively for climate protection in sectors that are difficult to decarbonize, such as heavy-duty transport or steel industry and on the other hand, to improve the flexibility of the energy system. It can also reduce dependence on fossil fuels, promote economic growth and create new jobs [17].
The production of blue hydrogen shall be eventually phased-out stepwise in long-term or otherwise be marginalized. By 2030, turquoise hydrogen from methane pyrolysis is seen as a bridging technology by 2030 in the national strategies specifically in Germany and the EU. The only longer-term perspective for turquoise hydrogen has been mentioned by Russia so far [15].
Perspectives of a future hydrogen supply
In addition to the domestic production of hydrogen, also (green) hydrogen imports (or exports from countries rich in renewable energy) have gained strategic importance. Specifically countries with large industry intensity such as Germany, Japan or South Korea will depend on hydrogen imports. In contrast Australia, Chile, Portugal, Spain, Morocco or Ukraine with high solar or wind potentials, understand hydrogen as an energy carrier for renewable energy with high economic potential [15].
It is obvious that new energy partnerships will develop, which can be observed already today. Both bilateral agreements between individual countries as well as superordinated regional cooperations will be needed in the future. An example for the first one is the cooperation between Australia and Japan for providing grey/blue hydrogen in the short-term and liquefying and shipping it to Japan at large scale [18] [19] or the declaration of cooperation between Germany and Ukraine to develop an energy partnership focusing on hydrogen among others [20].
The second option is reflected by the extensive EU programs currently in preparation to support innovative H2-projects such as e.g. the “Important Projects of Common European Interest“ (IPCEI), aiming at explicitly strengthening the cooperation of individual member states in superregional projects [21]. As this approach is technology neutral a harmonisation process is needed in respect to hydrogen quantities, type of hydrogen carrier (either gaseous or liquefied hydrogen versus hydrogen derivatives such as methane or liquid fuels versus ammonia or methanol), hydrogen colour (i.e. remaining CO2 burden) as well as transport routes and relevant future infrastructures.
Sufficient renewable energy potentials in Europe
From the European perspective, a number of criteria and open issues will have to be respected and/or decided to clarify important aspects of a large-scale hydrogen energy infrastructure, specifically with a view to the hydrogen import/export relations. The availability of renewable electricity to produce hydrogen in the EU or in Europe, in other words the green hydrogen potential, is paramount to be assessed for a fully green hydrogen portfolio in the long-term.
According to [22] the renewable electricity production potential within EU-27 and the UK amounts to a total of about 14,000 TWhel/a, the major share contributed by fluctuating wind (ca. 9,000 TWhel/a or 64%) and solar electricity (ca. 3,700 TWhel/a or 26%). In addition, this estimate is rather conservative as further potential might become available through the use of additional areas for PV plants and so-called floating technology for wind offshore.
Putting today’s electricity demand of ca. 3.000 TWh/a into perspective, it is found that close to 80 % of the total RES potential becomes available for further electrification of the energy system, e.g. for mobility (battery electric vehicles) or room heating (electrical heat pumps) as well as for the production of green hydrogen via electrolysis (Fig. 3). In view of the 2045 policy target of climate neutrality the electricity demand for direct electricity use and hydrogen production in Europe will sum up to 5,300-6,900 TWh/a [22]. Depending on the individual scenario, this would then be less than half of the total REN-potential as explained before. Further hydrogen quantities could be added as potential imports from neighbouring countries and regions such as Norway, North Africa but also Ukraine.
Fig. 4: Renewable electricity potential and electricity use in Europe
The findings of the above analysis show that the renewable electricity potential in Europe is sufficient to satisfy all demand for green hydrogen. For future discussions on green hydrogen import/export, it will thus not be Europe’s renewable electricity potential becoming the ceiling for domestic production. Instead, the focus should be directed at further criteria such as technical, economic, social and strategic hydrogen supply aspects such as hydrogen cost along full supply chains, energy supply independency, local value creation, political stability, established political relationships and public acceptance.
Of course, this relationship does not apply to every Member State, since both the renewable energy potential and the energy demand are unevenly distributed. Countries with high energy consumption such as Germany or the Netherlands will still be dependent on imports, which can, however, be served within the EU from countries with high RES potential such as Spain, Portugal or France.
Advantages of a “merit order“ for hydrogen supply in Europe
In this context, the future hydrogen production mix will become an important, but currently not fully resolved aspect of future regional energy systems with hydrogen as one of major energy carriers. In contrast to natural gas, the advantage of hydrogen is that it can also be produced regionally in modular electrolysers with similar efficiency as in large electrolysers around the globe. Due to its physical properties, hydrogen is similarly well transportable and storable as methane and – depending on the electricity source – can be produced at low cost. Both aspects will become relevant for the “Merit Order” for hydrogen supply seen from a regional perspective and could virtually turn it upside down in coparison to today’s fossil and centralised energy supply system.
Fig. 5: Supply options for a green hydrogen “merit order“, e.g. from the perspective of Mitteldeutschland [25]
Fig. 5 illustrates considerations for a “merit order” for green hydrogen supply given different supply options for a potential case of Central Germany (Mitteldeutschland) [25]. To benefit from an individual region’s opportunities in a robust way, (green) hydrogen supply should have more than one pillar. Providing hydrogen from regional renewable electricity should have highest priority from a local value creation standpoint, supplemented by national hydrogen sources imported from renewable energy rich regions e.g. by existing or refurbished hydrogen pipeline infrastructure with the ambition to safeguarding existing assets. In the case of Mitteldeutschland this could be hydrogen from on- and offshore wind in Northern Germany (e.g. in the federal state Mecklenburg-Vorpommern) through a pipeline.
Any further hydrogen demand surpassing the available local, regional and national energy resources need to be imported from farther away locations, such as other parts of the EU (e.g. from solar or wind power in Spain) or geographical Europe (e.g. from wind in East or Northern Europe) or even outside of Europe (e.g. from solar power in North Africa) simultaneously strengthening the European wide hydrogen pipeline infrastructure.
Should even these sources not prove to be sufficient e.g. during the transition phase then green hydrogen could be imported from other international resources yet at lowest priority. The long-distance import options would contribute to establish global hydrogen partnerships and a global hydrogen market, possibly lowering the global hydrogen energy price not only for industrialized countries.
Furthermore, hydrogen production costs are not the only criterion for decisions on hydrogen supply options. Other criteria such as independence, political stability, flexibility of the energy system and local value creation will come into play. Telling from the recent national hydrogen strategies, this paradigm shift has not been well understood, such that rethinking a sustainable energy system for the future by industry and politics is overdue.
Green hydrogen as local and global opportunity
Hydrogen has been identified as a central element of a future climate neutral energy system in Europe. It will facilitate the integration of renewable electricity and improve the security of energy supply. Moreover, hydrogen will generate economic welfare and entail new jobs. Even though fossil-based hydrogen is produced at large scale already today for industrial applications renewable hydrogen has been earmarked to replace the fossil-based processes by water electrolysis from renewable electricity.
Only Power-to-X concepts will fully exploit all advantages of a hydrogen-based energy system becoming the basis for a sustainable and lasting transition of the energy system. In the transition period until 2030, also low-carbon technologies using fossil energy such as e.g. natural gas through steam reforming enhanced by CCS (blue hydrogen) or methane pyrolysis (turquoise hydrogen) in some regions will activate the hydrogen market lowering the initial cost burden to develop large-scale gas infrastructures. However, in the long term, i.e. by 2050, Europe will push towards green hydrogen.
Analysis has proven that Europe‘s renewable electricity potential is sufficient for a self-sustaining renewable hydrogen supply, which will extend the considerations of import-export relations for green hydrogen. Further criteria addressing technical, social and strategic aspects will receive growing attention. For a region-specific evaluation the so-called “merit order“ of hydrogen supply need to be developed as multi-criterion analysis. It will be focused on nearby renewable energies and fill up the gap between regionally exploitable renewable energy potential and energy demand by green hydrogen from farther away regions. This approach will help to exploit and combine the different regional strengths and opportunities of hydrogen from different world regions.
We interpret the results of a recent analysis by the International Renewable Energy Agency (IRENA) [26] as first international evidence for the expected paradigm change. In a central graph the following four aspects have been illustrated from the viewpoint of an emerging European hydrogen energy market:
By 2050, hydrogen will be preferably provided from renewable energy sources within Europe (4,771 PJ/a),
All hydrogen imported to Europe will preferably be transported cost efficiently by pipeline from neighbouring North Africa (2,382 PJ/a),
Whereas only small quantities of ammonia are expected to be produced within Europe (136 PJ/a), a significant percentage will again be imported from North Africa by ship (1,606 PJ/a), further yet smaller quantities also from South America and the Near East.
The ammonia vectors are believed not to be applied for hydrogen transport (H2 derivative), but for later end-use as base chemical and here preferably for fertiliser production.
Yet, many aspects surrounding the production of (green) hydrogen have not been finally solved and require further analysis and instruments. Among others, an international hydrogen market will need to be established with an optimum balance between domestic hydrogen production and imports. In order to integrate Power-to-X concepts into international energy markets adequate regulations will have to be developed and agreed for safe and transparent hydrogen handling (e.g. certificates of origin as suggested by the European CertifHy project [24]).
Even though CO2 emissions will become the new currency in a future energy system lock-in effects (e.g. blocking investments and trained workforce, who would develop green technologies instead) from investing in durable but non-sustainable technologies (e.g. to produce blue hydrogen) need to be avoided. Green hydrogen based on renewable energy is one of the keys to achieve the 1.5 °C target from the Paris Agreement in a sustainable, socially acceptable and cost-effective manner.
Literature: To be acquired at Hydrogeit Verlag or from the authors
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