eFuels instead of hydrogen? Clean energies and the role of eFuels and hydrogen
eFuels instead of hydrogen? Clean energies and the role of eFuels and hydrogen
Sustainable mobility and the reduction of CO2 emissions are among the greatest challenges of our time. Many people see hydrogen as the “savior” for a climate-friendly future, while at the same time eFuels are becoming increasingly important. But which solution is really practicable and economical in everyday life?
Table of contents
Hydrogen - potential and stumbling blocks
Why hydrogen is tempting
Hydrogen raises great hopes as a climate-friendly energy source because it does not emit any CO2 during combustion and offers a high energy density per kilogram. The topic of hydrogen is also receiving political support in many countries: governments are funding research projects to achieve technological breakthroughs in production, transportation and storage. Examples of this include European programs such as IPCEI (Important Projects of Common European Interest) or national hydrogen strategies, in which millions to billions are invested in infrastructure and innovation projects.
All of these factors mean that hydrogen is often presented as the “saviour” of the energy transition. However, it is worth taking a closer look at the practical hurdles that make the widespread use of hydrogen more difficult.
Hydrogen is the lightest and smallest molecule in the universe. Although this sounds positive at first, it leads to considerable problems with storage and transportation:
- Extreme cooling: In order to liquefy hydrogen, it must be brought to around -253 °C. This corresponds to a temperature at which even nitrogen has long since frozen. The special tanks required for this are technically complex and expensive to purchase and operate.
- High pressure: Alternatively, hydrogen can be stored under high pressure (e.g. up to 700 bar). This in turn requires thick-walled and expensive pressure vessels.
- Material embrittlement: Hydrogen can penetrate metals and make them brittle over time. Pipes and containers therefore need to be checked and replaced more frequently than with conventional fuels.
Storage and transportation challenges
Hydrogen is an extremely small and light molecule. Although this sounds positive at first, it leads to considerable problems during storage and transportation:
- Extreme cooling: In order to liquefy hydrogen, it must be brought to around -253 °C. This corresponds to a temperature at which even nitrogen has long since frozen. The special tanks required for this are technically complex and expensive to purchase and operate.
- High pressure: Alternatively, hydrogen can be stored under high pressure (e.g. up to 700 bar). This in turn requires thick-walled and expensive pressure vessels.
- Material embrittlement: Hydrogen can penetrate metals and make them brittle over time. Pipes and containers therefore need to be checked and replaced more frequently than with conventional fuels.
To illustrate the order of magnitude: even with optimum insulation, measurable quantities of hydrogen escape from a 100 m³ tank at -253 °C every day. In the case of transport pipelines, the losses are sometimes even higher if high-quality seals and special pipes are not used. In comparison, fossil fuels can be transported over long distances in conventional pipelines without the need for such high levels of cooling or compression.
Indirect climate impact due to hydrogen leakage
As clean as hydrogen is during combustion, if it escapes into the atmosphere before it is used, this can have indirect effects on the climate:
- Prolonged methane retention: Hydrogen released into the atmosphere reacts with so-called hydroxyl radicals (OH). These radicals would normally break down methane – a very powerful greenhouse gas. However, if OH is increasingly “occupied” by hydrogen, the retention time of methane in the air increases.
- Magnitude of the effects: Current studies show that hydrogen can have around 12 times the impact on the climate over 100 years (GWP100) compared to the same amount of CO2. Depending on the loss and leakage rate in pipelines, tanks and vehicles, these indirect emissions could account for a noticeable proportion of overall warming. Estimates range from a few percent to almost 50 % of today’s CO2 emissions if a global hydrogen economy with high leakage rates were to be realized.
All of this makes it clear that a pure hydrogen economy can only be truly climate-friendly if leakages are minimized and the technical and infrastructural requirements are met. Accordingly, politicians and industry are faced with the challenge of taking these risks into account in future concepts.
High infrastructure costs and limited application options
Financing a comprehensive hydrogen infrastructure is one of the biggest economic challenges in the energy transition. In contrast to established fossil fuels such as crude oil or natural gas, hydrogen requires a large amount of energy:
Special pipelines and tanks
Many refineries and filling station networks are designed for hydrocarbon fuels (petrol, diesel, kerosene). In order to provide hydrogen on a large scale, entire segments of the infrastructure would have to be rebuilt or extensively modernized.
Filling stations for gaseous or liquefied hydrogen require additional safety and cooling equipment as well as complex compressor systems.
High running costs for maintenance and operation
Exposure to extremely low temperatures (-253 °C for liquid hydrogen) or high pressure (up to 700 bar) puts a strain on tanks and pipes. This significantly shortens the service life and requires more frequent maintenance intervals.
Replacement or repairs are more costly, as the material used is more expensive and less common than conventional fossil fuels.
Extensive conversion of existing systems
Many refineries and filling station networks are designed for hydrocarbon fuels (petrol, diesel, kerosene). In order to provide hydrogen on a large scale, entire segments of the infrastructure would have to be rebuilt or extensively modernized.
Filling stations for gaseous or liquefied hydrogen require additional safety and cooling equipment as well as complex compressor systems.
Limited application possibilities in everyday life:
Industry can use hydrogen directly in some processes (e.g. ammonia or steel production), but for smaller applications (e.g. car propulsion) the technical effort is high.
The service life of hydrogen-carrying components (tanks, pipes) is also comparatively short, meaning that investment costs can be incurred several times over the years.
Taken together, these factors mean that a pure hydrogen economy is by no means “easy” to establish. Instead, many technical adaptations, extensive re-evaluation of existing plants and high financial resources are required. These points limit the immediate deployment potential of hydrogen and represent a significant obstacle to rapid large-scale scaling.
eFuels as a carbon-based hydrogen carrier
eFuels or hydrogen? In contrast to pure hydrogen, which must either be deep-frozen or highly compressed, eFuels are stabilized by the chemical bonding of hydrogen to carbon atoms. This produces liquid or gaseous fuels such as eDiesel or eKerosene, which largely correspond to conventional fuels in terms of their handling.
eFuels and hydrogen: basic principle of eFuel production
The starting point is always hydrogen, which is obtained from water by electrolysis using renewable electricity. The hydrogen obtained is then combined with carbon (e.g. from COâ‚‚ capture). This produces synthetic hydrocarbons, which – depending on the process and the desired end product – can have different properties (e.g. liquid at room temperature or gaseous at lower pressure than pure hydrogen).
Net zero potential: When burned, these fuels release the previously bound COâ‚‚ again. If the CO2 has been extracted from the air, a closed carbon cycle can result.
- Hydrogen + carbon: eFuels are created by producing hydrogen through electrolysis and then combining it with COâ‚‚. The result is liquid or gaseous fuels such as eDiesel or eKerosene
- Net zero carbon cycle: The CO2 released during combustion can be captured from the atmosphere beforehand.
Advantages of eFuels in terms of infrastructure and logistics
Compatibility with existing structures
As eFuels have similar properties to conventional fuels, they can be used in existing tanks, pipelines and filling stations. This saves enormous investment costs and enables faster distribution.
No extreme cooling or high pressure required
eFuels are usually liquid at ambient pressure or slight overpressure. This eliminates both the complex cooling systems for liquid hydrogen (-253 °C) and the massive pressure vessels for compressed H2.
Easier handling
In everyday life, liquid fuels are easier to store and distribute - from tankers to pipelines. The risk of leaks is also significantly lower than with pure hydrogen.
To illustrate the order of magnitude: even with optimum insulation, measurable quantities of hydrogen escape from a 100 m³ tank at -253 °C every day. In the case of transport pipelines, the losses are sometimes even higher if high-quality seals and special pipes are not used. In comparison, fossil fuels can be transported over long distances in conventional pipelines without the need for such high levels of cooling or compression.
Energy efficiency in the overall system
- Energy consumption during production: Critics often criticize the fact that many conversion steps are involved in the production of eFuels (electrolysis, synthesis, separation if necessary). This reduces efficiency.
- However, this is comparable to H2 losses: when using hydrogen alone, high losses occur due to compression, liquefaction and leakage. In total, the overall energy efficiency of eFuels can therefore be competitive.
- Co-products & site selection: Many production processes for eFuels produce valuable by-products (e.g. eKerosene, oxygen, heat) that can be used economically. If eFuels are also produced in sunny or windy regions, the energy input is further reduced.
In summary, as a carbon-based hydrogen carrier, eFuels offer a viable alternative to a purely hydrogen-based energy supply. Their compatibility with existing infrastructure, lower susceptibility to leakage and greater suitability for everyday use are major plus points. Although production is still relatively expensive, with growing demand and technological advances, eFuels can play a key role in a climate-neutral future.
Efficiency in the context of global resources
Efficiency is particularly relevant when there is a shortage of a resource. However, there is no shortage of renewable energy worldwide. The German Aerospace Center (DLR ) shows that a relatively small area of solar parks would be enough to cover Germany’s or even the world’s entire energy needs.
The efficiency of eFuel production is strongly influenced by the location and the processes used. Regions with an abundance of renewable energy, such as windy countries (e.g. North Sea countries) or sunny regions (e.g. the Sahara desert), offer optimal conditions for resource-efficient eFuel production.
Comparison of eFuels and hydrogen
While hydrogen is seen as a key technology, the concrete implementation hurdles – from infrastructure costs and leakage problems to technical adaptation – often speak against using hydrogen in its pure form. eFuels, on the other hand, bind the hydrogen in a carbon-based way, making storage, transport and use much easier. In a variety of application areas, they therefore offer a realistic alternative that can be implemented more quickly and can be seamlessly integrated into existing structures. This makes eFuels a promising component of the global energy transition, especially in the coming decades.
| Hydrogen | eFuels | |
|---|---|---|
| Handling and infrastructure | Complex and expensive special tanks are necessary as the molecule is difficult to store even at very low temperatures (-253 °C) or high pressure (up to 700 bar). In addition, conventional pipes and tanks can quickly become brittle, which means that the infrastructure has significantly shorter life cycles than with fossil fuels. | Liquid or gaseous eFuels can generally be distributed via existing filling station networks and pipelines. This eliminates the need for massive new investments in special facilities and significantly reduces transportation losses. |
| Leakage and climate effect | One major problem is the escape of hydrogen ("leakage"). The molecule is so small that it diffuses through seals, hairline cracks in pipes or containers. Leaking hydrogen acts indirectly as a greenhouse gas because it slows down the decomposition of methane in the atmosphere - methane is an even stronger greenhouse gas than CO2. | As bound hydrogen (combined with carbon), eFuels do not escape as easily. The indirect climate impact is therefore significantly lower. |
| Energy efficiency over the entire life cycle | Although hydrogen has a very high energy density in relation to its weight, as soon as transportation, cooling/compression and leakage are taken into account, the actual yield drops. In addition, every conversion (e.g. liquefaction) requires additional energy. | Admittedly, the synthesis of eFuels also requires energy (electrolysis, combination of Hâ‚‚ and CO2). But in the end application, the losses are often lower: no permanent deep-freezing or extreme pressure conditions, fewer leaks, and they can be used directly in existing combustion engines without having to develop this technology from scratch. |
| Costs and investments | The development of a pure hydrogen economy is associated with high initial investments (pipelines, compressors, tanks). In addition, there are ongoing costs for maintenance, energy consumption for cooling or compression and frequent material replacement. | New production facilities are needed to produce eFuels on a larger scale. However, eFuels benefit from existing structures: filling station networks, pipeline systems and millions of existing vehicles. In the long term, this could mean fewer conversions and a faster transition to climate-friendly fuels. |
| Long-term contribution to decarbonization | Although decarbonization is conceivable with hydrogen alone, it is only realistic in practice if high costs and complex infrastructure measures can be managed and if leakages are minimized. | eFuels have the potential to retroactively "decarbonize" large parts of today's vehicle fleet without having to replace the entire technology surrounding engines, filling stations and pipelines. For developing and emerging countries in particular, which do not have high investment resources, this can be a decisive advantage in becoming more climate-friendly. |
Conclusion: eFuels as a more efficient and practical solution?
Looking at all factors – from production, storage and transportation to application – it becomes clear that eFuels can be the more practical and often more efficient choice in many cases. Although hydrogen and eFuels both have a reputation for being climate-friendly alternatives to fossil fuels, eFuels score particularly well in terms of handling, infrastructure and actual energy yield over the entire life cycle:
Integration into existing structures
Unlike with pure hydrogen, no massive expansion of expensive special infrastructure is required. Filling station and pipeline networks can largely continue to be used, which reduces investment costs and enables faster market penetration.
Fewer leaks and lower indirect climate impact
As a carbon-based hydrogen carrier, eFuels are less volatile and do not cause any serious methane or hydrogen leakage problems. This reduces the risk of indirect greenhouse gas effects, some of which can be significant with pure hydrogen.
Greater suitability for everyday use
In many respects, eFuels are better suited to the technical characteristics of combustion engines and power units. Existing fleets can continue to be used with minimal modifications, which makes the transition easier.
Compared to a pure hydrogen economy, eFuels show better feasibility, lower leakage risk and significant cost savings through the use of existing infrastructures in numerous application areas. Particularly in the coming decades, as the world gradually says goodbye to fossil fuels, eFuels therefore represent a convincing option for achieving climate targets more quickly and pragmatically
Frequently asked questions (FAQ) about hydrogen and eFuels
When using pure hydrogen, additional losses occur due to the need for cooling (down to -253 °C), compression (several hundred bar) and leakage in pipes and tanks. eFuels, on the other hand, are stored and transported in liquid form, which requires significantly less energy for conversion steps and infrastructure. This leaves more usable energy at the end of the process.
The production of eFuels also requires electrolysis (to obtain hydrogen) and a synthesis process with carbon. However, the energy required for transportation, distribution and storage is lower overall for eFuels than for pure hydrogen. In addition, eFuels provide co-products (e.g. eKerosene, oxygen, heat) that can be used economically and thus improve the overall balance.
Hydrogen molecules are extremely small and can escape through the smallest gaps or porous materials. Every molecule that escapes corresponds to a loss of energy and also increases the indirect climate impact (e.g. by increasing the retention time of methane).
eFuels can be used in existing tanks, filling stations and pipelines. Pure hydrogen, on the other hand, requires expensive special pipelines and highly developed storage systems. The adaptation and maintenance costs for eFuels are therefore lower – this increases the overall benefit in relation to the energy and cost expenditure.
This means that the hydrogen obtained during electrolysis is bound to a carbon building block (e.g. CO2 extracted from the ambient air), resulting in a synthetic hydrocarbon. This can be liquid or gaseous, but remains easier to handle at room temperature and is significantly less volatile than pure hydrogen.
Yes, of course. Hydrogen is an essential component of eFuels and both technologies can complement each other, depending on the intended use. For example, pure hydrogen can be advantageous in certain industrial processes, while eFuels are more practical for mobility. The assessment should always depend on the application and location.
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