A willingness to embrace all technologies is an immediate priority!

Carbon-neutral powertrains are essential for achieving climate goals. A willingness to embrace all technologies to achieve these goals is crucial and using hydrogen – as an infinitely available, renewably generated energy carrier that is easy to store and transport – to drive powertrains is a vital part of this. Hydrogen-fuelled, carbon-neutral internal combustion engines offer an outstanding solution in many areas. Hydrogen engines also have a long service life, after which they can be easily recycled using established processes.

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Unlike electricity, hydrogen can refuel machinery out in the field

Carbon-neutral agricultural machinery has the potential to reduce carbon emissions significantly in the food production industry. Agricultural machinery requires powerful, robust powertrain solutions that are as lightweight as possible to keep soil compaction to a minimum. This is where hydrogen comes in as a carbon-neutral energy carrier with a high energy density. What’s more, agricultural machinery with hydrogen engines can be quickly refilled out in the field.

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Hydrogen is more than powerful enough

Today’s infrastructure will need to be maintained and constructed long into the future. To make these activities more environmentally friendly, powerful and durable carbon-neutral powertrains are needed for the excavators, cranes, rollers, HGVs, dump trucks and other machinery required to move heavy loads. These powertrains must be able to withstand dust, dirt, heat, freezing conditions, water, snow and ice.

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100% ready for action

Climate change is increasing the risk of extreme weather events. This means that rescue teams – usually consisting of volunteers from the general public – need to be ready to spring into action around the clock to save lives and property in extreme conditions. Only reliable and robust carbon-neutral machinery has the power and endurance to provide the swift help needed in these high-pressure situations. Hydrogen engines were born for this task.

We would like to take this opportunity to thank all volunteers with the fire service, the German Federal Agency for Technical Relief (THW) and other civil defence organisations for their tireless work.

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Hydrogen engines – a key component of climate-neutral mobility

Executive Summary

  • When combined with all other climate-friendly technologies, hydrogen engines will help accelerate our transition to a climate-neutral mobility sector.

  • Germany and Europe will remain heavily dependent on energy imports for the foreseeable future, but the use of green hydrogen will at least allow us to import green energy.

  • Hydrogen must be used directly in the mobility sector to reduce the demand for renewable electricity.

  • We can only take wide-scale action to curb climate change if we are armed with a political framework that embraces all available technologies, including hydrogen engines as the best solution for specific areas.

  • The tried-and-tested piston principle must be developed further so that hydrogen engines can be made available as a rapidly deployable, efficient solution.

  • Hydrogen engines are the ideal powertrain technology for meeting the power and performance requirements of heavy-duty commercial vehicles and off-road applications.

  • Hydrogen engine operating costs are heavily influenced by tolls and taxes, making it essential for all carbon-neutral technologies to be treated equally.

  • Developing hydrogen infrastructure is crucial, and this infrastructure must be rapidly expanded along our main transport routes.

  • To achieve near-zero emissions, hydrogen engines must be considered as a zero-emission technology from a regulatory perspective.

  • Hydrogen engines have the potential to become an industrial policy success story through their ability to shape economic and social transformation.

Climate-neutral mobility – a non-negotiable for achieving climate goals

The Hydrogen Engine Alliance supports the EU’s goals to reduce carbon emissions (Fit for 55) and therefore advocates a rigorous approach to achieving these goals, encompassing the full scope of available vehicle powertrain technologies. It is crucial that emissions legislation considers all factors related to different climate-neutral powertrain technologies as part of a well-to-wheel analysis. This will enable plans to be made with greater certainty and allow the actual contribution made by the transport sector to the residual carbon budget to be taken into account, aiding compliance with the Paris climate goals. The recent review of Germany’s current climate action status by the German Federal Ministry for Economic Affairs and Climate Action (BMWK) also makes it clear that, to achieve these climate goals, Germany needs to triple the rate at which it is reducing its carbon emissions across all sectors. As things stand, the transport sector is expected to exceed its climate targets in cumulative terms by 271 Mt CO2 eq. by 2030 . By choosing to pin all hopes on a single technological solution, Germany risks failing to meet its ambitious climate goals. A comprehensive approach is needed if we are going to keep pace with the speed with which the transport sector needs to be transformed to achieve climate-neutral mobility by 2050. Against this backdrop, the Hydrogen Engine Alliance is calling for the direct use of green hydrogen in piston engines to form part of Germany’s overall efforts to transition to renewable energy within the transport sector. We firmly believe that an approach that uses all appropriate technologies without pushing the market in a single technological direction is the only road to success.
1Source: Germany’s current climate action status (BMWK, 2022)

Hydrogen as an energy carrier is indispensable for our energy supply

Given its high level of industrial and energy-intensive production activities, limited hydropower, wind power and solar power resources, and nuclear power phase-out, the energy transition is presenting Germany with a huge challenge. In recent years, Germany has stepped up its efforts to expand the generation of renewable energy, especially wind power, and renewables now account for the largest share of installed capacity. Despite this, Germany still has to import around 70% of its primary energy demand due to its need for a reliable and constant energy supply. At present, virtually all of this imported energy comes from fossil fuels and carbon-based energy sources. This situation is very similar around the world, both in industrial nations and in densely populated countries like China and India, which primarily cover their energy demand using coal power.

It is therefore clear that Germany can only decarbonise its primary energy supply by finding a replacement for its imported energy. In its review of Germany’s current climate action status, the BMWK unequivocally believes that importing green hydrogen will play a central role in this. Electrification alone will not be sufficient to achieve the goal of reaching carbon neutrality. The Hydrogen Engine Alliance supports this viewpoint, especially in terms of the mobility and transport sectors. Using green hydrogen to cover the primary energy demand worldwide is the only way to guarantee a reliable, carbon-free supply of energy to all sectors, especially the mobility and transport sectors. This is all the more important given how green electricity generated locally will remain a scarce commodity and the decarbonisation of the industrial and building sectors will also lead to a significant increase in the overall demand for renewable electricity. Germany is projected to have an electricity demand of up to 750 TWh in 2030 compared with the current demand of 560 TWh . Renewable energy generation in Germany must therefore be expanded at an enormous rate.

The EU also believes that producing and importing green hydrogen as a strategic energy carrier is indispensable for the future. This goal as well as the commercial objective of bringing the cost of hydrogen below EUR 1.80 per kilogram was recently reaffirmed by the President of the European Commission during the European Hydrogen Week . The Hydrogen Engine Alliance welcomes this objective and the EU’s clear intention to support the expansion of the infrastructure and commercial relationships needed to achieve it. It is therefore clear that the direct use of hydrogen is a worthwhile approach – especially in the area of commercial vehicles and off-road applications in the mobility and transport sectors.


2 Source: Germany’s current climate action status (BMWK, 2022)
3 Source: Opening keynote by President von der Leyen at the European Hydrogen Week 2021 (European Commission Press Corner, 29 November 2021)

No either/or approaches – a range of coexisting climate-neutral powertrain technologies is required

Since the climate goals cannot be achieved through electrification alone, it is already clear that green, imported hydrogen is an indispensable part of our future primary energy supply. In the same vein, when it comes to climate-neutral powertrains, focusing on one technology alone, such as solutions powered by electric batteries, will not be sufficient. The Hydrogen Engine Alliance therefore strongly believes that the only way to achieve climate neutrality in the area of powertrains is by following an approach that encompasses the full scope of available technologies, including fuel cells and hydrogen engines. This approach is all the more vital given the rapid depletion of the residual carbon budget, which must not be exceeded if we are to keep global warming to under 1.5 degrees above pre-industrial levels. We are calling for all relevant climate-neutral powertrain technologies to be developed and used in their respective ideal scenarios. Hydrogen engines operated using carbon-neutral hydrogen undoubtedly form a crucial part of this. Using hydrogen engines alongside fuel-cell powertrains will increase the speed with which hydrogen-based powertrains enter the market and the resulting strong demand for hydrogen will expedite the construction of the related infrastructure, in terms of both the tank systems and fuel quality requirements.

Technical challenges – time for an evolution not a revolution

Hydrogen engines are an attractive, efficient and rapidly deployable solution, especially in heavy-duty vehicles and machinery. Hydrogen engines convert energy into mechanical motion using proven piston engine technology. This means that conventional engines only need to be moderately adapted to harness hydrogen’s chemical energy. These adaptations can be made using existing development skills and established technologies.

Taking the relevant conditions into account, the interplay and interactions between these existing technologies must be reassessed and reconfigured for use with hydrogen. Since this involves evolving existing technology rather than developing brand new technology, hydrogen engines have the potential to be launched on the market quickly and to have an equally rapid impact on carbon emissions. This also means that hydrogen-powered engines could feasibly become highly sophisticated in no time at all, allowing them to meet end users’ requirements in all areas of application. Hydrogen engines are an ideal substitute for existing diesel engines in heavy-duty commercial vehicles and in agricultural and industrial machinery (e.g. earth-moving equipment, excavators, dump trucks) in particular. This is because they meet the space and range requirements, are highly durable and are ready for use at all times. As a general rule, the greater the range and/or load requirements or the more difficult the operating conditions, the more suitable hydrogen engines are as a means of decarbonisation.

The energy efficiency of hydrogen engines is a widely debated topic. Fuel cells in particular are regarded as more efficient than hydrogen-powered piston engines. However, usage scenarios should also be taken into account here. When comparing fuel cells with hydrogen engines, it is clear that their efficiency depends on the area of use and load profile. The results of these comparisons show that fuel-cell powertrains are advantageous in areas with low power requirements, while in areas with high power requirements, the efficiency of piston engines is similar to and, in some cases, clearly greater than that of powertrains. Like conventional engines, hydrogen engines generate waste heat. The cooling of this heat is another area in which fuel cells and hydrogen-powered piston engines differ. Fuel-cell powertrains raise the coolant temperature much more than hydrogen engines. This presents an additional technical challenge, especially given the lower temperature of the coolant in fuel cells. Cooling poses less of a problem in hydrogen engines, where the exact same cooling concept already well-established in diesel powertrains can be applied. For these reasons, neither technology can be regarded as being more efficient across the board than the other. Instead, it depends on how the technology is used, which is ultimately why an approach that embraces all available technologies is so crucial. Only in this way will it be possible to effectively reduce carbon emissions across the transport sector so that the residual carbon budget can be used sensibly. This is why the Hydrogen Engine Alliance strongly advocates solutions that make use of synergies and the full spectrum of suitable technologies.

Commercial aspects – success factors for hydrogen-based powertrains

Given that modern diesel engines only need to be developed and modified by a moderate amount to make them suitable for operation with hydrogen, vehicles fitted with a hydrogen-based powertrain will be attractively priced. Besides the tank system, the changes required to the system as a whole are limited to fuel injection and powertrain components. This means that the additional cost of manufacturing vehicles with hydrogen engines will be much lower compared with the cost of vehicles with fuel-cell powertrains.

In terms of operating costs, fuel costs will determine how these compare with the costs of today’s diesel-operated powertrains. The uncertainty currently surrounding future changes to carbon taxes and the anticipated reduction in the price of green hydrogen make fuel costs difficult to evaluate. Another factor that will have a considerable impact on costs is the debated EU-wide carbon-based road toll for heavy-duty commercial vehicles. Depending on future legislation, this toll has the power to encourage significantly greater use of carbon-neutral powertrain systems. The Hydrogen Engine Alliance believes that zero-emission vehicles should be given a blanket exemption from this toll in the same way as electric vehicles are already exempt from the HGV toll in Germany.

In terms of operating costs, fuel costs will determine how these compare with the costs of today’s diesel-operated powertrains. The uncertainty currently surrounding future changes to carbon taxes and the anticipated reduction in the price of green hydrogen make fuel costs difficult to evaluate. Another factor that will have a considerable impact on costs is the debated EU-wide carbon-based road toll for heavy-duty commercial vehicles. Depending on future legislation, this toll has the power to encourage significantly greater use of carbon-neutral powertrain systems. The Hydrogen Engine Alliance believes that zero-emission vehicles should be given a blanket exemption from this toll in the same way as electric vehicles are already exempt from the HGV toll in Germany.

During the European Hydrogen Week in Brussels in November 2021, the European Commission announced its target to bring the cost of hydrogen to below EUR 1.80 per kilogram by 2030. The current price of hydrogen at hydrogen filling stations has remained consistent at a standardised EUR 9.50 per kilogram (gross) over the past few years. This price is based on a voluntary amount set by the Clean Energy Partnership (CEP) in 2010 with the objective of achieving approximate cost parity with conventional fuels. The CEP is a union of companies from the automotive industry, as well as the fields of technology, energy, gas and mineral oil production, which are united by a commitment to expand green mobility using hydrogen and fuel cells. The target price set by the European Commission would make hydrogen a considerably more attractive energy carrier for the mobility sector.

As can be seen, hydrogen-based powertrains – both hydrogen engines and fuel cells – have the potential to become a cost-effective solution for the transport and industrial sectors. The Hydrogen Engine Alliance expressly welcomes the European Commission’s clear acknowledgment of the need for hydrogen infrastructure as well as its support for expanding production and trade to ensure that its target market rate can be achieved.

Hydrogen engines are expected to be able to be maintained and deployed in exactly the same way as diesel engines, meaning that end users can continue using existing infrastructure and service networks without the need for any large-scale adjustments.

4 Source: Opening keynote by President von der Leyen at the European Hydrogen Week 2021 (European Commission Press Corner, 29 November 2021)
5 Impact of the German government’s funding for hydrogen-powered cars – parliamentary question from the Alliance 90/The Greens party on 27 July 2021

Climate-neutral = zero emissions?

When examining emissions, it is important to distinguish between gases that harm the environment such as carbon dioxide and air pollutants such as particles and nitrogen oxides.

Since hydrogen (provided it is green) does not convert carbon into carbon dioxide, hydrogen engines can reduce carbon dioxide emissions by over 98% in comparison with current modern diesel engines, assuming that the latest lubricants and AdBlue fluid are used (intake air immission values not taken into account).

This is why the Hydrogen Engine Alliance supports the proposal made by the European Commission’s working groups on its vehicle energy consumption calculation tool (VECTO) – which is also used to determine carbon dioxide emissions – that vehicles with hydrogen powertrains be classified as climate-neutral or as zero-emission vehicles (ZEV).

The untreated nitrogen oxide emissions are only expected to amount to a fraction of those emitted by today’s standard high-efficiency diesel engines. Since, thanks to robust exhaust gas aftertreatment technologies that have already proven themselves in large-scale production, these engines already meet statutory requirements, and will in all likelihood continue to do so in the future, the lower emissions generated by hydrogen engines are yet another advantage.

Hydrogen engines – an opportunity for society and the economy

The transportation of goods and materials forms the backbone of modern society, making transport networks part of our critical infrastructure. Besides the aforementioned factors concerning procurement and operation, the impact on overall costs must also be considered. Hydrogen engines – used in synergy with fuel cells in areas with lower power requirements – are the obvious solution for tackling the challenge of creating a climate-neutral transport sector in the fields of heavy-duty commercial vehicles, agriculture, construction and industry. Hydrogen engines also have a role to play in keeping the logistical aspects of transporting goods and materials affordable, in maintaining secure and reliable food supplies and in ensuring basic needs are met. Other areas of use include emergency vehicles, which by their very nature need to be extremely reliable and ready for deployment around the clock, as well as other special vehicles and machinery that would today be inconceivable without a powertrain capable of functioning self-sufficiently and reliably at all times. The vehicles and machinery used in the agricultural, construction and industrial sectors also often have to contend with difficult conditions like dust or challenging operating temperatures. Hydrogen engines are ideally placed to meet these demands as well.

The transition to using climate-neutral energy in all sectors is one of the toughest challenges facing our economy and overall prosperity. In terms of the transport and mobility sectors, the diversification of powertrain technologies has created a whole new set of requirements and is jeopardising many jobs and existing investments. According to a study by PWC commissioned by the European Association of Automotive Suppliers (CLEPA), as many as 500,000 jobs are affected across Europe. In Germany, the vehicle manufacturing industry and its suppliers, the associated expertise in engine technology and all the skilled employees working in this sector are a hugely important part of the economy. Given the knowledge and production facilities already in place for manufacturing hydrogen engines, the use of hydrogen engines as a climate-neutral source of power presents a huge opportunity for Germany and the EU. Besides reducing geopolitical reliance on imported critical raw materials (e.g. lithium), the widespread use of hydrogen engines can help Germany and the EU to maintain their technological competitive edge over other regions of the world as well as boost the economy through exports. Hydrogen engines therefore have the potential to generate jobs and increase prosperity as well as make huge strides towards meeting the climate goals.

The Hydrogen Engine Alliance’s mission is to support, promote and use its members’ expertise and innovative strength to actively shape the achievement of these goals.