21. June 2017 | Engineering Service

"Mark it zero" - Zero Emission strategies from synthetic fuels to e-drives

FEV and RWTH experts discuss future drive concepts with regard to zero CO2 emissions

The automotive industry is currently in the middle of one of the greatest upheavals in its history. The new challenges surrounding connected and autonomous vehicles also pose major tasks for developers, such as the choice of the correct and appropriate drive for achieving a minimum level of emissions. What’s more, experts remain divided as to whether there is any ideal route to follow, or what that would be. Possible technologies include hybridization, partial or full electrification, or even fuel cells. It is a fact that the market penetration of these individual technologies continues to fall below expectations, despite a number of government initiatives. Accordingly, the corresponding infrastructure is also only growing slowly.

These days, referring to the further potential of combustion engines sounds rather anachronistic, and is increasingly perceived by the public as the perspective of those who are permanently behind the curve and have not adopted the change in direction towards alternative drive forms, or have only done so insufficiently. However, synthetic fuels actually offer an enormous amount of potential for ensuring sustainability and reduced pollution.

As an engineering service provider with a strong focus on drive development, FEV not only offers its customers the development of advanced drive solutions, but also provides assistance and advice in the selection of drive concepts. In SPECTRUM, experts from FEV and RWTH discuss e-mobility, fuel cell drives and synthetic fuels.


Mr. Ogrzewalla: It appears that the public has already agreed to say farewell to the combustion engine. As the Vice President of Electronics & Electrification, do you see this as the end of an era?

Ogrzewalla: It is a fact that drive development is entirely dominated by electrification at present. In recent months, virtually every OEM has announced development programs to the tune of millions. Even for us, as a development service provider, electro mobility has been a fixed component of our engineering business for more than a decade. Nevertheless, it needs to be stated that despite all of the advantages, the market penetration of electric vehicles is still low – and so are the growth rates. This means that the combustion engine will still be with us for some time – whether as a part of hybrid systems, range extenders, or as the sole powertrain. Especially in long-distance traffic and the transport sector, there are currently no conceivable alternative solutions.

In your opinion, what would a practical solution for this look like?

Ogrzewalla: The goal of a balanced fleet strategy must be to offer needs-appropriate drive solutions that ensure sustainable and clean mobility. With these ends in mind, a mix of electrification, optimized combustion engines and synthetic fuels is highly promising – while e-vehicles can reduce local emissions, especially for short distances and inner-city traffic, synthetic fuels have the potential to reduce the CO2 emissions of combustion engines to a minimum. These constitute an effective means of reducing the emissions of existing fleets and directly increasing the proportion of renewable energy in the mobility sector. Paired with further optimizations in combustion processes, this could lead to a sustainable reduction of CO2 emissions, culminating in zero emissions.

Mr. Heuser, as the Managing Director of the “Tailor-Made Fuels from Biomass” excellence cluster of RWTH Aachen University, can you briefly tell us more about the various forms of synthetic fuel and how they are manufactured?

Heuser: The term “synthetic fuels” can be used to describe an extremely diverse range of fuel types. It generally refers to any fuel not manufactured on the basis of petroleum. However, there are still fundamental distinctions within this designation, such as between biofuels or e-fuels.
Traditional first-generation biofuels, such as bioethanol or biodiesel, are primarily obtained through the fermentation of seed or fruit sugars into ethanol, or the esterification of vegetable fats with (primarily fossil) methanol. The second generation of biofuels uses all plant material for fermentation into alcohols or for synthesis into long-chain hydrocarbons by means of the biomass-to-liquid procedure. In this process, the plant material is first converted into synthesis gas (CO and H2) under anaerobic conditions, and is then combined into long-chain hydrocarbons. Similar procedures are also applied to produce synthetic fuels from natural gas or coal.
Hydrogenated vegetable oils (“HVOs”) are usually obtained from plant oils, but other fats can also be employed. These are converted to paraffinic fuels through the addition of hydrogen.
In addition, there is also the new technology of power-to-liquid or power-to-gas. These technologies use electrolysis to generate hydrogen from renewable power and water. In conjunction with CO2, this can be used to produce methane, which is already used as a fuel for gasoline engines. However, these processes also allow for completely new fuels to be defined, such as the liquid oxymethylene ethers (OME) group. These are as liquid as normal diesel fuel, and can be mixed with it easily as a result.

Mr. Adomeit, as the Executive Engineer for Thermodynamics at FEV, you also research alternative fuels. What are the advantages of these diverse technologies in terms of emissions?

Adomeit: With the new power-to-gas and power-to-liquid procedures, in which CO2 serves as a carbon source, CO2 savings of well over 90% are achieved. Previously, every carbon atom released into the environment from exhaust as CO2 would be absorbed into the atmosphere. The same applies for second-generation biofuels. But here, only carbon that has already been converted into biomass through the photosynthesis of atmospheric CO2 is burned in the engine. In addition to CO2 reduction, these fuels can also be formulated so that harmful emissions can also be substantially reduced, such as through the synthesis of oxygenated fuels that produce far lower levels of soot than fossil fuels.

What are the applications for which synthetic fuels are especially critical?

Heuser: On one hand, synthetic fuels are interesting for the passenger car sector. The attraction here lies in the fact that they can be used directly, whether in the form of an admixture with conventional fuels, or, depending on the fuel, as a pure substance and without substantial modifications to cars. In this area, synthetic fuels can directly help to reduce harmful emissions and immediately increase the share of renewable energy in existing fleets in the mobility sector. An admixture of only 30% of OMEs into conventional diesel reduces soot emissions by up to 90% – without any complex adjustment of the engine.
Furthermore, synthetic fuels are extremely important in any area where no alternatives exist for conventional liquid fuels with high energy density. This is especially the case for commercial vehicles, ships and aircraft. For the foreseeable future, the energy density of batteries will remain lower than liquid fuels by orders of magnitude. In the examples mentioned, it is totally impossible to accommodate the necessary energy quantities with batteries due to the enormous volume and weight requirements. With the help of synthetic fuels, it becomes possible to ensure long-term, clean and sustainable mobility in this area.

You mentioned the optimization of existing fleets – at present, how far away are we from a more-or-less comprehensive introduction of alternative fuels, and which of the procedures mentioned will become established?

Heuser: Currently, the EU has stipulated that 10% of the energy consumed in the transport sector be supplied from alternative energy sources by 2020. However, it will still be several years before “e-fuels,” i.e. those from the oxymethylene ether group, are used to refuel in large quantities. We already know that these fuels can be created from CO2 and renewable energy, but the realization of this on an industrial scale still requires more investment. However, such investment requires the framework conditions to be clear for all participants – certainty is required for planning purposes.

Adomeit: One critical factor in the prompt introduction of CO2-neutral fuels is their integration with existing infrastructure. This can allow fuel components that can be mixed into current fuels to reduce the CO2 emissions of existing vehicle fleets immediately. We are currently researching combinations of renewable fuels that approximate standard market fuel characteristics very closely when blended.

Who exactly should develop these fuels to suit the market?

Adomeit: For development, it is extremely important that oil companies and automotive manufacturers work hand-in-hand. Combustion engines and fuels need to be seen as two sides of the same coin that both affect and depend on each other. Engines are developed with the fuel to be used in mind, and new fuels also need to be developed with a view of engine requirements and environmental priorities – particularly with regard to the reduction of harmful emissions and fuel consumption, but also, for example, maximum combustion pressure, ignition characteristics, cooling features and acoustic behavior.

Heuser: As Dr. Adomeit said already, there will be no single developer. The appeal of synthetic fuels lies in the fact that we can influence their characteristics in a targeted manner, and thereby develop concretely better fuels. In this process, we can also adjust the engines in a second step, so that we can substantially reduce both fuel consumption and emissions simultaneously. To achieve this, however, we need close collaboration between science, industry and policy.

future drive concepts for zero CO2 emissions

Exemplary overview of tailored fuels from renewable sources which can be used in ICE combustion systems







Keyword – Ecology: Is an e-drive more environmentally friendly than a traditional combustion engine that has been improved with alternative fuels?

Ogrzewalla: When you only consider the production of fuels from renewable energy up to its conversion in the vehicle, an electric vehicle would be the most environmentally friendly. The efficiency of an electric car is very high, and the vehicles drive with no emissions. In contrast, synthetic fuels have the disadvantage that every step in the manufacturing process reduces the overall level of efficiency of the chain. One aspect that is frequently left out of the discussion is the manufacturing of the vehicles. For an objective analysis, however, this is indispensable. In this area, electric cars are at a disadvantage compared to conventional drive systems. Battery production, in particular, is demanding and cost-intensive, and the necessary materials create new dependencies on the global market. Both the extraction of these materials and the recycling of the batteries put stress on the environment. However, if renewable energies can be used with unlimited availability – in the future, it will often be the case that more power is produced than can even be used – this fact will no longer play such a large role. In this context, synthetic fuels offer an ideal technology for storing excess power in chemical form.

What role can fuel cells play in the future?

Ogrzewalla: Fuel cells could prospectively be used as a supplement to battery technology, or even replace it entirely. The hydrogen usage of fuel cells exhibits minimal CO2 emissions, since hydrogen does not contain any carbon that would be converted to CO2 and its production requires the fewest steps. FEV has created a corresponding demonstration vehicle together with its development partners, in the form of the “BREEZE!” joint project. This involved integrating a fuel cell range extender with a Fiat 500 from our e-vehicle fleet in order to combat the e-vehicle range problem. This allowed us to achieve a range of about 280 km. A tank refill of hydrogen can be completed within a few short minutes, and travel can be continued unhindered. However, this technology still faces the question of the necessary infrastructure, which is highly complex and thus very expensive. Not least of all, the series and small-series solutions of the last decade have failed. At present, however, there are more and more pilot projects in which public buses are being equipped with fuel cells. The advantage for regular transportation services lies in the fact that a comprehensive filling station network is unnecessary. A small number of filling stations at the transport company’s depots is enough to supply the fleet permanently.

Graphic - future drive concepts for zero CO2 emissions

PM/NOx emission reduction with OME use in Diesel test engine







Graphic - future drive concepts for zero CO2 emissions

PM/NOx emission reduction with OME use in Diesel test engine







We have now talked a great deal about the alternatives to electromobility. Due to the large number of possible technologies, the development, infrastructure and, not least of all, marketing costs will increase enormously as a matter of course. Why is it impossible to focus on a single technology?

Ogrzewalla: At present, there simply is not a panacea for emissions-free mobility. User behavior is too diverse, and the systemic strengths and weaknesses of various drive forms are too different. In my opinion, however, the essential message is the fact that needs-appropriate drives are the key to success. Not every powertrain can be reasonably employed for every objective. For e-vehicles, one of the major obstacles for buyers continues to be concerns related to range. In Germany, where the car has a special significance, users are reluctant to own a vehicle that does not cover all eventualities. This is illogical, however, since there is no need for a combustion engine for situations such as inner-city driving. An additional combustion engine would simply serve as extra weight for most drives, which is anything but efficient. Various studies have arrived at the result that as much as 87% of all trips could be covered by an e-vehicle. The success of electro mobility thus requires an ecosystem of specific services and new business models and, above all, a change in thinking on the part of consumers. In addition, advanced, quick-charging technologies can also contribute to success, since this will guarantee the range of electric cars for any trip.
Until then, we will absolutely need to fall back on other, additional technologies. As mentioned before, there are no alternatives at all for long-distance traffic.

Jürgen Ogrzewalla - future drive concepts for zero CO2 emissions

Jürgen Ogrzewalla Ogrzewalla@fev.com

Benedikt Heuser - future drive concepts for zero CO2 emissions

Benedikt Heuser

Dr. Philipp Adomeit - future drive concepts for zero CO2 emissions

Dr. Philipp Adomeit








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