«Electric Mobility Alone Will Not Make it Happen»
Electricity, hydrogen, biofuel, electricity-based fuels – there are many energy sources available for CO2-neutral transport. IAV’s Head of Technology Matthias Kratzsch discussed with Karsten Wilbrand, Shell Manager responsible for mobility research, what really contributes towards climate targets.
With its Climate Protection Plan 2050, Germany has adopted ambitious CO2 reduction targets for the individual sectors and thus also for the transport sector. Can this be achieved?
Wilbrand: In order to achieve the CO2 reduction target of -40 percent by 2030, which is the target in the transport sector, enormous efforts are required. Electric mobility alone will not succeed – we must also decarbonize fuels.
Kratzsch: The report of the National Platform “The Future of Mobility” says it clearly: The speed of change is not enough; you must become faster and be open to new technologies. A single technology alone will not get us there; we need a coherent mix of alternative drives and fuels. Incidentally, this is also the result of a study we conducted and submitted for this year’s International Vienna Motor Symposium on the evaluation of CO2 equivalents according to the life cycle for various powertrain fleet scenarios up to 2035.
«We must find solutions that reduce emissions, especially from existing vehicles.»
— Senior Principal Scientist Mobility at Shell
What opportunities do you see for accelerating change?
Wilbrand: We expect the share of electric drives in new registrations to rise; but we will still have many combustion engines in our inventory – with ten million electric drives (including fuel cell vehicles), there would still be almost 40 million passenger cars plus commercial vehicles in 2030. So we have to find solutions that reduce emissions, especially from existing vehicles. From our point of view, liquid biofuels would be suitable for this purpose, as they could usually be used immediately and seamlessly – but unfortunately the enthusiasm for biofuels has been somewhat lost after Super E10. Nevertheless, we are convinced that we will need something like E20 in the 2020s. By contrast, we do not (yet) see any relevant quantities of electricity-based fuels in this decade – at best the first pilot plants. We also see gas fuels, especially biogenic ones such as BioLNG, as an alternative for heavy commercial vehicles, whose fleet turnover is significantly higher than for passenger cars.
Kratzsch: As far as engines are concerned, much higher blending rates with synthetic liquid fuels than today would be possible. Depending on the type of fuel and combustion process, it is technically possible to replace up to 100 percent of fossil fuels in the existing fleet with CO2-neutral, biogenic or synthetic fuels. And as our IAV study shows, a higher blending quota would be the most effective measure to reduce the fleet’s CO2 equivalents over its life cycle by 2030. What is missing are the appropriate political framework conditions and investment incentives in favor of larger fuel production capacities.
Wilbrand: In Germany, for example, hydrogenated vegetable oil, i.e. HVO, can be added to B7 diesel fuel up to a share of 26 percent, and the fuel named R33 will then have a total share of one third of renewable energy. The CO2 advantage over purely fossil diesel is then around 20 percent. That would be the CO2 reduction that would still be missing for ten million electric cars in 2030.
«One technology alone will not allow us to achieve our goal; we need a coherent mix of alternative drives and fuels.»
— Responsible on the IAV Management Board for the core area of technology
And what path do you propose for the gasoline engine?
Wilbrand: We can increase the ethanol content in gasoline. Bio-waste materials such as straw are available for this purpose, and plant capacity is also being further expanded. E20 would make a good contribution towards CO2 reduction and would be compatible with most of today’s vehicles. The biggest challenge, however, is probably to convince consumers of E20 – for this we also need the commitment of the car manufacturers. This is because the share of Super E10 has for years been at only 13 % of the industry average – and the trend is constant. If future engines are designed for E20 from the outset, the high knock resistance will also increase efficiency. The CO2 avoidance costs would be low.
Kratzsch: On the engine side, this is feasible for ethanol blends. Of course, the compatibility of older engines must be looked at again, for example with regard to the seals. But technically, I don’t see any major problem there. Particularly in the case of diesel engines in the existing fleet, apart from compatibility with the DIN EN 590 fuel standard, there is no technical problem in using blending rates of HVO fuel higher than 26 %. This would in any case make a contribution towards reducing fleet CO2 emissions in both the new and existing fleet in the very short term.
There are currently still several competing approaches for electricity-based fuels. Do you already have a clear preference?
Wilbrand: Electricity-based fuels can be produced well in the Fischer-Tropsch process for diesel fuels; for gasoline by methanol synthesis, we prefer to work with FT processes. We already make around seven million tons of gas-to-liquids products in Qatar. Shell GTL fuel can be used immediately in fleet vehicles – and leads to significant air quality improvements for older vehicles.
Kratzsch: Advanced fuels can make a valuable contribution towards reducing the CO2 emissions of existing fleets, so it is also important to supply them with power-to-liquid and biomass-to-liquid fuels. However, if we are building a hydrogen economy anyway, then from a thermodynamic perspective it makes sense to use hydrogen directly – either in the H2-capable internal combustion engine or in the fuel cell. We are working intensively on both technologies and are convinced that market penetration will not be long in coming. CNG, on the other hand, is an interim solution that immediately reduces CO2 emissions by 20 to 25 percent in gasoline engines. This path only makes sense, however, if in the medium term we generate methane not from natural gas but from hydrogen or biogenic sources such as residual materials.
Wilbrand: I agree with you that hydrogen should be used as directly as possible. After all, hydrogen can achieve an efficiency of around 30 percent over the entire energy chain, while other e-fuels can achieve 15 percent at best. However, it will be a long time before corresponding vehicles come onto the market – and this in turn raises the question of what we do with the fleet. By contrast, the Fischer-Tropsch process allows us to produce both synthetic diesel and kerosene. In the long term, we believe that aviation, in particular, will be dependent on liquid electricity-based fuels, as this sector in particular is dependent on the highest possible energy density. And this is where liquid energy sources in light tank systems remain unbeatable over the long term.
What proportion of defossilized transport can electricity-based fuels achieve?
Wilbrand: The energy requirement for the production of synthetic fuels is particularly high. If the necessary carbon is removed from the air, this is (currently still) very expensive. But the necessary quantities of renewable electricity are also far from being available.
Would you use hydrogen in the fuel cell or the combustion engine?
Kratzsch: In the transport sector, the technologies that have the lowest costs over the life cycle will always prevail. Furthermore, the use case will determine which technology is used in a specific application. While the efficiency of the fuel cell is very good, especially at low power levels, the combustion engine is more likely to show its strength at high loads. To this extent, the application and TCO will drive this decision. We believe that both technologies are justified and will be used.
Wilbrand: In the medium term, however, I see no reason why fuel cells should not become significantly cheaper than they are today. In addition, fuel cells do indeed operate emission-free, whereas the combustion of hydrogen in the engine still requires exhaust aftertreatment.
Kratzsch: Indeed, exhaust aftertreatment is necessary – and that is what we are working on at the moment.
«And I am convinced: New consumption-optimized combustion engines and electricity-based fuels would also be a good complement to electromobility in Germany.»
— Responsible on the IAV Management Board for the core area of technology
Are we following a special path in Germany?
Kratzsch: Let’s look at China: The country has cut back on subsidies for electric vehicles. There are to be government subsidies or credits for low-consumption vehicles and the use of methanol as a fuel. These credits, in turn, can be used to reduce the necessary quota of battery electric vehicles that a manufacturer must bring to market. This will most likely lead to a surge in the development of new, very efficient combustion engines in hybrid environments, as the consumption targets will not be achievable with pure combustion engine drives. And I am convinced: New consumption-optimized combustion engines and electricity-based fuels would also be a good complement to electromobility in Germany.
To what extent can the efficiency disadvantage of electricity-based fuels be compensated for by innovative engine technology?
Kratzsch: If we manage to improve the average efficiency by ten percentage points, this will save 25 percent primary energy retroactively via the energy chain. We can only achieve this boost if we reduce losses at low loads, for example by reducing wall heat losses in the combustion chamber, by using an electrified turbocharger or by driving electrically in low load ranges.
Wilbrand: The efficiency chain of battery electric drives is excellent, with all transmission one still reaches more than 70 percent – this will never be achieved by an internal combustion engine, even if it is being further optimised to its theoretical limits. However, heavy vehicles that are used a lot in long-distance operations would require very large batteries and very high charging currents. This not only costs payload, but also an incredible amount of money. And that’s where it can make sense to use hydrogen in the medium term. Electricity-based fuels, on the other hand, are not only comparatively inefficient; they are also difficult to place in the highly competitive road haulage industry.
Kratzsch: In our strategy for the use of hydrogen in transport, we must not forget other sectors such as the chemical and steel industries, as a result of which demand will exceed generation potential in Germany. We will therefore have to import energy sources, and liquid fuels will be available, the production of which in geographically favorable locations will also allow correspondingly lower prices.
How much diversity can we afford in terms of drives and fuels?
Kratzsch: That is not the crucial question for me. The question must be: From a technological point of view, what is the best way to achieve the greatest potential for reducing CO2 emissions? And for us at IAV, the answer is: We will have to pursue several paths in the long term: on the one hand, the direct use of green electricity – in the coming years, we expect a significant increase in battery electric vehicles. On the other hand, we predict that hydrogen will become increasingly important. At the same time, combustion engines will have to be made fit for the Euro 7 emissions standard by 2025. In the next step, we will then have to look even more closely at how the efficiency of combustion engines can be increased – right up to engines that are specially designed for hybrid operation.
Wilbrand: We should also work on the increased blending of biofuels, as they are technically advanced. At the same time, however, we should not neglect research and development of electricity-based fuels.
The article was published in automotion 02/2020, the automotive engineering magazine of IAV. Here you can order the automotion free of charge.