Benedikt Heuser explains how electricity-based liquid fuels can help to reduce CO2 emissions as an important complement to electric mobility in the transport sector.
The joint project ‘C3-Mobility’ focuses on the utilisation of such e-fuels based on green methanol for the passenger and goods transport sector. Society and politics are extensively addressing climate change. The overall goal is energy transition to significantly reduce carbon dioxide (CO2) emissions in all relevant sectors that still burn fossil fuels today. Legally-binding global targets are laid down in the Paris Agreement of 2015. To implement the EU’s commitment under this Agreement, European objectives are set in the 2030 ‘Energy and Climate framework’. The framework includes EU-wide targets and policy objectives for the period 2021-2030.
One key target is to achieve a cut of at least 40% in greenhouse gas (GHG) emissions compared to 1990. By 2050, the electrical power sector is targeted to become completely carbon neutral, and the CO2 footprint of the transport sector shall be reduced by 60% compared to 1990 – despite an ever-increasing transport volume. This reduction may even not be enough: some countries are lagging behind, and the Intergovernmental Panel on Climate Change (IPCC) Special Report presented in Kattowice in 2018 assumes a remaining global CO2 budget of ~400Gt for keeping the 1.5°C target. With an actual annual rate of 40Gt/a, this leaves no time to shift an immediate CO2 reduction further into the future.
The ambitious goals especially appeal to the energy and transport sectors. On reviewing the current debates, media, and political agendas, it appears that the emphasis is almost exclusively being placed on the comprehensive use of battery electric vehicles (BEVs). Certainly, for some cases they might be the best solution to rapidly reduce the CO2 emissions of the ground traffic sector. For urban traffic and short distances, the advantages are clear. Nevertheless, the market penetration of BEVs is still pretty low because of the relatively high purchase price, a limited driving range, long battery charging times, and the high investment cost related to the charging infrastructure.
Especially for long haul or heavy-duty transport, liquid or gaseous fuels will remain the means of choice due to their high energy density. ‘E-Fuels’ – synthetic fuels produced from renewable electricity and CO2 – are a very promising approach for these applications.
“Not only can they be used in every application of road transport, but also air and sea traffic could benefit,” said Benedikt Heuser from FEV Europe GmbH, the co-ordinator of the joint research project ‘C3-Mobility – Closed Carbon Cycle – Climate-neutral Fuels for the Traffic of the Future’.
This project is funded by the German Federal Ministry for Economic Affairs and Energy through the funding initiative ‘energy transition in the transport sector: sector coupling through the use of electricity-based fuels’. The use of chemicals with a high energy density as CO2-neutral energy carriers or fuels seems to be the most efficient way to reduce the CO2-footprint of the specified applications.
The annual demand of electrical energy in Germany amounted to 600TWh in 2015. Assuming a further rise due to the increase of digitalisation and partially electrical traffic in the coming years, which can only be compensated partly by an optimisation of the efficiency of electrical systems, a constant consumption can be expected in the best case.
The transport sector plays a major role in these calculations; nearly 30% of the German total energy consumption is caused by road traffic, aviation, and shipping. In addition to this, greenhouse gas emissions are still very high in this sector. Despite constant efficiency improvements through weight savings, higher engine efficiencies or strengthened electrification or hybridisation, the overall energy needs are not expected to change in the long run, as a Roadmap from the European Road Transport Research Advisory Council (ERTRAC) and statements from the German Federal Ministry of Transport and Digital Infrastructure expect a steady transportation increment of about 30-40% in the next 30 years.
The German Environment Agency (Umweltbundesamt UBA) has published a value for the overall energy consumption of Germany in 2015: 2466TWh. Power generation from renewable energy sources (wind and solar, no biomass) is assigned a potential of 629TWh in 2050. Considering that electrical energy gained from wind or sun does not always match the current demand, about 100TWh can be anticipated for long time storage in the form of hydrogen, ‘power to gas (methane)’ or ‘power to liquid’.
These facts and calculations reveal a supply gap of 1767TWh renewable energy in Germany which needs to be imported from in- and outside of Europe as GHG-neutral energy. With only a small number of exceptions, like Norway or Spain, Europe will not be able to fully supply itself with renewable energy. A direct import of electrical power does not seem realistic and imports of hydrogen or gas are also limited due to the transport distances of existing or newly-built pipelines. Thus, for long distance imports (from areas with an extremely low cost of renewable electricity like Chile or Australia) it seems to be a solution to count on, for example, methanol as a liquid energy carrier.
Heuser explains: “Methanol is considered to be a very good choice as a liquid energy carrier. The main advantages are that methanol is easy to store, transport, and distribute. It is quite cheap to produce and globally standardised, available, and already shipped in large amounts as a base chemical. Thus, methanol is a very good choice as an intermediate product on the way to a final drop-in capable fuel. In addition to this, methanol has low particle emissions, a high burning rate, and high evaporation enthalpy when used in internal combustion engines as a direct fuel. Methanol also dilutes very fast in water and is biodegradable.”
Thus, the project C3-Mobility assumes that methanol obtained from CO2 and regeneratively produced hydrogen can initially be imported by train or ship until the above-mentioned supply gap can be closed in the more distant future. For further use in Europe, methanol can then be processed into various types of fuels.
“By doing this, the transport sector, initially the whole existing vehicle fleets and in the long-term especially long distance and freight transportation, can be supplied with a renewable fuel,” Heuser points out. “It is important to mention that besides its long-term vision, C3-Mobility also examines ways to achieve a short-term reduction of the effective CO2 emissions (‘Well-to-Wheel’) of today’s fleet by taking also the admixture of electricity-based renewable fuels (‘Drop-in fuels’) into account.
“Once we have capable fuels, they could immediately be applied without any big changes in the infrastructure or the engines. However, the long-term overall goal is to point out the most promising ways into a CO2-neutral mobility of the future by using electricity-based liquid fuels for long distance transport and freight as a complement to electric mobility in cities. Therefore, we evaluate the long-term use of methanol-based fuels in all kinds of internal combustion engines – pure renewable fuels and blends. The result is a comprehensive evaluation of each fuel in terms of environmental sustainability in production and consumption chains, gradually further efficiency improvements, as well as distribution and market launch. Methanol-to-Gasoline (MtG) and 2-Butanol will serve as blends for our investigations of gasoline engines and 1-Octanol and Oxymethylenether (OME) as blends for Diesel engines.”
Besides these fuels, Dimethyl ether (DME) is also considered. Even though DME is gaseous under ambient conditions (like LPG), its advantages lie in the efficient production process, rather easy engine application, the already existing fuel standard, and the non-hazardousness.
Criteria for synthetic fuels
Bearing on state-of-the-art research, various Synthetic fuels based on regenerative methanol have been assessed with regard to the following criteria:
- Use in today’s vehicle stock;
- Market launch scenarios via fleets or large stocks or as drop-in fuels complying with the current legislation;
- Production routes based on methanol and their efficiencies; and
- Efficiency and emission behaviour of internal combustion engines in conventional and hybrid powertrain configurations
Fig. 1 shows introduction timelines for fuel candidates that meet these criteria. Next to the direct use of methanol, two very promising liquid fuel alternatives for each combustion method are indicated, differing in respective applications, timescale for usage and production method.
On the one hand, there are coherent possibilities to harness climate-neutral fuels in a short to medium term. But on the other, the research also reveals gaps and discrepancies in the degree of maturity of production and use. To allow a fast and smooth transition to an overall regenerative and efficient transport system, the project aims to close, or at least reduce, those gaps.
Objectives of C3-Mobility
The consortium consists of 30 partners comprising energy providers, process engineering experts, engine and automotive manufacturers, as well as research and development providers. Together, they are working on the challenges of a CO2-neutral transport through synthetic fuels. Focusing on methanol-based fuels, the entire value chain from fuel synthesis to engine application and to market launch will be evaluated. “Our interdisciplinary work allows a holistic approach to find answers to fundamental questions in this field. The unique character of the concept is reflected in this broad horizon“, Heuser said.
The work scope of the partners addresses questions such as: how to design a cross-sectoral energy analysis to consider all energy consuming areas in the most efficient, ecological, and economic way, or which production pathways for electricity-based fuels do exist and how does their efficiency compare to established processes? Also, it is of major interest to investigate how the synthetic fuels and their efficient application can contribute to minimise the dependency on energy imports. Another key question to be asked in the overall context is if it is more reasonable to adapt the fuels to existing engines or to optimise the engines for the new fuels?
The first step is to take a closer look at the methanol production from CO2 and hydrogen (H2) as an important product for the generation of new fuels. Methanol production from synthesis gas (carbon monoxide (CO) and H2) is a state-of-the-art technology.
Cost determining variables
Cost determining variables for further steps are the deployment of H2 as main energy carrier and CO2 with less impact depending on source. In the project, three different cases for carbon dioxide usage are theoretically analysed based on their specific possibilities for separation: industrial regions (CO2 sequestration from exhaust gas streams), rural areas (biomass and municipal waste-based CO2 or carbon streams) and desert regions (carbon capture from air, where no CO2 is available from dedicated sources). The production of hydrogen as a reactant for methanol only plays a theoretical role in C3-Mobility. It is considered as a product of an electrolysis process which is an available technology where ‘only’ the upscaling is missing due to until now limited market demand.
The project assumes that renewable methanol produced in favourable regions for renewable energies will be imported mainly by ship or via pipeline. Once in Europe, the methanol is appropriately processed into various fuels. Examined fuels in C3-Mobility are methanol itself, Polyoxymethylendimethylether (OME 3-5), 2-Butanol (mainly as drop-in component for gasoline fuel), synthetic gasoline (via Methanol-to-Gasoline process), 1-Octanol (as drop-in component for Diesel fuel) and DME (as Diesel replacement). 2-Butanol, synthetic gasoline and 1-Octanol will be synthesised experimentally. For this purpose, synthetic gasoline will be produced in pilot scale in the order of 20-40t.
In terms of the application for passenger cars, commercial vehicles and industrial engines, the project follows two main approaches: Firstly, achieving a short-term CO2 reduction in existing fleets and vehicles of the next generation through fuel blends and drop-in fuels. Possible issues of material interactions and compatibility, miscibility, mixture preparation or temperature effects will be investigated here. A small fleet of demonstrator vehicles will test and show the usage of the new fuels in real driving conditions.
Secondly, optimising these different engine classes for fuel options burning with very low pollutant emissions and a very high efficiency. OME, DME and 2-butanol as well as methanol itself are as pure replacements not compliant with the existing norms EN228 for gasoline and EN590 for diesel fuel.
For both cases, different tests will be conducted with single cylinder research engines, and later the project demonstrator vehicles will be set up. Fundamental topics like the development of new adapted injection systems, emission monitoring, fuel deterioration, ignition systems, and implications on exhaust gas aftertreatment systems are key for the overall research approach. Also, other engine concepts, like dual- or flex-fuel systems, are taken into consideration. These types of engines are useful when the distribution of the new fuels is not comprehensive yet. ‘Old’ fuels could still be used and thus the flex-fuel engines could ease the market launch of the new ones in the same way as current CNG engines which mostly can still run on standard gasoline.
For larger engines – especially in truck, train or ship applications – methanol is a very promising alternative as a liquid and very clean burning fuel. Hence, C3-Mobility also examines the potentials of methanol as a fuel for large engines with a cylinder volume of more than two litres. In this case, the goal is to keep the efficiency degree of a Diesel engine and still launch and use methanol as renewable fuel in the short-term.
A rather critical aspect for these fuels is their market launch. Major barriers are found to be legislative issues, costs, fuel application, fuel availability, and infrastructure. “A problem is that, since current legislation does not include the CO2 reduction potential of e-fuels, market stakeholders do not yet see a business case that would be sufficient to invest in. The new European Renewable Energy Directive II doesn’t stipulate any sector coupling for e-fuels,” Heuser explains. For a fast market introduction of e-fuels, he proposes a certificate system which allows carmakers to buy the CO2-neutral fuel with corresponding certificates, which can then be used to reduce the carmaker’s CO2 fleet targets. Another idea is a relaxation of the energy tax on renewable energy carriers and an increase of the cost level for fossil CO2 with a given, but adjustable slope. Heuser is convinced that such legislative changes would immediately lead to a better business model which would enable and secure the needed long term investments.
Hybridisation as well as fuel cell and battery electric vehicles will contribute significantly to a CO2 reduction of the transport sector in the future. But the almost exclusive focusing in legislation, media and discussions is critical as many studies show that electrification alone will not reach the climate targets and is far more expensive than a well balanced approach and a mixture of different solutions which can still make use of existing infrastructure.
Initiative ‘energy transition in the transport sector: sector coupling through the use of electricity-based fuels’
C3-Mobility is part of the research initiative ‘energy transition in the transport sector: sector coupling through the use of electricity-based fuels’ by the German Federal Ministry for Economic Affairs and Energy. The initiative forms an interface between the sectors energy and traffic. Thus, various synergies can be made visible and interdisciplinary approaches can be used to investigate new, electricity-based fuels for the transport by road, sea or air. The sector coupling also expands the political options for action to achieve the climate goals from Paris. The first projects of the initiative – including C3-Mobility – have already started in autumn 2018. They all look at the production, the transport, or the use of electricity-based fuels from different point of views.
AVL Deutschland GmbH
AVL qpunkt GmbH
Chemieanlagenbau Chemnitz GmbHContinental
DENSO AUTOMOTIVE Deutschland GmbH
FEV Europe GmbH
Forschungszentrum Jülich GmbH
Fraunhofer Institute for Solar Energy
Hyundai Motor Europe Technical Center GmbH
Liebherr-Components Deggendorf GmbH
Opel Automobile GmbH
RWTH Aachen University
Shell Global Solutions (Germany) GmbH
TU Bergakademie Freiberg
bse Engineering Leipzig GmbH
Umicore AG & Co. KG
Weissgerber engineering GmbH
The project that this report is based on is supported with funds from the Federal Ministry for Economic Affairs and Energy under Project Number 19I18006. The author is responsible for the content of this publication.