Tailor-made fuels for the engines of tomorrow Great progress has been made over recent years in improving the efficiency of biofuel production, with scientists working on both optimising processes and improving fuel quality. Now the Fuel Science Center will be established to work towards the development of bio-hybrid fuels, as Dipl.-Ing. Bastian Lehrheuer explains. Many governments across the world are keen to harness the potential of waste material from plants and animals as a source of energy, part of the wider goal of reducing CO2 emissions. This is a central part of the agenda for researchers in Tailor-Made Fuels from Biomass (TMFB), a German Research Foundation (DFG) funded research Cluster of Excellence based at RWTH Aachen University in Germany. “We are targeting closed carbon cycles, so that we can help to reduce the impact of fuel and combustion on the climate and environment,” says Bastian Lehrheuer, Chief Operating Officer (COO) of the cluster. The wider goal is to efficiently produce fuels from biomass; Lehrheuer says it is important to consider the entire cycle in this respect. “CO2 is bound in biomass by nature. We don’t want to carelessly burn that biomass, we want to use that energy in the most efficient way,” he explains. “So we want to reduce CO2 and pollutant emissions on the production side as well as on the propulsion side.”
Well-to-wheel Researchers are looking at this from wellto-wheel, i.e. from the source of biomass,
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to the transport of the materials and further processing, right through to the eventual use of the fuel in a vehicle. The biomass itself has to be formed of waste material, so that it does not limit food production capacity or negatively affect it in any other way. “With the processes and methodologies that we are investigating, it is possible to use not only wood chips as feedstock for biofuel
Lehrheuer. “We want to develop, on a more fundamental basis, the methodologies necessary to evaluate the whole life cycle of bio-based fuels.” The fuel production process itself is highly complex, and many different factors need to be taken into account to build a more complete picture and identify where efficiency could be improved.
We develop methodologies to evaluate holistically the potential of new sustainable fuel candidates to reduce CO and pollutant emissions.
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production, but also waste from the forestry industry, or straw,” outlines Lehrheuer. The aim here is not to develop the perfect fuel, but rather to develop effective, reliable methodologies. “We develop methodologies to evaluate holistically the potential of new biofuel candidates to reduce CO2 and pollutant emissions. We are devising simulation models that help us to find the optimum fuel components, or combinations of those components,” continues
Some steps of the fuel production process may produce some heat for example, which could potentially be used elsewhere within the process. “We look at the energy flows, the energy demand, and the resulting CO2 and pollutant emissions. The target is to reduce those, and to ultimately produce climateneutral fuels,” explains Lehrheuer. A balance needs to be struck here between enhancing the quality of the fuel and optimising the production process; Lehrheuer is convinced
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that improved simulation methods will help lead to the development of more sustainable solutions. “We have successfully established a model-based fuel design process within TMFB and now have the chance to substantially improve and extend it within the scope of the upcoming Fuel Science Center,” he stresses. This enables researchers to identify which combinations of processes and molecules are most effective. The main bio-based alternative fuel currently used for gasoline engines is ethanol, but Lehrheuer says other options could be explored as well. “If we use some other components in a fuel, like butanol, then this actually could lead to advantages in terms of both production and combustion. On the production side, a lot of effort is required to get a very pure molecule, so we can improve efficiency if we target fuel mixtures from the very beginning. It is also helpful on the combustion side, as we can increase the octane number, thereby improving efficiency and reducing the particulate emissions,” he explains. The fuel design process has been developed to identify these kinds of benefits, so that fuels can be designed and tailored in an integrated way. “We tailor the fuel to achieve an overall optimum in production and propulsion. The primary motivation behind this work is to reduce CO2 and pollutant emissions,” outlines Lehrheuer. Researchers are also considering the way a fuel candidate performs in an engine. While gasoline and diesel engines are the most common combustion systems currently on the market, other systems are in development, all with different requirements, so identifying the parameters by which the effectiveness of a fuel can be assessed is a complex task. “It is not only about finding those parameters, it is also about how we measure them. How do we determine those parameters? What is the allowable range, and what boundary conditions do we have to consider?” Lehrheuer points out. In the case of diesel fuel, the most obvious parameter is the cetane number, an indicator for the ignition behaviour, while other important aspects include the density of a fuel or the entropy of evaporation. “How well does the fuel evaporate under in-cylinder conditions?” continues Lehrheuer.
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Another important consideration beyond a fuel’s performance in an engine is cost efficiency. A lot of attention is paid to developing biofuels that work efficiently in a combustion engine, yet it is also essential to consider their economic viability. “That is also a very interesting point, and it is incorporated in the model,” says Lehrheuer. This does not mean just looking at the overall cost of the eventual fuel, but also considering the by-products generated during production; Lehrheuer points to the example of ethanol again. “We have learned that sometimes by-products are more valuable than the product which is actually targeted. With ethanol, if we aim for 100 percent ethanol, we reduce the generation of by-products that can be very valuable, for example in the chemical sector,” he explains. “If we balance that efficiently, we can produce both ethanol and by-products. So we also have to consider such economic effects in our models.”
Fuel Science Center The DFG has recently approved funding for a further seven years of research that builds on the achievements of TMFB, and the new Fuel Science Center (FSC) will start in January 2019. “We are extending the work to include molecules derived from renewable energy sources,” outlines Lehrheuer. This involves combining the benefits of renewable energy and biomass to create what Lehrheuer and his colleagues call bio-hybrid fuels. “Biomass is a long-chain carbon source, and we combine those molecules with those from E-fuels to form new fuel candidates,” he says. “The FSC will officially start working in January, focusing on this combination. It will build on our ten years of experience with TMFB, and in particular on our model-based fuel design processes.” The flexibility of the production and the propulsion system is an important aspect of this research. It may be that in one season a high amount of biomass is available but a low amount of renewable energy, so a certain degree of flexibility is essential. Using resources more efficiently is central to developing sustainable fuel solutions, a topic that will be at the core of the FSC’s research. “We are doing fundamental research, and developing an entire methodology,” stresses Lehrheuer.
Tailor-Made Fuels from Biomass Cluster of Excellence EXC 236 Project Objectives
• TMFB was established in 2007 with the scientific objective of optimizing the entire process chain from biomass to vehicle propulsion. Using an interdisciplinary approach to perform research on new synthetic fuels obtained from biomass feedstock via targetdesigned production routes, TMFB explores efficient and clean future combustion systems. • Vision of the Cluster: Establish innovative and sustainable processes for the conversion of whole plants into fuels which are tailormade for novel low-temperature combustion engine processes with high efficiency and low pollutant emissions, paving the way to new generations of biomass fuels. • Continuing to pursue its long-term vision, the CoE “Tailor-Made Fuels from Biomass” aims to achieve the model-based description and optimization of the entire process chain from biomass to propulsion in the second funding period.
Project Funding
Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany´s Excellence Strategy – EXC 236. http://www.dfg.de/en/index.jsp
Project Partners
Host University: RWTH Aachen University Participating non-university research institutions: • Max-Planck-Institut für Kohlenforschung Mühlheim • Forschungszentrum Jülich • Max-Planck-Institute for Chemical Energy Conversion
Contact Details
Dipl.-Ing. Bastian Lehrheuer Institute for Combustion Engines VKA RWTH Aachen University Fuel Design Center Schinkelstraße 8 52062 Aachen, Germany T: +49 241 80 95352 E: lehrheuer@vka.rwth-aachen.de W: www.vka.rwth-aachen.de / www. fuelcenter.rwth-aachen.de
Dipl.-Ing. Bastian Lehrheuer
Dipl.-Ing. Bastian Lehrheuer (m) studied Mechanical Engineering at RWTH Aachen University. In 2012 he started his academic career at the Institute for Combustion Engines. He was working for numerous research projects for gasoline combustion system development. In July 2018, he took over the responsibility as Chief Operating Officer (COO) of the Cluster of Excellence TMFB.
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