The Future Fuels project combines research in several institutes of the German Aerospace Center (DLR) on the production and use of synthetic fuels for space, energy, transportation, and aviation. This article gives an overview of the research questions considered and results achieved so far and also provides insight into the multidimensional and interdisciplinary project approach. Various methods and models were used which are embedded in the research context and based on established approaches. The prospects for large-scale fuel production using renewable electricity and solar radiation played a key role in the project. Empirical and model-based investigations of the technological and cost-related aspects were supplemented by modelling of the integration into a future electricity system. The composition, properties, and the related performance and emissions of synthetic fuels play an important role both for potential oxygenated drop-in fuels in road transport and for the design and certification of alternative aviation fuels. In addition, possible green synthetic fuels as an alternative to highly toxic hydrazine were investigated with different tools and experiments using combustion chambers. The results provide new answers to many research questions. The experiences with the interdisciplinary approach of Future Fuels are relevant for the further development of research topics and co-operations in this field.Synthetic fuels based on renewable energies (RE) are widely seen as a key element to achieving climate-neutral transport (e.g., [1,2]). As liquid hydrocarbons have a high energy and power density, they are primarily discussed as fuels for (heavy) road vehicles, ships, and aircraft. Due to their low storage and transport losses, they are also conceivable as a complementary long-term electricity storage option [3]. The challenges of producing and implementing these fuels are manifold. Chemical processes and renewable electrical or thermal energy can be used to produce liquid hydrocarbons from various carbon sources and hydrogen (and sometimes oxygen). Synthetic fuels have several advantages: they can be easily integrated into our existing energy and mobility infrastructures, can be used in all areas of the transport sector, and they can be optimized with regard to their chemical properties. The main disadvantages are the high energy losses and production costs.In this research context, eleven research groups at the German Aerospace Center (DLR) are working together on the Future Fuels project on synthetic fuels. The aim of the interdisciplinary approach is to realize synergies and joint research activities, as well as new research impulses through different perspectives. The scientists and engineers are investigating how synthetic fuels can be produced using solar energy and electrolysis processes (Solar Fuels), and are developing concepts for the re-conversion of these fuels into electricity. They are working on emission-optimized fuels for transport and aviation (Designer Fuels), as well as advanced space ap...
Plug-in hybrid electric vehicles (PHEVs) show a high pollutant emission variability that strongly depends on the operating conditions of the internal combustion engine. Additionally, studies indicate that driving situations outside of the real driving emissions boundary conditions can lead to substantial pollutant emission increases. The objective of this study is to measure and analyze the particulate number (PN) and nitrogen oxides (NOx) emissions of a Euro 6 PHEV for a selected real-world driving test route in the Stuttgart metropolitan area. For this purpose, the vehicle is set out with multiple measurement devices to monitor vehicle internal and external parameters. Particle distribution results show an overall uniform pattern, which allows a comparative analysis of the different test scenarios on the basis of the PN concentration. While the trip-average PN emissions are in good agreement, transient effects during highway driving can substantially increase emissions, whereas the fuel consumption does not necessarily increase in such situations. PN measurements including ultrafine particles (UFP) show a significant increase in urban emissions due to higher cold start emission peaks. Additionally, low ambient temperatures raise the uncertainty of NOx and PN cold start emissions. With regard to future emission regulations, which claim that vehicles need to be as clean as possible in all driving situations, PHEV emission investigations for further situations outside of the current legislations are required.
<p>The transport sector accounts for about one quarter of worldwide anthropogenic carbon dioxide emissions. Since a robust growth in transport activity is expected over the coming decades, reducing associated emissions to mitigate human-caused climate change is a particular challenge. In order to achieve high-quality comparative monitoring, to develop scenarios for future emissions, and to enable a robust assessment of climate protection measures, the allocation of emissions to the subsector level is a necessary prerequisite. The DLR project ELK &#8211; EmissionsLandKarte (en.: emission map) contributes here in several respects: (1) requirements are specified in an application-based manner, i.e. compatibility with existing inventories, such as the ones generated for IPCC, is ensured and insufficiencies in spatial resolution and methodological detail are addressed, (2) an input database congruent with both statistical data and SSP scenarios is provided, and (3) bottom-up calculations are performed that allow attribution of climate impacts to specific transport services, as well as prospective analyses where, for example, activity levels change or alternative fuels affect regional emission factors. The resulting prototype global gas and particle emission inventories for land transport, aviation and shipping reflect the status quo as of 2019.</p><p>For land transport, fine-grained activity and vehicle fleet data as well as technology-specific emission factors are applied. This allows emissions from passenger and freight transport to be disaggregated by mode and vehicle type. New approaches for spatial disaggregation of emissions will increase transparency of the methodology. For aviation, calculations are based on fleet composition and transport performance for both passenger and cargo traffic at the airport pair level, while real flight tracks serve as the foundation for spatial allocation. For both transport sectors, complementary analyses are performed to characterize particulate emissions in order to fill gaps in data availability. For shipping, transport performance on inland waterways and maritime routes are considered, including technical data describing propulsion and bunkering. Finally, all mode-specific results are subjected to an innovative uncertainty assessment aligned with the needs of other emission inventory creators through a detailed evaluation per uncertainty factor, as well as aggregated values for climate modelers and practitioners. The consistent assessment of uncertainty factors along the entire calculation chain, such as activity levels, emission factors, and proxy data used for spatial or temporal disaggregation, promotes comparability across all transport sectors. In this paper, we outline the new methodological approaches for mapping transport emissions and present first results.</p>
This study presents the carbon dioxide (CO2), particulate matter (PM2.5) and nitrogen oxides (NOx) tailpipe emission analysis of passenger cars in 9 different world regions up to 2050 based on a bottom-up calculation method. A diffusion model which considers current policy electrification targets is used to analyze market entry and development of different drivetrain/fuel technologies in the respective vehicle stocks of each world region. Drivetrain- and country-specific emission factors are weighted according to the modelled stock compositions. The obtained stock-fleet-average emission factors are multiplied with the transport demand in order to obtain total passenger car emissions which are then spatially distributed using proxy raster emission data. The results of this study reveal that global passenger car CO2, NOx and PM2.5 emissions decrease from 2015 until 2050 by approx. 45%, 63% and 54%, respectively. The market analysis indicates that gasoline will continue to be a significant energy carrier in 2050 with a stock share of approx. 25%; however, electric vehicles will take the lead, especially after 2040. Furthermore, China and Europe stay as advancing markets for passenger car fleet electrification, while the majority of developing countries follow up with low shares. It can be obtained that even if the passenger car fleets become cleaner, an increase of the transport demand can dampen or even nullify the total emission reduction effect. As a conclusion, the bottom-up approach enables to quantify passenger car emissions in a transparent way. However, challenges exist regarding the uncertainty caused by lacking data availability.
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