Publications

Current railway track work machinery is mainly operated with diesel fuel. As a result track maintenance of Austrian Federal Railways (OeBB) amounts to nearly 9000 t CO2 equivalent per year according to calculations from Graz University of Technology. OeBB’s total length of railway lines only accounts for 0.56% of the world’s length of lines. This indicates huge potential for mitigating greenhouse gas emissions considering the need for track maintenance worldwide. Environmental concerns have led to the introduction of alternative drives in the transport sector. Until now R&D (Research & Development) of alternative propulsion technologies for track work machinery has been widely neglected. This paper examines the possibility of achieving zero direct emissions during maintenance and construction work in railways by switching to alternative drives. The goal is to analyze alternative propulsion solutions arising from the transport sector and to assess their applicability to track work machinery. Research results together with a calculation tool show that available battery technology is recommendable for energy demands lower than 300 kWh per construction shift. Hydrogen fuel cell technology is an alternative for energy demands higher than 800 kWh. For machinery with energy requirements in between enhancements in battery technology are necessary and desirable for the coming years.

The effects of climate change and global warming are arising a new awareness on the impact of our daily life. Power generation for transportation and mobility as well as in industry is the main responsible for the greenhouse gas emissions. Indeed currently 80% of the energy is still produced by combustion of fossil fuels; thus great efforts need to be spent to make combustion greener and safer than in the past. For this reason a review of the most recent gas turbines combustion strategy with a focus on fuels combustion techniques and burners is presented here. A new generation of fuels for gas turbines are currently under investigation by the academic community with a specific concern about production and storage. Among them biofuels represent a trustworthy and valuable solution in the next decades during the transition to zero carbon fuels (e.g. hydrogen and ammonia). Promising combustion techniques explored in the past and then abandoned due to their technological complexity are now receiving renewed attention (e.g. MILD PVC) thanks to their effectiveness in improving the efficiency and reducing emissions of standard gas turbine cycles. Finally many advances are illustrated in terms of new burners developed for both aviation and power generation. This overview points out promising solutions for the next generation combustion and opens the way to a fast transition toward zero emissions power generation.

The ability to remotely monitor hydrogen and map its concentration is a pressing challenge in large scale production and distribution as well as other sectors such as nuclear storage. We present a photonicsbased approach for the stand-off sensing and mapping of hydrogen concentration capable of detecting and locating <0.1% concentrations at 100m distance. The technique identifies the wavelength of light resulting from interaction with laser pulses via Raman scattering and can identify a range of other gas species e.g. hydrocarbons ammonia by the spectroscopic analysis of the wavelengths present in the return signal. LIDAR Light Detection and Ranging – analogous to Radar is used for ranging. Laserbased techniques for the stand-off detection of hydrocarbons frequently employ absorption of light at specific wavelengths which are characteristic of the gas species. Unfortunately Hydrogen does not exhibit strong absorption however it does exhibit strong Raman scattering when excited in the UV wavelength range. Raman scattering is a comparatively weak effect. However the use of solid-state detectors capable of detecting single photons known as SPADS (Single Photon Avalanche Photodiode) enables the detection of low concentrations at range while making use of precise time-of-flight range location correlation. The initial safety case which necessitated our development of stand-off hydrogen sensing was the condition monitoring of stored nuclear waste supported and funded by Sellafield and the National Nuclear Laboratory in the UK. A deployable version of the device has been developed and hydrogen characterisation has been carried out in an active nuclear store. Prior to deployment a full ignition risk assessment was carried out. To the best of our knowledge this technique is the strongest candidate for the remote stand-off sensing of hydrogen.

The rise in intermittent renewable electricity production presents a global requirement for energy storage. Biological hydrogen methanation (BHM) facilitates wind and solar energy through the storage of otherwise curtailed or constrained electricity in the form of the gaseous energy vector biomethane. Biological methanation in the circular economy involves the reaction of hydrogen – produced during electrolysis – with carbon dioxide in biogas to produce methane (4H2 + CO2 = CH4 + 2H2) typically increasing the methane output of the biogas system by 70%. In this paper several BHM systems were researched and a compilation of such systems was synthesized facilitating comparison of key parameters such as methane evolution rate (MER) and retention time. Increased retention times were suggested to be related to less efficient systems with long travel paths for gases through reactors. A significant lack of information on gas-liquid transfer co-efficient was identified

A 100% renewable energy-based stand-alone microgrid system can be developed by robust energy storage systems to stabilize the variable and intermittent renewable energy resources. Hydrogen as an energy carrier and energy storage medium has gained enormous interest globally in recent years. Its use in stand-alone or off-grid microgrids for both the urban and rural communities has commenced recently in some locations. Therefore this research evaluates the techno-economic feasibility of renewable energy-based systems using hydrogen as energy storage for a stand-alone/off-grid microgrid. Three case scenarios in a microgrid environment were identified and investigated in order to select an optimum solution for a remote community by considering the energy balance and techno-economic optimization. The “HOMER Pro” energy modelling and simulating software was used to compare the energy balance economics and environmental impact amongst the proposed scenarios. The simulation results showed that the hydrogen-battery hybrid energy storage system is the most cost-effective scenario though all developed scenarios are technically possible and economically comparable in the long run while each has different merits and challenges. It has been shown that the proposed hybrid energy systems have significant potentialities in electrifying remote communities with low energy generation costs as well as a contribution to the reduction of their carbon footprint and to ameliorating the energy crisis to achieve a sustainable future.

This paper is based on a position paper of the German Industry Association Concentrated Solar Power e.V. to the German government and discusses options on how to decarbonize the heat demand of the domestic industry. Among other option concentration solar collectors are a suitable option in Germany which has not been expected by many experts. The paper derives requirements that are needed to ensure a quick and sustainable way to decarbonize industrial heat demand. They are considered to also be relevant for many other countries that follow the same ambition to become climate neutral in the next decades. They major statements are: A mix of different renewable energy technologies in conjunction with efficiency measures is needed to ensure a secure climate-friendly and cost-efficient heat supply for the industry; The different technology options for the provision of heat from renewable sources through electrification and through hydrogen can and must be combined and integrated with each other. In this context concentrating solar thermal represents an important part of the hybrid supply portfolio of a decarbonized industry This requires: The definition of an expansion target for process heat and the flanking measures; Ensuring the equivalence of renewable heat renewable electricity and green hydrogen - also as hybrid solutions; The promotion of concentrating solar thermal reference projects as an impetus for market ramp-up in Germany; The launch of an information campaign for heat consumers and the establishment of a pool of consultants.

This article aims to present the potential of energy transition in insular systems for social and economic transition and development when planned and implemented appropriately with the active involvement of local communities. To this end the example of Sifnos Energy Community is examined and presented as a pilot case. It proves that energy transition apart from its obvious energy conservation and climate necessity can provide a strong contribution to the development of remote areas and the remedying of crucial issues especially in insular communities such as unemployment low standards of living isolation and energy supply security. Energy transition on Sifnos has been undertaken by the Sifnos Energy Community (SEC) with the target to achieve 100% energy independency through effective and rational projects. The major project is a centralized hybrid power plant consisting of a wind park and a pumped hydro storage system. It was designed to fully cover the current electricity demand and the anticipated forthcoming load due to the overall transition to e-mobility for the transportation sector on the island. Through the exploitation of the excess electricity production with the production of potable water and hydrogen energy transition can facilitate the development of new professional activities on the island and reduce the local economy’s dependence on tourism. Additionally a daily link to the neighboring larger Cyclades islands can be established with a hydrogen powered-passenger vessel ensuring the secure and cheap overseas transportation connection of Sifnos throughout the whole year. The overall energy transition process is executed with the active involvement of the Sifnos citizens ensuring wide public acceptance and the minimization of the projects’ impacts on the natural and human environment. At the same time the anticipated benefits for the insular communities are maximized highlighting the energy transition process on Sifnos as a new sustainable development pattern. For all this effort and the already achieved results Sifnos has been declared as one of the six pilot islands of the European Community’s initiative “Clean Energy for EU Islands”.

The achievement of a carbon-free emissions economy is one of the main goals to reduce climate change and its negative effects. Scientists and technological improvements have followed this trend improving efficiency and reducing carbon and other compounds that foment climate change. Since the main contributor of these emissions is transportation detaching this sector from fossil fuels is a necessary step towards an environmentally friendly future. Therefore an evaluation of alternative fuels will be needed to find a suitable replacement for traditional fossil-based fuels. In this scenario hydrogen appears as a possible solution. However the existence of the drawbacks associated with the application of H2 -ICE redirects the solution to dual-fuel strategies which consist of mixing different fuels to reduce negative aspects of their separate use while enhancing the benefits. In this work a new combustion modelling approach based on machine learning (ML) modeling is proposed for predicting the burning rate of different mixtures of methane (CH4 ) and hydrogen (H2). Laminar flame speed calculations have been performed to train the ML model finding a faster way to obtain good results in comparison with actual models applied to SI engines in the virtual engine model framework.

Public acceptability of low-carbon energy projects is often measured with one-off polls. This implies that opinion-shifts over time are not always taken into consideration by decision makers relying on these polls. Observations have given the impression that public acceptability of energy projects increases after implementation. However this positive shift over time has not yet been systematically studied and is not yet understood very well. This paper aims to fill this gap. Based on two psychological mechanisms loss aversion and cognitive dissonance reduction we hypothesize that specifically people who live in proximity of a risky low-carbon technology—a hydrogen fuel station (HFS) in this case—evaluate this technology as more positive after its implementation than before. We conducted a survey among Dutch citizen living nearby a HFS and indeed found a positive shift in the overall evaluation of HFS after implementation. We also found that the benefits weighed stronger and the risks weaker after the implementation. This shift did not occur for citizens living further away from the HFS. The perceived risks and benefits did not significantly change after implementation neither for citizens living in proximity nor for citizens living further away. The societal implications of the findings are discussed.

This paper reports on an experimental evaluation of the hydrogen separation performance in a proton exchange membrane system with Pt-Co/C as the anode electrocatalyst. The recovery of hydrogen from H2/CO2 H2/CH4 and H2/NH3 gas mixtures were determined in the temperature range of 100–160 ◦C. The effects of both the impurity concentration and cell temperature on the separation performance of the cell and membrane were further examined. The electrochemical properties and performance of the cell were determined by means of polarization curves limiting current density open-circuit voltage hydrogen permeability hydrogen selectivity hydrogen purity and cell efficiencies (current voltage and power efficiencies) as performance parameters. High purity hydrogen (>99.9%) was obtained from a low purity feed (20% H2 ) after hydrogen was separated from H2/CH4 mixtures. Hydrogen purities of 98–99.5% and 96–99.5% were achieved for 10% and 50% CO2 in the feed respectively. Moreover the use of proton exchange membranes for electrochemical hydrogen separation was unsuccessful in separating hydrogen-rich streams containing NH3 ; the membrane underwent irreversible damage.