Talks

Battery Section

Recently, the amount of research and number of papers devoted to the development of active materials for Na-ion batteries has increased exponentially, leading the community to consider the commercialization of Na-ion batteries in the near future. To achieve commercialization, suitable anodes and cathodes must be developed and studied in depth as the Na-system is often not analogous to the Li-system. After establishing a careful guideline to optimize the electrode engineering and the electrolyte formulation both of which strongly influence electrochemical cycling performance, we developed new materials (negative and positive electrodes) for cheap Na-ion batteries. For the former, the most common binder used in Li-ion batteries, polyvinylidene difluoride, was found to be unsuitable for Naion batteries due to it decomposing to form NaF. Additionally, a systematic investigation of particle size, binder and conductive additive ultimately led to an optimized electrode composition consisting of 70wt% micron-sized active material, 18wt% carbon black and 12wt% sodium carboxymethyl cellulose (Na-CMC) binder.
For the latter, we have developed a new research direction to drastically reduce the cost of the Na-ion batteries by making carbonaceous materials (negative electrodes) based on bio-wastes and by developing new cathode materials based on the 20th more abundant elements in Earth crust.
Along this talk, we will review the synthesis procedure, the characterization of those novel materials and finally reveal their electrochemical performances in half-cell Na-ion batteries but also in full-cell configuration.

Thermal Energy Section

In this presentation, I will describe some of the approaches for high-temperature heat storage systems which we research and develop in the framework of the SCCER. These include storage design, modeling, implementation, optimization and testing of combined sensible and latent heat storage approaches, development of advanced latent heat storage units, and dedicated material system investigations and testing under harsh conditions in order to shed light on the long-term performance and degradation.

Hydrogen Section

Grid to Mobility


Hubert Girault (EPFL, Lausanne)

Electric vehicles (EVs) are about to become the vehicle of choice for many drivers. Fuel cell vehicles (FCEVs) will be attractive mainly for professional users, e.g. taxis, ambulances, delivery vans, etc… The key question is: how to adapt the infrastructure to meet these new challenges? In this talk, we shall present an experimental service station for EVs and FCEVs. First, we shall discuss the use of megabatteries to fulfil the need of fast DC-DC charging. At EPFL Martigny, we have chosen a vanadium redox flow battery (200kW-400kWh) as a storage medium. This battery can be used to charge EVs at a power ranging from 50 to 80 kW. The charging time should be about 30 minutes. To fill FCEVs, we have used a 50 kW alkaline electrolyser producing about 1 kg of hydrogen per hour. This hydrogen is first stored in cylinders at 200 bars, about 1 kg/cylinder. A compression station bring H2 first to 500 bars in reservoirs holding about 3 kg to charge cars operating at 350 bars, e.g. Renault Kangoo with a a range extender from Swiss Hydrogen, and then further pressurised to 900 bars in reservoirs holding 12 kg to charge cars operating at 700 bars, e.g.. Hyundai ix35. The charging of cars takes place simply to equilibrating the pressure between the reservoirs and the car. The charging time is about 3 minutes. The goal is this demonstrator is to evaluate the performance of a service station for EVs and FCEVs

Synthetic Fuel Section

The increase of CO2, a greenhouse gas, in the atmosphere is mostly anthropogenic and related to our use of fossil fuels. Finding efficient processes to convert CO2 to fuels and chemicals would lead to a tremendous advance towards a more sustainable world, as proposed for instance in the methanol economy. It is well-know that is a large amount of excess and/or intermittent energy is not properly used in Europe. Here, we will discuss the effort of Hae towards the conversion of CO2 to fuels and chemicals via homogeneous, heterogenous and electrochemical processes. We will show the most recent advances and the direction of Hae into incorporating CO2 into the value chain, by the use of the excess intermittent energy.
 

Technology Assessment Section

Energy storage can provide valuable flexibility to power systems and help with the integration of large shares of variable and uncertain renewable generation. However investment costs remain high for storage technologies. In addition, there are many competing, often lower cost sources of flexibility. EASAC’s (European Academies Science Advisory Council) soon to be published report “Valuing Dedicated Storage in Electricity Grids” considers the scope for the expansion of energy storage in electricity grids. The current status of electricity storage technologies is reviewed, as well as the potential impact of recent and expected developments in storage technologies. The talk includes an overview of existing and potential applications of energy storage within the power system. Modelling methodologies, including gaps and priorities for further research, and findings from a selection of modelling assessments are also presented.
In 2013 the German government together with the KfW banking group has set up a funding scheme for PV-homestorage systems. The program was prolonged in early 2016. Besides the funding scheme an academic project was funded to monitor the development and to supervise the set quality standards.1 The presentation will be composed of the market monitoring as well as of the lessons learned from the detailed measurements in the field. The performed measurements were done over one year and can be utilized to evaluate the influence of PV-homestorage systems on the distribution grid. Furthermore, the possibility to serve the grid besides lowering the power peak will be elaborated.
This presentation is an analysis of the operating experiences during the first year of running the PtG plant. The talk is divided into a technical and an economic section. The technical evaluation contains the calculation of the efficiency of the PtG plant based on the total power consumption, as well as the energy conversion factor of several months. The economic section evaluates the different options of electricity procurement for the PtG plant. The three options, electricity purchase at the European power exchange, excess electricity from a direct marketing company, and participating in the control reserve market have been analyzed. It has been shown that economic feasibility can mainly be improved through participation in the secondary control reserve market. Another important economic aspect is selling the hydrogen as a cost premium product compared to conventional produced hydrogen. A potential for hydrogen with a cost premium is expected for example from the mobility sector or from injecting the hydrogen into the gas grid and using it as "windgas".
Concerns about climate change, development of new technologies and many other factors are contributing to major changes in the energy system. Renewable energy sources, particularly variable renewables, are an increasingly large and growing part of the energy mix. Other important changes in the energy system include the advent of new technologies such as ‘power-to-gas’ and ‘vehicle-to-grid’, which create links between energy sectors hitherto considered and managed separately. The deployment of these new technologies affects supply and demand profiles, changes the balance of the energy system, and can also shift loads between energy vectors. Energy storage has the potential to help address these changes and smooth the transition, to contribute to balancing mismatches between supply and demand, and to support the deployment of renewables. The overarching objectives of this study are to identify policy-relevant issues relating to renewables and storage that could affect the transition to a largely renewable energy system, and to identify the types of policy interventions that could optimise the role of storage in this transition. The issues involved in the energy system transition are complex and multi-dimensional and accompanied by much uncertainty. Energy related regulations, market structures, policies and infrastructure vary dramatically from country to country and even locally within countries. The direction and path of the system transition is still unclear. What is clear is that evolution is towards an ever more interconnected and interdependent system.
We present a harmonized methodology for the evaluation of energy storage technologies, integrating techno-economic analysis and environmental assessment using Life Cycle Assessment (LCA), applied for two case studies in Switzerland: assessment (a) of various electricity storage technologies for different time scales; and (b) of different power-to-gas (P2G) systems. The first study (a) shows that at short time scales (0.01 h), batteries have an advantage in terms of levelised cost, whereas for greenhouse gas emissions pumped hydro storage (PHS) is also competitive. For the medium time scale (4.5h), PHS, compressed air energy storage (CAES) and battery storage technologies are at a comparable level both in terms of cost and global warming potential. In the case of long-term (seasonal) storage, power-to-gas-to-power is found to have lower costs than the other technologies, but higher greenhouse gas emissions due to the relatively low efficiency of the complete process chain.