Evaluation of the energy consumption in different mobility scenarios to meet the goal of a 2000-watt society

Greenhouse gas emissions related to energy production is the main cause of climate change. Transportation accounts for 30% of the total energy consumption, and a reduction in the energy used for mobility is necessary. The 2000-watt society is an environmental concept that fixes a sustainable limit to the energy consumption in different sectors, including mobility. This paper evaluates the energy consumption in several mobility scenarios, and it assesses whether the goal suggested by the 2000-watt society is achievable. We investigate the social characteristics and mobility habits of the population living in a case study area. Then, we calculate the modal shift induced by transportation policies such as car-sharing, car-pooling and car-free district. We evaluate the resulting energy consumption, and we compare it with the 2000-watt society limit. We conclude that only a set of measures combining car usage reduction, increase in walking and cycling, and reduction in the total travel distance can achieve the needed energy reduction.

Needed reduction in mobility energy consumption to meet the goal of a 2000-watt society

Michel Bierlaire, Frédéric Rast, Riccardo Scarinci

Greenhouse gas emissions related to energy production is the main cause of climate change. Transportation accounts for 30% of the total energy consumption, and a reduction in the energy used for mobility is necessary. The 2000-watt society is an environmental concept that fixes a sustainable limit to the energy consumption in different sectors, including mobility. This paper evaluates the energy consumption in several mobility scenarios, and it assesses whether the goal suggested by the 2000-watt society is achievable. We investigate the social characteristics and travel habits of the population living in a case study area. Then, we calculate the modal shift induced by transportation policies such as car-sharing, car-pooling and car-free district. We evaluate the resulting energy consumption, and we compare it with the 2000-watt society limit. We conclude that only a set of measures combining car usage reduction, increase in walking and cycling, and reduction in the total travel distance can achieve the needed energy reduction.

Pergamon-Elsevier Science Ltd2017

Methodology for the identification of promising integrated biorefineries

Ayse Dilan Celebi

Steady increase in global energy consumption, greenhouse gas emissions, and depletion of fossil energy resources, together with increased attention towards sustainable development has prompted researchers to discover economical and environmentally competitive non-petroleum alternatives and biomass is considered to be one of the most promising renewable sources of energy and carbon of this matter to address the aforementioned issues within a biorefinery platform. A biorefinery is an integrated processing facility that converts biomass into transportation fuels, value-added chemicals, heat, and electricity via biochemical and thermochemical conversion routes. Integrated biorefineries are capable of mimicking petroleum refineries via application of advanced process synthesis methods including modeling, simulation, integration and optimization techniques. This thesis presents a comprehensive synthesis methodology for the integration of bioprocessing technologies in biorefineries by addressing techno-economic and environmental sustainability analysis. The proposed systematic design approach combines advanced process modeling approaches, process integration techniques, and multi-objective optimization algorithms to assess the performance of the overall system with respect to economic, environmental, and energetic indicators. The design strategy is applied based on different case studies. Results indicate that multi-product processes can yield significant cost and environmental benefits. Additionally, the integration of biochemical and catalytic processes with thermochemical conversion pathways results in increased carbon efficiency and economic and environmental competitiveness. Synergies between biorefineries and energy system are assessed by integrating industrial plants with a cogeneration system producing biofuels and process heat. In doing so, system efficiency is increased by coupling the proposed cogeneration system with carbon capture and sequestration (CCS) and power-to-gas technologies to store the renewable intermittent electricity in the form of biofuels. The results exhibit that through system expansion, integrated biorefinery systems allow us to imitate fossil refineries with a large spectrum of bio-based products. This further increases the resource efficiency while offering a promising solution to mitigate CO2 emissions and hence reaching the longer-term decarbonization target set by the Paris Agreement.

EPFL2019

Redox dual-flow battery for combined electricity storage and hydrogen production

Danick Reynard

The energy transition towards a carbon-neutral and sustainable economy is one of the greatest challenges of the 21st century to combat global warming and pollution. The decarbonization process is affecting every sector of the economy (electricity, transportation, industrialâŠ). For power generation, renewable energy resources are realistic alternatives to replace fossil resources such as gas and coal. However, the intermittent nature of wind and solar power limits their penetration into the conventional grid and increases the need for energy storage (battery, hydrogen storageâŠ) for smoothing out fluctuations between electric supply and demand. In this context, the concept of the redox dual-flow battery was introduced to propose a hybrid storage solution that can store electrical energy both electrochemically and in the form of hydrogen fuel. The system differs from a traditional redox flow battery by including a secondary energy platform, in which the electrolytes can be discharged chemically in external catalytic reactors through redox-mediated water electrolysis to produce clean hydrogen. The dual storage feature improves the flexibility and enhances significantly the capacity of the system by storing energy beyond the capacity of the electrolytes in the form of hydrogen. Additionally, the redox-mediated water electrolysis offers several advantages over conventional electrolysis in terms of safety, durability and purity. In this thesis, the proof-of-concept of a dual-flow circuit using a vanadium-manganese redox flow battery for combined electricity storage and hydrogen production is demonstrated. The redox flow battery employs vanadium sulfate (V3+/V2+) and manganese sulfate (Mn3+/Mn2+) dissolved in concentrated sulfuric aqueous solution as negative and positive electrolyte, respectively. The galvanic cell achieves energy efficiency of 68% at a current density of 50 mAÂ·cmâ2 (cell voltage =1.92 V) and a relative battery energy density 45% higher than the conventional all-vanadium RFB in the same conditions. Once charged, the electrolytes can be spontaneously discharged through redox-mediated oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in RuO2 and Mo2C catalytic reactors, resulting in an energy consumption for hydrogen production of ca. 50 kWh/kg H2. The system provides a competitive alternative for large-scale energy storage in renewable energy and transport applications.