Primary energy | EPFL Graph Search

Primary energy (PE) is the energy found in nature that has not been subjected to any human engineered conversion process. It encompasses energy contained in raw fuels and other forms of energy, including waste, received as input to a system. Primary energy can be non-renewable or renewable. Primary energy is used in energy statistics in the compilation of energy balances, as well as in the field of energetics. In energetics, a primary energy source (PES) refers to the energy forms required by the energy sector to generate the supply of energy carriers used by human society. Total primary energy supply (TPES) is the sum of production and imports, plus or minus stock changes, minus exports and international bunker storage. The International Recommendations for Energy Statistics (IRES) prefers total energy supply (TES) to refer to this indicator. These expressions are often used to describe the total energy supply of a national territory. Secondary energy is a carrier of energy, such a

The Optimized Integration of Biomass Fuel in the District Heating System in Poznan, Poland: Part 2

Energy demand continuously increases what contributes to higher emissions of GHG. Moreover, the primary energy sources like coal, natural gas and oil are depleting. To manage this problem, the scientists have worked on the different possibilities of renewable energy conversion technologies in order to get the most useful and cleanest type of energy. In this work, there are investigated possible biomass conversion technologies in order to satisfy energy demand for Poznan, the city in Poland. Actually, the energy demand is met by coal combined with heat and power plant (CHP). There is an interest of changing actual coal CHP plant with biomass to minimize emissions. The aim of this work is to choose the best thermo-chemical biomass conversion option in the concept of minimum investment cost. To achieve this goal, the thermo-economic analysis and optimization of different biomass conversion technologies have to be conducted. First, on the basis of the literature review, the models of biomass conversion processes are modeled in Belsim Vali software. Then, from 2008, two different scenarios of energy demand are defined for the city. In the next step of this work, there is conducted energy integration in order to find an optimal set of designed boundary conditions through maximizing the units of performance for the most promising types of biomass conversion processes. Finally, an optimal configurations and sizes of the equipments are found by thermo- economic optimization.

2011

Technical and architectural energy strategies for the smart living lab, a sustainable building with reliable environmental objectives

Stefano Cozza

Currently, energy efficiency in buildings is a primary objective of energy policy at regional, national and international levels. On a local scale, this trend has been detected also in Switzerland, where almost 40% of energy consumption has been assumed to be used for heating, ventilation and lighting in buildings. The smart living lab project is born under this scenario, aiming to be a building icon and a sustainability example. Via reducing environmental impacts and its footprint on the local ecosystem, the project intends to reach certain authoritative objectives, like the ones given by the 2000 Watt-Society. The smart living lab is a research centre on future built environment in Fribourg, Switzerland. It accommodates interdisciplinary and inter-institutional research groups and provides infrastructures for experiment on developing innovative concepts and technologies related to inhabitation and work environment. The purpose of this thesis is to identify the main technical and architectural macroparameters and their contribution to energy consumption. The latter in the smart living building is calculated in the aspects of both quantity [kWh/m2] and quality [kg CO2/kWh]. Global sensitivity analysis (SA) was selected as the method to demonstrate the contribution of certain key design parameters to the building energy consumption and their correlations along with the changes of variables. Several energy simulations have been conducted with the variation of each design parameter independently. Finally, due to the elaborated cases, the SA was completed with the identification of the predominant factors on the main energy outputs e.g. primary energy.

2015

Electrochemical systems for hydrogen fuel cell and battery electric vehicle infrastructure

Yorick Ligen

Thermodynamics and heat engines are the core disciplines which enabled the development of the thermo-industrial society during the 20th century. Liquid hydrocarbon fuels are one of the easiest and most convenient solutions offered by the thermophysical constraints of our world. However, an alternative to these dense energy carriers is required to enable a transition to a low carbon transport sector. Climate change mitigation, local air pollution reduction and energy independency are some of the key advantages that hydrogen fuel cell and battery electric vehicles can bring in this context. Beyond a shift from fossil fuels, the entire value chain, from primary energy to powertrains must be reconsidered, redesigned and redeployed to include renewable energies, robust powergrids, charging stations and electric powertrains. The prominent role of the infrastructure in terms of energy efficiency is demonstrated in chapter 2, introducing a grid to mobility segmentation for life cycle studies. In addition, the shortcomings of local and off-grid solutions are highlighted in the same chapter. Nevertheless, the grid integration also requires innovative solutions to comply with the physical constraints of current networks. In particular, the role and the sizing of stationary buffer batteries is detailled in chapter 3. The stochastic nature of charging events is used to develop a battery sizing algorithm including grid tie constraints. This research was intrinsically motivated by the perspective of infrastructure operators. A full scale demonstrator is at the core of the scientific questioning of this thesis. The design, the construction and the operation of a grid to mobility demonstrator is reported in chapter 4. Including a 200 kW / 400 kWh Vanadium redox flow battery, a 50 kW alkaline electrolyser, and a hydrogen refueling station, this demonstrator enabled a better understanding and characterization of process engineering, of control and programming and of electrochemical phenomenons. In particular, the data analysis on the electrolysis side and purification solutions are reported in chapter 5. Finally, the intrinsic characteristics of air driven gas boosters, a robust small scale compression solution, are analyzed in chapter 6 and the challenges for a full scale hydrogen mobility are discussed with an economic and logistics perspective.

EPFL2020

Electrochemical systems for hydrogen fuel cell and battery electric vehicle infrastructure

Yorick Ligen

EPFL2020