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Download Free Pdfs on Solar, Wind, and Hydro Energy Fundamentals

Undergraduate and first year graduate engineering and physics students taking courses on renewable energy topics; engineers, scientists, investors and technicians working in energy-related disciplines

Fundamentals Of Renewable Energy Processes Pdf Free Download


Studies and surveys require significant lead time, and hearings followed by permit issuance and statutory appeals processes can be lengthy and expensive. Early and active engagement with the local community and permitting authorities will not only build regional support, but will also make your project more attractive to corporate offtakers who are increasingly scrutinizing how developers work with local communities. Best practices include using local workforces, implementing organizational diversity measures, going above and beyond with project siting to ensure minimal wildlife impact, and ensuring supply chains are free from human rights violations. Such efforts will help build positive local relationships, will make a project more attractive to potential buyers, and above all, creates many positive impacts beyond the carbon-free electricity a project brings online.

NEW TO THIS EDITION: -All new chapter on pivotal renewable energy storage technologies -Now includes discussion of power grid and transmission issues -Expanded coverage of Hydropower and advances in PV cells -New and improved figures and additional end-of-chapter problems

Abstract:Alkaline water electrolysis is a key technology for large-scale hydrogen production powered by renewable energy. As conventional electrolyzers are designed for operation at fixed process conditions, the implementation of fluctuating and highly intermittent renewable energy is challenging. This contribution shows the recent state of system descriptions for alkaline water electrolysis and renewable energies, such as solar and wind power. Each component of a hydrogen energy system needs to be optimized to increase the operation time and system efficiency. Only in this way can hydrogen produced by electrolysis processes be competitive with the conventional path based on fossil energy sources. Conventional alkaline water electrolyzers show a limited part-load range due to an increased gas impurity at low power availability. As explosive mixtures of hydrogen and oxygen must be prevented, a safety shutdown is performed when reaching specific gas contamination. Furthermore, the cell voltage should be optimized to maintain a high efficiency. While photovoltaic panels can be directly coupled to alkaline water electrolyzers, wind turbines require suitable converters with additional losses. By combining alkaline water electrolysis with hydrogen storage tanks and fuel cells, power grid stabilization can be performed. As a consequence, the conventional spinning reserve can be reduced, which additionally lowers the carbon dioxide emissions.Keywords: alkaline water electrolysis; hydrogen; renewable energy; sustainable; dynamic; fluctuations; wind; solar; photovoltaic; limitations

This article presents some crucial findings of the joint research project entitled Storage of electric energy from renewable sources in the natural gas grid-water electrolysis and synthesis of gas components. The project was funded by BMBF and aimed at developing viable concepts for the storage of excess electrical energy from wind and solar power plants. The concept presented in this article suggests the conversion of CO2-containing gases into methane in a pressurized reactor using hydrogen produced via electrolysis. The produced gas can be upgraded to synthetic natural gas (SNG) and fed into the well-developed German natural gas grid. This concept benefits from the high storage capacity of the German gas grid and does not require any extensions of the current gas or power grid. The reaction heat released by the exothermic methanation reaction leads to a temperature rise of the gas in the fixed bed catalyst of the reactor. The conversion of carbon dioxide is limited in accordance to the chemical equilibrium which depends strongly on temperature and pressure. For maximum carbon dioxide conversion, it is convenient to split the methanation into several stages adding cooling sections in between. This article focuses on the methanation process and its transfer onto an industrial scale evaluating the different plant capacities and feedstock mixtures used. The methanation takes place in a staged fixed bed reactor. This staged reactor concept is an in-house development based on know-how from the sulfuric acid production technology.

Huge efforts are currently being made to replace the conventional energy sources such as nuclear power or fossil fuels by renewable energy sources such as wind or solar energy. However, most of the renewable energy sources cannot provide base load electric power due to their intermittent nature (e.g., wind energy). To overcome this problem, storage systems have to be integrated in the power grid.

A comparison of the described storage technologies with regard to their storage capacity and their characteristic charge/discharge times is shown in Figure 1[1]. A crucial requirement for storage technologies in the context of the present article (storage of energy from renewable resources) is an elevated storage capacity combined with high charge/discharge periods. Only chemical secondary energy carriers such as hydrogen and carbon-based fuels (SNG) fulfill this requirement. Storage technologies such as flywheels and batteries, on the other hand, are strongly limited regarding their capacity and charge duration. Therefore, these technologies are only used for compensating short-term fluctuations by supplying electric energy over a time period of several minutes up to several hours.

The conversion of electrical energy into hydrogen causes efficiency losses of about 20% due to the internal cell resistance which will be realized as heat losses. The subsequent transformation of hydrogen in the methanation step reduces the efficiency down to 64%. For the whole process from renewable energy to the storage in the gas grid, an efficiency of approximately 63.6% can be reached [2]. At this stage, the highly developed natural gas grids in Germany can be used for the transport of excess energy. The German network for natural gas offers a huge storage capacity taking into account the high energy density of compressed methane. Moreover, the gas grid allows for a nearly time-independent storage. The natural gas grid is hence very well suited for balancing the transport bottlenecks of the power grid caused by excess energy production in the northern part of Germany and an elevated energy demand in southern Germany. In contrast to this, a mere expansion of the German power grid cannot efficiently reduce the bottlenecks: It has been shown in surveys that additional 3,600 km of high-voltage power lines are needed until 2020 to eliminate the transport bottlenecks in Germany. Up to now, only 200 km of new power lines have been built because of tedious planning and approval processes and because of strong opposition to high-voltage power lines and their pylons in the population [3],[4].

The joint research project Storage of electric energy from renewable sources in the natural gas grid-water electrolysis and synthesis of gas components focused on a concept for the conversion of electrical energy from renewable sources into methane (power to gas). A schematic overview of the whole concept is shown in Figure 3. Comprehensive studies and investigations into this concept taking into account technical and economical aspects have been carried out by a consortium consisting of various scientific research institutes and industrial partners.

A suitable quantity to estimate which of the above products can be expected at a certain process temperature is the Gibbs free energy ΔG. Figure 4 summarizes the development of the Gibbs enthalpy with temperature for all reactions introduced above. The lines in the diagram have been calculated using the software tool HSC Chemistry.

The present and future need for the storage of renewable energy from wind and solar power plants opens up even new markets for innovative methanation process designs. Some current research activities in this field include liquid-phase methanation with novel cooling agents [24], biological methanation [25], and innovative reactor concepts using so-called comb catalysts [2].

Some results of the joint research project entitled Storage of electric energy from renewable sources in the natural gas grid-water electrolysis and synthesis of gas components are presented in this article. The article focuses on the methanation process as one of the crucial steps in the conversion of electric energy from renewable sources to synthetic natural gas (power to gas). In a first section of the article, results of experimental investigations on a lab-scale methanation pilot plant are presented. The second part then addresses different plant concepts for the scaling-up of the investigated methanation process to an industrial scale.

If energy integration is strictly applied, the energy demand of both proposed processes can be completely covered by the heat generated in the process. The excess thermal energy can be used in various ways (e.g., electricity generation via steam turbine, district heating, etc.)

Prerequisite: MECHENG 520. (3 credits) Viscous flow fundamentals; vorticity dynamics; solution of the Navier-Stokes equations in their approximate forms; thin shear layers and free surface flows; hydrodynamic stability and transition to turbulence; fundamental concepts of turbulence; the turbulent boundary layer; introduction to turbulence modeling.


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