Analyses and assessments of threee renewable energy based integrated systems for multingeneration

Abstract

The modern world depends on the fossil fuel consumption as a primary energy source, and this is especially obvious in all industrialized countries. Due to the resource depletion and non-sustainable resources, fossil fuels are not capable of compensating the growing energy needs. In addition, the easily extractable fossil fuels are facing an increase in their prices. It is worth mentioning that greenhouse gases (mainly CO2) have been accumulated in the atmosphere by burning fossil fuels. Therefore, recently scientific research and academic studies as well as energy policies have been focused to find a permanent solution for the environmental issues by utilizing from the non-polluting resources such as renewable energy and hydrogen. Furthermore, one other way to reduce the greenhouse gases emissions is to design the energy systems in a more effective manner by producing multiple useful commodities from the system. Therefore, one of the main goals of the thesis is to design three different types of renewable based energy systems which provide higher energy and exergy efficiencies by producing electricity, heating, cooling, hot domestic water and hydrogen outputs, as useful outputs. One of the most important enviromental issues related to the using geothermal operating fluids to generate electricity is non-condensable gases (NCG) emissions. Hydrogen sulfide (H2S), which is one of these gases, has many adverse effects on the environment and human body. Therefore, another objective of the present study is to reduce the hydrogen sulfide emissions in the geothermal power plants. For this purpose, an AMIS (AMIS® - acronym for “Abatement of Mercury and Hydrogen Sulfide” in Italian language) unit and an electrolyzer system are integrated to the presently developed systems. In this way, not only the negative effects of hydrogen sulfide are reduced, but also hydrogen is generated as a clean fuel which has a vast potential to replace fossil fuels.To accomplish the specific objectives and evaluate the newly developed systems and their performance both energetically and exergetically, a detailed thermodynamic analysis is performed by using Engineering Equation Solver (EES) software. The results show that overall energy and exergy efficiencies for the studied systems becomes 67.95% and 60.94%, respectively. In addition, hydrogen sulfide emissions are reduced by 738.8 g/s, while the inlet mass flow rate of geothermal fluid is 60 kg/s. Also 6.234 MW additional power can be produced through hydrogen fuel from the geothermal power plants.