Life Cycle Assessment (LCA) of various solar heat technologies

Winterbach, Francois (Stellenbosch : Stellenbosch University, 2011-12)

With the current technology available, concentrated solar thermal energy is seen as a viable solution for renewable and clean energy. Although this is seen as clean energy, there is little information available about the effects that solar power tower plants may have on the environment. The environmental effects of the manufacturing, construction, operation and maintenance of the system and its components need to be considered before this renewable energy technology can be claimed as environmental friendly. The entire life cycle, from cradle to grave, of the system must be considered to obtain reliable results that give a true reflection of the environmental impacts. This report, however, will only focus on one of the components of the solar power tower, namely the collector field, which consists out of heliostats. Other components of the system such as the storing of energy, generation of electricity, and processes such as the Brayton and Rankine cycle will not be discussed in this report.

Final year project, 2011

Technical Report

ENGLISH ABSTRACT: Energy is an essential part of the world today. It is difficult to imagine a world without it. Modern day households rely on it for daily activities and preservation of food. Industries rely on it for manufacturing and processing. The business world relies on it for ease of transactions and transfers. Media depends on it for the gathering and distribution of information. Night life will be much more difficult without advantage of lights. The major concern is that the means by which most of the energy is produced causes harm to humans and the environment, including the fauna and flora. Coal fire is the most prominent way of producing energy, but since it creates the most harm to the environment, alternatives ways of energy production must be looked at. Other non-renewable energy sources include oil, natural gas and nuclear energy. All of these have the potential to be very harmful to the environment. That is why renewable sources of energy should be considered. Such sources include wind energy, hydro-energy, solar energy and geothermal energy. Solar power towers are a solar thermal alternative for energy production. It uses solar radiation as fuel for the energy generation process. The physical components of this technology are the heliostat field, the power tower and various machines used in the power generation cycles. The function of the heliostat field is to intercept, redirect and concentrate direct solar radiation to a receiver which sits at the top of a power tower. In this project the heliostats that are necessary to fuel a 100 MW power tower is analysed to determine the environmental impact throughout their life time. This is a cradle to grave assessment, which means that the entire life cycle is considered from the acquiring of raw materials to the disposal of the functional unit. Software was used to do the life cycle assessment of the heliostat field. From the result obtained it could be seen which emissions are produced during which processes and the magnitude of the effect that they have on different environmental categories.

AFRIKAANSE OPSOMMING: Energie is ʼn belangrike deel van die wêreld vandag. Dit is moeilik om aan ʼn wêreld daarsonder te dink. Moderne huishoudings maak staat op energie vir daaglikse aktiwiteite en om kos te preserveer. Nywerhede maak staat daarop vir vervaarding en prosessering. Die besigheidswêreld maak staat daarop vir die gemak van transaksies en oordragte. Media is afhanklik daarvan vir die versameling en verspreiding van informasie. Naglewe sou moeiliker gewees het sonder die voorreg van ligte. Die grootste bekommernis is dat die manier waarop meeste energie produseer word skadelik vir die mens en die natuur is, insluitend die fauna en flora. Steenkool is die mees prominente manier van energie produsering, maar aangesien dit die meeste skade aan die omgewing aanrig, moet daar gekyk word na alternatiewe maniere van energie produsering. Ander nie-volhoubare energie bronne sluit in olie, natuurlike gas en kernenergie. Al hierdie het die potensiaal om baie skadelik vir die omgewing te wees. Dit is waarom hernubare bronne van energie oorweeg moet word. Sulke bronne sluit in wind energie, hidro-energie, son energie en geotermiese energie. Sonkrag torings is ʼn son hitte alternatief vir energie produsering. Dit gebruik radiasie van die son as brandstof vir energie opwekking. Die fisiese komponente van hierdie tegnologie is die heliostat veld, die kragtoring en ʼn verskeidenheid ander masjinerie wat benodig word vir die kragopwekking siklusse. Die funksie van die heliostat veld is om direkte radiasie van die son te onderskep, weerkaats en dan te konsentreer na ʼn ontvanger wat bo-op ʼn kragtoring sit. In die projek word die heliostats wat benodig word vir die aandrywing van ʼn 100 MW kragtoring geanaliseer om die impak op te omgewing te bereken gedurende hulle leeftyd. Hierdie is ʼn wieg tot die graf assessering, wat beteken dat die hele lewensiklus in ag geneem word vanaf die verkryging van grondstowwe tot die wegdoening van die funksionele eenheid. Sagteware was gebruik om die lewenssiklus assessering van die heliostat veld te doen. Vanaf die verkrygde resultate kan gesien word watse uitlaatgasse produseer word gedurende watter prosesse en die grootte van die impak wat dit op verskillende omgewings kategorieë het.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/18135
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