Exergy and Sustainability

Exergy and Sustainability Insights into the Value of Exergy Analysis in Sustainability Assessment of Technological Systems Lydia Stougie Exergy and Sustainability Insights into the Value of Exergy Analysis in Sustainability Assessment of Technological Systems PROEFSCHRIFT ter verkrijging van de graad van doctor aan de Technische Universiteit Delft, op gezag van de Rector Magnificus prof.ir. K.C.A.M. Luyben, voorzitter van het College voor Promoties, in het openbaar te verdedigen op donderdag 16 oktober 2014 om 12.30 uur door Lydia STOUGIE Scheikundig ingenieur geboren te Gouda. Dit proefschrift is goedgekeurd door de promotor: Prof.dr.ir. M.P.C. Weijnen Copromotor: Dr.ir. R.M. Stikkelman Samenstelling promotiecommissie: Rector Magnificus voorzitter Prof.dr.ir. M.P.C. Weijnen Technische Universiteit Delft, promotor Dr.ir. R.M. Stikkelman Technische Universiteit Delft, copromotor Dr.ir. H.J. van der Kooi Technische Universiteit Delft Prof.ir. P.G. Luscuere Technische Universiteit Delft Prof.dr.ir. J. Dewulf Universiteit Gent Prof.dr. D. Favrat Ecole´ Polytechnique Fédéralede Lausanne Prof.dr. M.A. Rosen University of Ontario Prof.dr.ir. P.M. Herder Technische Universiteit Delft, reservelid Dr.ir. H.J. van der Kooi heeft als begeleider in belangrijke mate aan de totstandkoming van het proefschrift bijgedragen. ISBN 978-94-6186-365-2 Copyright ○c 2014 by L. Stougie Cover photo by T. Stougie, used with permission Printed by CPI - Koninklijke WöhrmannB.V., Zutphen, Netherlands Available at http://repository.tudelft.nl Acknowledgements I'm very grateful for the advice and support I received during my PhD research. First of all, I'd like to thank Margot Weijnen for giving me the freedom to do this PhD research and for her valuable comments on my work and suggestions for improvement. Many thanks go to Rob Stikkelman for his unique way of supervising and coaching me and for pulling me back to reality at moments I was in danger of spending too much time on calculations and finding data. The infectious enthusiasm of Hedzer van der Kooi for research in the field of exergy and sustainability, his encouraging words, his very broad knowledge of al- most everything (like a walking encyclopedia) and his willingness to spend his spare time on advising me mean a lot to me. I'd also like to thank the members of my PhD committee for their willingness to participate in the committee and for their valuable comments which helped me to improve my thesis. I'm very happy with my colleagues and former colleagues at the Energy & Industry section. Thank you for your companionship, collegiality, inspiring discussions and lunch meetings, and the hands-on help with LATEX, Subversion, Ubuntu and non- booting dual-boot computers. A special word of thanks goes to Prisca Koelman, Margot's secretary, for her practical support in finishing my PhD trajectory. The exchange of knowledge and discussions with my TU Delft colleagues of the informal exergy group were also very inspiring. The same holds for all my other colleagues at TU Delft, business contacts and researchers in the field of exergy and sustainability. And thank you Joost Vogtländerfor helping me with the SimaPro software. My thanks also go to my family and friends for their interest and encouragement, especially to my parents and my sister. Dad, thank you for the beautiful picture on the cover of this thesis as well. I'd also like to thank my daughters, Astrid and Marjolein, for their understanding when I was too busy with my research to spend more than only little time with them. Let's celebrate, mum is back! And last but not least, many thanks go to Guus, my husband, thank you, thank you, thank you! Without your love and support, I wouldn't have been able to write this thesis. Lydia Stougie - September 2014 iii Summary Exergy and sustainability - insights into the value of exergy analysis in sustainability assessment of technological systems A major challenge in striving for a more sustainable society is the selection of technological systems. Given the capital intensity of industrial production plants, power generation systems and infrastructure, investment decisions create path depend- encies for decades to come. It is difficult to know which technological system is preferable when considering the multiple objective of environmental, economic and social sustainability. E.g., a system that is preferred from the environmental point of view is not necessarily the system that is preferred from the economic and/or social point of view. Furthermore, the results of the assessments change over time because of new insights into environmental, economic and social sustainability and because they are prone to changing needs, economic conditions and societal prefer- ences. Because of these uncertainties, it is hard to decide which technological system or systems should be chosen, e.g. to meet national and international targets with regard to climate change. Another way of assessing technological systems is the use of exergy analysis, a ther- modynamic assessment method. Exergy analysis makes visible where work potential is lost. This work potential is needed for all the things we would like to do, i.e. noth- ing happens without the consumption of some work potential. Work potential that is lost, is lost forever. The only way to replenish the amount of work potential available on earth is by capturing new work potential from solar and/or tidal energy. Researchers active in the field of exergy and sustainability claim that the loss of work potential, also known as exergy loss, and sustainability are related. However, the loss of work potential is no part of the regular sustainability assessment methods. The objective of this research is to provide insight into the value of exergy analysis in sustainability assessment of technological systems. A literature research into the relationship between exergy and sustainability resulted in a theoretically founded relationship between exergy losses and the environmental impact of technological systems. A problem with investigating the relationship between exergy and sustainability is that there is no single measure of sustainability. Combining the results of the environmental, economic and social sustainability assessments into one sustain- v vi Summary ability indicator leads to a loss of information and necessitates the use of weighting factors. Another difficulty is that a commonly accepted operationalization of the term `sustainability' does not exist. Accordingly, a list of requirements to methods for sustainability assessment of technological systems has been drawn up. All assessment methods cover the operational phase of installations, equipment and infrastructure including the amounts of inputs and outputs. Not all methods take into account the phases of construction and decommissioning of the installations, equipment and infrastructure and the following components of sustainability: the depletion and/or scarcity of the inputs, the distinction between renewable and non- renewable inputs, the disposal and/or abatement of emissions and waste flows, land use, exergy losses, economic aspects and social aspects. In addition, methods for the calculation of sustainability indicators should be objective and sufficient data should be available to calculate these indicators. The sustainability assessment methods found in the literature appear to be incom- plete with respect to the list of requirements. The environmental life cycle assessment methods are not fully objective because they make use of weighting factors and because no consensus exists about all models used for quantifying environmental impact. The economic methods do not include all indirect costs and their indicators change over time because of market developments. The social methods suffer from the limited availability and qualitative or semi-quantitative nature of many data. The exergy analysis methods found in literature do not consider all components of sustainability and/or make use of indicators, equations and weighting factors that are not commonly accepted. It was therefore decided to develop a new exergy analysis method on the basis of fundamental scientific equations. The newly developed exergy analysis method has been named the Total Cumulative Exergy Loss (TCExL) method and takes into account as many of the designated components of sustainability as possible. The TCExL is the summation of the exergy loss caused within the technological system including its supply chains, the exergy loss caused by abatement of the resulting emissions and the exergy loss related to the land occupied by the technological system including its supply chains. The latter is relevant because land use prevents capturing new exergy from sunlight by the ecosystem. Components of the list of requirements that can only indirectly be considered when calculating the exergy loss caused by a technological system are the depletion and scarcity of resources as well as the economic and social aspects of sustainability. The TCExL method is an improvement compared to existing exergy analysis methods in the sense that it is solely based on the calculation of exergy losses and that it takes into account all exergy losses caused by a technological system during its life cycle. However, until now the abatement exergy loss of only a few emissions is included because of the lack of data regarding other emissions. The value of exergy analysis in sustainability assessment of technological systems has been investigated by conducting two case studies that comprise several power generation systems and subsequently comparing the results of the assessment methods with and without exergy of the systems of each case study. Power generation was chosen as the subject of the case studies because of the major role of electricity Summary vii in our society. The choice of the systems of the case studies is not meant to in- dicate that these systems are preferable and/or desirable compared to other central or decentral power generation systems, nor that it is not important to look at the transport, distribution, use and/or storage of electricity.

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