On using CO2 and renewable energy for autonomous cities
Considering that 75 % of the population will live in urban areas in the future, energy consumption in cities represent a major challenge for the energy transition. The density of the urban systems introduces the need and the opportunity to share resources and equipment, therefore district heating solutions have to be considered. An innovative concept of district heating using carbon dioxide is proposed to supply energy services in cities. Based on the concept of exergy, the idea is to divide heat pumps into 2 parts. The first part is harvesting heat at the best places while the second part is adapting the temperature of the heat to its requirement. In order to transfer heat from one part to the other, the idea is to use CO2 as a district heating fluid distributed in liquid and gas form at a temperature around 15 to 20 °C. Heating needs are then supplied by condensing CO2 while cooling needs are supplied by evaporation, the temperature levels being adjusted using decentralised heat pumps. The energy balance is closed by exchanging heat between the district heating fluid and the environment accessing therefore attractive sources by centralised heat pumps. The advantage of such system is the supply of the heating/cooling services at the temperature it requires and the possible synergies between heating and cooling demands. The use of the district heating system allows indeed to connect the most attractive environmental sources (geothermal, lake, river, waste water, industrial waste heat,...) with the users in order to maximise the efficiency of the system. Using this type of technology, it has been demonstrated that heating and cooling the city center of a European city can be reduced by a factor 5 to 6 (i.e. 80% energy savings) while having a pay back period of around 5 to 7 years . The concept can be extended to integrate the renewable energy resources in particular solar photovoltaics (PV). One of the difficulty of the PV systems is the excess of electricity available in the summer that needs to be stored to supply services in the winter. The idea here is to electro-chemically convert excess of electricity into methane by combining electrolysis of water and the Sabatier reaction that converts CO2 and H2 into methane. This can be done in co-electrolysis concepts using solid oxide electrochemical membranes. Methane can then be stored in liquid form in the summer. In the winter time, the methane is converted in decentralised solid oxide fuel cells into electricity and heat while separating the CO2. The CO2 is collected in the district CO2 network at 50 bar and stored in the liquid form for the summer season when it will again be converted into methane. The produced electricity is used to supply the needs of the households, to drive the heat-pumps of the CO2 based district network and even electrical cars. It is therefore possible to develop cities that are supplied only by renewable sources. Furthermore, the methanation concept can also be applied to convert the waste biomass produced in the city into methane making the cities autonomous.
Prof. François Maréchal
Ecole Polytechnique Fédérale de Lausanne
François Marechal holds a process engineering degree (1986) and a Ph D from University of Liège in Belgium (1995). In 2001, he moved to Ecole Polytechnique Fédérale de Lausanne in Switzerland where he joined the Industrial Energy Systems Laboratory. He is now professor in EPFL in the EPFL Valais-Wallis Campus, heading the Industrial Process and Energy Systems Engineering group. He is conducting research in the field of the process and energy systems engineering for the rational use of energy and resources in industrial processes and energy systems. His activities are focussing on the development of computer aided methods applying process integration and optimization techniques.
He has produced more than 200 scientific papers and directed 28 PhD thesis in the field of energy efficiency in the industry, process system design for biofuels, electricity production and CO2 capture, industrial ecology and sustainable energy systems in urban areas studying the optimal integration of renewable energy resources.
Professor Marechal is chairing the energy section of the European Federation of Chemical Engineering. He is expert to the scientific committee of IFP Energies Nouvelles and is the representative of Switzerland in the Working Party on the Use of Computers in Chemical Engineering of the European Federation of Chemical Engineering and the speciality chief editor of the open access journal Frontiers in Energy research, Specialty Process and Energy Systems Engineering.
Publications of François Marechal may be found on http://www.researcherid.com/rid/B-5685-2009
Benchmarking the Sustainability of Urban Energy, Water and Environment Systems with the SDEWES City Index and Envisioning Scenarios for the Future
Urban systems provide strategic settings for realizing solutions to attain more sustainable energy, water and environment systems. Benchmarking the sustainability of these systems is essential to stimulate action to improve city performance and promote cooperation to share best practices. The Sustainable Development of Energy, Water and Environment Systems (SDEWES) Index to which this lecture is devoted was developed as a composite indicator to benchmark cities. The Index has the namesake of the SDEWES Center and SDEWES Conferences that are dedicated to advancing the level of knowledge on multi-disciplinary issues to address challenges of sustainable development.The SDEWES Index spans 7 dimensions and 35 main indicators that relate to aspects of energy, water, and environment systems as well as their supporting frameworks, such as R&D, innovation and sustainability policy. In the last four years, the SDEWES Index has been applied to six samples that cover cities from South East Europe, Mediterranean port cities, and cities around the world that are selected based on multiple criteria, including cities with the most authors in the SDEWES Book of Abstracts. The 12th SDEWES Conference in Dubrovnik will mark the application and analysis of the SDEWES Index based on 120 cities. The Index provides well-rounded guidance in the process of guiding cities to become living laboratories for resource saving technologies, systems, and concepts. The results of the SDEWES Index are useful to compare cities in multiple ways. First, specific cities that have leading or lagging performance in a particular dimension and/or the overall ranking are identified and analysed. Second, pairs of cities that have common or opposite patterns are determined based on a search algorithm so that joint processes of policy learning and/or exchange may be triggered. Third, a selected city, city pair and/or the entire city sample are subjugated to scenarios that aim to improve city performance in at least one dimension. The scenarios underline the interconnected nature of urban systems and the need for solutions that provide integrated urban approaches. The various pathways of stimulating city level policy learning are supported with the development of original tools that provide direction for envisioning future scenarios. In a time when the Sustainable Development Goals underline sustainable cities and communities, renewable energy, clean water, and climate action, the SDEWES Index can provide timely support in providing the basis of promoting a policy learning network of cities towards future urban systems.
Dr. Şiir KILKIŞ
The Scientific and Technological Research Council of Turkey (TÜBİTAK)
Dr. Şiir KILKIŞ is alumna of KTH Royal Institute of Technology, School of Architecture and the Built Environment, Faculty of Civil and Architectural Engineering, and Georgetown University, where she graduated magna cum laude as the gold medalist in Science, Technology, and International Affairs. She is a member of the International Scientific Committee of the SDEWES Center. In her interdisciplinary research work, she developed and applied a SDEWES Index to benchmark cities, ranked international airports and airlines, analyzed sustainable campuses, and deployed a novel net-zero district concept for the pilot project of the Östra Sala backe district in Uppsala Municipality in Sweden. She also developed the Rational Exergy Management Model (REMM) to provide guidance to curb CO2 emissions in the built environments of the future. Her research foci centers on integrated energy system analysis, net-zero targets, exergy mapping, and benchmarking studies. She is now Associate Professor in Energy Systems Engineering and Senior Researcher at the Scientific and Technological Research Council of Turkey (TÜBİTAK) with specialization in sustainable urban systems and transition management for sustainable development. During her nine year work experience at TÜBİTAK, she contributed to national policies on science, technology and innovation, coordinated the Energy Efficiency Technology Roadmap, organized high level meetings, and served as a delegate to the UN. Dr. KILKIŞ also led R&D and innovation study visits on behalf of TÜBİTAK to Singapore, China, Brazil, and India. She is lecturer of the “Energy Economy” and “Energy Policy” courses within the Energy Engineering Graduate Program at Başkent University and “Sustainable Development” at the Middle East Technical University Earth System Science Graduate Program. She is actively involved in the International Energy Agency Annex 64 on “Optimised Performance of Energy Supply Systems with Exergy Principles.” Dr. KILKIŞ is the author of numerous SCI publications, a chapter on “Green Cities and Compound Metrics Using Exergy Analysis” in the Encyclopedia of Energy Engineering and Technology, and co-author of a book on Cogeneration with Renewable Energy Systems.
Implementing More Effective Tools to Analyse the Sustainability of Social-Ecological Systems in Relation to the Water-Energy-Food Nexus
The nexus between water, energy, and food poses a challenge to the quantitative analysis of complex social-ecological systems and clearly exposes the limitations of scientific reductionism. Conventional solutions, such as re-adjusting the mix of production factors –substituting a less-limited resource to compensate for a shortage of another– or externalization of the problem by taking full advantage of presently favourable terms of trade, are bound to become unsustainable in the long run. Relational analysis of the metabolic pattern of social-ecological systems across dimensions and scales is based on complexity thinking and represents a promising novel approach to the quantitative analysis of complex systems. It uses MUlti-Scale Integrated Analysis of Societal and Ecosystem Metabolism (MuSIASEM) for the quantitative accounting, which makes it possible to check the feasibility (compatibility with external constraints determined by processes beyond human control), viability (compatibility with internal constraints determined by processes under human control), and desirability (compatibility with existing institutions and normative values) of the actual metabolic pattern of socio-ecological systems and of proposed scenarios under various national and EU directives. Rather than simplifying the information space, MuSIASEM focuses on revealing the complex interrelations between structural and functional elements of social-ecological systems across various hierarchical levels and scales of organization. Three applications of this novel approach are presented: (i) green-house vegetable production in Almeria, Spain; (ii) animal production in Scotland, UK; and (iii) an integrated system of using alternative energy to desalinate sea-water for use in agricultural production in the Canary Islands.
Prof. Mario Giampietro
Universitat Autònoma de Barcelona / ICREA
Mario Giampietro is ICREA Research Professor at the Institute of Environmental Science and Technology (ICTA) of the Universitat Autònoma de Barcelona (UAB), Spain. He works on integrated assessment of sustainability issues using new concepts developed in complex systems theory. He has developed a novel scientific approach called Multi-Scale Integrated Analysis of Societal and Ecosystem Metabolism (MuSIASEM) integrating biophysical and socioeconomic variables across multiple scales, thus establishing a link between the metabolism of socio-economic systems and the potential constraints of the embedding natural environment. Recent research focuses on the nexus between land use, food, energy and water in relation to sustainable development goals. He has (co)authored over one hundred publications, including six books, in research themes such as multi-criteria analysis of sustainability; multi-scale integrated assessment of agroecosystems; energy analysis; alternative energy technologies; biofuel; bioeconomics; science for governance.