related metrics presents an opportunity to trigger policy learning, action, and cooperation to bring cities closer to sustainable development.
At present very different approaches regarding the national implementations of legislative stipulations with respect to recycling exist. Whereas there are national implementations deeming the quantity of separately collected recyclables as “recycled” other national implementations count the output of sorting plants resp. the input in the effective recycling process as “recycled”. These different approaches make comparisons of recycling rates difficult and even meaningless as any step down the processing chain of wastes / recyclables from collection down to the effective substitution of primary materials leads to quantitative losses. The same recycling-situation of a specific waste stream can for example result in a recycling rate of anything between 40 % and 80 % based on the different approaches regarding the reporting rules of recycling.
Therefore, mandatory standards with regard to recyclability and clear definitions regarding recycling become even more important when quantitative recycling targets are defined. Quantitative recycling targets are one mean to help secondary raw materials markets to evolve and thereby they are helpful in achieving waste management objectives.
This special session invites contributions dealing with the topics of recyclability of goods as well as issues of the definition of recycling and end-of-waste. Conceptual papers as well as exemplary case studies are welcome. The aim of the special session is to discuss ways to increase the recyclability and harmonize the reporting of recycling of waste in order to foster recycling as one of the main objectives of modern waste management.
1) The main topics
Industrial production and regional economies require a considerable and continuous supply of energy delivered from natural resources – principally fossil fuels. The increase in our planet human population and its growing nutritional demands result in continuous increase of energy demands. This includes forerunners in recent economic development such as China and India. The growing energy consumption also creates the problems with greenhouse gas emissions as well as other pollution effects including toxins and particulates. It has become increasingly important to ensure that the production and processing industries take advantage of recent developments in energy efficiency and in the use of non-traditional energy sources. The additional environmental cost is related to the amount of emitted carbon dioxide (CO2) and may take the form of a centrally imposed tax. A workable solution to this problem would be to reduce emissions and effluents by optimising energy consumption, increasing the efficiency of materials processing, and increasing also the efficiency of energy conversion and consumption. The sectors of energy use are diverse – including industry, agriculture, transportation, residential and commercial activities.
Although industry requires large supplies of energy to meet production targets, it is not the only sector of the world economy that is increasing its energy demands. The particular characteristics of these other sectors make optimizing for energy efficiency and cost reduction more difficult than in traditional processing industries, such as oil refining, where continuous mass production concentrated in a few locations offers an obvious potential for large energy savings. In contrast, for example, agricultural production and food processing are distributed over large areas, and these activities are not continuous but rather structured in seasonal campaigns. Energy demands in this sector are related to specific and limited time periods, so the design of efficient energy systems to meet this demand is more problematic than in traditional, steady-state industries.
In recent years there has been increased interest in the development of renewable, non-carbon-based energy sources to counter the increasing threat of greenhouse gas emissions and subsequent climatic change. These sources are characterized by spatial distribution and variations as well as temporal variations with diverse dynamics. More recently, the fluctuations and often large increases in the prices of oil and gas have further increased interest in employing alternative, non-carbon-based energy sources. These cost and environmental concerns have led to increases in the industrial sector efficiency of energy use, although the use of renewable energy sources in major industry has been sporadic at best. In contrast, domestic energy supply has moved more positively toward the integration of renewable energy sources; this movement includes solar heating, heat pumps, and wind turbines, as well as photovoltaic electricity generation. There have been already interesting scientific results on designing combined energy systems that include both industrial and residential buildings toward the end of producing a symbiotic system.
Another important issue is water – both as raw material and effluent. Fresh water is widely used in various industries. It is also frequently used in the heating and cooling utility systems (e.g., steam production, cooling water) and as a mass separating agent for various mass transfer operations (e.g., washing, extraction). Strict requirements for product quality and associated safety issues in manufacturing contribute to large amounts of high-quality water being consumed by the industry. In addition, large amounts of aqueous waste streams are released from the industrial processes, often proportional to the fresh water intake. Stringent environmental regulations coupled with a growing human population that seeks improved quality of life have led to increased demand for quality water. These developments have increased the need for improved water management and wastewater minimization. Adopting techniques to minimize water usage can effectively reduce both the demand for freshwater and the amount of effluents generated by the industry. In addition to this environmental benefit, efficient water management reduces the costs for acquiring freshwater and treating effluents.
2) Cross-cutting issues
There are two important issues running through the mentioned topics. One is the quantification of environmental performance and the other is knowledge management and transfer.
The environmental performance of a process or activity can be assessed in various ways. The most prominent concepts used for this have been footprints – quantifying the impact of pollutant emissions; natural/ecological capital – measuring in a combined way the fresh resources and service capacities of a system (e.g. a region); eco-cost, eco-benefit and eco-profit – a scheme for quantification of the possible actions for improving the environmental performance of a process or activity. Not the least, one has to evaluate the emissions and impacts on a global basis, which gives rise to virtual footprints – accounting for these impacts from the consumer perspective as opposed to the goods producer perspective.
Another key issue is the knowledge development and management. The currently dominating societal system, or pattern, of knowledge management is to document the research and demonstration outcomes in scientific articles and books. While the scientific articles can be viewed as “work in progress” or the current cutting edge of the knowledge development in the relevant areas, books are intended as a kind of summaries useful for learning and everyday reference.
As such, the books can be viewed as limited knowledge bases, containing summaries and interpretations of the research works by the book authors, as well as relevant references to other pieces of knowledge – books, scientific articles, patents, etc. When the content of a book gets outdated compared to new developments, frequently new editions of the same book are devised or new books are written in their stead.
However, as the number of research projects and scientific articles grows, there is an increasing chance that repetitions of certain research topics or re-discoveries of same principles and research results occur. While such a phenomenon is generally beneficial within small extent, its increasing rate would result in significant waste or misuse of resources dedicated to knowledge development and hinder knowledge exploitation.
This is where comes the need for employing sophisticated systems for knowledge management, which should enable key features for efficient knowledge development, update, tracking and transfer (including education). Some such features include: integrated research-training-update life cycle, increased interactivity and variety of the content delivery, Internet-based training and knowledge transfer, Emphasis should be put on Internet-based interactive working sessions (learning objects) in addition to written exercises. These will allow involving additional associations and senses in the training process further improving the quality and speed of e-learning.
This session provides a platform for development of modern technologies for energy and water efficiency and for exchanging ideas in the field, supplemented by key contributions geared towards more efficient knowledge management. They include, beside the others, the Process Integration and optimisation methodologies and their application to improving the energy and water efficiency of mainly industrial but also nonindustrial users. An additional aim is to evaluate how these methodologies can be adapted to include the integration of waste and renewable energy sources for energy conversion and water supply/purification. The session is outlining the field of energy and water efficiency, including its scope, actors, and main features. The deals with energy and water saving techniques. An increasingly prominent issue is assessing and minimizing emissions and the the environmental footprints: carbon and water footprints. The carbon footprint (CFP) is defined by the U.K. Parliamentary Office for Science and Technology as the total amount of CO2 and the other greenhouse gases emitted over the full life cycle of a process or product. IN a similar way the water footprint embodies the various water quantities used for the manufacturing and delivery of a product. For energy supply, there have been numerous studies that emphasize the “carbon neutrality” of renewable sources of energy. However, even renewable energy sources make some contribution to the overall carbon footprint, and assessment studies frequently do not account for this. The carbon footprint should also be incorporated into any product life-cycle assessment (LCA).
The direct interlinkages between food, energy and water (FEW) resources and their infrastructures and institutions will require a comprehensive and effective FEW nexus management concept based on intense and coordinated global efforts.
The ability to confront the challenges significantly depends on the resilience of urban infrastructures, which is to a large degree managed by institutions with the objective to protect social cohesion and minimize ecological pressure. To balance trade-offs and maximize synergies among the FEW resources, significant transitions in urban governance structures will become necessary. Precondition for these transitions is a comprehensive understanding of the feedbacks and interlinkages between the urban FEW systems and the surrounding systems.
Given this complexity and the diverse challenges, the focus in this session will be set on the discussion of both (a) the dynamics of the decision-making landscapes in the urban FEW nexus including questions of governance and institutions, and (b) viable data- and model-driven methodical approaches for the integrated assessment of socio-ecological urban FEW systems.
1. UN-HABITAT, State of the world's cities 2012/2013. Prosperity of cities. 2012, United Nations Human Settlements Programme (UN-HABITAT): Nairobi.
2. WBGU (German Advisory Council on Global Change), Der Umzug der Menschheit: Die transformative Kraft der Städte Zusammenfassung. 2016: Berlin.
3. UN Habitat, 2015 Global City Report. 2016.
4. WBGU – German Advisory Council on Global Change, WBGU – German Advisory Council on Global Change (2016): Humanity on the move: Unlocking the transformative power of cities. 2016, WBGU: Berlin.