Modern organized societies require robust infrastructures, among which hydraulic projects, such as water supply and drainage systems, are most important, particularly in water-scarce areas. Athens is a unique example because it is a big city (population 3.7 million) located in a very dry area. In order to support the development of the city, large hydraulic projects had to be constructed during its history and, as a result, Athens currently has one of the largest water supply systems in the world. Could Athenians choose smaller scale infrastructures instead? Analyzing social, technical and economical historical data, we can see that large capital investments were required. In order to evaluate these investments this paper presents a technical summary of the development. An economic analysis displays historical values of these investments in present monetary values. The cost of existing infrastructure is compared to the cost of constructing smaller reservoirs and a model is created to correlate the price of water and the cost of water storage with the size of reservoirs. In particular, if more and smaller reservoirs were built instead of the large existing ones, the cost of the water would significantly increase, as illustrated by modelling the cost using local data.

Our work analyzes the biophysical and economic foundations of the Sherwood Plot (SP). In general, the SP depicts the theoretical relationship between the cost of recovering a target material or an identified Value Added Compound (VAC) from a waste matrix and its dilution in the waste matrix; specifically suggesting that the recovery cost is reverse proportional to the VAC’s dilution in it. We further utilize the SP as a scientifically consistent and economically coherent analytical framework for measuring resource recovery performance. Initially, we analyze the SP’s fundamental physical properties, as well as its many potential economic extensions. Specifically, we substantiate the relation between a VAC’s Entropy, Dilution and Recovery Cost. On these grounds we present the SP’s remarkable and numerous economic properties that make it consistent to its physical foundations; thus integrating concisely its physical and economic aspects and postulate a generalized SP function. We further test econometrically the validity of an SP based on both deterministic and stochastic real data from a small-scale industrial unit of polyphenols’ recovery from natural fruit juice production residual wastewater. In turn, based on the fusion of our theoretical argumentation and empirical findings we dive into the epistemological extensions of the SP. Specifically, we study how the recovery cost structure at the single industry level is revealed by the SP and can be useful for postulating cost structure ontologies. Cost ontologies are in turn useful as a diagnostic of the formation process of VAC recovery markets as well as their structure and concentration, defining the industrial shares when many industries operate in the recovery of the same VAC.

Ecosystems provide humanity with a wide variety and high economic value-added services, from biomass structuring to genetic information, pollutants’ decomposition, water purification and climate regulation. The foundation of ecosystem services is the Eltonian Pyramid, where via prey–predator relationships, energy metabolism and biomass building take place. In the context of existing ecosystem services classification and valuation methods (e.g., CICES, MEA, TEEB), financial investments in ecosystem services essentially address the conservation of trophic pyramids. Our work’s main target is to investigate how trophic pyramids’ dynamics (stability or instability) impact the long-run discounting of financial investments on ecosystem services’ value. Specifically, a trophic pyramid with highly fluctuating populations generates higher risks for the production of ecosystem services, hence for ecological finance instruments coupled to them, due to higher temporal uncertainty or information entropy that should be incorporated into their discount rates. As this uncertainty affects negatively the net present value (NPV) of financial capital on ecosystem services, we argue that the minimization of biomass fluctuations in trophic pyramids via population control should be among the priorities of ecosystem management practices. To substantiate our hypothesis, we construct a logistic predation model, which is consistent with the Eltonian Pyramid’s ecological energetics. As the logistic predator model’s parameters determine the tropic pyramid’s dynamics and uncertainty, we develop an adjusted Shannon entropy index (H(N)_ADJ) to measure this effect as part of the discount rate. Indicatively, we perform a Monte Carlo simulation of a pyramid with intrinsic growth parameter values that yield oscillating population sizes. Finally, we discuss, from an ecological energetics standpoint, issues of competition and diversity in trophic pyramids, as special dimensions and extensions of our analytical framework.

For the present work, we utilized Leslie White’s anthropological theory of cultural evolutionism as a theoretical benchmark for econometrically assessing the macrodynamics of energy use in agrarian societies that constituted the human civilization’s second energy paradigm between 12,000 BC and 1800 AC. As White’s theory views a society’s ability to harness and control energy from its environment as the primary function of culture, we may classify the evolution of human civilizations in three phases according to their energy paradigm, defined as the dominant pattern of energy harvesting from nature. In this context, we may distinguish three energy paradigms so far: hunting–gathering, agriculture, and fossil fuels. Agriculture, as humanity’s energy paradigm for ~14,000 years, essentially comprises a secondary form of solar energy that is biochemically transformed by photosynthetic life (plants and land). Based on this property, we model agrarian societies with similar principles to natural ecosystems. Just like natural ecosystems, agrarian societies receive abundant solar energy input but also have limited land ability to transform and store them biochemically. As in natural ecosystems, this constraint is depicted by the carrying capacity emerging biophysically from the limiting factor. Hence, the historical dynamics of agrarian societies are essentially reduced to their struggle to maximize energy use by maximizing the area and productivity of fertile land –in the role of a solar energy transformation hub– mitigating their limiting factor. Such an evolutionary forcing introduced technical upgrades, like the leverage of domesticated livestock power as a multiplier of the caloric value harvested by arable and grazing land combined. According to the above, we tested the econometric performance of four selected dynamic maps used extensively in ecology to reproduce humanity’s energy harvesting macrodynamics between 10,000 BC and 1800 AC: (a) the logistic map, (b) the logistic growth map, (c) a lower limiting case of the Hassel map that yields the Ricker map, and (d) a higher limiting case of the Hassel map that yields the Beverton–Holt map. Following our results, we discuss thoroughly our framework’s major elaborations on social hierarchy and competition as mechanisms for allocating available energy in society, as well as the related future research and econometric modeling challenges.

The concept of Circular Economy, although not entirely new, has in recent years gained traction due to growing concern with regards to the Earth’s natural reserves. In this context, Sewer Mining, a wastewater management method based on extracting wastewater from local sewers for reuse applications, presents an interesting option that lies in the interplay between reuse at a household scale and centralized reuse at a wastewater treatment plant. As part of the EU-funded program NextGenWater, a new unit is being prepared for operation in Athens’s Plant Nursery, in Goudi. This paper examines the water flow within the proposed installation, using the Urban Water Optioneering Tool (UWOT). Further research is focused on the economic viability of Sewer Mining and the proposed investment. The results produced are promising regarding Sewer Mining’s capabilities and benefits, as well as its future prospects, in the hopes that this technology can provide an attractive alternative to conventional water sources within the urban water cycle.

Although the Circular Economy (CE) has made remarkable technological progress by offering a wide range of alternative engineering solutions, an obstacle for its large-scale commercialization is nested in the adoption of those business and financial models that accurately depict the value generated from resource recovery. Recovering a resource from a waste matrix conserves natural reserves in situ by reducing demand for virgin resources, as well as conserving environmental carrying capacities by reducing waste discharges. The standard business model for resource recovery is Industrial Symbiosis (IS), where industries organize in clusters and allocate the process of waste matrices to achieve the recovery of a valuable resource at an optimal cost. Our work develops a coherent microeconomic architecture of Chemical Leasing (Ch.L.) contracts within the analytical framework of the Sherwood Plot (SP) for recovering a Value-Added Compound (VAC) from a wastewater matrix. The SP depicts the relationship between the VAC’s dilution in the wastewater matrix and its cost of recovery. ChL is engineered on the SP as a financial contract, motivating industrial synergies for delivering the VAC at the target dilution level at the market’s minimum cost and with mutual profits. In this context, we develop a ChL market typology where information completeness on which industry is most cost-efficient in recovering a VAC at every dilution level determines market dominance via a Kullback–Leibler Divergence (D_KL) metric. In turn, we model how payoffs are allocated between industries via three ChL contract pricing systems, their profitability limits, and their fitting potential by market type. Finally, we discuss the emerging applications of ChL financial engineering in relation to three vital pillars of resource recovery and natural capital conservation.