Synthesis of trigeneration systems: sensitivity analyses and resilience.

This paper presents sensitivity and resilience analyses for a trigeneration system designed for a hospital. The following information is utilized to formulate an integer linear programming model: (1) energy service demands of the hospital, (2) technical and economical characteristics of the potential technologies for installation, (3) prices of the available utilities interchanged, and (4) financial parameters of the project. The solution of the model, minimizing the annual total cost, provides the optimal configuration of the system (technologies installed and number of pieces of equipment) and the optimal operation mode (operational load of equipment, interchange of utilities with the environment, convenience of wasting cogenerated heat, etc.) at each temporal interval defining the demand. The broad range of technical, economic, and institutional uncertainties throughout the life cycle of energy supply systems for buildings makes it necessary to delve more deeply into the fundamental properties of resilient systems: feasibility, flexibility and robustness. The resilience of the obtained solution is tested by varying, within reasonable limits, selected parameters: energy demand, amortization and maintenance factor, natural gas price, self-consumption of electricity, and time-of-delivery feed-in tariffs.

Scientists' warning against the society of waste.

The metabolism of contemporary industrialized societies, that is their energy and material flows, leads to the overconsumption and waste of natural resources, two factors often disregarded in the global ecological equation. In this Discussion article, we examine the amount of natural resources that is increasingly being consumed and wasted by humanity, and propose solutions to reverse this pattern. Since the beginning of the 20th century, societies, especially from industrialized countries, have been wasting resources in different ways. On one hand, the metabolism of industrial societies relies on non-renewable resources. On the other hand, yearly, we directly waste or mismanage around 78% of the total water withdrawn, 49% of the food produced, 31% of the energy produced, 85% of ores and 26% of non-metallic minerals extracted, respectively. As a consequence, natural resources are getting depleted and ecosystems polluted, leading to irreversible environmental changes, biological loss and social conflicts. To reduce the anthropogenic footprint in the planet, and live in harmony with other species and ourselves, we suggest to shift the current economic model based on infinite growth and reduce inequality between and within countries, following a degrowth strategy in industrialized countries. Public education to reduce superfluous consumption is also necessary. In addition, we propose a set of technological strategies to improve the management of natural resources towards circular economies that, like ecosystems, rely only upon renewable resources.