Multi-Criteria Comparison of Energy and Environmental Assessment Approaches for the Example of Cooling Towers

Abstract

Cooling towers remove economically or technically unusable heat using considerable amounts of electricity and, in many cases, water. Several approaches, which vary in methodology, scope, and level of detail, are used for environmental evaluations of these cooling systems. Although the chosen approach has a significant impact on decisions made at the plant level, no methodology has yet been standardized for selecting the approach that best serves the objectives of the evaluation. Thus, this paper provides comparison criteria for the systematic selection of suitable evaluation methods for cooling towers and classifies how the methods score in this respect. These criteria, such as ‘life cycle thinking’, ‘inventoried physical quantities’, ‘temporal resolution’, ‘formalization’, and ‘data availability’, are grouped by overall evaluation objectives such as ‘thoroughness’, ‘scientific soundness’, and ‘usability’. Subsequently, these criteria were used to compare material flow analysis, energy analysis, environmental network analysis, life cycle inventory, life cycle assessment, environmental footprint methods, emergy analysis, exergy analysis, and the physical optimum method. In conclusion, material flow analysis is best suited for the analysis of cooling towers when impact assessment is not required; otherwise, life cycle assessment meets most of the defined criteria. Moreover, only exergy-based methods allow for the inclusion of volatile ambient conditions.

Catalyzing Cooling Tower Efficiency: A Novel Energy Performance Indicator and Functional Unit including Climate and Cooling Demand Normalization

“…Definitions for the exergy efficiency of cooling towers are different from the cost-benefit concept but refer to the thermodynamic input-output balance, and the electricity consumption is mostly omitted. Beyond that, several studies outline the landscape of methods and indicators for environmental and energy efficiency evaluation [36][37][38].…”

“…All three have one physically ideal case (highlighted in green). In practice, technical imperfections cause additional effort or losses (in gray), resulting in the actual situation (in blue).The efficiency values of the ventilation, motor, fan, or flat belt and control system are approximate benchmarks by literature[47,48] (pp [35][36][37][38][39][40][41][42],. [49] (pp.…”

Extending effectiveness to efficiency: Comparing energy and environmental assessment methods for a wet cooling tower

“…Each method has a different focus, so the selection can significantly impact the conclusions. Therefore, previous studies developed approaches to systematically select an assessment method at the beginning of the study (Ness et al., 2007; Rodríguez et al., 2019; Wenzel & Radgen, 2022). Additionally, case study comparisons are essential for the application area of cooling towers since only practical use reveals the specific advantages and disadvantages, and these rarely exist for cooling towers hitherto.…”