Carbon Footprint Reduction by Reclaiming Condensed Water

Abstract

Everyday activity incurs carbon footprints, which are classified as personal, production, organizational and national, and may be assessed by input–output analysis (IOA), life-cycle assessment (LCA), or the combination of LCA and IOA methods. Notwithstanding international standards, like ISO 14064 and Publicly Available Specification (PAS) released for standardization, carbon footprint results can vary and sometimes lack consistency that due to variations in data sources, crossover boundary definitions, and operational boundaries for indirect emissions. The novelty of this study is the direct utilization of condensed water in an existing cooling water system, without the need for prior wastewater treatment, as typically required for greywater. The lack of practical case studies exploring the water–energy nexus in the context of reclaiming condensed water for evaporative cooling tower systems makes this research particularly significant. This highlights that condensed water can be a straightforward and cost-effective solution for both water conservation and energy savings. This case study highlights the benefits of reclaiming condensed water as supplementary cooling water, which proved effective in water quality treatment and dilution augmentation, considering that a higher cycle of concentration (CoC) was achieved, leading to reduced bleed-off that resulted in a water saving of 44% for make-up and 80% for bleed-off water, and energy savings from 6.9% to 13.1% per degree Celsius of condensing refrigerant temperature (CRT). The analytical assessment revealed that reclaiming condensed water is a promising answer for green building and is a by-product of condensation without extra power demands, avoiding the generation of an increased carbon footprint and exacerbation of greenhouse gas (GHG) emissions from freshwater resource extraction, and for the production of energy-efficient devices or substitutions. By eliminating the need for wastewater treatment, this research enhances the practicality and feasibility of direct use of condensed water in various applications. This approach not only promotes sustainability by conserving water and energy but also renews interest among proponents of green building practices. It has the potential to accelerate the adoption of this method and integrate it into green building designs.