Assessment of environmental sustainability indexes of water supply and sewage treatment companies listed on the BM&FBOVESPA

Abstract The critical level of the water reservoirs of the Brazilian hydroelectric power plants represents a breach of the first condition of sustainability. The algebraic sum of the volumes of affluence and diffluence shows an unfavorable result of 6418 m3 of water per second to the national system. In this study, we present an environmental accounting methodology that measures the use of resources per solar eMergy common unit aiming to assess the interaction of environmental sustainability indexes in water supply and sanitation companies listed on the BM&FBOVESPA in 2014. The measurement was performed by defining the boundaries of the system of each company with the sources of energy and materials that feed it. A system energy diagram was constructed and the flows were summarized in an aggregate diagram of the energy flows. From the inventory of energy and material inputs of the companies in 2013, the resources R, N, and F were inventoried in units, transformations, and eMergy/unit. It has been found that consumers are paying, in seJ/J or seJ/R$, for the resources received from natural ecosystems when they buy products and services in cash. The calculation of accounting indicators in eMergy (EYR, ELR, and SI) and the ternary diagram in eMergy and their sustainability lines indicated the companies' positions in relation to environmental sustainability indicators. Investors of the BM&FBOVESPA acknowledge and perceive positive value in companies labeled as sustainable. Between 2006 and 2015, the ESI obtained a performance index 131% higher than the Ibovespa index. Clients of the companies CASAN, COPASA, SABESP, and SANEPAR pay in their water and sewage treatment bills (average values in R$) for 72.5% of the total eMergy they receive. There is a disadvantageous relation between the biosphere and the water and sewage treatment systems operated by the assessed companies.

摘要
巴西水电站水库的临界水位已然违背了可持续性的首要准则。入流与出流水量的代数和给巴西全国电力系统造成了每秒6418立方米的不利水量赤字。本研究提出了一种以太阳能能值（eMergy）通用单位衡量资源消耗的环境核算方法，旨在评估2014年在巴西证券期货交易所（BM&FBOVESPA）上市的供水与污水处理企业的环境可持续性指标交互关系。该核算通过划定各企业的系统边界，明确其所需的能源与物质供给来源来开展。研究构建了系统能值流图，并将各类能流汇总为综合能流总图。基于2013年各企业的能源与物质投入清单，研究按资源单位、转化系数及能值/单位对R、N、F三类资源进行了清查。研究发现，消费者以现金购买产品与服务时，实则以太阳能焦耳/焦耳（seJ/J）或太阳能雷亚尔/雷亚尔（seJ/R$）的形式，为其从自然生态系统获取的资源完成付费。通过计算能值核算指标（能值投资率EYR、能值加载率ELR与能值可持续性指数SI），以及能值三元图及其可持续性边界，明确了各参评企业在环境可持续性指标体系中的定位。巴西证券期货交易所的投资者认可并认同，贴上可持续标签的企业具备正向市场价值。2006至2015年间，能值可持续性指数（ESI）的表现指数较伊博维斯帕股指（Ibovespa）高出131%。CASAN、COPASA、SABESP及SANEPAR四家企业的客户，在水费与污水处理费账单中（以雷亚尔为单位的平均金额），为其获取的总能值中的72.5%完成了付费。本次评估的企业所运营的供水与污水处理系统与生物圈之间，存在不利的交互关系。