Water Degradation by China’s Fossil Fuels Production: A Life Cycle Assessment Based on an Input–Output Model

Yuqi Su,Liu Yang,Yi Liang,Jiaxuan Lyu,Li Chai,Sai Ma,Zhiping Li,Zixuan Han

doi:10.3390/su11154130

Abstract

Fossil energy production not only aggravates water depletion but also severely contaminates water resources. This study employed a mixed-unit input–output model to give a life cycle assessment of national average water degradation in production of common types of fossil fuels in China. The results show that the amount of grey water generated is much more than that of consumptive and withdrawn water in all cases. Although there is a high discharge amount of chemical oxygen demand (COD) in fossil fuel production, the pollutants of petroleum (PE) and volatile phenols (VP) require more dilution water than COD. PE is the greatest contributor to water degradation caused by primary fossil fuels, while VP pollution is prominent in production of upgraded fossil fuels. Basically, the main causes of water degradation, PE and VP discharge, occurs at coal mines, oil fields, refinery plants, and coking factories, rather than in the upstream sectors. A scenario analysis showed that water pollution can be significantly reduced if VP discharge in the coking process is controlled to be at the standard concentration. PE requires a standard withalower discharge concentration in order to further mitigate water pollution in production of fossil fuels. The coal production industry has a much lower pollutant removal rate but spends more on wastewater treatment, up to 12% of its profit. The other fossil fuel industries have high removal rates of PE and VP (97%–99%) and thus demand technological renovation to further remove those pollutants at a low concentration.

Highlights

Global energy demand is expected to increase by 48% from 579 billion GJ in 2012 to 860 billion GJ in 2040, posing a severe challenge to limited natural resources such as freshwater for energy production [1]
In order to understand the comprehensive impacts of fossil energy production on water resources, we assessed the life cycle water use and pollution per unit of energy for five common types of fossil fuels in China, including coal, crude oil, natural gas, coke, and petroleum products
This study developed a mixed-unit input–output model to perform a lifecycle assessment of water degradation in production of China’s most common fossil fuels, including coal, crude oil, natural gas, coke, and petroleum products

Summary

Introduction

Global energy demand is expected to increase by 48% from 579 billion GJ in 2012 to 860 billion GJ in 2040, posing a severe challenge to limited natural resources such as freshwater for energy production [1]. Water resources are severely depleted and polluted in the life cycle processes of fossil energy production, e.g., oil and gas extraction, coal mining and washing, coking, and crude oil refining. Freshwater is used in tunnel wash, dust removal, mining and drilling equipment, refining and coking reactors, and fracture of rocks. Water pollutants discharged into the environment from energy industries greatly threaten the regional water security [7,8]. There exists a high intensity of water pollution discharge (e.g., chemical oxygen demand, ammonia nitrogen, petroleum, and volatile phenols) in the fossil energy production [9,10]

Methods

Results

Conclusion