Study On Coupling Simulation Of Water And Energy Nexus And Integrated Risk Evaluation

Water and energy,which are important material foundation for social and economic development and people's livelihood,are directly related to national security,social stability and sustainable development of resources.In the context of climate change,rapid urbanization,socio-economic development and population growth,the contradiction between the supply and demand of water and energy is increasingly prominent.There is an indivisible interdependence and mutual restriction between water and energy.Traditional water or energy planning often separated from each other,resulting in the pursuit of the development of the one at the expense of the resources of the other,and this decision-making method can no longer meet the current needs.This paper scientifically analyzes the relationship between water and energy,build the coupling simulation model of water and energy,and construct the integrated risk evaluation method.Taking Beijing as an example,this paper empirically study the energy consumption of water resources system,the water use for energy production and the virtual water transfer caused by energy supply form external provinces in typical year,and simulated the change trend of the water and energy coupling system in Beijing and the response of coupling system under climate change.The control plans of social dimension,economic dimension,technical dimension and policy dimension are set up respectively,and the effectiveness of each plan and the synergy conservation of energy and water are evaluated.Based on the optimal Frank Copula function,the two-dimensional coupling equation of the coupled system is constructed,and the integrated shortage risk of the coupled water and energy system is evaluated.The main conclusions of the paper include the following aspects:(1)Based on the physical process,the basic model of systematics and the attribute of the nexus,this paper scientifically analyzes the nexus between water and energy from multiple angles.There is a multi-angle,multi-layer and multi-dimensional nexus between water and energy.In terms of physical process,the extraction,mining,and production of energy are accompanied by the use water resources,and the water production process requires the consumption of energy to meet the water use standard.In the transportation stage,energy is the power guarantee of water resources in the process of water intake,water distribution and drainage,and each transportation process of water is accompanied by the consumption of energy.In the end use stage,the nexus between water and energy is reflected by the coupling of water as the carrier and energy as the power,whose purpose is to provide services for maintaining normal live in department of life.The industrial sectors often use water as a coolant and fossil fuels as a power to participate in industrial production.From the perspective of the basic model of systematics,the causal feedback relationship between water and energy can be summarized as four models:reinforcing loop,limits to growth,fixes and fail and success to success.From the attribute of the nexus,the coupling relationship between water and energy has obvious attribute in the dimensions of environment,society,economy,technology and policy.(2)The water and energy nexus in Beijing are calculated quantitatively.This paper quantitatively calculates the relationship between water and energy in Beijing from three aspects:energy consumption of water system,water use volume of energy production and virtual water transfer caused by external provinces energy supply.The results show that the energy consumption in the total process of water resource utilization in Beijing was 6.78 million tons of standard coal,accounting for about 9.51%of the total energy consumption in Beijing in 2017(71.33 million tons of standard coal).Among them,the water use section is the largest,accounting for 92.08%of the total process energy consumption.In 2017,the total amount of water used for energy production in Beijing and external provinces energy production for Beijing was 492 million m3,of which 202 million m3 was used for local production and 290 million m3 for external provinces energy production.Water use volume for energy production accounts for 5.1%of the city's total water use and 57.7%of industrial water use.In 2012,the amount of virtual water inflow caused by energy supply transfer outside Beijing totaled 503 million m3.Among them,the production and supply industry of power and heat(211 million m3)is the largest amount of virtual water inflow in the energy industry,accounting for 42%of the amount of virtual water inflow in total energy industry.Moreover,the provinces with more virtual water inflow caused by energy supply outside Beijing mainly come from the northern provinces where water resources are scarce.(3)The evolution trend of the coupling system of water and energy in Beijing is simulated,and validity of each dimension plan and the synergy of energy and water conservation are evaluated.The prediction results of the coupling water and energy simulation model based on the system dynamics show that Beijing's total water demand will reach 6.7 billion m3 by 2035,up 1.7 times from the base year of 2017,the total energy demand will reach 111.30 million tons of standard coal,an increase of 1.49 times compared with the base year,and the total energy consumption increased to a stable state after 2030.The energy consumption in the water resource utilization process reached 9.49 million tons of standard coal,accounting for 8.53%of the total energy consumption of the society,which increased by 1.52 times compared with the base year.The water use volume of energy production reached 1.17 billion m3,accounting for 17.5%of the total water consumption of the society,which increased by 2.4 times compared with the base year.Different policy scenarios have different water-saving and energy-saving effects.Social dimension,economic dimension,technical dimension and policy dimension--measures to import external electricity have synergistic energy-saving effects.Also,the measures of social dimension and economic dimension play the most obvious energy and water synergistic saving effect.Policy dimensions-renewable water reuse and south-to-north water diversion measures have alleviated the contradiction between the supply and demand of local water resources,but to some extent they have increased the burden on the energy system(4)The integrated shortage risk of the coupled system is evaluated.Based on the optimal marginal distribution function and the two-dimensional coupling equation of Frank Copula for the coupled system,the integrated shortage risk of the coupled water and energy system is calculated.The results show that by 2035,the shortage risk of water resources subsystem in Beijing will reach 0.90,the shortage risk of energy subsystem will reach 0.87,and the shortage risk of water and energy coupling system will reach 0.86.The implementation of policy dimensions-reclaimed water reuse measures is the most effective for the improvement of water resource subsystem shortage risk,followed by social dimension policies and policy dimensions—south-north water diversion measures.However,the implementation of the economic dimension policy is the most effective for the improvement of the shortage risk of the energy subsystem,followed by the social dimension and the technical dimension-energy conservation measures.For the coupling system of water and energy,the economic dimension policy is the most beneficial to the reduction of its shortage risk,followed by the social dimension and the policy dimension—the measures of renewable water.After the implementation of the policy dimension--the measures of renewable water,the shortage risk of the water resource subsystem decreased to 0.70,and after the implementation of the ecnomic dimension policy,the shortage risk of the energy subsystem decreased to 0.71,and the shortage risk of the coupled system decreased to 0.68.The findings of this paper provide a new perspective for the research on the relationship between water and energy,furnish technical support for the synergetic,sustainability and risk management of water and energy,and have practical value for improving the regional water resources and energy safeguard rate.