Categorising virtual water transfers through China’s electric power sector

New research led by ECI DPhil student, Xiawei Liao explores the interconnections between electricity generation and water consumption in China.

Hydro and thermoelectric power plants account for almost all of China’s electricity power generation2. Both processes lead to the loss of large volumes of water: hydropower, via reservoir evaporation; thermoelectric plants, via cooling processes.

Much has been done to quantify such inter-sector impacts and dependencies 3, 4. However, few appreciate that while electricity can be transmitted across geographical boundaries, water can also be redistributed through virtual water transfers embodied in the transmitted electricity.

Existing studies quantifying sub-national virtual water fluxes within China’s electric power system have adopted a production-based approach, which failed to address the inter-sector contributions among the final electricity users5,6.

New research, led by Xiawei Liao, a doctoral student at the University of Oxford’s Environmental Change Institute (ECI), proposes a new framework based on Multi-Regional Input-Output (MRIO) model. The paper, recently published in Applied Energy, uses the MRIO model to map the water flows in China’s electric power sector, linking physical water consumed in the generation of electricity, to virtual water embodied in electricity consumption.

The water embodiments are characterised as 1) virtual water embodied in the final consumption (VWEF) i.e. electricity consumption by final demand, including urban and rural household consumption, the public sector etc. and 2) virtual water in electricity used by industries (VWEI).

The researchers applied this framework to 30 provinces in China. They found that China’s thermoelectric and hydroelectric power production consumed 3.8 and 14.6 billion m³ of water respectively in 2010 (see Fig. 1), 60.2% of this driven by the intermediate electricity demands of industry (VWEI).

Figure 1. Water fluxes from physical water consumption to virtual water embodiments in China’s power sector (million m³). Dark Grey – Physical Water; Light Grey – Virtual Water. The width of the fluxes are proportionate to the volume of water.

Nearly half (47.5%) of water consumed in China’s power sector (8.77 billion m3 in 2010) was used for inter-provincial trading purposes, i.e. driven by electricity demands from other provinces.

Many coastal provinces in eastern China, e.g. Beijing, Tianjin, Hebei, Shandong, Jiangsu and Shanghai, are facing varying levels of demand-driven water scarcity due to extensive population growth and advanced development. Importing virtual water through the power sector helps alleviate physical water scarcity.

However, in China’s northern and north-western provinces, water scarcity is aggravated by virtual water outflows. This area is home to significant coal mining and coal-fired power generation. Much of the power generated in the region’s thermoelectric power plants is exported to other parts of China (Figure 2).

Figure 2. Provincial water scarcity in China and their net virtual water transfers through the power sector.

China initiated its West-to-East Power Transmission Project (WEPT) in the Tenth Five-year Plan (2000-2005)1 to stimulate economic development in Western China, while, alleviating resource pressure in the east. Despite concerns about water scarcity, coal-fired electricity transmissions from water-stressed provinces in the north and northwest through the WEPT Northern corridor to the capital region, Jing-jin-ji (Beijing-Tianjin-Hebei) Metropolitan Region, are encouraged in China’s 13th Five-Year Electricity Planning2.

The study warns that, without holistic planning, electric power provision to China’s electricity-importing regions, could threaten water resources in other parts of the country, and ultimately the sustainability to power generation in these exporting provinces. Increased electricity imports could inadvertently expose these net importing regions, which tend to have higher levels of population density, urbanisation and industrialisation, to increased water risk.

Liao, X., Zhao, X., Hall, J. W., & Guan, D. (2018) Categorising virtual water transfers through China’s electric power sector. Applied Energy. Vol. 226, 252–260.

References:

  1. National People’s Congress. 2001. The Tenth Five-Year Plan. Beijing, China.
  2. National Development and Reform Commission. 2016. ‘Electric Power Development 13th Five-Year Plan’. Beijing, China.
  3. Liao, X., Jim W. Hall and Nick Eyre. 2016. ‘Water use in China’s thermoelectric power sector’, Global Environmental Change, 41: 142-52.
  4. Zhang, C., L. Zhong, X. Fu, J. Wang, and Z. Wu. 2016. ‘Revealing Water Stress by the Thermal Power Industry in China Based on a High Spatial Resolution Water Withdrawal and Consumption Inventory’, Environ Sci Technol, 50: 1642-52.
  5. Zhang, Chao, L. Zhong, S. Liang, Kelly T. Sanders, J. Wang and M. Xu. 2017. ‘Virtual scarce water embodied in inter-provincial electricity transmission in China’, Applied Energy, 187: 438-448.
  6. Zhu, Xiaojie, R. Guo, B. Chen, J. Zhang, T. Hayat and A. Alsaedi. 2015. ‘Embodiment of virtual water of power generation in the electric power system in China’, Applied Energy, 151: 345-54.