Virtual Water Embodied in Interregional Energy Trade in China: A City-Level Analysis

Large volumes of water are used in
energy production for both primary
(e.g., fuel extraction) and secondary energy (e.g., electricity).
In countries such as China, with a large internal trade in fuels and
long-distance transmission grids, this can result in considerable
water inequalities. Previous research focused on the water impacts
of energy production at the national and provincial levels, which
is too coarse to identify the spatial differences and make specific
case studies. Here, we take the next step toward a spatially explicit
economically integrated water-use for energy assessment by combining
a bottom-up assessment approach with a city-level multiregional input–output
model. Specifically, we examine the water consumption of energy production
in China, distinguishing between water for primary and secondary energy
at the level of coal mines, oil and gas fields, and power plants for
the first time. Of the total energy-related freshwater consumption
of 4.9 Gm3 in 2017, primary energy accounted for 19% (940
Mm3) and secondary energy accounted for 81% (3955 Mm3). Coal was the largest water consumer for both primary and
secondary energy (540 and 3880 Mm3, respectively), with
both oil (361, and 0.5 Mm3, respectively) and gas (7 and
69 Mm3, respectively) also consuming large amounts. Intercity
virtual water, that is, water embodied in energy trade across cities,
reached 54% (2.6 Gm3) of energy-related freshwater consumption.
Across China, 32% of cities see a bilateral trade in secondary- and
primary-energy-related virtual water (e.g., Daqing city exports virtual
water embodied in primary fuel to other cities that is then used to
produce electricity in those cities, part of which is used back in
Daqing via transmission). For these 32% of cities, 73% export more
virtual water than import and 27% import more virtual water than export.
This study reveals significant differences in city-level virtual water
patterns (e.g., scale and direction) between primary and secondary
energy to provide information for cities about their virtual water
inflow and outflow and the potential collaboration partners for water
management.