Embedded water is everywhere, from the shirts we wear to the cereals we eat, not to mention beef. Less well-known is the water that transits through electricity grids, that is, the water used to generate electricity that “flows” in the grid from electricity production regions to electricity consumption ones. A recent article sheds some light on these hidden water flows, and, as in the case of international trade, sub-optimal configurations prevail: China’s dry provinces feed relatively wetter provinces with water-intensive electricity. The development of long distance transmission lines might reinforce these outflows of scarce water, further exacerbating local water issues in these provinces.
Geographical mismatch means dry regions produce most of thermal power generation
China is a country of geographical mismatch; this is especially true on the energy front. Coal and hydropower resources, the main sources of China’s electricity, are located far from urban electricity clusters where a growing share of electricity is consumed.
Most of China’s coal (85%) is mined in fifteen Northern provinces. Given that electricity often proves easier to move than coal, many thermal power plants are located in these same regions, raising tensions with limited water resources (these same fifteen provinces only account for around 15% of China’s freshwater resources). In contrast, hydropower generation mainly lies in South and Southwestern regions, with Sichuan, Yunnan and Hubei representing almost 60% of China’s hydropower generation.
As a consequence, Northern/Northwestern as well as Southern/Southwestern provinces are mainly net electricity exporters whilst coastal regions are net electricity importers, as shown in the map below.
Northern and western regions: net electricity exporters;
Coastal regions: net importers
(click to enlarge)
Water embedded in power generation
Coal is a relatively thirsty source of power generation, especially when it is located in inland provinces where it cannot rely on seawater for cooling. As a result, each electron “generated” by a coal power plant comes with its associated water consumption, and interprovincial electricity transfers translate into interprovincial virtual water flows.
Water withdrawal vs. Water consumption
Water withdrawal is the water removed from the ground or diverted from a municipal source for use in the plant.
From electricity importers to water importers – urban clusters remain dependent
Given the dominant role played by coal in Northern provinces and the water intensity of coal-fired power plants, these net electricity exporters regions automatically become net water exporters of water through the electrical grid. A recent study by Chinese and American researchers looked precisely at these virtual water flows. Based on this study’s results, the map below shows the provinces exporting and importing virtual water embedded in electricity.
Northern and western regions: net exporters of virtual water through electricity distribution;
Coastal regions: net importers
(click to enlarge)
This resonates with Professor Hoekstra’s view that cities, or more generally urban areas, are by definition unsustainable – read our interview with Professor Hoekstra here. For instance, around 60% of the water footprint associated with Beijing’s electricity consumption comes from other provinces, namely Inner Mongolia and Shanxi. This should put into perspective recent media headlines that praised Beijing city for closing its last coal power plant.
Virtual water transfer represents around 13% of the power sector’s water consumption
The diagram below, directly extracted from the same study, further details these inter-grid and inter-provincial flows.
If you are lost in the chords, here are some key takeaways from the chart:
Inner Mongolia (combining West and East Inner Mongolia) is the largest exporter of virtual water. The total outflow of virtual water is around 130 million m3. Other major exporters include Anhui, Shaanxi, Guizhou, Ningxia and Hubei.
Hebei, Guangdong, Beijing and Liaoning are the largest importers.
More than half of inter-provincial virtual water transfers happen across sub-national grid networks. This highlights the role of long-distance transmission lines and the ability they grant to outsource the pressure on resources (and air quality) to ever more remote provinces.
Overall, inter-provincial virtual water transfers account for around 13% of the national thermoelectric water consumption.
Accounting for water stress: not every drop of water is equal
In the study, authors also adopt a “scarcity-adjusted” measurement of virtual water. The underlying assumption is that a drop of water in a water-stressed province should count for more when the local water stress is higher. Surely this approach is to some extent arbitrary – see Prof. Hoekstra’s opinions on water stress-adjusted LCA analysis. However, it can prove useful to highlight the flows of scarce water i.e. sourced from water stressed provinces – see the updated chart below.
Results clearly show how Inner Mongolia, Shanxi, Gansu and Ningxia, despite being highly water-stressed, export scarce water through the electricity grid. Beijing, Hebei and Shandong are the three largest destinations of this scarce water.
Flows will rise as grid develops – reducing curtailment could curb pressure on water
This kind of study sheds light on the hidden water that lies virtually everywhere, and the need to consider the associated constraints when devising energy and food policies. With the expected development of long-distance transmission capacity, especially from West to East and from North to South, the pressure on North and Northwestern water resources might grow even further.
This further stresses the need to reduce renewable energy curtailment in Northern provinces. The irony is that three out of the four largest exporters of “scarce water” through the electricity grid (namely Inner Mongolia, Gansu and Ningxia) also belong to the five provinces with highest curtailment rates of wind power. With the water footprint of wind and solar PV power generation being substantially lower than thermal power, addressing curtailment would also help curb the pressure on local water resources.
- Water Footprint: The Road Ahead - Prof. Arjen Hoekstra, the creator of the water footprint concept, talks to China Water Risk about hard truths on the challenges ahead over virtual water trade, water scarcity & over-consumption
- Water Footprint: Why It Matters - Despite growing recognition, water footprint is not without its detractors. China Water Risk’s Woody Chan reviews the concept and gives five reasons why it is still relevant for policy-making in China
- Fast Fashion: Sucking Aquifers Dry? - Groundwater is over-extracted to grow cotton. As the world’s largest importer of cotton, is it China’s fault? Or is fast fashion to blame? China Water Risk’s Tan explores trends in the growth across major brands, China’s imports & global cotton production
- FreshWater Watch: Citizen Science At Work - Earthwatch Institute’s Benita Chick explores how the public can work with scientists to fast-track 11 years worth of water research. Find out what local and global impacts such programmes can make
- China’s Increasing Use Of Public Environmental Data – China is trying to develop a green credit rating system. Dr Guo Peiyuan, a member of China Financial Association’s Green Finance Expert Committee, expands on publicly available environmental data & how it can help
- Wind & Sun: Relief For China’s Dry North - China’s North is parched but is home to a significant amount of coal reserves & arable land. Can wind & solar power help bring relief? CWR’s Thieriot on how but be warned, challenges remain
- China’s Hidden Water Flows - Prof Hubacek & Dr. Feng contributing authors of ”Virtual Scarce Water in China” share key findings. Find out why developed but water-scarce regions like Beijing, Tianjin and Shanghai are contributing to the country’s water depletion