Preamble

ARID LAND GEOGRAPHY Vol. 48 No. 8 Aug. 2025

Water-saving Potential of Renewable Energy-based Hydrogen Production in the Yellow River Basin from a Water Footprint Perspective

LI Hui¹, YAO Xilong²
¹ School of Economics and Management, Taiyuan University of Science and Technology, Taiyuan, Shanxi, China
² College of Economics and Management, Taiyuan University of Technology, Taiyuan, Shanxi, China

Abstract: Scientifically quantifying and analyzing the water footprint and water-saving potential of renewable energy-based hydrogen production is crucial for the high-quality development of the hydrogen energy industry and the sustainable utilization of water resources in the provinces (autonomous regions) of the Yellow River Basin. This study constructs a "bottom-up" water footprint evaluation model for hydrogen production technologies based on life cycle theory to analyze and compare the water footprints and their components for renewable energy-based hydrogen production and coal-based hydrogen production. Focusing on the provinces (autonomous regions) in the Yellow River Basin, we investigate the water-saving intensity of renewable energy-based hydrogen production under different scenarios. Simultaneously, considering the differences in provincial power structures and water scarcity footprints, we explore the water-saving potential of replacing coal-based hydrogen production with renewable energy-based hydrogen production using the Available Water Remaining indicator. The results show that: (1) The water scarcity footprint of renewable energy-based hydrogen production is largest in the northern Yellow River Basin, particularly in the northwestern region, with Inner Mongolia exhibiting the highest water scarcity footprints for photovoltaic and wind power hydrogen production at 637.73×10⁶ m³ and 1167.7×10⁶ m³, respectively. (2) The water-saving intensity of renewable energy-based hydrogen production demonstrates a "high in the southwest, low in the northeast" pattern, with average water-saving intensities of 1.04 L·kg⁻¹ for photovoltaic hydrogen production and 31.29 L·kg⁻¹ for wind power hydrogen production when replacing coal-based hydrogen production. (3) Inner Mongolia has the greatest water-saving potential for wind power hydrogen production, followed by Qinghai, Gansu, and Shanxi. Qinghai has the greatest water-saving potential for photovoltaic hydrogen production, followed by Gansu and Sichuan. These findings not only establish a foundation for improving water resource utilization efficiency in the Yellow River Basin but also provide important guidance for the scientific planning and layout of the hydrogen energy industry in each province (autonomous region) of the basin.

Keywords: renewable energy; hydrogen energy; water footprint; water-saving potential; Yellow River Basin

1 Introduction

Energy and water resources are the material foundation and strategic resources for sustainable economic and social development, representing the most fundamental support for human society's transition to a sustainable future. Under the "dual carbon" goals, hydrogen energy plays a pivotal role in constructing a new energy system, not only facilitating deep decarbonization in transportation, industry, and construction sectors but also coupling with wind and photovoltaic power generation to promote renewable energy utilization and consumption. China is accelerating the deployment of its hydrogen energy industry. Among existing hydrogen production technologies, renewable energy-based water electrolysis demonstrates the highest water use efficiency. The Yellow River Basin is one of China's most important hydrogen production regions, with the majority of hydrogen enterprises concentrated in the nine provinces (autonomous regions) along the Yellow River. Most of these enterprises are located in areas experiencing water stress or extreme water scarcity, where water supply-demand conflicts are prominent. Against the backdrop of decreasing total water resources and rapidly growing water demand from the hydrogen energy industry, the water shortage situation in the Yellow River Basin remains severe. How to scientifically evaluate the water resource utilization status of the hydrogen energy industry and improve water use efficiency has become key to promoting high-quality development of the hydrogen energy industry.

The concept of water footprint was first proposed by Hoekstra based on virtual water theory to measure the volume of water resources consumed in producing a product or providing a service during a certain period. Water footprint links physical water with virtual water, identifying not only direct water use by consumers or producers but also their indirect water use. This concept has effectively broadened the theoretical connotation of water resources research and has become an important indicator for studying water scarcity and water resource impacts. Scholars have applied water footprint theory to investigate water resource utilization, consumption, water-energy nexus relationships, and spatial water transfer in energy product production and consumption. For instance, Yan et al. conducted a water footprint quantification assessment of Xinjiang's power industry, analyzing the contribution pathways of different power generation technologies and providing a basis for water footprint accounting in other sectors. Shi et al. established a water footprint evaluation framework for electrolytic hydrogen production, comparing water footprints of grid electricity and renewable energy-based hydrogen production and examining influencing factors. Current indicators related to energy product water footprints primarily include water-saving intensity, water-saving potential, and water scarcity footprint. Water-saving intensity and potential measure water savings from technological improvements or substitutions, while water scarcity footprint measures resource consumption trajectories and ecological pressure caused by water supply-demand imbalances in specific regions or populations.

Existing literature has extensively analyzed energy product water footprints, providing a rich foundation for this study. However, several gaps remain: (1) Compared with other sectors, research on the water footprint of the hydrogen production industry is relatively limited, with some studies analyzing only the production phase rather than the entire life cycle. (2) Few studies have examined the impact of hydrogen technology substitution on water resources at the provincial level, particularly in the Yellow River Basin where hydrogen production is high but water supply-demand conflicts are acute. (3) The influence of inter-provincial differences in power structure on water-saving intensity and potential has not been fully considered, and quantitative research on the water-saving potential of renewable energy-based hydrogen production remains insufficient. Therefore, this study constructs a "bottom-up" water footprint evaluation model for hydrogen production technologies based on life cycle theory, considering both direct water use in hydrogen production and indirect water use from upstream raw materials. The model analyzes water footprints and their components for different hydrogen production technologies. Focusing on the provinces (autonomous regions) in the Yellow River Basin and considering variations in power structure and remaining available water, this study investigates the water-saving intensity and potential generated by hydrogen technology substitution, providing a reference for the coordinated development of the hydrogen industry and water resources in the Yellow River Basin.

1.1 Study Area Overview

The Yellow River Basin is an important energy and basic industrial base in China, playing a crucial role in ensuring energy supply security and promoting economic development. The Yellow River stretches 5,464 km with a total area of 795,000 km², covering nine provinces (autonomous regions): Sichuan, Qinghai, Ningxia, Inner Mongolia, Gansu, Shaanxi, Shanxi, Henan, and Shandong. The basin is a typical resource-scarce watershed, with most areas located in arid and semi-arid regions. Total water resources account for less than 2% of the national total, and per capita water availability is only 23% of the national average. Coal-based hydrogen production in the Yellow River Basin has an average annual water extraction of 1.04×10⁹ m³ and an average annual water consumption of 0.65×10⁹ m³, with water consumption accounting for 62.5% of water extraction. For a long time, water supply-demand contradictions have been prominent in the Yellow River Basin, and water scarcity has severely limited economic and social development. Therefore, studying the water-saving potential of renewable energy-based hydrogen production in the Yellow River Basin is of great significance for coordinated economic, social, and ecological development.

1.2 Data Sources

This study utilizes water resources data from the Water Resources Bulletins (2020–2022) of each province (autonomous region). Power generation data are obtained from the China Electric Power Statistical Yearbook (2020–2022), while renewable energy data come from the China Energy Statistical Yearbook (2020–2022) and the National Economic and Social Development Statistical Bulletins (2020–2022) of each province. Hydrogen industry data are collected from official government websites, hydrogen industry development plans, and the hydrogen industry big data platform (https://www.chinah2data.com/#/client/home) of each province (autonomous region).

1.3 Methods

1.3.1 Water Footprint Calculation Methods

Grounded in life cycle principles, water footprint comprehensively quantifies water resource consumption from human production activities and effectively reflects the water-energy nexus. This study examines coal-based hydrogen production and renewable energy-based water electrolysis hydrogen production, considering both direct water use in hydrogen production and indirect water use from upstream raw materials. The system boundaries for coal-based and renewable energy-based hydrogen production are illustrated in [FIGURE:1] and [FIGURE:2], respectively.

The water footprint of coal-based hydrogen production is calculated as follows:

$$
HWF_{cth} = WF_{cm} + WF_{ct} + WF_{cg} + WF_{es}
$$

where $HWF_{cth}$ is the water footprint of coal-based hydrogen production (L·kg⁻¹); $WF_{cm}$ is water use for coal mining and washing (L·kg⁻¹); $WF_{ct}$ is water use for coal transportation (L·kg⁻¹); $WF_{cg}$ is water use for coal gasification hydrogen production (L·kg⁻¹); and $WF_{es}$ is water use for electricity supply (L·kg⁻¹).

The life cycle water consumption intensity of electricity supply is calculated as:

$$
WI_{ele} = \sum_{n=1}^{m} WI_n \times \frac{PG_n}{PG_{total}}
$$

where $WI_{ele}$ is the life cycle water consumption intensity of electricity supply in the nine Yellow River provinces (L·kWh⁻¹); $WI_n$ is the water consumption intensity of the $n$th power generation technology (L·kWh⁻¹); $PG_n$ is the annual power generation of the $n$th technology in a province (kWh); $PG_{total}$ is the total annual power generation in a province (kWh); and $m$ is the number of power generation technologies. Detailed water consumption intensities for different power generation technologies are provided in [TABLE:1].

The water footprint of renewable energy-based water electrolysis hydrogen production is calculated as:

$$
HWF_{rel} = WF_{el} + WF_{re} + WF_{co}
$$

where $HWF_{rel}$ is the water footprint of renewable energy-based hydrogen production (L·kg⁻¹); $WF_{el}$ is water use in the electrolysis process (L·kg⁻¹); $WF_{re}$ is water use for renewable electricity generation (L·kg⁻¹); and $WF_{co}$ is cooling water (L·kg⁻¹).

1.3.2 Water-saving Potential Evaluation Methods

If the water footprint of renewable energy-based hydrogen production is smaller than that of coal-based hydrogen production, the water-saving intensity is positive, indicating water-saving benefits. Conversely, a negative water-saving intensity indicates increased water consumption pressure.

The water-saving intensity is calculated as:

$$
HWSI_i = HWF_{cth}^i - HWF_{rel}^i
$$

where $HWSI_i$ is the water-saving intensity of renewable energy-based hydrogen production in province $i$ (L·kg⁻¹).

The water-saving potential is calculated as:

$$
HWSP_i = HWSI_i \times HP_i
$$

where $HWSP_i$ is the water-saving potential of renewable energy-based hydrogen production in province $i$ (m³); and $HP_i$ is the planned hydrogen production capacity in province $i$ (kg).

To better reflect how changes in hydrogen production technology affect available water resources in each province (autonomous region), this study introduces the Available Water Remaining (AWARE) indicator. AWARE evaluates the absolute quantity of available freshwater in each region, considering human and environmental freshwater demands. The greater the remaining freshwater, the smaller the burden caused by new or increased freshwater consumption. This indicator quantifies the likelihood of water scarcity caused by new water consumption and provides comparability of water consumption impacts across regions.

The AWARE characterization factor is calculated as:

$$
AMD_i = \frac{WS_i - WC_i}{AM_i}
$$

$$
AMD_{ref} = \frac{\sum_{i=1}^{n} HWC_i}{\sum_{i=1}^{n} AMD_i}
$$

$$
AWARE_{CF}^i = \frac{AMD_{ref}}{AMD_i}
$$

where $AMD_i$ is the remaining available freshwater per unit area in province $i$ (m³ m⁻²); $WS_i$ is the total water supply in province $i$ (m³); $WC_i$ is water consumption in province $i$ (m³); $AM_i$ is the actual land area of province $i$ (m²); $HWC_i$ is human water consumption in province $i$ (m³); $AMD_{ref}$ is the reference value of available water remaining per unit area (m³ m⁻²); and $AWARE_{CF}^i$ is the characterization factor for province $i$. A larger $AMD_i$ value corresponds to a smaller $AWARE_{CF}^i$ value, indicating greater remaining available water per unit area.

This study couples water-saving intensity and potential with the $AWARE_{CF}$ factor. The water scarcity footprint, adjusted water-saving intensity, and adjusted water-saving potential are calculated as:

$$
HWSF_i = HWF_{rel}^i \times AWARE_{CF}^i
$$

$$
HWSIA_i = HWSI_i \times AWARE_{CF}^i
$$

$$
HWSPA_i = HWSP_i \times AWARE_{CF}^i = HWSI_i \times HP_i \times AWARE_{CF}^i
$$

where $HWSF_i$ is the water scarcity footprint (L·(kg eq)⁻¹); $HWSIA_i$ is the adjusted water-saving intensity (L·(kg eq)⁻¹); and $HWSPA_i$ is the adjusted water-saving potential (m³).

2 Results

2.1 Water Footprint of Hydrogen Production Technologies

The water footprints of coal-based hydrogen production in Yellow River Basin provinces (autonomous regions) are shown in [FIGURE:3]. Without carbon capture, utilization, and storage (CCUS) technology, the top three provinces in terms of water footprint are Sichuan, Qinghai, and Gansu, with values of 69.57 L·kg⁻¹, 82.87 L·kg⁻¹, and 104.76 L·kg⁻¹, respectively. After adding CCUS technology, the water footprints of coal-based hydrogen production increase across all provinces. The water footprints for Sichuan, Qinghai, and Gansu increase to 111.32 L·kg⁻¹, 140.63 L·kg⁻¹, and 182.14 L·kg⁻¹, respectively. CCUS technology consumes substantial water resources during carbon capture, storage, and utilization processes. Although it reduces carbon emissions from coal-based hydrogen production, it increases the life cycle water consumption.

Variations in water footprints among provinces primarily stem from differences in power structure. For example, Sichuan has a high proportion of hydropower, followed by coal power, with minimal wind and photovoltaic generation. In contrast, Ningxia has a high proportion of coal power, moderate wind and photovoltaic generation, and minimal hydropower. These differences in power structure lead to varying life cycle water consumption intensities of electricity supply, consequently resulting in different water footprints for coal-based hydrogen production.

As shown in [FIGURE:4], the water footprint of renewable energy-based water electrolysis hydrogen production consists primarily of water used in the electrolysis process, electricity generation, and cooling. The water footprints for wind power hydrogen production and photovoltaic hydrogen production are 36.40 L·kg⁻¹ and 41.25 L·kg⁻¹, respectively, showing significant differences in composition. Electricity generation accounts for 30.22% of the water footprint in wind power hydrogen production, while it represents 61.89% in photovoltaic hydrogen production. Hydropower-based hydrogen production has a water footprint of 740.40 L·kg⁻¹, substantially higher than photovoltaic and wind power hydrogen production, with electricity generation accounting for 96.57% of the water footprint at 715.00 L·kg⁻¹.

2.2 Water-saving Intensity of Renewable Energy-based Hydrogen Production

To investigate the impact of hydrogen production technology substitution on water resources in Yellow River Basin provinces, this study establishes two scenarios: Scenario 1 involves photovoltaic hydrogen production replacing coal-based hydrogen production, and Scenario 2 involves wind power hydrogen production replacing coal-based hydrogen production. Hydropower-based hydrogen production is not considered due to its significantly higher water footprint compared to other renewable energy sources.

The water-saving intensities of renewable energy-based hydrogen production are presented in [FIGURE:5]. Under the photovoltaic replacement scenario, water-saving intensity shows a "high in the southwest, low in the northeast" pattern across the nine provinces. Sichuan, Qinghai, and Gansu exhibit positive water-saving intensities of 16.22 L·kg⁻¹, 14.69 L·kg⁻¹, and 2.92 L·kg⁻¹, respectively, while Henan, Shanxi, and Shandong show negative values of -6.84 L·kg⁻¹, -8.64 L·kg⁻¹, and -8.34 L·kg⁻¹, respectively. This pattern occurs because southwestern regions have high hydropower proportions with substantial water consumption, making photovoltaic hydrogen production relatively less water-intensive. In contrast, northeastern regions have high coal power proportions, and photovoltaic hydrogen production has a higher water footprint than coal-based hydrogen production, thus increasing water demand.

Under the wind power replacement scenario, all nine provinces show positive water-saving intensities, indicating water-saving benefits across the board. The average water-saving intensity for wind power hydrogen production is 31.29 L·kg⁻¹. The three provinces with the highest intensities are Sichuan (33.17 L·kg⁻¹), Qinghai (32.96 L·kg⁻¹), and Gansu (32.35 L·kg⁻¹), while Ningxia has the lowest at 20.81 L·kg⁻¹. Therefore, promoting wind power hydrogen production technology can effectively reduce water consumption in the hydrogen industry and alleviate water-energy tensions in the Yellow River Basin.

2.3 Water Scarcity Footprint of Renewable Energy-based Hydrogen Production

The water scarcity footprints of renewable energy-based hydrogen production are shown in [TABLE:2]. The average water scarcity footprints for photovoltaic and wind power hydrogen production across the nine provinces are 80.80×10⁶ m³ and 147.96×10⁶ m³, respectively. Inner Mongolia exhibits the largest water scarcity footprints for both photovoltaic (1167.70×10⁶ m³) and wind power (637.73×10⁶ m³) hydrogen production, followed by Qinghai, Gansu, Shanxi, Shandong, Ningxia, and Henan. Sichuan shows the smallest water scarcity footprints for both technologies at 0.88×10⁶ m³ and 0.48×10⁶ m³, respectively.

2.4 Water-saving Potential Based on AWARE Characterization Factor

Using the $AWARE_{CF}$ factor for each province, this study adjusts the water-saving intensity of renewable energy-based hydrogen production technologies, as shown in [FIGURE:6]. Under the photovoltaic scenario, the average adjusted water-saving potential across the nine provinces is -1665.98×10⁶ m³. Qinghai, Gansu, and Sichuan show positive potentials of 1525.01×10⁶ m³, 205.89×10⁶ m³, and 50.47×10⁶ m³, respectively, while Inner Mongolia, Shanxi, and Shaanxi show negative potentials of -16119.35×10⁶ m³, -470.04×10⁶ m³, and -1525.01×10⁶ m³, respectively.

Under the wind power scenario, the average adjusted water-saving potential is 5049.20×10⁶ m³. Inner Mongolia has the greatest potential at 36878.42×10⁶ m³, followed by Qinghai (4368.60×10⁶ m³), Gansu (2336.23×10⁶ m³), and Shanxi (1175.48×10⁶ m³). The adjusted water-saving potentials for Henan and Shandong are relatively small at 1092.08×10⁶ m³ and 11.64×10⁶ m³, respectively.

To better compare differences between adjusted and unadjusted water-saving potentials, this study analyzes typical provinces including Shanxi, Gansu, and Sichuan. As shown in [FIGURE:8], Gansu and Sichuan have photovoltaic water-saving potentials of 58.47×10⁶ m³ and 41.92×10⁶ m³, respectively. Although Gansu's potential is 1.4 times that of Sichuan, after accounting for differences in remaining available water resources, Gansu's adjusted potential becomes 4.1 times that of Sichuan, indicating that photovoltaic replacement would yield greater water-saving benefits in Gansu.

Shanxi and Shandong have photovoltaic water consumption potentials of 174.54×10⁶ m³ and 110.87×10⁶ m³, respectively. Shanxi's potential is 1.6 times that of Shandong, but after adjustment, Shanxi's water consumption potential becomes 2.8 times that of Shandong, suggesting that photovoltaic replacement would create more severe water pressure in Shanxi.

As shown in [FIGURE:9], Shandong and Shaanxi have wind power water-saving potentials of 291.45×10⁶ m³ and 198.30×10⁶ m³, respectively. Shandong's potential is 1.5 times that of Shaanxi, but after considering local remaining available water resources, Shandong's adjusted potential becomes 0.3 times that of Shaanxi, indicating that wind power replacement would yield greater water-saving benefits in Shaanxi. Gansu and Shanxi have wind power water-saving potentials of 663.47×10⁶ m³ and 436.51×10⁶ m³, respectively. Although Gansu's potential is 1.5 times that of Shanxi, its adjusted potential becomes 2.0 times that of Shanxi, demonstrating that wind power replacement would generate greater water-saving benefits in Gansu.

3 Discussion

This study finds that replacing coal-based hydrogen production with renewable energy-based hydrogen production can effectively conserve water resources and improve water use efficiency in water-scarce regions. The water-saving intensity of renewable energy-based hydrogen production shows a "high in the southwest, low in the northeast" pattern, consistent with previous research. The varying water-saving potentials across Yellow River Basin provinces primarily result from two factors: (1) Different provincial power structures lead to variations in the water footprint of coal-based hydrogen production, and (2) Different remaining available water resources in each province.

Taking Qinghai and Sichuan as examples, Qinghai's power structure is dominated by hydropower (50.71%), followed by wind and photovoltaic generation (34.22%), while Sichuan's hydropower accounts for 82.21%, coal power for 3.07%, and wind/photovoltaic for only 14.72%. Based on the water footprint calculation method, the water footprints of coal-based hydrogen production in Qinghai and Sichuan are 82.87 L·kg⁻¹ and 104.76 L·kg⁻¹, respectively. Additionally, according to water resource utilization and land area, the remaining available freshwater per unit area in Qinghai and Sichuan is 0.001 m³ m⁻² and 0.023 m³ m⁻², respectively. These factors collectively result in different water-saving potentials: Qinghai's photovoltaic and wind power hydrogen production potentials are 1525.01×10⁶ m³ and 4368.60×10⁶ m³, respectively, while Sichuan's are 50.47×10⁶ m³ and 90.53×10⁶ m³, respectively.

Furthermore, compared with photovoltaic hydrogen production, wind power hydrogen production can more effectively reduce water consumption in the hydrogen industry and safeguard water resources security in the Yellow River Basin. Wind power hydrogen production represents the optimal pathway for sustainable development of the hydrogen industry in Yellow River Basin provinces.

4 Conclusions

To investigate the water-saving potential of renewable energy-based hydrogen production in the Yellow River Basin, this study constructs a "bottom-up" water footprint evaluation model from a life cycle perspective, analyzes water footprints and their components for different hydrogen production technologies, examines water-saving intensity under different scenarios, and evaluates water-saving potential using the Available Water Remaining indicator. The main conclusions are:

1. Significant differences exist in water footprints and their components across hydrogen production technologies. For coal-based hydrogen production, water used in the hydrogen production process and electricity generation accounts for the largest proportion of the water footprint. For renewable energy-based hydrogen production, electricity generation water use dominates, followed by cooling water, with electrolysis process water use being the smallest. Moreover, the water scarcity footprint of renewable energy-based hydrogen production is largest in northern Yellow River Basin provinces, particularly in northwestern regions.

2. The water-saving intensity of renewable energy-based hydrogen production shows a "high in the southwest, low in the northeast" pattern. The average water-saving intensity for photovoltaic hydrogen production is 1.04 L·kg⁻¹, with positive values only in Sichuan, Qinghai, and Gansu, while other provinces show negative values, indicating that photovoltaic hydrogen production would increase water demand in those regions. The average water-saving intensity for wind power hydrogen production is 31.29 L·kg⁻¹, with all provinces showing positive values, demonstrating that wind power hydrogen production substitution can significantly reduce water consumption and alleviate water pressure.

3. Inner Mongolia has the greatest water-saving potential for wind power hydrogen production, followed by Qinghai, Gansu, and Shanxi. Qinghai has the greatest water-saving potential for photovoltaic hydrogen production, followed by Gansu and Sichuan. Therefore, from the perspectives of efficient water resource utilization and sustainable hydrogen industry development, Qinghai and Gansu are suitable for developing both wind and photovoltaic hydrogen production, while Inner Mongolia and Shanxi are suitable for wind power hydrogen production.

This study has certain limitations. For instance, the scenario simulation only considers hydrogen production technology substitution without forecasting other development trends. Future research will incorporate detailed predictions of social, economic, and technological development trends related to hydrogen production to provide scientific foundations and decision-making support for regional water-energy synergy and hydrogen industry planning.

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