Recently, Visiting Assistant Professor Bin Ye (School of Environmental Science and Engineering, ESE) from Southern University of Science and Technology (SUSTech) published a paper on atop journal of resource, Resources, Conservation & Recycling (IF 8.086).

The paper was entitled ” Feasibility of coupling PV System with long-distance Water Transfer: A case study of China’s ‘South-to-North Water diversion.’”

The study puts forward a new model to use limited land resources to develop and make use of renewable energy and reduce carbon emissions in inland areas.

To nationally optimize limited water resources, the Chinese government has had to build several nationwide long-distance water transfer channels. Some channels require large quantities of electrical energy to lift the water to a higher altitude. Within the context of the decrease of solar power generation cost, this study attempts to make full use of local solar energy resource and upper space of water channel to construct an on-channel photovoltaic (PV) system.

Fig. 1. SNWT project routes on the map.

This study firstly determines the installation area of solar panels. Based on image data, the longitude and latitude of critical points on the middle route of the south-to-North water Diversion Project were determined. Since the width of the river is between 9 and 40 meters, and the greening width of both sides of the river is 100 to 200 meters, although the average width of photovoltaic modules laid on the river is determined, two schemes are proposed in this study:

Scheme 1: Solar panels cover the channel water surface area, and the average width of the installation area is 40 meters, as demonstrated in Fig. 2. This scenario has a limited impact on the ecological system of the channel and the nearby environment.

Fig. 2. Scenario 1 (40 m width).

Scheme 2: The SNWT requires a 100 m greenbelt along each side of the channel, such that the total width of the channel is between 409 and 440 meters. Therefore, if 1/2 of the area is covered by solar panels, the influence on the ecological environment of the channel can be controlled to some extent. Based on this argument, the assumption of scenario 2 is as follows: the solar panels are supported 10–20 meters above the water surface via pillars. The rooftop’s average width is assumed to be 200 meters, covering both the channel and offering slope protection. This scenario is demonstrated in Fig. 3.

Fig. 3. Scenario 2 (200 m width).

This study shows that the cost of produced energy for the two cities are 0.36 Yuan/kWh and 0.35 Yuan/kWh, respectively, considering both initial investment and operating costs. Comparatively, the desulfurized coal-fired power plant baseline prices of the two provinces are 0.3779 Yuan/kWh and 0.3720 Yuan/kWh, respectively. Therefore, the feed-in price of solar electricity is lower than the desulfurized coal-fired baseline price.

According to the financial parameters setting, without subsidy, this project’s payback period is 19.8 years; however, if the renewable energy subsidy for PV is considered, the payback time can be dramatically reduced to 11.2 years. For return on investment (ROI), the two scenarios are 4.6% without subsidy, which means the project location’s influence is not significant. This weak influence may be that the initial investments are almost the same for the two scenarios, while the energy output has very limited disparity. Although ROI is only 4.6%, it is very close to the Chinese long-term treasury bond yield in September 2020. This result demonstrates that the rooftop solar projects are on the edge of the break-even line even without any government subsidy.

Alternatively, the evapotranspiration analysis shows that the solar panels’ shadow effects can reduce channel water evaporation to a certain degree. Furthermore, the carbon balance analysis shows the carbon reduction rate of solar energy can be 98.45% compared to the current coal dominated power system in the project installation provinces.

Replacing high-carbon coal power with renewable energy represented by photovoltaic power generation and wind power generation is one of the key ways to achieve the goals above. The research above provides a new way of thinking for developing renewable energy in inland areas where land resources are scarce.

The first author is Dr. Bin Ye. Associate Professor Jingjing Jiang (Harbin Institute of Technology, Shenzhen) and Professor Junguo Liu (ESE, SUSTech) are the corresponding authors. Southern University of Science and Technology is the first author affiliation.

This work appreciates the support of the National Natural Science Foundation of China, Natural Science Foundation of Shenzhen City, and the High-level Special Funding of the Southern University of Science and Technology.

Paper link: https://doi.org/10.1016/j.resconrec.2020.105194