Environmentally feasible potential for hydropower development regarding environmental constraints

In addition to technical and economical reasons, environmental impacts are becoming an increasingly important issue in the policy making of hydropower development. According to different spatial scales, environmental impacts of hydropower projects can be divided into environmental impacts around a plant and environmental impacts downstream. The former can be transformed into a uniformed quantification based on CO2 equivalent (CO2-e), while the latter can be quantified in terms of reduced downstream flow. Environmental constraints around a plant are presented as the minimum production of environmental impacts around a plant, while those downstream are presented as not affecting the downstream environmental flow requirements. Based on five large hydropower projects (LHPs) and 10 small hydropower projects (SHPs) cases in Tibet, China, LHPs have greater environmental impacts around a plant when compared with SHP, but the opposite is true for downstream environmental impacts. For environmental constraints around a plant and downstream, the environmentally feasible potential for hydropower development on the Lhasa River is 398.3MW, which accounts for 15.6% of its theoretical potential, while the optimized hydropower mode choice is 285.7MW for LHP and 112.6MW for SHP. Environmentally feasible potential aims to balance hydropower generation with environmental protection, and tends to maximize the low carbon attributes of hydropower.