Du Tianyang, Dugdale Stephen J, Johnson Matthew F
School of Geography, University of Nottingham, University Park, Nottingham, NG7 2RD.
School of Geography, University of Nottingham, University Park, Nottingham, NG7 2RD.
Water Res. 2025 Sep 1;288(Pt A):124529. doi: 10.1016/j.watres.2025.124529.
Thermoelectric power plants are the backbone of global power production, providing a consistent and reliable electricity supply while offering great flexibility to meet rapidly fluctuating demands. However, the discharge of cooling water from these plants, particularly those employing once-through cooling systems, raises the temperature of receiving rivers, acting as a potentially concerning additional stressor in the context of existing climate change impacts on river temperature. This study employed synthetic boundary conditions, using a UK-typical river as a template, to create a generalised model representing a large, low-gradient, single-threaded river channel to examine the whole-river-scale impacts of cooling water discharge from thermoelectric power plants. A conceptual, process-based model of power plant effluent impacts on stream temperature was developed to simulate stream temperatures at hourly time scales across a series of scenarios with different combinations of effluent discharges, temperatures, and distances between power plants. Results showed that thermal energy from power plants can propagate considerable distances downstream, even if the energy input is low, and cause cumulative thermal impacts when combined with inputs from other downstream plants. Comparative analyses indicate that to minimise the impact of multiple power plants along the river, it is crucial to fully utilise the river's cooling capacity by placing the power plant with the largest thermal input downstream and as far from the upstream plant as possible. This study also found that effluent discharge contributed to greater increases in river temperature than effluent temperature, indicating its potentially greater importance in the management and regulation of power plant discharge. Power plant operation mode and climate change were also considered by adjusting operation schedules and climate variables. Thermal effluent from single-day operations of a peaking plant caused additional short-term temperature fluctuations. With sufficiently large heat inputs, these effluents interacted across space and time, leading to cumulative impacts that extended both the duration and length of the river affected by temperature increases. Climate change, as a gradual and long-term process, caused only minor increases in river temperature in comparison to power plant effluent, but exacerbated the impact of this effluent. These findings emphasise the importance of strategic placement and discharge management of power plants to mitigate thermal pollution and safeguard riverine ecosystems.
热电厂是全球电力生产的支柱，提供持续可靠的电力供应，同时具有很大的灵活性以满足快速波动的需求。然而，这些电厂排放的冷却水，尤其是那些采用直流冷却系统的电厂，会提高接纳河流的温度，在现有气候变化对河流温度影响的背景下，这成为一个潜在的令人担忧的额外压力源。本研究采用合成边界条件，以一条英国典型河流为模板，创建了一个代表大型、低坡度、单河道的通用模型，以研究热电厂冷却水排放对全河尺度的影响。开发了一个基于过程的概念模型，用于模拟电厂废水对溪流温度的影响，该模型在一系列不同废水排放、温度和电厂之间距离组合的情景下，以小时为时间尺度模拟溪流温度。结果表明，即使能量输入较低，电厂的热能也能在下游传播相当远的距离，并且与其他下游电厂的输入相结合时会造成累积热影响。比较分析表明，为了将沿河流多个电厂的影响降至最低，至关重要的是通过将热输入最大的电厂置于下游并尽可能远离上游电厂，来充分利用河流的冷却能力。本研究还发现，废水排放比废水温度对河流温度升高的贡献更大，表明其在电厂排放管理和监管中可能具有更大的重要性。通过调整运行时间表和气候变量，还考虑了电厂运行模式和气候变化。调峰电厂单日运行产生的热废水导致了额外的短期温度波动。在有足够大的热输入时，这些废水在空间和时间上相互作用，导致累积影响，延长了受温度升高影响的河流的持续时间和长度。气候变化作为一个渐进的长期过程，与电厂废水相比，仅导致河流温度小幅升高，但加剧了这种废水的影响。这些发现强调了电厂战略布局和排放管理对于减轻热污染和保护河流生态系统的重要性。
