Development of Wet-Bulb-Temperatures in Germany with special regard to conventional thermal Power Plants using Wet Cooling Towers

• Published in: Meteorologische Zeitschrift
• Main Authors: Aich, V., Strauch, U., Sieck, K., Leyens, D., Jacob, D., Paeth, H.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2011
• Subjects: North Atlantic; North Atlantic oscillation
• Online Access: http://hdl.handle.net/11858/00-001M-0000-000F-4E3E-A; http://hdl.handle.net/21.11116/0000-000B-6875-D

Wet-bulb-temperature (WBT) defines the cooling distance of cooling water in wet cooling towers (or wet honeycomb radiators) at water-cooled power plants. Thus, the development of WBT in the 21st century under different scenarios of future climate change is highly relevant for the electricity production sector and is examined in this study for Germany. We use high-resolution simulated data from the regional climate model REMO. As WBT is no direct model output, it is calculated using dry-bulb-temperature (DBT), relative humidity and surface air pressure using two alternative methods. The iterative method provides better results for validation. The computed WBT is quite close to the observations. It reveals a statistically significant exponential increase until 2100 ranging from 1.6 degrees C to 2.4 degrees C in the B1 scenario and from 2.6 degrees C to 3.4 degrees C in the A2-scenario. Furthermore the study indicates that changes of the DBT will be the decisive factor for the ! WBT-increase in the 21st century. Significant differences in the increase of extreme heat events between a region in northern and one in southwestern Germany are highlighted by a threshold analysis. The increase of hourly extreme values in southwestern Germany is about 30% higher than in the north. A detected west-east gradient is probably related to the North Atlantic Oscillation and a general increase in westerly situations over Germany. The discrepancies between B1 and A2 scenario are striking and highlight the impact of different levels of global greenhouse gas emissions on regional climate.