Measurement and Mitigation of Radon Concentration in a Traditional Dwelling in Galicia, Spain

Radon is a naturally occurring radioactive gas which tends to build up within structures. It is therefore necessary to include techniques to mitigate radon concentration when undertaking refurbishment. The goal of this study is to assess the effectiveness of a mitigation technique based on pressurizing the interior of a building, by testing a prototype of the mitigating device, developed by Siglo 21 Consultores and the LaRUC of the University of Cantabria, under real conditions, to determine its effectiveness during refurbishment. The methodology involved installing the proposed solution in a traditional country dwelling in an area characterized by high radon concentration, on the coast of Galicia, Spain. In order to measure the effectiveness of the solution, continuous measurement sensors, set in an ionization chamber, and properly calibrated by the LaRUC laboratory, were installed. The results obtained show that pressurizing the living quarters brings about an effective reduction in the radon concentration, with a relatively simple building solution. This solution, which is compatible with the principle of minimum intervention, is seen to be especially appropriate when work is undertaken in structures recognized as heritage.

Mid-fidelity simulations and comparisons of five techniques for axial induction control of a wind turbine

As wind turbines are more frequently placed in arrays, the need to understand and mitigate problems arising from their wakes has increased. When downstream turbines are in the wakes of upstream ones, the downstream turbines produce less power, require more maintenance, and have shorter lifetimes. One wake mitigation technique is known as axial induction control (AIC) and it involves derating (operating suboptimally) upstream turbines such that more energy remains in their wakes for downstream turbines to harvest. While there has been considerable research on this technique, much of it has suffered from a misunderstanding of the most important parameters in optimizing AIC. As such, the research has been largely inconclusive. Herein, we seek to rectify several perceived shortcomings of previous work by using mid-fidelity simulations to compare five different techniques for AIC at three different derate percentages against a baseline case and examining the recovery of the wake. We find that only the case with the lowest derate, 10 %, and using maximum thrust exceeds the baseline when estimating the combined power of the simulated turbine and a virtual turbine five diameters downstream and that it produced 10 % more power. Furthermore, these results help to validate previous work that concluded that the excess energy that is in the wake of a derated turbine will be at the edges of the wake unless the wake can sufficiently recover before the next downstream turbine. Finally, all together this suggests that the precise combination of derate percentage and the method used to derate turbines (i.e., the precise combination of pitch and torque controls), as well as the spacing and arrangement of turbines, must all be considered when optimizing AIC, and that substantial power gains may be possible.