The Impact of Tobacco Production Liberalization on Smallholders in Malawi

Burley tobacco production in Malawi was liberalized to permit production by smallholders in the early 1990s. The purpose of this paper is to show which smallholders began producing burley tobacco after liberalization and which smallholders still continue to produce it. Analysis of the characteristics of burley tobacco producers shows that only smallholders who had adequate farm size and adequate funds could start to produce it. With regard to the farm size requirements, only smallholders who had enough acreage to sell tobacco on the auction floors and who had enough acreage to rotate crops could start to produce. With regard to the financial requirements, only smallholders who could procure funds through informal institutions or who possessed their own capital to meet the necessary agricultural expenditures could start. So, it was only the wealthy households which could start to produce tobacco after liberalization and continue to produce it.

Prediction of wake effects on wind farm power production using a RANS approach. Part II. Offshore: Case studies from the UPWIND project

The estimation of power losses due to wind turbine wakes is crucial to understanding overall wind farm economics. This is especially true for large offshore wind farms, as it represents the primary source of losses in available power, given the regular arrangement of rotors, their generally largerdiameter and the lower ambient turbulence level, all of which conspire to dramatically affect wake expansion and, consequently, the power deficit. Simulation of wake effects in offshore wind farms (in reasonable computational time) is currently feasible using CFD tools. An elliptic CFD model basedon the actuator disk method and various RANS turbulence closure schemes is tested and validated using power ratios extracted from Horns Rev and Nysted wind farms, collected as part of the EU-funded UPWIND project. The primary focus of the present work is on turbulence modeling, as turbulent mixing is the main mechanism for flow recovery inside wind farms. A higher-order approach, based on the anisotropic RSM model, is tested to better take into account the imbalance in the length scales inside and outside of the wake, not well reproduced by current two-equation closure schemes.