No abstract

Wind energy in cold climates offers vast wind energy potential. Cold climate, in this context, means icing conditions and/or low temperatures outside the normal operational limits of the wind turbines. Cold climate areas are often located in low population density surroundings. The combination of good wind resources and low population density makes such areas attractive for wind energy generation, but weather conditions hinder the exploitation of these resources. Many technical issues as well as health and safety related ones need to be addressed before wind energy projects can be economically feasible in cold climates. Icing of wind turbines reduces energy yield, reduces the mechanical life time of turbines, and poses safety risks in the form of ice throw, among other challenges. Progress to solve these challenges has been made in recent years, for example, anti-and de-icing systems have been developed, but still more is to be done to reduce further the cost of wind energy in cold climates.

Numerical simulations of ice accumulation on four different wind turbine blade profi les, from 450 kW, 600 kW, 1 MW and 2 MW, fi xed speed, stall controlled, wind turbines, were performed to determine how wind turbine size affects atmospheric icing. The simulations indicate that dry rime icing is less severe for larger wind turbines both in terms of local ice mass and in terms of relative ice thickness.

The dependence of atmospheric icing on temperature and wind turbine size was studied by performing numerical simulations of ice accumulation on five different wind turbine blade profiles at four different temperatures. The profiles were for 450 kW, 600 kW, 1 MW, 2 MW and 5 MW wind turbines, and the temperatures −10°C, −7.5°C, −5°C and −2.5°C. The simulations indicate that generally atmospheric icing is less severe for larger wind turbines in terms of how much the aerodynamics are disturbed, but the opposite can be true under certain specific conditions. It is indicated that the air temperature range at which the transition between glaze and rime ice occurs is lower for the larger wind turbines.

This chapter discusses how key questions in the practice of intellectual history tie in with the preoccupations of international relations scholars. It begins by discussing the mainstream, largely ahistorical, early 20 th century approach to intellectual history, nowadays most notably associated with the work of Lovejoy. As well as the similarities of this viewpoint with the conventional notion of conceptualizing international thought in terms of timeless patterns of thought, as practiced by for example the classical English school. It then lays out Skinner's 1969 contextualist challenge to the notion of political thought as a timeless conversation across the ages as well as how a new historicist sensibility has been applied to the study of international thought. The following section evaluates the traction of critiques of contextualism within the contemporary literature on international thought with a focus on the role of ideas in political practice. The chapter concludes with a brief consideration of whether there is any point in doing intellectual history. The challenge is, to steal a phrase from Nietzsche, whether historians of international thought are doomed to be either antiquarians or gravediggers.