Bengt Tammelin

The Influence of Climate Change on Energy Production & Heating Energy Demand in Finland

In this study we have examined how the anticipated anthropogenic climate change will affect the heating power demand of buildings, hydropower production, the climatological potential of peat production, bioenergy, and wind energy. The study concentrates on conditions in Finland and the future period studied was 2021–2050. The future climate conditions were primarily taken from simulations by the Hadley Centres global climate model, HadCM3. According to the climate scenarios used in this study, the heating energy demand for the period 2021–2050 will decrease on average by some 10 % from the period 1961–1990. At the same time hydropower production will increase by 7–11 %, the climatological potential of peat production by 17–24 %, the climatological potential of biomass (mainly wood) by 10–15 % and the climatological potential of wind power by 2–10 %. These results must still be considered as preliminary, mainly because there are still large uncertainties related to the estimation of the magnitude of climate change.

Calculations on the wind climate in northern Finland: the importance of inversions and roughness variations during the seasons

The wind power potential around Pyhatunturi Fell in northern Finland is calculated with WAsP and the Karlsruhe Atmospheric Mesoscale Model (KAMM) using a climatology of the geostrophic wind from the global reanalysis of NCEP/NCAR. The importance of roughness variations between summer and winter due to snow cover and of strong, low-level inversions during winter is investigated. At the position of a telemast on the fell the changing roughness led to an increase in the predicted wind power density of only 1% at 61 m. However, frequent inversions in winter have a major influence on the wind potential on the fell areas. Accounting for them increased the predicted wind power density by 10%–16%, giving better agreement with the observations. As expected, the wind in the plains is reduced during conditions with inversions. The simulations with KAMM were performed for a grid map with a resolution of 350 m. This is too rough to resolve the steep slopes of Pyhatunturi Fell. Therefore the predicted wind speed on the summit is underestimated by up to 15% depending on the wind direction. Copyright

Aerodynamic characteristics of an iced cup-shaped body

The negative effects of ice accretion on wind speed measurements by a cup anemometer have been indicated by analyses of field test results and already been studied numerically and experimentally by the authors of this paper. Implementation of calculations of the dynamic behavior of a cup anemometer with or without ice was carried out employing the fictitiously altered aerodynamic characteristics of an iced or clean cup based on NACA test results for a conical cup because no information covering the aerodynamic characteristics of an iced cup had been provided up to that point. In light of the absence of solid data, wind tunnel tests of the aerodynamic characteristics of iced cup-shaped bodies were performed. Imitated ice models were built and used for the test based on test results from an icing wind tunnel test conducted separately. We found that, depending on its amount, ice accretion in dry-growth conditions results in big penalties to the aerodynamics of cup-shaped bodies, while ice deposits of wet growth cause little effect, regardless of the thickness of ice.

Predicting Wind Speed for Wind Energy; Progress of the WINDENG Project:

The suitability of the computer model MM5 for predicting wind speed, and hence wind energy, is investigated by performing simulations for different geographical regions. The focus is on wind speed in the lowest 200 m of the planetary boundary layer (PBL). The dependency of the simulated wind speed on PBL parameterization and atmospheric stability is studied. The smallest deviation between measured and simulated wind speed, averaged over a three-day period, is 1% and occurs for an off-shore simulation with unstable stratification. The largest deviations of 31% and 20% occur with orographically structured terrain, stable stratification and weak synoptic forcing. The results suggest that unstable conditions are simulated with better accuracy by MM5. Changes of the PBL scheme cause wind speed variations between 9% and 40% of the average wind speed. None of the PBL schemes is clearly the best and their performance can strongly vary for different conditions. Nevertheless, the Mellor-Yamada-Janjic (ETA) and the Blackadar PBL parameterization (BLK) schemes seem to be the most suitable schemes for wind energy applications. Additionally, MM5 was successfully adapted for idealised, stationary simulations in order to calculate a wind-climatology for Sardinia using a statistical-dynamical downscaling approach.

Precipitation and evaporation budgets over the Baltic Proper : Observations and modelling

Precipitation and evaporation budgets over the Baltic Sea were studied in a concerted project called PEP in BALTEX (Pilot study of Evaporation and Precipitation in the Baltic Sea), combining extensive field measurements and modelling efforts. Eddy-correlation-measurements of turbulent heat flux were made on a semi-continuous basis for a 12 month period at four well-exposed coastal sites in the Baltic Proper (the main basin of the Baltic Sea). Precipitation was measured at land-based sites with standard gauges and on four merchant ships travelling between Germany and Finland with the aid of specially designed ship rain gauges (SRGs). The evaporation and precipitation regime of the Baltic Sea was modelled for a 12 month period by applying a wide range of numerical models: the operational atmospheric High Resolution Limited Area Model (HIRLAM, Swedish and Finnish versions), the German atmospheric REgional-scale MOdel, REMO, the operational German Europe Model (only precipitation), the oceanographic model PRO...

WindEng — Research Activity in an European Training Network

This paper describes research in progress, with the aim of allowing other interested individuals and organisations to relate to the work. Communications are welcome. The project ‘WindEng’, (Wind energy assessment studies and wind engineering) studies wind characteristics in different European environments so the design of wind turbines and wind farms can be improved. This is a European ‘training-through-research’ network, see www.WindEng.net , funded within the EU FP5 “Improving Human Potential” programme, “Research Training Network” activity. The Network started in September 2002 for young scientists and experienced researchers to work together on a common project. An underlying purpose is to exchange experiences and personal contacts collaboratively to strengthen academic, research and private organisations.