Keywords: Wind resources assessment, Wind maps, Baltic Sea, GIS

Transcription

1 Advanced Materials Research Online: ISSN: , Vol. 827, pp doi: / Trans Tech Publications, Switzerland Mapping of Offshore Wind Climate and Site Conditions for the Baltic Sea within Latvian Territorial Waters Lita Lizuma 1,a, Sergejs Rupainis 2, Artis Teilans 1 1 Institute of Physical Research and Biomechanics, Artilerijas Street 40, LV Riga, Latvia 2 Rezekne Higher Education Institution Atbrivosanas aleja 90, LV-460, Rezekne, Latvia a lita.lizuma@lvgmc.lv Keywords: Wind resources assessment, Wind maps, Baltic Sea, GIS Abstract. The paper describes the assessment and mapping of wind climate and environmental conditions of the study region extending from 56.03N 20.2E to 57.22N 21.33E. Maps of wind resources and environmental conditions are the primary method used for presenting the offshore wind resources as well as site conditions data. A GIS database was chosen to house the offshore resources data because the datasets have a significant spatial component. A visualization of the geospatial data is created using the Google Maps platform. The maps datasets consist of gridded 1) climatological information on wind speed and direction, air temperature, air pressure, wind power potential at 10m, 80m, 90m and 100m height; 2) oceanographical information on water temperature, height and direction of sea waves, speed and direction of currents, ice conditions; 3) geological data on bathymetry and sea sediments. The horizontal resolution of the database grid cells is 5 km by 5 km. All the component datasets are spatially referenced to the same spatial base, allowing rapid indexing of the different datasets to each other. A database user may compare information from different datasets in the same geographic location. The GIS database also allows portions of a dataset to be quickly updated as new information becomes available. Introduction The exploitation of renewable energy sources can help the European Union meet many of its environmental and energy policy goals, including its obligation to reduce greenhouse gases under the Kyoto Protocol and the aim of securing its energy supply [1]. The current situation regarding wind energy production in Latvia is unsatisfactory. According to the data from Latvenergo AS, out of the total electricity generation in Latvia, approximately 1535 MW (76%) are generated by hydropower plants, while around 474 MW (23%) are generated at thermal power plants and from fossil fuels, but only around one percent is generated by wind power. Offshore wind energy development promises to be a significant domestic renewable energy source for Latvia. The first stage for exploiting wind energy is the evaluation of wind resources at wind farm sites, which means a site-specific evaluation of wind climatology and vertical profiles of wind. Reliable prediction of the wind resources as well as site conditions at offshore sites is crucial for project planning and selecting suitable locations. In the focus area of this study there is a lack of such data sets. Material and methods The assessment of the wind climate was performed for the study region extending from 56.03N 20.2E to 57.22N 21.33E (Fig. 1). Previous studies have shown that this territory has high wind energy generation potential [1]. There are plans for several wind turbines to be mounted here in the near future. The Regional Climate Model (RCM), atmospheric model Hirlam and High Resolution Operational Model for the Baltic Sea (Hiromb) simulations were used to obtain the climatological and oceanographical data for the study area. All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, (ID: , Pennsylvania State University, University Park, USA-09/05/16,05:04:23)

2 154 Solar Energy Materials and Energy Engineering Fig. 1. The study area with sites of in-situ observation stations and grid point locations. 1;2;3locations of coastal weather stations. The RCM simulations used in this research were obtained from the ENSEMBLES Project [2]. The Regional Climate Model simulations have been extensively evaluated and ETHZCLM_SCN_HadCM3Q0_25km (CLM) was chosen for obtaining the climate data. The oceanographical data were obtained from the BOOS (Baltic Operational Oceanography System) DMI ocean forecast models (DMI/COI) and the EU Project MyOcean FiMAr information system [3]. The atmospheric components of CLM were interpolated using the Kriging interpolation method from grid cells with horizontal 25km x 25km to a resolution of 5 x 5 km. Wind energy, like many renewable technologies, is also susceptible to climate change. The principal and most direct mechanism by which global climate change may impact the wind energy industry is by changing the geographical distribution and/or the inter- and intra-annual variability of the wind resources. The maps of the future climate were produced using CLM simulations under SRES [4] A1B forcing for two future periods and The oldest bathymetry and seabed sediments maps were generated from data obtained from the Latvian Environment, Geology and Meteorology Centre. The geological information was updated using the latest information available during direct measurements in the target territory in autumn GIS database components Maps of wind resources and environmental conditions are the primary method used for presenting the offshore wind resources as well as the data of the site conditions. A GIS database was chosen for storing the data on the offshore resources because the datasets have a significant spatial component. The maps datasets consist of gridded climatological, oceanographical and geological information on: wind speed and direction, air and water temperature, height and direction of sea waves, speed and direction of currents, ice conditions, water depth, and seabad sediments. The wind resources are presented at 10m, 80m, 90m and 100m height. All the component datasets are spatially referenced to the same spatial base, allowing rapid indexing of the different datasets to each other. A database user may compare information from different datasets in the same geographic location. The GIS database also allows portions of a dataset to be quickly updated as new information becomes available. The database is sufficiently flexible to allow new elements, for example, environmental exclusion areas and shipping lanes/navigation zones, to be included in future versions.

3 Advanced Materials Research Vol Using the database components, it is possible to calculate the new parameters that are important in the estimation of wind power resources and environmental conditions (wind power density, number of ice days, wind speed variability, percent active wind speed, etc.). Interactive maps The Geographic Information System is designed as a website, and allows meteorological and hydrological geospatial data to be obtained. The system provides data requests for the whole region and for particular territory points. The request results include modeled values and statistically collected and analysed data. The interactive map is based on the GoogleMaps service. Communication with the service is implemented through GoogleMapsJavaScript API V3. The system is tested on Mozilla Firefox (version 10.0), Microsoft Internet Explorer (version 8.0), Google Chrome (version 9.0) web browsers. The browser must enable JavaScript and Cookie support. The system s main page is shown in Fig. 2. Fig. 2. System s main page: annual average wind speed at 10m height and meteorological parameters for selected point. Interactive maps are available for authorised system users. Researchers can select requested geographical points by entering geographical coordinates or select the investigation point directly on the displayed map with the cursor pointer. Request results are provided as a table or in graphic form (Fig. 2). The created maps provide a better estimate of the offshore wind climate than was previously available using the in-situ data from coastal stations (Fig. 1). This database serves as the foundation for future modifications that may include specific exclusion areas for the calculation of offshore wind resource potential. The database provides the core information needed for the planning of resource-based offshore renewable energy development. The database incorporates the best estimates of offshore wind resources with parameters that have a significant impact on offshore resource development.

4 156 Solar Energy Materials and Energy Engineering Conclusions For definition and assessment of the magnitude and distribution of wind power resources, a standard and flexible database was created. There were several sources for the offshore wind potential and environmental conditions maps. Developed using Geographic Information System (GIS) techniques, the database includes parameters that are important in the assessment of wind power potential as well as the design of offshore wind turbines wind speed, wind direction, air temperature, atmospheric pressure, sea wave statistics, current speed, water temperature, ice conditions, bathymetry, and seabed sediments. The created database combines the wind power resource characteristics for present and future climate conditions. In general, the results of wind speed mapping and wind power potential assessment indicated that offshore wind resources in the territory are promising for the expansion of national electricity generation and reduction of the country s gas emissions. Future wind resources maps suggest that wind energy will continue to be a stable resource for electricity generation in the region over the 21st century. Acknowledgment Financial support for this research was given by European Regional Development Fund Project 2DP/ /10/APIA/VIAA/123 (Analysis of energy resource production possibilities within Latvian territorial waters and the EEZ) Corresponding Author Lita Lizuma, lita.lizuma@lvgmc.lv, Mobile phone: References [1] Europe's onshore and offshore wind energy potential. An assessment of environmental and economic constraints. EEA Technical Report 6, (2009), p. 85. [2] C.D. Hewitt: Ensembles-based predictions of climate changes and their impacts. EOS, Transactions, American Geophysical Union, (2004), Vol. 85, Issue 52, p [3] Baltijas jūras operacionālās meteoroloģijas un okeanogrāfijas sistēma FIMAR (Operational Meteorological and Oceanographical system for Baltic Sea FIMAR). University of Latvia, (2009). [4] N. Nakicenovic, R. Swart (eds): Special Report on Emissions Scenarios. A Special Report of Working Group III of the Intergovernmental Panel on Climate Change. Cambridge University Press: Cambridge, UK and New York, (2000), 570 p. [accessed 20 December 2010] Information on

5 Solar Energy Materials and Energy Engineering / Mapping of Offshore Wind Climate and Site Conditions for the Baltic Sea within Latvian Territorial Waters /