Seasonal Correction of Offshore Wind Energy Potential due to Air Density: Case of the Iberian Peninsula

Abstract

A constant value of air density based on its annual average value at a given location is commonly used for the computation of the annual energy production in wind industry. Thus, the correction required in the estimation of daily, monthly or seasonal wind energy production, due to the use of air density, is ordinarily omitted in existing literature. The general method, based on the implementation of the wind speed’s Weibull distribution over the power curve of the turbine, omits it if the power curve is not corrected according to the air density of the site. In this study, the seasonal variation of air density was shown to be highly relevant for the computation of offshore wind energy potential around the Iberian Peninsula. If the temperature, pressure, and moisture are taken into account, the wind power density and turbine capacity factor corrections derived from these variations are also significant. In order to demonstrate this, the advanced Weather Research and Forecasting mesoscale Model (WRF) using data assimilation was executed in the study area to obtain a spatial representation of these corrections. According to the results, the wind power density, estimated by taking into account the air density correction, exhibits a difference of 8% between summer and winter, compared with that estimated without the density correction. This implies that seasonal capacity factor estimation corrections of up to 1% in percentage points are necessary for wind turbines mainly for summer and winter, due to air density changes.

Moisture Recycling over the Iberian Peninsula: The Impact of 3DVAR Data Assimilation

“…Additionally, WRF precipitation generated with 3DVAR data assimilation showed a similar performance as the one obtained by means of statistical downscaling [75]. Furthermore, as wind in this simulation showed also an improvement over ERAI, WRF outputs were used to calculate the offshore wind energy potential around the Mediterranean [74] and at every coast of the IP [76]. Due to the good results obtained by the experiment including 3DVAR data assimilation, the simulated period has been extended until the end of 2018 for the analysis of recycling ratio with a longer perspective.…”

“…Finally, due to the good capacity of the simulation including data assimilation to correct to some extent the bias in soil moisture observed between both simulations (presented in this study), and due to its ability to reproduce the spatial and temporal evolution of variables involved in the water balance as presented in previous studies by the authors [73,74,76], this simulation was extended until 2018. This is why this simulation (WRF D) was chosen to show the interannual variability of areal mean moisture recycling over the IP for the period 2010-2018.…”

Evaluation of Lebanon’s Offshore-Wind-Energy Potential

“…In recent publications [13,32,33], the authors developed a technique to seasonally estimate the influence of instantaneous air density changes on the capacity factor of a given turbine. Floors et al [34] emphasized, like us, the importance of air density, and also used ERA5 to study its effects.…”

What about Marine Renewable Energies in Spain?

“…A lot of studies have been carried out to estimate it, but mainly focused on one category, for instance, offshore wind or wave power. There are some examples of these studies focused on different areas in the world: one of themis about the analysis of methodologies for the assessment of wind resource in European Seas [5]; another one is only focused in offshore wind around Korean peninsula [6]; another one is about wave energy along the Cornish coast (UK) [7]; another one analyzes the renewable mix to satisfy the needs of energy of Pantelleria, a real island in the Mediterranean Sea, focusing on starting to study minor island, including the study of different renewable sources: wind, solar and wave [8]; another one studies the possible energy independence in Malta based on the use of Wave Energy Converters [9]; another one is about wave energy resource variation in the coast of Ireland [10]; and another one analyzes the influence of air density changes in the offshore wind potential over Northeastern Scotland [11].Furthermore, there are some resource analyses in Spain: one of them determines the wave energy resource in the Estaca de Bares area (Spain) [12]; another one includes the evaluation of wave energy potential in the Spanish coast [13]; another one is about a review of combined wave and offshore wind energy [14]; another one is focused in wave energy in Menorca (Spain) [15]; another one is related to wave energy trends and its variation, and is very important to be taken into account in the Bay of Biscay [16]; and another one is about seasonal corrections due to the use of real values of air density for the assessment of offshore wind energy potential in the Iberian Peninsula [17].Regarding wave energy, it is can be stated that UK and Spain are pioneering countries. In Spain, some Wave Energy Converters (WEC) were installed in Mutriku breakwater, and this facility is in operation [18][19][20].Some investigations used different algorithms that included an importance sampling-based expectation-maximization algorithm for sequence detection in a single-photon avalanche diode underwater optical wireless communication [21].…”

“…Furthermore, there are some resource analyses in Spain: one of them determines the wave energy resource in the Estaca de Bares area (Spain) [12]; another one includes the evaluation of wave energy potential in the Spanish coast [13]; another one is about a review of combined wave and offshore wind energy [14]; another one is focused in wave energy in Menorca (Spain) [15]; another one is related to wave energy trends and its variation, and is very important to be taken into account in the Bay of Biscay [16]; and another one is about seasonal corrections due to the use of real values of air density for the assessment of offshore wind energy potential in the Iberian Peninsula [17].…”