Prospects for generating electricity by large onshore and offshore wind farms

Volker, Patrick; Hahmann, Andrea N.; Badger, Jake; Jørgensen, Hans Ejsing

doi:10.1088/1748-9326/aa5d86

Cited by 65 publications

(94 citation statements)

References 27 publications

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“…This is consistent with previous research for a theoretical very large onshore wind farm (i.e. > 1×10 5 km 2 area covered by over 160,000 WT placed with a 10.5 rotor diameter spacing) that found the distance downstream from the edge of the wind farm at which the asymptotic wind speed at hub-height is reached is 30 km in simulations with the Fitch scheme, but is only 17 km downstream in the EWP [19]. To quantify the impact of the WT parameterization on the total system performance, systemwide capacity factors are computed.…”

Section: )supporting

confidence: 92%

Downstream effects from contemporary wind turbine deployments

Pryor

Barthelmie

Hahmann

et al. 2018

J. Phys.: Conf. Ser.

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The Long distance wake behind Horns Rev I studied using large eddy simulations and a wind turbine parameterization in WRF O Eriksson, M Baltscheffsky, S-P Breton et al. Resulting analyses indicate that for both WT parameterizations impacts on temperature, specific humidity, precipitation, sensible and latent heat fluxes from current wind turbine deployments are statistically significant only in summer, are of very small magnitude, and are highly localized. It is also shown that use of the relatively recently developed new explicit wake parameterization (EWP) results in faster recovery of full array wakes. This in turn leads to smaller climate impacts and reduced array-array interactions, which at a systemwide scale lead to higher summertime capacity factors (2-6% higher) than those from the more commonly applied 'Fitch' parameterization. Our research implies that further expansion of wind turbine deployments can likely be realized without causing substantial downstream impacts on weather and climate, or array-array interactions of a magnitude that would yield substantial decreases in capacity factors.

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Section: )supporting

confidence: 92%

Downstream effects from contemporary wind turbine deployments

Pryor

Barthelmie

Hahmann

et al. 2018

J. Phys.: Conf. Ser.

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“…Additionally, the WFP of Fitch et al (2012) adds turbulent kinetic energy (TKE) at the rotor area whereas the WFP of Volker et al (2015) suggests that the TKE should be allowed to develop due to the resolved shear. However, both WFPs delivers similar results when calculating the power density (Volker et al, 2017).…”

Section: Introductionmentioning

confidence: 75%

Observed and simulated turbulent kinetic energy (WRF 3.8.1) overlarge offshore wind farms

Siedersleben

Platis

Lundquist

et al. 2019

Preprint

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Abstract. Because wind farms affect local weather and microclimates, parameterizations of their effects have been developed for numerical weather prediction models. While most wind farm parameterizations (WFP) include drag effects of wind farms, models differ on whether or not an additional turbulent kinetic energy (TKE) source should be included in these parameterizations to simulate the impact of wind farms on the boundary layer. Therefore, we use aircraft measurements above large offshore wind farms in stable conditions to evaluate WFP choices. Of the three case studies we examine, we find the simulated ambient background flow to agree with observations of temperature stratification and winds. This agreement allowing us to explore the sensitivity of simulated wind farm effects with respect to modeling choices such as whether or not to include a TKE source, horizontal resolution, vertical resolution, and advection of TKE. For a stably stratified marine atmospheric boundary layer (MABL), a TKE source and a horizontal resolution in the order of 5 km or finer are necessary to represent the impact of offshore wind farms on the MABL. Additionally, TKE advection results in excessively reduced TKE over the wind farms, which in turn causes an underestimation of the wind speed above the wind farm. Furthermore, using fine vertical resolution increases the agreement of the simulated wind speed with satellite observations of surface wind speed.

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“…Two wind farm parameterizations are available for use in the WRF Model to characterize wind farm wakes: 1) the Fitch parameterization (Fitch et al 2012), and 2) the Explicit Wake Parameterization (EWP) scheme (Volker et al 2015). The Fitch parameterization has been part of WRF Model releases since version 3.3.…”

Section: Wind Farm Parameterizations In Wrfmentioning

confidence: 99%

“…One pertains to differences in the manner in which the extraction of kinetic energy over the rotor plane is described and allocated in the vertical coordinate system. This leads to a gridcell-averaged lofting of the wake from the WT hub height in the Fitch parameterization, while the maximum deficit is centered at the WT hub height in EWP (Volker et al 2015). There are also differences in the manner in which WT are allocated to horizontal grid cells.…”

Section: Wind Farm Parameterizations In Wrfmentioning

confidence: 99%

“Wind Theft” from Onshore Wind Turbine Arrays: Sensitivity to Wind Farm Parameterization and Resolution

Pryor

Shepherd

Volker³

et al. 2020

Journal of Applied Meteorology and Climatology

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High-resolution simulations are conducted with the Weather Research and Forecasting Model to evaluate the sensitivity of wake effects and power production from two wind farm parameterizations [the commonly used Fitch scheme and the more recently developed Explicit Wake Parameterization (EWP)] to the resolution at which the model is applied. The simulations are conducted for a 9-month period for a domain encompassing much of the U.S. Midwest. The two horizontal resolutions considered are 4 km × 4 km and 2 km × 2 km grid cells, and the two vertical discretizations employ either 41 or 57 vertical layers (with the latter having double the number in the lowest 1 km). Higher wind speeds are observed close to the wind turbine hub height when a larger number of vertical layers are employed (12 in the lowest 200 m vs 6), which contributes to higher power production from both wind farm schemes. Differences in gross capacity factors for wind turbine power production from the two wind farm parameterizations and with resolution are most strongly manifest under stable conditions (i.e., at night). The spatial extent of wind farm wakes when defined as the area affected by velocity deficits near to wind turbine hub heights in excess of 2% of the simulation without wind turbines is considerably larger in simulations with the Fitch scheme. This spatial extent is generally reduced by increasing the horizontal resolution and/or increasing the number of vertical levels. These results have important applications to projections of expected annual energy production from new wind turbine arrays constructed in the wind shadow from existing wind farms.

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Prospects for generating electricity by large onshore and offshore wind farms

Cited by 65 publications

References 27 publications

Downstream effects from contemporary wind turbine deployments

Downstream effects from contemporary wind turbine deployments

Observed and simulated turbulent kinetic energy (WRF 3.8.1) overlarge offshore wind farms

“Wind Theft” from Onshore Wind Turbine Arrays: Sensitivity to Wind Farm Parameterization and Resolution

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