In The Open Wind

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However, high wind speeds only translate into elevated potentials for wind power generation if the increased near-surface drag exerted by the wind turbines can be sustained at least partially by the local downward KE flux over the wind farm area. This study focuses on the spatial and temporal variability of the large-scale geophysical limit imposed on wind energy power generation by the vertical downward transport of KE from regions of high wind speed in the free troposphere down to the near surface.

We find that, over some ocean areas, downward transport of KE from the free troposphere may be sustained at levels several times greater than may be sustained over land. Nevertheless, we find that the sustainable generated power is still maintained at a rate similar to the electric power consumption of the European Union of 0. However, estimates for smaller-sized wind farms remain uncertain because of insufficient model resolution and an incomplete mechanistic understanding of the underlying physical drivers sustaining elevated downward KE transport over the analyzed regions.

Furthermore, extracting KE in vast amounts over the open ocean induced considerable changes in surface temperatures inside the wind farms of 2. Therefore, while this study highlights the potential for open ocean wind technologies in the North Atlantic, it also illustrates the need for additional research addressing: Furthermore, the extent to which the open ocean potential may be used is likely to be strongly dependent on factors, such as sociopolitical and economic constraints as well as technical ingenuity required to construct, maintain, and operate potential wind energy technologies under such remote and harsh conditions, with wave heights frequently exceeding 3 m in the monthly mean On an annual mean basis, the wind power available in the North Atlantic could be sufficient to power the world.

All simulations are performed with the CESM, version 1. The model is run in its fully coupled ocean configuration under preindustrial conditions at a horizontal resolution of 0. Each simulation was run for y, and the last 50 y, by which time our simulations had equilibrated, were used in our analysis.

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Using momentum conservation at each turbine, which was prescribed to operate at the Betz limit i. As this paper is focused on the large-scale geophysical limit imposed on the vertical transport of KE through the troposphere to the near surface, our parameterization of wind turbines was built to ensure maximization of near-surface drag. A more detailed discussion of the wind turbine parameterization is presented in Supporting Information , including Fig. Scaling of extracted KE as a function of the area per turbine for globally homogeneous distribution of wind turbines over the oceans.

Black line indicates perfect scaling. As stated in Methodology , the wind turbines were implemented as a source of drag in our simulations. In the CESM, the surface-layer transfer of momentum, heat, and moisture is parameterized on land following the parameterization by Bonan 33 and over the ocean following the parameterization by Bryan et al.

The cross-sectional area of the turbines at each model level A swept is given by the intersection between the rotor area and the model-level interfaces. The rotor area is specified by the hub height m and the rotor blade radius m. The model-level interface of the two model levels closest to the surface is situated at an average height of m within the wind farms.

Therefore, most of the prescribed turbines intersect the two model levels closest to the surface. While turbines of these dimensions are not yet in operation, they are estimated to be commissioned in the near future Then, there are four possible scenarios. For most simulations, A turb was chosen to be 1 km 2 , which corresponds to the area per turbine of the currently largest operational offshore wind farm—the London array with a size of km 2.

Furthermore, the areal density of one turbine per kilometer corresponds to a high effective interturbine spacing of four times the turbine diameter in the downwind direction but is fine for across mean wind turbine spacing. The effect of reducing the interturbine spacing to 10 times the rotor diameter in all directions is shown in Fig.

Geophysical potential for wind energy over the open oceans

The total wind farm area for each of the discrete wind farms simulated was determined as an integer multiple of the grid box areas. Therefore, the smallest structurally resolved wind farm consists of at least nine grid boxes. The total wind farm area varies slightly with latitude among different wind farms, which contain an equal number of grid boxes. We thank the CESM project for code development, maintenance, and support. We also thank Elizabeth Barnes of Colorado State University for her helpful comments regarding storm track dynamics.

This article contains supporting information online at www.

This is an open access article distributed under the PNAS license. We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. We do not capture any email address. Skip to main content. Geophysical potential for wind energy over the open oceans Anna Possner and Ken Caldeira.

This article has a correction. Correction for Possner and Caldeira, Geophysical potential for wind energy over the open oceans. Significance Wind speeds over open ocean areas are often higher than those in the windiest areas over land, which has motivated a quest to develop technologies that could harvest wind energy in deep water environments.

Abstract Wind turbines continuously remove kinetic energy from the lower troposphere, thereby reducing the wind speed near hub height. View inline View popup. Discussion of KEE Rates Our findings indicate that more wind energy may be extracted in the North Atlantic than over land for equivalent wind farm domains and turbine densities. Conclusions Previous research has shown that onshore wind energy resources deployed at large spatial scales are limited by the energetics of the atmosphere. Wind Turbine Parameterization As stated in Methodology , the wind turbines were implemented as a source of drag in our simulations.

The authors declare no conflict of interest. Nat Clim Change 3: Miller LM , et al. Geophys Res Lett J Geophys Res Hasager CB , et al. Remote Sens Environ Renew Sustain Energ Rev Keith DW , et al. Miller LM , Gans F , Kleidon A Estimating maximum global land surface wind power extractability and associated climatic consequences. Earth Syst Dyn Discuss 2: Environ Res Lett 8: Fitch A Climate impacts of large-scale wind farms as parameterized in a global climate model. Calaf M , Meneveau C , Meyers J Large eddy simulation study of fully developed wind-trubine array boundary layers.

J Phys Conf Ser A large-eddy simulation study. J Wind Eng Indus Aerod Wind Energ Sci 1: Fitch A , et al. Mon Weather Rev Vanderwende BJ , Lundquist JK The modification of wind turbine performance by statistically distinct atmospheric regimes. Environ Res Lett 7: Accessed March 25, Hartmann DL The atmospheric general circulation and its variability. Brayshaw DJ The basic ingredients of the north Atlantic storm track.

Land-sea contrast and orography. J Atmos Sci Kaspi Y , Schneider T Downstream self-destruction of storm tracks. Hurrell JW The community Earth system model: A frameowork for collaborative research. B Am Metereol Soc Rodrigues S A multi-objective optimization framework for offshore wind farm layouts and electric infrastructure. Renewable Sustainable Energy Rev Thank you for your interest in spreading the word on PNAS. You are going to email the following Geophysical potential for wind energy over the open oceans.

The Open Road | The Wind in the Willows | Kenneth Grahame | Lit2Go ETC

Geophysical potential for open ocean wind energy. Anna Possner , Ken Caldeira. Nevertheless, we find that the sustainable generated power is still maintained at a rate similar to the electric power consumption of the European Union of 0. However, estimates for smaller-sized wind farms remain uncertain because of insufficient model resolution and an incomplete mechanistic understanding of the underlying physical drivers sustaining elevated downward KE transport over the analyzed regions.

Furthermore, extracting KE in vast amounts over the open ocean induced considerable changes in surface temperatures inside the wind farms of 2. Therefore, while this study highlights the potential for open ocean wind technologies in the North Atlantic, it also illustrates the need for additional research addressing: Furthermore, the extent to which the open ocean potential may be used is likely to be strongly dependent on factors, such as sociopolitical and economic constraints as well as technical ingenuity required to construct, maintain, and operate potential wind energy technologies under such remote and harsh conditions, with wave heights frequently exceeding 3 m in the monthly mean On an annual mean basis, the wind power available in the North Atlantic could be sufficient to power the world.

All simulations are performed with the CESM, version 1. The model is run in its fully coupled ocean configuration under preindustrial conditions at a horizontal resolution of 0. Each simulation was run for y, and the last 50 y, by which time our simulations had equilibrated, were used in our analysis. Using momentum conservation at each turbine, which was prescribed to operate at the Betz limit i. As this paper is focused on the large-scale geophysical limit imposed on the vertical transport of KE through the troposphere to the near surface, our parameterization of wind turbines was built to ensure maximization of near-surface drag.

A more detailed discussion of the wind turbine parameterization is presented in Supporting Information , including Fig. Scaling of extracted KE as a function of the area per turbine for globally homogeneous distribution of wind turbines over the oceans. Black line indicates perfect scaling. As stated in Methodology , the wind turbines were implemented as a source of drag in our simulations. In the CESM, the surface-layer transfer of momentum, heat, and moisture is parameterized on land following the parameterization by Bonan 33 and over the ocean following the parameterization by Bryan et al.

The cross-sectional area of the turbines at each model level A swept is given by the intersection between the rotor area and the model-level interfaces. The rotor area is specified by the hub height m and the rotor blade radius m. The model-level interface of the two model levels closest to the surface is situated at an average height of m within the wind farms. Therefore, most of the prescribed turbines intersect the two model levels closest to the surface. While turbines of these dimensions are not yet in operation, they are estimated to be commissioned in the near future Then, there are four possible scenarios.

For most simulations, A turb was chosen to be 1 km 2 , which corresponds to the area per turbine of the currently largest operational offshore wind farm—the London array with a size of km 2. Furthermore, the areal density of one turbine per kilometer corresponds to a high effective interturbine spacing of four times the turbine diameter in the downwind direction but is fine for across mean wind turbine spacing.

The effect of reducing the interturbine spacing to 10 times the rotor diameter in all directions is shown in Fig. The total wind farm area for each of the discrete wind farms simulated was determined as an integer multiple of the grid box areas. Therefore, the smallest structurally resolved wind farm consists of at least nine grid boxes. The total wind farm area varies slightly with latitude among different wind farms, which contain an equal number of grid boxes.

We thank the CESM project for code development, maintenance, and support. We also thank Elizabeth Barnes of Colorado State University for her helpful comments regarding storm track dynamics. This article contains supporting information online at www.


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We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. We do not capture any email address. Skip to main content. Geophysical potential for wind energy over the open oceans Anna Possner and Ken Caldeira. PNAS published ahead of print October 9, https: This article has a correction. Correction for Possner and Caldeira, Geophysical potential for wind energy over the open oceans. Significance Wind speeds over open ocean areas are often higher than those in the windiest areas over land, which has motivated a quest to develop technologies that could harvest wind energy in deep water environments.

Abstract Wind turbines continuously remove kinetic energy from the lower troposphere, thereby reducing the wind speed near hub height. View inline View popup. Discussion of KEE Rates Our findings indicate that more wind energy may be extracted in the North Atlantic than over land for equivalent wind farm domains and turbine densities.

Conclusions Previous research has shown that onshore wind energy resources deployed at large spatial scales are limited by the energetics of the atmosphere. Wind Turbine Parameterization As stated in Methodology , the wind turbines were implemented as a source of drag in our simulations. The authors declare no conflict of interest. Freely available online through the PNAS open access option.


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Nat Clim Change 3: Miller LM , et al. Geophys Res Lett J Geophys Res Hasager CB , et al. Remote Sens Environ Renew Sustain Energ Rev Keith DW , et al. Miller LM , Gans F , Kleidon A Estimating maximum global land surface wind power extractability and associated climatic consequences. Earth Syst Dyn Discuss 2: Environ Res Lett 8: Fitch A Climate impacts of large-scale wind farms as parameterized in a global climate model. Calaf M , Meneveau C , Meyers J Large eddy simulation study of fully developed wind-trubine array boundary layers.

J Phys Conf Ser A large-eddy simulation study. J Wind Eng Indus Aerod Wind Energ Sci 1: Fitch A , et al. Mon Weather Rev Vanderwende BJ , Lundquist JK The modification of wind turbine performance by statistically distinct atmospheric regimes. Environ Res Lett 7: Accessed March 25, Hartmann DL The atmospheric general circulation and its variability. Brayshaw DJ The basic ingredients of the north Atlantic storm track. Land-sea contrast and orography.

J Atmos Sci Kaspi Y , Schneider T Downstream self-destruction of storm tracks. Hurrell JW The community Earth system model: A frameowork for collaborative research. B Am Metereol Soc Rodrigues S A multi-objective optimization framework for offshore wind farm layouts and electric infrastructure. Renewable Sustainable Energy Rev Thank you for your interest in spreading the word on PNAS.

You are going to email the following Geophysical potential for wind energy over the open oceans. Geophysical potential for open ocean wind energy.

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Anna Possner , Ken Caldeira. Tweet Widget Facebook Like Mendeley. More Articles of This Classification Physical Sciences Collimated ultrabright gamma rays from electron wiggling along a petawatt laser-irradiated wire in the QED regime. Schlieren optics for visualisation of Mach lines and shock waves on drag bodies; interchangeable walls in the measuring section produce velocities up to Mach 1,8.


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The GUNT team will be glad to support you. Service performances In addition to our range of equipment we offer training courses and commissioning of the equipment as well as assistance in laboratory planning. References Would you like to check directly with other universities about their experience with the equipment? Here is a selection of universities with laboratories that have recently been equipped by GUNT. Technical data Measuring section flow cross-section WxH: Dimensions and weight LxWxH: HM Open wind tunnel Pdf. HM Selected experiments Pdf.