This position paper examines the profile of wind power, its impact on the network, security of supply and the quality of the energy delivered. It further deals with the reasons to establish certain technical requirements for the connection of wind power generation to the network.
Editor's Note: This is a worthwhile read in its entirety (attached pdf file). Selected extracts appear below.

This paper examines a number of issues associated with the introduction of increasing amounts of wind energy into the Irish electricity network. It draws upon international experience and, in particular, operational data from western Denmark, where wind produces 21% of total electricity consumption. Particular characteristics of the Irish network are identified and a mixture of empiricism and "first principles" analysis is used to derive estimates of the capacity credit of wind plant, the extra costs of operational reserve and the total extra costs of operating with increasing quantities of wind energy.

It is concluded that the total extra cost to the electricity consumer of installing enough wind to provide 10% of electricity consumption may be around €0.7/MWh, but much depends on timing (as wind costs are falling rapidly), and the mix between onshore and offshore wind. The need for market mechanisms to be cost-reflective and promote technical efficiency in electricity networks is emphasised, recognizing the advantages of integrated electricity systems. It is noted that this is not in conflict with the requirements for efficient assimilation of wind energy.

The attached Pdf file provides a comprehensive overview of wind turbine noise related issues.

This document prepared by Gamesa contains the specifications for building access roads to service the wind facility as well as the platform areas where each turbine will be sited. Wind developers often cite in their marketing literature that access roads will be 16-feet in width following construction. According to the document, the minimum width of an access road between wind turbines must be 10 meters (33-feet). This width does not include side slopes or additional clearing for culverts.

In the beginning of the nineties, ECN and consultants in the Netherlands were approached by local authorities and developers of wind farms with the question: “Is it safe to erect a wind turbine at this location?”

This study by the Irish grid manager finds that the benefits of wind-generated power are small and that they decrease as more wind power is added to the system and as the system grows itself. Their model assumes that all energy produced from wind facilities would be used and did not consider output fluctuations within a time period of less than an hour.

They decribe three problems that mitigate the benefits of wind power:

-large amount of extra energy required to start up thermal generators that would otherwise not have been turned off

-mechanical stresses of more frequent ramping of production levels up and down

-increased prices of energy necessary to pay for any lower usage of thermal plants.

They notice that there is very little possibility of closig any non-wind facilities, because their capacity would still be needed to respond to periods of peak demand. Wind plants add more capacity (requiring more infrastructure) with almost no reduction on non-wind capacity, the latter of which must be used more inefficiently than otherwise.

As for carbon dioxide reduction-one of the primary arguments for wind-generated power- the study concludes that the cost of carbon dioxide abatement arising from using large levels of wind energy appears high relative to other alternatives.

In this thesis the meteorological effects of a large-scale (9000 km2) offshore wind farm in the North Sea were simulated using the MM5 mesoscale model. The wind farm was simulated by introducing a higher roughness length (0.5 m) in the area of the wind farm. The meteorological effects were examined by comparing model runs with and without wind farm. Turbulent kinetic energy, cloud formation, precipitation and wind speed reduction were studied. Two case studies with westerly flows were performed. The first case study begins at 00 UTC July 1st 2001 and ends at 18 UTC July 3rd 2001. The second is from 00 UTC October 2nd 1999 to 18 UTC October 4th 1999.

A CASE IN POINT: THE VALENCIAN WINDPOWER PLAN

"The Valencian windpower plan ("Plan Eólico") was approved July 26th, 2001. It calls for the implantation of 2700 wind turbines in the Comunidad Valenciana, many of them in the mountains of the Costa Blanca.

After two years of negotiations behind closed doors, the pieces of the subsidized pie have been allocated. Soon the bulldozers will start destroying the ultimate asset of this region: its unspoiled interior. See the narrow valleys, smell the orange blossom, marvel at the olive groves: they will never be the same. Neither will the craggy mountains, warm shades of amber in the winter sun. All of this will go, marred by industrial structures. The almond trees will bloom under ugly pylons, and we´ll view the cherry blossoms against a backdrop of rotors and power lines."

Journal of Sound and Vibration

"Since the start of the operation of a 30MW, 17 turbine wind park, residents living 500m and more from the park have reacted strongly to the noise; residents up to 1900m distance expressed annoyance. To assess actual sound immission, long term measurements (a total of over 400 night hours in 4 months) have been performed at 400 and 1500m from the park. In the original sound assessment a fixed relation between wind speed at reference height (10 m) and hub height (98 m) had been used. However, measurements show that the wind speed at hub height at night is up to 2.6 times higher than expected, causing a higher rotational speed of the wind turbines and consequentially up to 15 dB higher sound levels, relative to the same reference wind speed in daytime. Moreover, especially at high rotational speeds the turbines produce a ‘thumping’, impulsive sound, increasing annoyance further. It is concluded that prediction of noise immission at night from (tall) wind turbines is underestimated when measurement data are used (implicitly) assuming a wind profile valid in daytime."

Wind power is a relatively new generator of electricity in Sweden. Legislation and regulation regarding noise from wind turbines in Sweden have been discussed. Eja Pedersen at Halmstad University has at the request of the Swedish Environmental Protection Agency prepared this report as a base for further discussions on regulation and guidelines on noise from wind turbines in Sweden. The report reviews the present knowledge on perception and annoyance of noise from wind turbines in residential areas as well as in recreational areas. It also summarizes regulations in some European countries. The author Eja Pedersen is responsible for the content of the report.

Stockholm, August 2003

SWEDISH ENVIRONMENTAL PROTECTION AGENCY Report 5308