Site Suitability Analysis For Wind Farming Using GIS


T.Shakthi Varman.
III YEAR, B.E.,
GEO-INFORMATICS
COLLEGE OF ENGINEERING
GUINDY
CHENNAI-25


P.Priyadharshini
P.Priyadharshini
III YEAR, B.E.,
GEO-INFORMATICS
COLLEGE OF ENGINEERING
GUINDY
CHENNAI-25


R.R.Charanya
R.R.Charanya
III YEAR, B.E.,
GEO-INFORMATICS
COLLEGE OF ENGINEERING
GUINDY
CHENNAI-25


S.Durga
III YEAR, B.E.,
GEO-INFORMATICS
COLLEGE OF ENGINEERING
GUINDY
CHENNAI-25

ABSTRACT:

In this era owing to the depletion of non-renewable resources, tapping of renewable resources is the need of the hour. Wind energy is a clean green energy that proves to be the fastest growing & viable alternative. The objective of this paper is to deploy GIS for effective site selection for wind farming. This is done based on various site-screening criteria. The current system in existence worldwide is analyzed and its feasibility in the Indian scenario is also discussed.

INTRODUCTION

The highly demanding energy era of the present necessitates the effective utilization of the non-conventional energy resources. Concerns about the impacts of traditional power generating methods have on the environment have led many to believe that a radical rethink is now needed as to how our energy of the future is generated. Wind energy is one of the most promising alternatives. Wind energy is a clean green energy which aids to bridge the gap in energy demand. It is therefore a need to identify potential sites for trapping this clean-green energy.

Renewable energy sources - Need of the hour

have a vital significance in the context of growing concern about sustainable energy supplies and protection of the environment from adverse effects of fossil fuel utilisation. The current pattern of energy consumption and the growing energy requirements on account of development, economic growth, population increase etc., are considered to be essentially unsustainable. The staggering increase in oil import burden, the crippling effects of power shortage and the deterioration in environmental quality are some of the critical issues facing India today.

Worldwide, vast amounts of carbon-di-oxide and other greenhouse gases that are being dumped into the atmosphere by fossil fuel burning and other economic activities are causing grave concern about the possible global warming and attendant consequences. It is becoming increasingly clear that any effective strategy to contain global warming must involve rational and efficient use of energy and a gradual transition from reliance on fossil fuels to alternative, environment friendly energy technologies. A major component of this strategy will admittedly be the promotion of renewable energy systems in a big way, and in this scenario, wind energy is expected to figure prominently. Among the renewable energy sources, wind is the most matured one.

The advantages of harnessing wind energy include:

  • wind energy is available free
  • the production and use of wind energy does not pollute the atmosphere
  • it does not cause acid rain and contribute to the greenhouse effect which leads to global warming
  • a windfarm irrespective of its size has a low gestation period
  • for every 1 Kwh of electricity generated by wind, emission of CO2 is reduced by 1 Kg
  • the operation of a wind turbine weighing 50 tonnes saves the annual burning of 500 tonnes of coal
  • the primary energy used to produce a wind turbine is recovered in about a year
  • wind is available during day and night

ROLE OF GIS
GIS can be defined as “a system of hardware, software and procedures designed to support the capture, management, manipulation, analysis, modeling, and display of spatially referenced data (i.e., data identified according to their position) for complex planning and management problems.”

Site selection criteria can be developed to determine the optimum locations for wind farms and even positions of individual turbines to maximize resource potential.

CURRENT SYSTEMS WORLDWIDE:
The countries of the world such as Australia, Germany, America have their own wind energy associations. These associations through their programmes for renewable energy have made these energy sources available even for domestic purposes. Wind energy plays an integral role in California's electricity portfolio. In 2004, turbines in wind farms generated 4,258 gigawatt-hours of electricity - about 1.5 percent of the state's gross system power. That's enough to light a city the size of San Francisco. Additionally, hundreds of people are using smaller wind turbines to produce electricity for their homes and businesses. In India large scale tapping of this energy & extending this clean green energy source to serve domestic needs is the need of the hour.

NUANCES OF THE SYSTEM

The primary data of the system is the wind speed information. The other data layers required are the landuse, roadways, power transmission lines, slope map, etc. These are the layers which are overlaid for our geographic study area Pusaripatti. In addition many other layers such as soil, geomorphology etc. can also be incorporated to extend the study as a decision support system.

The system not only includes the effects of the presence of natural features but also man-made features. Since it is not possible to include all criteria, a few of them are considered.

SITE SELECTION
There are many criteria that can be used as determinants for selecting sites that may be suitable for a new wind farm development. We select certain exclusion features. Buffers are generated around these features at a specific distance to create a number of new polygonal coverages. The areas within the polygons are then taken in turn to cut the coverage representing the study area. The result is a number of good sites that satisfy the requirements of a proposed wind farm.The size of these pockets could be too small. So a size criterion is applied to establish a economically viable farm.

MICRO-SITING
Wind turbine installed in a stream of wind would take out kinetic energy and convert the same into electrical energy.In this process, the winds behind the turbine would have lower speeds. This area having lower wind speeds behind the turbine rotor is called the wake. This wake expands in the shape of a cone.At some distance from the rotor plane the winds are expected to regain the lost kinetic energy.But in finite distances the recovery is never complete. This wake is expected to expand in a 3 dimensional mode. The wind turbine should be placed in an area minimizing the inter machine influences. This is known as micro-siting.

CRITERIA FOR SITE SCREENING
GIS has been designed to be as flexible as possible, allowing the user to specify which criteria will be used for the site selection, and if included what buffer distance to use around each excluded feature. The criteria include various parameters and exclusion factors such as:
  • Wind speed information
  • Elevation above msl
  • Slope
  • Distance to power lines
  • Distance to roadways/railways
  • Distance to military zones
  • Distance to built up area
  • Distance to forest area
  • Distance to scenic area

METHODOLOGY:
The study area chosen is near a monitoring station Pusaripatti near Pollachi town in the district of Coimbatore (TN). The study area extends from 1000’40” N to 10045’N and 7701’57” E to 7708’30” E.The primary data, the wind speed information is obtained from the Center for Wind Energy Technology
(C-WET, Chennai) .The base map and other collateral data were obtained from satellite imagery & toposheet.

PREPARATION OF THEMES:
  • Wind speed map
  • Land cover(predominantly built up areas)
  • Road networks
  • Power transmission lines
  • Slope(disregarded for this area)
  • Exclusion criteria;

    • - airports
    - scenic areas
    - military zones
The wind speed data is converted into the visual interpretation as wind map, a vector layer. The other themes are also digitized using the software arcgis 9 from the base map as vector layers.The separate themes are stored in one dataset and they are overlayed one over the other for further vector spatial analysis using tools available in arcgis.

  • Base map prepared from satellite imagery & toposheet overlayed on wind speed information.

The separate digitized layers are:


The built-up layer is buffered for a distance of 500 m for the safety and other purposes. The other layers such as power lines (in green) are then buffered for a distance of 300 m. These criteria are for the effective cost estimation for the setting up of wind farm. The road layer (in violet) is then buffered for a distance 0f 200 m. this is shown below;


For the buffered exclusion layers of built up area, scenic areas, military danger zone are then erased from the wind speed map and overlayed with the other inclusion buffer layers of power line and roadways. The relevant attribute data of wind speed and buffer information are incorporated into the attribute table of respective layers. The slope is an important criterion, but it’s disregarded in this paper because the study area is found to be nearly level with uniform slope characteristics. Also the average elevation of the area is 300m above msl so the entire area is susceptible for wind farming development.

From the above buffers the layers are joined by union tool and the final suitability layer is highlighted by giving an ordinary or SQL expression. It is highlighted as below:

  • Final suitable area(highlighted)


ASSUMPTIONS

Based on micro-siting the following assumptions are made as recommended by C-WET:
  • For flatter areas a gap of at least 2 times the rotor diameter in a direction normal to the major wind direction & 4 times the rotor diameter in the direction of predominant winds should be left vacant.
  • If land holdings are small and the above stipulations cannot be adhered to, the owners of the land should consider suitable arrangements with neighbouring land owners.
  • For the ridge sites, the windmills were placed three diameters apart.

CREDIBILITY
Rather than depending on a single generic resource to represent wind potential, a number of actual sites could be evaluated individually. The cost of development at each site can be estimated using site specific information.

Wind farm revenues can be estimated based on the patterns of generation derived from actual wind observations & estimates of time-varying market prices.

GIS can also be used to estimate the proximity of wind sites to road & transmission lines.These distances serve as the basis for an estimated cost function of wind development. Wind power classes can be assigned based on the available windy land & wind electric potential grid cell.

All weather access is required by maintenance crews. The roads also need to be built such that heavy equipment can be moved to the sites during construction

CAPITAL OUTLAY & OPERATING COSTS
The capital will include the cost of the generator, cost of the land where it is erected, cost of connecting individual generators to the grid, cost of building access road. Maintenance costs depend upon the rotor diameter. Turbines having a diameter of 50m & below have almost the same maintenance costs. Wind turbines occupy only a small fraction of the land area they are built over. Usually, the area can still be used for farming or grazing animals. Thus the cost factor can also be incorporated to perform a cost – benefit analysis while considering a decision support system.

CONCLUSION:

From the analysis performed through GIS it is inferred that of the approximate study area of 130 sq.km the total suitable area for installing wind farms is 46 sq.km(approx.) .Thus GIS can be used as a valuable tool by wind farm developers for selecting suitable sites and for performing the necessary visibility analysis. GIS can give us the results and information we require of it, but with a greater understanding of the issues involved, we can soon appreciate how GIS can revolutionize these current basic approaches. Also the study can be extended by including the eco-wildlife protection parameters by considering visible intrusion & noise factors affecting the local neighbourhood. Further scope for improvement in harnessing this clean green energy is the development of a spatial decision support system.

References:

  • British wind energy association. "Best Practice Guidelines for Wind Energy Development”
  • Danish wind energy association. (windpower.org)
  • California wind energy association (www.energy.ca.gov/wind)

ACKNOWLEDGEMENT

We wish to place on record our sincere thanks to Dr.Thirumalaivasan, Asst professor, Institute of Remote sensing, Anna University for his valuable guidance for this paper.

We express our deep gratitude to Dr.Kaliappan, Director, Institute of remote sensing, Anna University for his constant support throughout the project.

We also extend our thanks to C-WET (Center For Wind Energy Technology , Chennai)for providing us vital data required for the project.