Wind Farm Siting

Dennis Scanlin (Department of Technology)

Xingong LiChris Larson

(Department of Geography & Planning)Appalachian State University

Multi-Criteria Evaluation (MCE)

Evaluates a number of alternatives in the light of multiple criteria / factors.

Factor scores of the alternatives Factor weights

Relative importance of the factors Ranking scores of the alternatives

Weighted combination of factors

Factor 1 (1/3)

Factor 2 (1/3)

Factor 3 (1/3)

Score

A1 3 6 8 5.7

A2 8 7 5 6.7

A3 4 5 3 4.0

Analytic Hierarchy Process

Determines factor weights Difficult to determine factor weights

(numbers) directly Derives weights by comparing the

relative importance between two factors

Organizes factors into a tree structure

Innate model of operation of human mind

Helps complex decisions by decomposing the problem

AHP Factor Weights Determination

Factor relative importance pairwise comparison (9-point scale)

1—equally importance 3—moderately more importance 5—strongly more importance 7—very strongly more importance 9—extremely more importance

The best weights fit into the pairwise comparisons.

Spatial Analytical Hierarchy Process

Wind farm siting Find the best wind farm sites based on siting factors

Alternatives Location—infinite Divide the space into squares/cells (200m * 200m)

Evaluate each cell based on the siting factors

Preliminary Siting Factors Accessibility to roads

Distance to primary roads Distance to secondary roads Distance to rural roads

Accessibility to transmission lines

Distance to 100K lines Distance to 250K lines Distance to above250K lines

Wind power (or wind speed) Visibility

Viewshed size # of people in viewshed

Siting Steps Factor generation

Distance calculation Visibility calculation

Factor standardization (0 – 100) Each factor is a map layer

Factor weights determination by AHP

Final score Weighted combination of factors

Exclusion areas

Factor Layers

(Turbine: 50m; Observer: 1.5m; Visual distance: 20mi)

Wind Turbine visibility--Viewshed

Wind Turbine Viewshed Size

Red—505km2

Greed--805km2

Blue--365km2

Software tool developed to calculate viewshed size for each cell

Visibility Factor—Viewshed Size

Computational expensive About 700,000 cells Each cell requires 10 seconds About 76 days

Parallel computing 12 computers Each computer runs two

counties About 55000 cells

6 days Succeed with 3000 cells

but failed with 55,000 cells

2000 census block data

Visibility Factor--# of People in Viewshed

Final Score Layer

Candidate Sites

Exclusion Zones

Sites

Software Tools for Wind Farm Siting

Software Tools for Wind Farm Siting

Thanks! Questions?

Using AHP in GIS AHP is implemented as a software component AHP is integrated with ArcMap GIS(ESRI, Inc.)

as an extension

ArcMap GISArcMap GIS

GISGIS AHPAHP