EASTERN PLAINS TRANSMISSION

PROJECT

Tri-State Generation & Transmission

and Western Area Power

Administration

EASTERN PLAINS TRANSMISSION PROJECT

Resource Additions► 2 x 600 MW supercritical coal units at

Holcomb substation 2011, 2012 – near Garden City, Kansas

► Possible 600 MW addition at Lamar Energy Center in 2020.

► Task was how to integrate into existing Western Interconnection transmission system

EASTERN PLAINS TRANSMISSION PROJECT

Transmission Additions► Began with 345-kV alternatives and corridors

► Expanded to look into 500-kV alternative along same corridors

► Following slides show this progression

Initial Design

BURLINGTON3 X 345/230

HOLCOMB

1200 MW

WRAY

PAWNEESTORY

COMANCHE

BOONE

SMOKY HILL

CORNER POINT

LAMAR ENERGY CENTER

Sensitivities with and without

LAMAR2 X 345/230

BIG SANDY2 X 345/230

DANIELS PARK3 X 345/230

WATERTON2 X 345/230

New 345

New 230

Planned 345

Existing 230

S A-1S A-1

345 kV Minimum for 1200 MW

BURLINGTON

2 X 345/230

HOLCOMB

1200 MW

WRAY

PAWNEESTORY

COMANCHE

SMOKY HILL

CORNER POINT

LAMAR ENERGY CENTER

BIG SANDY2 X 345/230

BOONE2 X 345/230

LAMAR2 X 345/230

Sensitivities with 0 autos

DANIELS PARK3 X 345/230

WATERTON2 X 345/230

MIDWAY1 X 345/230

New 345

New 230

Planned 345

Existing 230

150 miles

3 mile separation

80 miles

100miles

45 miles

80 miles B.Sandy – Midway

80 miles

70 miles

65 miles

125 Mile Rd. Sub

3/09/06

345 kV Minimum for 1800 MW

BURLINGTON

2 X 345/230

HOLCOMB

1200 MW

WRAY

PAWNEESTORY

COMANCHE

SMOKY HILL

CORNER POINT

LAMAR ENERGY CENTER

600 MW

Preliminary Stability Sensitivities evaluated two lines. Not preferred

BIG SANDY2 X 345/230

BOONE2 X 345/230

LAMAR2 X 345/230

Sensitivities with 0 autos

DANIELS PARK3 X 345/230

WATERTON2 X 345/230

MIDWAY1 X 345/230

New 345

New 230

Planned 345

Existing 230

150 miles

135 miles

Preferred instead of 2 Holcomb-Burlington

3 mile separation

80miles

100miles

45 miles

125 Mile Rd. Sub

80 miles

70 miles

65 miles

80 miles

3/09/06

500 kV Minimum for 1200 MW

BURLINGTON

2 X 500/230

HOLCOMB

1200 MW

WRAY

PAWNEESTORY

COMANCHE

SMOKY HILL

CORNER POINT

2 X 500/230

BIG SANDY2 X 500/230

BOONE2 X 500/230

LAMAR210 +90

DANIELS PARK3 X 345/230

WATERTON2 X 345/230

Double-ckt 230

New 345

New 230

Planned 345

Existing 230

New 500

150 miles

70 miles

80 miles

80miles

100miles

45 miles

80 miles MIDWAY2 X 500/230

3/09/06

65 miles

125 Mile Rd. Sub

500 kV Minimum for 1800 MW

BURLINGTON

2 X 500/230

HOLCOMB

1200 MW

WRAY

PAWNEESTORY

COMANCHE

SMOKY HILL

CORNER POINT

LAMAR ENERGY CENTER

2 X 500/230

600 MW

BIG SANDY2 X 500/230

BOONE2 X 500/230

LAMAR210 +90

DANIELS PARK3 X 345/230

WATERTON2 X 345/230

Double-ckt 230

New 345

New 230

Planned 345

Existing 230

New 500

150 miles

70 miles

80 miles

80miles

100miles

45 miles

80 miles MIDWAY2 X 500/230

3/09/06

65 miles

125 Mile Rd. Sub

EASTERN PLAINS TRANSMISSION PROJECT

1200 MW Cost Comparison Minimum 345 kV Cost – $598.1 Million Minimum 500 kV Cost – $715.8 Million Difference of $117.7 Million

► 20 MW Less Losses on 500 kV System► Average Cost of Energy $32.7/MWh► 70% Plant Factor► 26.4 Years to Payback

EASTERN PLAINS TRANSMISSION PROJECT

1800 MW Cost Comparison Minimum 345 kV Cost – $676.7 Million Minimum 500 kV Cost – $786.4 Million Difference of $109.7 Million

► 30 MW Less Losses on 500 kV System► Average Cost of Energy $32.7/MWh► 70% Plant Factor► 16.5 Years to Payback

EASTERN PLAINS TRANSMISSION PROJECT

Questions?