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 ► ► 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 BURLINGTON 3 X 345/230 HOLCOMB 1200 MW WRAY PAWNEE STORY COMANCHE BOONE SMOKY HILL CORNER POINT LAMAR ENERGY CENTER Sensitivities with and without LAMAR 2 X 345/230 BIG SANDY 2 X 345/230 DANIELS PARK 3 X 345/230 WATERTON 2 X 345/230 New 345 New 230 Planned 345 Existing 230 S A-1

345 kV Minimum for 1200 MW BURLINGTON 2 X 345/230 HOLCOMB 1200 MW WRAY PAWNEE STORY COMANCHE SMOKY HILL CORNER POINT LAMAR ENERGY CENTER BIG SANDY 2 X 345/230 BOONE 2 X 345/230 LAMAR 2 X 345/230 Sensitivities with 0 autos DANIELS PARK 3 X 345/230 WATERTON 2 X 345/230 MIDWAY 1 X 345/230 New 345 New 230 Planned 345 Existing 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 PAWNEE STORY COMANCHE SMOKY HILL CORNER POINT LAMAR ENERGY CENTER 600 MW Preliminary Stability Sensitivities evaluated two lines. Not preferred BIG SANDY 2 X 345/230 BOONE 2 X 345/230 LAMAR 2 X 345/230 Sensitivities with 0 autos DANIELS PARK 3 X 345/230 WATERTON 2 X 345/230 MIDWAY 1 X 345/230 New 345 New 230 Planned 345 Existing 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 PAWNEE STORY COMANCHE SMOKY HILL CORNER POINT 2 X 500/230 BIG SANDY 2 X 500/230 BOONE 2 X 500/230 LAMAR DANIELS PARK 3 X 345/230 WATERTON 2 X 345/230 Double-ckt 230 New 345 New 230 Planned 345 Existing 230 New miles 70 miles 80 miles 100miles 45 miles 80 miles MIDWAY 2 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 PAWNEE STORY COMANCHE SMOKY HILL CORNER POINT LAMAR ENERGY CENTER 2 X 500/ MW BIG SANDY 2 X 500/230 BOONE 2 X 500/230 LAMAR DANIELS PARK 3 X 345/230 WATERTON 2 X 345/230 Double-ckt 230 New 345 New 230 Planned 345 Existing 230 New miles 70 miles 80 miles 100miles 45 miles 80 miles MIDWAY 2 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?