Energy Storage in Alaska Today. David Lockard PE Alaska Energy Authority September 27 th, 2011

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1 Energy Storage in Alaska Today David Lockard PE Alaska Energy Authority September 27 th, 2011

2 Why Is Energy Storage Even More Important Today? Renewable energy is often: Intermittent (wind, tidal, wave, solar) Unpredictable (wind, solar) Energy storage allows these resources to be used more effectively The rising cost of energy makes it more attractive to consider energy storage

3 Discussion of Existing Energy Storage in Alaska What is the roundtrip efficiency of each of these systems? How long will they last? What are the standby loads and other operation and maintenance costs? Which can respond fastest to changing loads? Which can provide ancillary services such as power quality improvement?

4 Storage Hydro Systems Have a dam or impoundment to contain the water Alaska has many systems of this type This presentation will address two: Bradley Lake Hydro Terror Lake Hydro in Kodiak One benefit of storage hydro for energy storage is that as the water level rises the power output per unit of water flow increases No pumped storage in Alaska but it is under consideration

5 Bradley Lake Hydro Description: largest hydro project in Alaska 120MW of capacity Output is split between the six railbelt utilities Operated by Homer Electric 125 high rock-filled dam is 610 long Cost: $328 million In 2008, Bradley produced 287,000 MWh of power at approximately $0.054/kWh Average output was 33 MW in 2008

6 Bradley Lake Energy Storage Maximum lake elevation: 1,180 feet Intake elevation: 1,080 feet Maximum turbine flow: 3,000 acre-feet/day Dispatch strategy: peak shaving for railbelt utilities (maximizes value of water stored) Output is limited by transmission line capacity

7 Terror Lake Hydro (Kodiak) 22MW Two hydro turbines Utility in process of increasing to three turbines and 34MW 69kV transmission line Hydro used in part to provide energy storage for 4.5MW wind farm Precipitation is lower in winter, but wind output is higher due to higher wind speeds and air density

8 Golden Valley Electric Association Battery Energy Storage System Completed in December 2003 Can provide 27MW for 15 minutes Up to 40MW maximum output 13,760 liquid electrolyte-filled Ni-Cad cells Total weight = 1,500 tons Battery life: years Project cost $35M 138kV output Roundtrip efficiency? Standby power use? O&M cost?

9 Metlakatla Battery System Built in MW capacity 1.4MWh energy storage 1997 startup Valve-regulated lead acid battery technology Originally installed to support large motor loads and in-rush currents at a local sawmill Ancillary benefit is smoothing hydro output Batteries were replaced after 11 years

10 Kokhanok High Penetration Wind-Diesel-Battery System 45 kw average village load/peak = 106kW 483,000 kwh/year 490kW diesel powerhouse with heat recovery built by AEA Remanufactured Vestas V17 90kW Wind Turbine (two) Substantial controls upgrade Electric boiler added in heat recovery loop Projected fuel savings 19,297 gallons (51%)

11 Kokhanok Battery 200 kva of battery storage Valve-controlled lead acid batteries Designed to operate with diesels off Grid-forming Inverter

12 Discussion of Existing Energy Storage in Alaska What is the roundtrip efficiency of each of these systems? How long will they last? What are the standby loads and other operation and maintenance costs? Which can respond fastest to changing loads? Which can provide ancillary services such as power quality improvement?