After a year, Chugach Electric Association has purchased about 50,000 megawatt hours of electricity from Cook Inlet Region Inc.'s wind farm on Fire Island, off Anchorage, the utility told the Regulatory Commission of Alaska on Jan. 30.
The wind farm started outputting power at the end of August 2012, though formal commercial operation did not start until Dec. 31. According to Chugach data, power output from the farm peaked in January 2013, when the utility purchased 6,880 megawatts of electricity. The lowest monthly power purchase was 2,213 megawatt hours in July 2013.
On average, the wind farm generated about 30 percent of its theoretical maximum power output, Chugach said.
Chugach Electric said it declined to use 4,799 megawatt hours of the power purchased in 2013. Curtailment of power from the wind farm mainly occurred from an outage of the power transmission line that connects hydroelectric power on the Kenai Peninsula to Anchorage, Chugach said.
The consequent lack of access to hydropower, coupled with constraints on the gas-fired power generation facilities elsewhere on the power grid, limited Chugach Electric's ability to accommodate the fluctuating Fire Island power output. That caused the utility to decline some of the wind-generated power, Chugach said.
Nevertheless, the resulting curtailment of less than 10 percent of Fire Island's total output was well below the 25 percent curtailment assumed for the first year of wind farm operation, the utility said.
The wind power Chugach used enabled the utility to register 44,725 renewable energy credits; the utility is marketing these credits with any proceeds from credit sales being used to reduce the cost of renewable electricity for customers.
Before the startup of the wind farm in 2012, one major point of contention in power sale negotiations between CIRI and Railbelt utilities was the potential extra cost for the utilities to handle power fluctuations caused by variable wind strength. Power utilities need spare generating capacity to compensate for dips in wind power output. Spare capacity costs money.
Railbelt utilities had also expressed concern that fluctuating wind power would cause power instability in the power grid. CIRI argued that, with the output from Fire Island being small compared to total generation capacity on the grid, such power fluctuation effects would be negligible.
In its report, Chugach said there isn't yet a definitive verdict on this issue, and six to 12 more months of data gathering, analysis and discussion will be required to determine the total effect of wind power on the grid.
The report said that, as part of this analysis, Chugach has asked Anchorage utility Municipal Light & Power to provide information about any costs and effects it incurred as a result of connecting Fire Island to the grid.