The Electric Department’s 24 employees operate and maintain three power plants and the associated power substations and lines to provide Sitka’s electric utility service. The power plants are:
|Blue Lake, Hydro||8 megawatts||62,500 megawatt-hours|
|Green Lake, Hydro||18 megawatts||60,000 megawattt-hours|
|Jarvis Street, Diesel||12 megawatts||Supplemental/Stand-by as required|
|Total||38 megawatts||122,500 megawatt-hours hydro|
The power requirement of Sitka in calendar year 2007 was a peak demand of 22.3 megawatts in December and the total energy generated over the year was 112,524 megawatt-hours. The amount of energy available from the hydroelectric projects varies from year to year, depending upon the amount of precipitation. It ranges from 104,000 megawatt-hours in a low rainfall year to 136,000 megawatt-hours in a high rainfall year.
The average home in Sitka uses about 1,000 kilowatt-hours per month. Here is a comparison of the cost of 1,000 kilowatt-hours for a residential customer in various towns around Alaska in January, 2008:
|Utility||Bill for 1,000 kWh||Average Cents/kWh|
|Fairbanks - Golden Valley Electric Assoc.||$ 162.80||16.3|
|Anchorage - Chugach Electric Assoc.||$ 122.90||12.3|
|Juneau (Winter Rates) - Alaska Electric Light & Power||$ 119.48||11.9|
|Ketchikan - Ketchikan Public Utilities||$ 94.20||9.4|
|Sitka - City & Borough of Sitka||$ 92.42||9.2|
The electric power systems in Juneau and Ketchikan are very similar to Sitka with over 95 percent of their electric energy normally generated by hydroelectric. In the rail belt, most of the electricity is generated with coal, oil and natural gas-fired generators, and their fuel costs are going up. Sitkans enjoy some of the most stable and low cost power rates in the state, thanks to our renewable hydroelectric energy source.
Due to low rainfall, the forecast for 2008 is that there will be a 2.4% or 2,800 megawatt-hours shortfall in meeting the energy requirement of Sitka with hydroelectric. The 2,800 megawatt-hour shortfall will be made up with diesel generation, consuming an estimated 212,000 gallons of diesel fuel in 2008. This is in part due to the fact that, at low lake levels in the early summer, the load carrying capacity of the hydroelectric generators is reduced by as much as 50%, from 26 megawatts down to 13 megawatts compared to summer load levels of 15 megawatts.
Planning and preliminary design work is in progress to expand the existing Blue Lake Hydroelectric Project to its maximum capacity. That expansion will entail additions to the rock tunnel penstock, constructing a new powerhouse housing a 10 megawatt third turbine and raising the dam by as much as 83 feet. These improvements would increase the power production of the Blue Lake Hydroelectric Project by over 50%. This project is expected to cost about $50 million and require about seven years to complete. The goal is to complete the work and have it in service in 2015.
A significant reliability concern of the Electric System is the lack of adequate stand-by diesel generating capacity. Sitka’s hydroelectric plants are at one end of the system and the loads are at the other end. The interconnecting 15 miles of single transmission line is vulnerable to land slides and storm damage that has in the past isolated Sitka from its hydroelectric power supply. In August of 2002, the transmission line was knocked down by a landslide at Heart Lake. Fortunately, that occurred in the summer when the loads were low. Even at that time, Sitka barely had enough diesel capacity to carry the load with Sitkans cutting their power use as much as they could. If such an event should occur during the winter, the load would be in the order of 20+ megawatts compared to 12 megawatts of stand-by diesel capacity. The result would be rotating black-outs in Sitka until the transmission line interconnection was restored, which could take several days if not weeks. If such an event occurs, the priority will be to keep Japonski Island and the downtown area in power, with the outlying areas on rotating black-outs as required keeping the load within the available diesel capacity.
Planning and design work is in progress to build a second 69 kV transmission line along Sawmill Creek Road from the Blue Lake plant to Thimbleberry Park. This section of new transmission line will by-pass the off-road Heart Lake area and provide a second route to get power from the Blue Lake plant into Sitka, which reduces the amount of stand-by diesel generating capacity required. A related issue is the existing diesel generating plant which is limited to burning 327,000 gallons of diesel fuel under the state’s air quality permit. Work is in progress to substantially increase that air quality emissions permit.
The Electric Department normally averages about $1 million of capital improvements or major maintenance on the electric system each year. The system is maintained in a good state of repair and in regulatory compliance to ensure reliable and good quality electric service.
105 Jarvis Street, Sitka, Alaska 99835
(907)747-4000, Emergency number (24 hours a day): 907-747-6634 Fax: 907-747-3208
Business Hours: Monday through Friday, 8:00 a.m. to 5:00 p.m.