Wind Powering America asked Rich Stromberg, wind program manager for the Alaska Energy Authority, to share lessons learned while working to further wind development in the state.
Alaska has a high cost of energy because of imported diesel fuel. How important has wind energy development been for the state in terms of mitigating energy costs and emissions?
The cost of diesel fuel in rural and remote Alaska is driven not only by the price of oil and diesel fuel at the pump but also by the cost to deliver that fuel via barge or in some cases by air. As fuel costs increase, the delivery costs increase, so the cumulative impact is even greater. These transportation costs also impact construction costs related to the mobilization of heavy equipment and the delivery of foundation materials, wind turbine components, power poles, conductors, transformers, etc. The challenge remains to design a project that has a positive payback over the 20-year economic life of a project.
Wind turbines in the ~100-kilowatt (kW) size range typically cost $12,000 to $17,000 per kilowatt to install and integrate. Remanufactured turbines can be installed from $6,500 to $11,000 (per kilowatt). Megawatt (MW)-scale turbines cost around $5,000 to $6,000 (per kilowatt) to install and integrate, but as turbine sizes increase, so do renewable energy contribution levels (to the overall peak demand). High-contribution systems have not yet been proven in Alaska.
Wind energy has been a viable option in several parts of Alaska, but our higher fuel costs don’t necessarily make the installation of a wind turbine the “slam dunk” solution some might expect.
Also, Independent Power Producers (IPPs) have a more difficult time developing wind projects in Alaska because the state is exempt from some of the FERC1 rules in the Lower 48. Utilities don’t have to accept wind power from an IPP even if it costs less than the avoided cost.
The state has a harsh climate in terms of cold and moisture. How does that impact the evaluation of the wind resource?
The primary impact is making sure that someone from the local community goes out to the met tower site and actually pulls the data. Harsh weather can make people less than eager to walk or snowmobile out to the site.
One issue is icing of the vanes and anemometers. The higher we go in elevation at sites near the coast, the more severe and frequent is the icing. We don’t have solid data to tell us how to treat icing periods in our data. Simply deleting the icing period and synthesizing the data gap likely overestimates actual wind turbine production with icing.
Our climate can cause wear and tear on data cables, wiring panels, and instruments, but we typically can get 2 years of successful operation out of these systems and 5 years or more out of the tubular towers and guy wires.
Anchors and tower base support can be difficult in an area with solid frozen ground in the winter and a wet active layer in the top 3 feet of permafrost in the summer.
What lessons have you learned in terms of selecting and maintaining turbines for the Alaskan climate?
Turbine tip brakes can be problematic. Low-temperature lubricants are a must, as are controllable heaters in the nacelle. Low-temperature steel is needed in many parts of the state. Remote SCADA2 with good Internet connectivity is an absolute requirement to allow for quick troubleshooting.
Tell us about the Kodiak Wind Farm.
Kodiak was the first project to install megawatt-scale turbines in the state. Kodiak Electric Association is a high-functioning utility, and the initial 4.5 MW of wind power installed was small enough to make this a low-contribution system. Kodiak was able to set the benchmark of how well a wind project could perform compared with what the modeling tools predicted. In a Class 7 wind site, Kodiak Electric Association achieves between a 33% and 35% net capacity factor3.
Can you discuss wind project logistics in Alaska compared to the rest of the country? What lessons have been learned?
It can be very difficult to combine nearby projects to achieve economies of scale. In many locations, heavy equipment must be mobilized and demobilized when the ice is out and barges can access the beach. Unfortunately, most places have permafrost, and the ground must freeze before the heavy equipment can be moved out to the construction site. This prevents using the same equipment for multiple villages in the same construction season. It also increases equipment rental costs when heavy equipment must sit idle for 6 to 8 months waiting for freeze up or waiting to be barged out. It’s not like the Lower 48 where you only have to pay for a crane for a few weeks.
Are there any other lessons about wind energy in Alaska that you would like to share?
We now differentiate between very-low and low-contribution levels. Only contribution levels of 8% average wind or less can be controlled simply with the diesel gensets. Greater contributions of wind require turbine curtailing, batteries, or secondary loads and controls.
Proper sizing and dispatch strategies for secondary loads can make a huge difference in whether a wind project achieves the modeled performance goals.
Harsh conditions can delay the arrival of technicians and spare parts. The most remote communities like St. George, Savoonga/Gambell, and the western Aleutian communities can see travel delays of 1 or 2 weeks. Meanwhile, equipment downtime accumulates.
Distributed generation of power requires a more thorough analysis of the entire wind-diesel system to ensure good power quality control.
It is relatively straightforward to install and connect a wind turbine. Integration of power at average contributions of 20% to 50%, as seen in Alaska, is a much more challenging task.
Source: NREL Wind
For more information on: NREL Wind