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Alaska wind farms learn from experience Integrating wind technology into rural power systems requires robust diesel power and ways to use excess power production Alan Bailey Petroleum News
With rural communities in Alaska suffering from the excessive cost of diesel powered electricity generation, wind farms have been sprouting up at remote locations across the state as a means of providing more affordable rural energy. And, as the rural wind energy business matures, people have learned some key lessons in how to make the wind technology work effectively and reliably for isolated communities, where electricity is essential for day-to-day living, but where electrical loads are low.
During a Nov. 6 meeting of the board of AEA, or the Alaska Energy Authority, Sean Skaling, AEA deputy director for alternative energy and energy efficiency, said that key lessons learned include the need for robust diesel generation systems, to integrate the varying wind power into a stable overall electricity supply. Also, to make the most economical use of the wind power it is generally necessary to have some form of secondary load that can be brought into play, to use excess power during wind power peaks, Skaling said.
Skaling said that there are now 24 operational wind farms in Alaska, with a total installed capacity of 67 megawatts, representing about 3 percent of the state’s total electricity load. Just a few years ago the total wind farm capacity only accounted for about 0.3 percent of total load, he said.
Wind power grants For a number of years AEA has been providing state grants to support the development of wind power systems. And as part of its rural energy grant process, AEA guides projects from the reconnaissance of potential wind farm sites, through feasibility studies and wind farm design to eventual construction. The idea is to evaluate the feasibility of a potential wind farm site, and to evaluate its potential economic value to a community, before committing funds to design and construction, Skaling explained. At present there are 45 active wind farm grants at various stages of the evaluation, design and construction process, he said.
Once a wind farm has been completed, it becomes owned and operated by the community that it serves, with the community taking responsibility for operation and maintenance. But, given the investment of state money in the ventures, the AEA grants include requirements for maintenance schedules and operations plans, with provisions for AEA to verify that the schedules and plans are being implemented.
Sara Fisher-Goad, AEA executive director, commented that as the availability of state funds tightens in the future, one option may be for AEA to go through a feasibility study and some portion of a design, to determine whether a proposed wind farm makes sense, but then seek alternative financing options to bring the farm to fruition.
Need for diesel Skaling emphasized the importance of having a strong diesel power generation system, with modern controls, that enables the integration of the fluctuating wind power into a rural power generation arrangement.
“The biggest challenge is building the wind on top of a diesel system that can handle it,” he said, adding that correctly sizing the power generation facilities for maximum efficiency is also very important.
Fisher-Goad cited the example of the village of St. George, on the Pribilof Islands in the Bering Sea. AEA and the Denali Commission approved funding for a wind farm to supply power for the village but subsequently realized that village’s existing powerhouse was incapable of handling the wind power integration, she said. As a consequence the wind power project had to be put on hold while the diesel powerhouse was improved. Now, after some frustration with the wind power delay, the village has an effective diesel power system and the wind farm is being commissioned, Fisher-Goad said.
Unalakleet The village of Unalakleet in western Alaska provides another interesting case study. Kris Noonan, AEA program manager for rural power, told the AEA board that when this village upgraded the capacity of its existing wind farm from 400 kilowatts to 600 kilowatts the result was some significant instability in the village power grid. Essentially, the village’s old mechanically controlled diesel power plant could not integrate the additional wind power, Noonan said. AEA helped the village install a new diesel power plant with electronic controls, he said.
But Unalakleet continued to experience issues relating to the generation of excess wind power during period of strong wind conditions. Rather than resolving this problem by curtailing the wind power output and thus eroding the economics of the wind farm, AEA has worked with the Unalakleet utility to find system improvements that enable all of the wind farm turbines to run continuously, Noonan said.
In fact, AEA has found that a village tends to need a secondary load, perhaps a heating loop in a school or some electric boilers, that can be brought into play when the wind peaks. It will probably be necessary to have a secondary load available, even with wind power providing as little as 8 percent of a village’s electricity usage, Skaling said.
“You need some place to put that energy, otherwise you’re going to be curtailing wind and it will be less economic,” he said.
Kodiak The island of Kodiak has implemented a 9-megawatt wind farm that has replaced what used to be diesel power, Skaling said. A hydropower facility, which came into operation in the 1980s and which in the days of diesel generation supplied 80 percent of Kodiak’s electricity, remains a major source of power on the island while also being used to integrate the variable output from the wind farm. But the hydropower facility tends to be sluggish in responding to sudden changes in wind strength, with a 30 to 90 seconds delay in its response if the wind suddenly cuts out. The power utility uses a battery to fill in the resulting power supply gaps. However, after taking many hits in its power balancing role, the battery has a limited lifespan - the utility is going to install a flywheel system to smooth out the energy fluctuations, Skaling said, adding that the port of Kodiak is also installing an electrically powered crane.
With an electricity rate now 15.8 cents per kilowatt hour, Kodiak has saved about $4.5 million per year in fuel costs, Skaling said.
“That’s real savings to the community,” he said.
Home heating? AEA has also investigated the potential for using wind generated electricity to heat homes and buildings in rural Alaska, but has found this to be economically very challenging. For example, with a 10 percent replacement of fuel oil by wind-generated heat, breakeven economics would require a fuel oil cost of $9 per gallon and a wind power cost of 3 cents per kilowatt hour, Skaling said.
“It’s basically a high hurdle to jump over,” he said.
Assistance and research Meantime, as much improved wind modeling and wind mapping enable better evaluations of prospective wind power applications and better understandings of wind-farm performance, AEA is continuing to provide communities with technical assistance. And the agency is partnering with the Alaska Center for Energy and Power in wind-farm related research, Skaling said.
One line of research relates to the effectiveness of wind turbine foundations in Arctic conditions. In another project AEA is about to test a system called SpiDAR for measuring wind strengths. This system uses an upwards directed radar beam to measure wind velocities over a wider range of altitudes and in more detail than can a conventional met tower. The system has been used successfully in the Lower 48 states but AEA wants to test its capabilities in the cold, dry conditions of an Alaska winter. An initial test will take place at Delta Junction, at a location next to an existing met tower, Skaling said.
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