The National Renewable Energy Laboratory (NREL) recently released its analysis of renewable energy retrofits in Kokhanok, Alaska.
The report is available for download here: Kokhanok Renewable Energy Retrofits Analysis
The NREL analysis key findings are:
1. Achieving a 50% reduction in imported fuel requires a combination of energy efficiency and renewable energy (specifically wind energy in this case).
2. Energy efficiency, particularly weatherization, is crucial to achieving high levels of imported fuel reduction.
3. The lowest life-cycle cost option is a two-turbine architecture (with energy efficiency). This is not particularly surprising. Kokhanok has an excellent wind resource.
4. The thermal electric stove capacity generally scales with the turbine capacity. As the number of turbines increases, an increasing proportion of the wind turbine energy goes toward meeting the thermal load.
5. The converter size does not scale with the number of turbines. Since the wind turbines in this case are connected directly to the AC bus, the converter needs only to be large enough to facilitate needed energy draws to/from the battery.
6. The battery storage does not scale with increasing number of turbines. The economically optimal battery size is 0.5 to 3 hours of autonomy (based on the average load).
7. Dispatch strategy: The models indicate that cycle charging is the economically preferred strategy. For a two-turbine configuration, load following increases the life-cycle cost by roughly 4% compared to cycle charging.