- Assessment of wind resource;
- Evaluation of offshore wind electricity generation profile;
- Summarization of existing generation and load in Humboldt County before addition of offshore wind;
- Analysis of the interaction between offshore wind and local load, generation, and transmission.
2. Materials and Methods
2.1. Load Compatibility Node Model
2.1.1. Electricity Demand
2.1.3. Existing Power Plants
2.2. Offshore Wind Resource Model
2.2.2. Study Scenarios
- Baseline—No offshore wind development. Current generation profile and energy demand are projected to 2030 for comparison.
- Pilot Scale—48 MW nameplate capacity. This scale is assumed to be the smallest wind array that might be installed.
- Small Commercial—144 MW nameplate capacity. This scale was selected because it is the approximate scale of a wind farm proposed in an unsolicited lease request for an overlapping offshore wind area .
- Large Commercial—1836 MW nameplate capacity. This scale was selected because it represents a full build out of the Humboldt Call Area, using turbine and mooring line spacing discussed in Section 2.2.4.
2.2.4. Turbine Layout
2.2.5. Modeled Wind Speed
2.2.6. Analysis Methods
- U, the wind speed at height h = 136 m
- U0, the wind speed at height h0 = 100 m
- α, the wind shear exponent of 0.1.
2.3. Power Plant Dispatch Model
3.1. Offshore Wind Generation
3.1.1. Wind Speed Distribution
- Below cut in speed: 0 to 3 m/s; no power output because wind turbine is not spinning;
- Increasing power output: 3 to 11 m/s; power output increases with wind speed;
- Rated wind speed: 11 to 25 m/s; power production is constant at rated power output;
- Above cut out speed: 25+ m/s; no power output because wind speed is too high.
3.1.2. Wind Speed Variability
3.1.3. Offshore Wind Power Generation
3.2. Offshore Wind Compatibility with Local Generation and Load
3.2.1. Baseline Generation in Humboldt
3.2.2. Daily Generation Profiles
- Pilot Scale—A 48-MW wind farm (top row) would operate in tandem with HBGS and other resources to meet electricity demand. Even during windy days, offshore wind generation would not exceed regional load, and no offshore wind energy would be exported out of the region.
- Small Commercial Scale—The 144-MW wind farm would output 133 MW during high wind speed periods. With HBGS at minimum output, the total electricity generation of 169 MW would be balanced with local load by exporting offshore wind energy. During periods of low load and high wind (e.g., midnight to 6 am on the high wind speed day), offshore wind would be curtailed to limit exports to 70 MW.
- Large Commercial Scale—Production from an 1836-MW wind farm would far exceed the region’s electricity demand. During periods of moderate to high wind speed, offshore wind energy would be exported at maximum capacity, but the majority of the production would be curtailed because of transmission limitations. Importantly, even with a large offshore wind installed capacity, local generation from HBGS would be needed during low and variable wind speed days to meet the regional energy demand. Given current transmission limitations, this demand could not be met entirely by imports.
3.2.3. Annual Generation Summary
3.2.4. Monthly Generation Summary
Conflicts of Interest
Appendix A. Method for Calculation of Hourly Generation of Extant Plants
- Daily cycling: In this mode of operation, “HBGS may be operated at maximum continuous output for as many hours per year as scheduled by load dispatch, and limited by operational constraints of the permit to operate (approximately 75% annual capacity factor)” . The engines may operate for a sum of up to 80 h per calendar day at output levels between 50% and 75% (8–12 MW). Engines are not permitted to continuously operate below 50% capacity .
Appendix B. Loss Effects
|Loss Category||Loss Origin||Loss Factor||Depends On||Effect on Model|
|Wake Effect||Internal Wake Effect of the Project [a]||Varies||Wind farm scale and density, see Table 4||Even reduction|
|Wake Effect of Existing or Planned Projects [a]||0.0%||Even reduction|
|Availability||Contractual Turbine Availability [a]||3.0%||O&M plan; Proven reliability/newness of turbine||Turn to 0 MW|
|Non-contractual Turbine Availability [a]||1.3%|
|Availability Correlation with High Wind Events [a]||1.3%||Frequency of high wind events||Turn to 0 MW|
|Availability of Collection and Substation [a]||0.2%||Timing of substation downtime||Turn to 0 MW|
|Availability of Utility Grid [a]||0.3%||Timing of grid blackouts||Turn to 0 MW|
|Plant Re-start after Grid outages [a]||0.2%||Timing of grid blackouts||Turn to 0 MW|
|First-Year Plant Availability [a]||0.0%|
|Electrical||Electrical Efficiency [a]||2.0%||Distance between turbines and substation||Even reduction|
|Power Consumption of Weather Package [a]||0.1%||Even reduction|
|Turbine Performance||Sub-optimal operation [a]||1.0%||Even reduction|
|Power Curve Adjustment [a]||2.4%||Even reduction|
|High Wind Control Hysteresis||1.0%||Wind regime at site; turbine model||Turn to 0 MW|
|Inclined Flow [a]||0.0%||Even reduction|
|Environmental||Icing [a]||0.0% [c]||Temperature||Turn to 0 MW|
|Blade Degradation [a]||1.0%||Even reduction|
|Low/High Temperature Shutdown [b]||0.0% [c]||Temperature, turbine limits||Turn to 0 MW|
|Site Access [a]||0.1%||O&M plan, availability of parts, staff, vessels||Turn to 0 MW|
|Lightning [b]||0.1%||Turn to 0 MW|
|Curtailments||Directional Curtailment [a]||0.0%||Layout and spacing||Turn to 0 MW|
|Environmental Curtailment [a]||0.0%||Local environmental regulation||Turn to 0 MW|
|PPA Curtailment [a]||0.0%||Wind farm scale and density||Turn to 0 MW|
Appendix C. Study Locations
|BOEM Northern California Call Area|
|General area||Offshore Humboldt Bay|
|West-East width||12 NM (22 km)|
|North-South width||25 NM (46 km)|
|Total area||207 mi2 (537 km2)|
|Perimeter||81 NM (150 km)|
|Distance to shore||Min.||17.4 NM (32.2 km)|
|Max.||30.4 NM (56.3 km)|
|Average annual wind speed at 90 m height||Min.||8.875 m/s|
|Ocean depth||Min.||1640 ft (500 m)|
|Mean||2673 ft (815 m)|
|Max.||3610 ft (1100 m)|
|Construction and maintenance port||Name||Redwood Marine Terminal 1|
|Centroid to port distance, approximate ship route||27 NM (50 km)|
|Interconnection point||Name||Humboldt Bay Generating Station|
|Centroid to interconnection point distance, approximate cable route||25 NM (46 km)|
Appendix D. Turbine Layouts and Spacing
Appendix E. Spatial Averaging: Using the Centroid to Represent an Area
|Wind Farm Capacity||Number of Data Points|
|Wind Farm Capacity||Capacity Factor||Availability|
Appendix F. Humboldt Bay Generating Station Emissions Intensity Calculation
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|Plant Name||Nameplate Capacity||Plant Type||Annual Electricity Production 1|
|Baker Station Hydro 2||1.5 MW||Small Hydro||4340 MWh|
|DG Fairhaven Power Plant 3||15 MW||Biomass 4||116,000 MWh|
|Scotia 3||25 MW 5||Biomass 4||118,000 MWh|
|Humboldt Bay Generating Station 7||163 MW 6||Natural Gas||422,000 MWh|
|Scenario||Number of Turbines||Turbine Nameplate Power|
|48 MW||4||12 MW|
|144 MW||12||12 MW|
|1836 MW||153||12 MW|
|Rated Power||Hub Height||Rotor Diameter||Blade Length|
|12 MW||136 m||222 m||107 m 1|
|Capacity Factor||Annual Energy Production, GWh/year|
|Year||48 MW||144 MW||1836 MW||48 MW||144 MW||1836 MW|
|Coefficient of variation||5.80%||5.80%||5.80%|
|Baseline||48 MW||144 MW||1836 MW|
|Offshore Wind Production, MWh||0||203,000||602,000||7,570,000|
|HBGS Output, MWh||674,000||476,000||334,000||241,000|
|Emissions Reduction, tons CO2e 1||-||44,000–92,000||75,000–158,000||95,000–202,000|
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