This analysis examines the suitability of wave power to serve the energy needs of an isolated Northern coastal community. Yearly seasonality patterns suggest that the wave energy resource is a good match for community load. The wave energy resource in a location such as the Gulf of Alaska and energy demand in Northern communities are both winter peaking.
Daily patterns show similarities in wave power patterns and demand patterns. Both of these series have evening peaks. However, there are significant differences, suggesting an important role for energy storage. An energy storage system that can store energy over several hours can help the community save the energy generated during the early morning peak in wave power for use later in the morning when demand picks up.
The sample of yearly energy demand for a representative Pacific Northern coastal community is generated using the hourly electricity operating data for Tacoma Department of Public Utilities Light Division, or Tacoma Power (“U.S. Energy Information Administration” 2019). The demand for power from a Pacific Northwestern utility such as Tacoma power exhibits similar seasonal and hourly patterns as energy demand in Alaskan villages Devine (2004).1
The plot below shows the average hourly demand for electricity for a representative Alaskan community. The series is constructed as the 2018 electricity demand for TPWR scaled to have the average power demand of 612 kilowatt, the average power demand of Yakutat, AK. Yakutat is a community on the Gulf of Alaska coast with 613 residents. It is investigated for wave power deployment by the Alaska Center for Energy and Power. The wave resource near the coast of Alaska has been shown to be sufficient to power the community. The community is isolated from the larger grid, depends entirely on diesel generation and has an electricity rate of $.50/kWh (“Statistical Report of the Power Cost Equalization Program ”2017).
Source: Demand for Tacoma Department of Public Utilities Light Division Hourly https://www.eia.gov/opendata/qb.php?category=2122628&sdid=EBA.TPWR-ALL.D.H| Mean | Standard Deviation | |
|---|---|---|
| Wave | 2.006966 | 1.208351 |
| Wind | 6.427868 | 3.717028 |
The standard deviation of wind speed is over 3 times higher than that of wave height. Note that wave power is proportional to wave height squared, and wind power is proportional to wind speed cubed(https://www.windpowerengineering.com/construction/calculate-wind-power-output/). Thus, power generated by wind turbines is substantially more variable than wave power.
The daily patterns in energy demand of a coastal community and wave power have substantial differences. While both have evening peaks, wave power has another peak during early morning, when demand is at its lowest. This shows the value that an energy storage system storing energy over several hours can provide.
Demand for energy is lowest at 3-4 am. It has 2 peaks, at 11 am and at 8 pm. The energy demand during the peak hours is 30 % higher than at 4 am.
Wave power for energy generation (represented by wave height) peaks at 4 am and at 6 pm. Without energy storage a wave energy converter connected to an isolated grid would need to curtail its power at night. Within-day energy storage can conserve the energy generated at night for use to satisfy morning peak demand.
Devine, M. 2004. “The Alaska Village Electric Load Calculator the Alaska Village Electric Load Calculator,” no. October. doi:10.2172/15011687.
“Statistical Report of the Power Cost Equalization Program.” 2017. Alaska Energy Authority. http://www.akenergyauthority.org/Portals/0/Programs/PCE/Documents/FY17 PCE Statistical Report By Utility.pdf.
“U.S. Energy Information Administration.” 2019. Accessed July 22. https://www.eia.gov/opendata/.
The electricity operating data for large PNW utilities, such as the largest utility PSE, exhibit similar seasonal and daily patterns as Tacoma Power.↩