By Juan Guerrero and Tom Wheeler
Humboldt County is serviced by old and undersized transmission lines, capable of only meeting a portion of the energy demand of the region. These undersized lines, three running east/west and one north/size, are insufficient to meet the local energy demand. Because that demand can’t be met outside of the region, it must be produced locally—currently the majority of this local production is at the Humboldt Bay Generating Station, a methane gas power plant located just south of Eureka. The transmission capacity of the existing lines—how much electricity can be imported and exported—both limits the development of local renewable energy and prevents Humboldt County from moving from fossil fuel-generated power.
How energy moves from, say, a wind turbine to power your computer requires a complex network of generation, transmission, and distribution, linking energy source to energy need. Imagine a power source like a wind turbine producing electrons. Next, that energy is transmitted through large, high voltage transmission lines. Once the electricity travels to populated areas, two things can happen. Either the consumer is connected to the high voltage transmission line or a substation steps down the electricity to a safer and practical level and distributes the electricity to feeder lines, which are smaller transmission lines. Those feeder lines have smaller transformers that further step down the electricity to its final form to be used for commercial and residential use.
Offshore wind energy is on its way to Humboldt County. BOEM has designated an area in the outer continental shelf near Humboldt County to be leased for wind energy development. The area is known as the Humboldt Wind Energy Area. If fully developed, the Humboldt Wind Energy Area has the potential to generate up to 1.6 gigawatts of energy, enough to power 560,000 homes. Currently BOEM is in the process of finalizing the lease and will begin the bidding stage soon. A large-scale offshore wind form is going to be transformational to Humboldt County's efforts to combat climate change by supplementing conventional sources of energy production with renewable energy. But current transmission capacity constraints limits power generation, both increasing the cost of energy and blunting one of our most important tools for fighting climate change.
Transmission lines are limited to the amount of electricity they can transmit at a given time, exceeding this capacity would otherwise damage the systems and increase hazards for consumers. The undersized lines means that initial development of offshore wind is also limited to approximately 174 MW (which is about one-tenth of what the existing wind area is capable of producing). Even then, there will be situations where it is likely we need to “turn on” offshore wind turbines from producing energy. Schatz Energy Research Lab at CalPoly Humboldt recently produced a report looking at how transmission constraints limit offshore wind development.
Why can’t offshore wind directly replace power created by the Humboldt Bay Generating Station? It can, but only in part. That’s because of something called “base load.” The base load is the amount of electricity needed at any given time to support the county’s electricity demand. Conventional sources of electricity are good at tracking and meeting base load demand. Wind on the other hand fluctuates as a result of wind conditions at any given moment. The more we can ensure the reliability of the grid to meet demands, the more we began to power down the methane power plant. The amount that wind can offset the power produced at the Humboldt Bay Generating Station depends then, in part, on how strong our connection to the larger state grid might be—whether we can import sufficient energy produced elsewhere when necessary. In other words, we can’t begin plans to shut down the methane power plant until we have stronger grid connections.
When there is “surplus” power that otherwise can’t go on the grid, we can store that power through hydrogen or battery storage. Through electrolysis, we can produce hydrogen from water and electricity. That hydrogen can then be used for transportation needs, like Humboldt Transit Authority’s new fleet of hydrogen buses, or the hydrogen can be incorporated into the fuel mix at the methane power plant, up to around 30% of the fuel load.