Distributed vs. Centralized Offshore Wind Farms

Last week, we discussed the many benefits of distributed offshore wind farms, which are vital energy production facilities in the face of climate change. Distributing offshore wind farms among numerous coastal communities in Oregon will introduce fewer environmental impacts and will be more cost effective than building one or two large, centralized offshore wind farms. Each distributed offshore wind farm will produce fewer megawatts than a centralized offshore wind farm, but all together will produce more energy at a lower upfront cost.


There are several obstacles to distributed offshore wind farms. Past practice and tradition within the electric utility industry often spurs utilities to support more of the same ideas, in this case, centralized power generation via one or two new, massive offshore wind farms.


In this article, we take a brief look at the history that led to the rise of centralized power production facilities. We’ll also explore the cost of construction associated with both centralized and distributed offshore wind farms to showcase the cost savings of distributed wind generation.


A Brief History of Electric Energy Production


During the birth of the electric power industry, power production facilities were located in every town, especially near industrial areas. These small generating facilities essentially created grids like the microgrid of today, historically known as a mini-grid, a small scale, self-sufficient system. To learn more about historical mini-grids, check out the white paper Lehigh Navigation Coal Company Electrical System: A Turn of the Twentieth Century Mini-Grid.


After World War II, mergers and acquisitions led to the creation of large electric utilities, rather than the many locally owned and operated utilities of the past. These electric utility conglomerates commissioned and owned large, central power production facilities with interconnected, high voltage transmission systems. Power was produced some miles away from urban centers, and was transported to consumers via a series of transmission and distribution lines.


The Grid Must Update for Distributed Renewables


This is the model that most electric utilities still rely on today. However, as distributed renewable energy sources become more widespread, this model has become outdated. A modern electric power grid must include both distributed energy generation from offshore wind farms and rooftop solar panels, and centralized energy generation from large scale solar and wind farms, hydropower dams, and other clean power producing technologies.


The benefit of this past practice is that many transmission lines already exist to support new wind farms and other distributed, renewable energy. Unfortunately, due to the near century of tradition within the electric utility industry, it is often challenging for utilities to break away from the consensus that centralized power production is best, and embrace new ideas about distributed renewables.


Wind power is recognized by most in the industry as the most prudent source of electric energy generation as we face a future with climate change. Though today’s consensus is beneficial to climate change mitigation strategies, the belief that centralized generating stations are the best and only way to produce energy remains an issue.


Centralized Wind: High Cost for All New Construction


A centralized offshore wind farm in Coos Bay, Oregon, would include about 300 wind turbine generators with a capacity of 4,500 MW. According to records from Homeland Infrastructure Foundation-Level Data (HIFLD), existing transmission lines in the Coos Bay area are 115 KV lines. To transfer the newly produced 4000 MW of electric energy from a Coos Bay wind farm to inland Oregon, at least three new 500 KV transmission lines must be constructed.


New lines will require 100 foot towers and bundled, 2000 gauge aluminum conductors. If the transmission lines are built to connect to more than two inland substations, then more transmission lines will be needed. Additionally, a large portion of the right of way (ROW) for these lines will be through natural, forested areas.


Figure 1 illustrates the electric energy grid that will be needed for a centralized offshore wind farm near Coos Bay. As is evident in the figure, this project would require construction of all new lines, including underwater cables, underground and overhead transmission lines, in addition to new substations.

Figure 1 illustrates the electric energy grid that will be needed for a centralized offshore wind farm near Coos Bay, Oregon.


Engineering firms, construction companies, and equipment manufacturers have lined up to support the proposed centralized offshore wind farm because building three 500 KV transmission lines from Coos Bay to an interconnection point will be about a $1 billion effort. This estimate does not include the cost of building the offshore wind turbine generators or offshore collector substations.


In all, this project will cost well over $4 billion. It would be a poor use of funding from the Inflation Reduction Act, especially when a significantly lower cost alternative is available.


Distributed Offshore Wind: Lower Cost, Greater Yield


Rather than build a centralized offshore wind farm, several smaller offshore wind farms should be constructed off the coast at multiple locations in Oregon. Most coastal towns already have existing 115 KV transmission lines with 80 foot towers and 556 gauge, aluminum conductors, built to carry electric energy from an inland, centralized power plant.


The flow of electric energy can be reversed so that these transmission lines transfer 150 MW of electric energy from the coast, inland. Distributed offshore wind farms could be located near Astoria, Cannon Beach, Tillamook, Pacific City, Lincoln City, Newport, Coos Bay, and Brookings. According to HIFLD data, each of these towns has existing 115 KV transmission lines. Although each distributed offshore wind farm will produce fewer megawatts than a centralized offshore wind farm, they will produce more megawatts when considered as a whole.


Figure 2 illustrates the electric energy grid that will be needed for each distributed offshore wind farm. This diagram looks specifically at an offshore wind farm located near Tillamook; however, the same principles would apply to all distributed offshore wind farms along the Oregon coast.

Figure 2 illustrates the electric energy grid that will be needed for a distributed offshore wind farm near Tillamook, Oregon.


Constructing distributed offshore wind farms that utilize existing transmission infrastructure will nearly eliminate the cost of transmission line construction. Each new offshore wind project will require new construction to build out wind turbine generators, underwater cables, etc.; however, without the construction costs of extra high voltage transmission lines on land, the cost of the entire project will be reduced by at least 30%.


The Best Path Forward: Distributed Offshore Wind Farms


Existing transmission lines can provide sufficient transmission capacity to transfer energy from distributed offshore wind farms to inland areas. Though these existing lines were designed to transfer energy from inland power production facilities to coastal communities, the flow can be reversed at no cost to energy producers, electric utilities, or consumers. By using existing lines, damage to forested and natural areas will be minimized.


Prescient’s vision is that every coastal community in Oregon will receive their electric energy from a combination of offshore wind farms and energy storage facilities, built into the electric energy warehouses that replace substations. To learn more about Prescient’s ideas for the next generation electric power system, contact us or check out our next generation blog collection.

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