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The Case for Floating Wind Turbines in California

15 January 2019

When California passed a state bill earlier this year targeting zero emissions from energy sources by 2045, it showed the world that Californians are serious about addressing climate change. After this year’s tragic season of wildfires and their direct attribution to anthropogenic climate change, Californians feel more urgency to push forward in environmental endeavors. Ever since renewable energy technologies like solar and wind have reached maturity and market viability, California has been committed to their implementation, both in the residential and utilities sector. For this reason, renewable energy already accounts for an impressive 29% of the state’s total energy generation. However, new reports suggest that renewable energy implementation, specifically in regards to residential photovoltaics, has begun to plateau and even slow down. In order to combat this concerning trend, the state has begun creating incentives and legislation, including the upcoming mandate that all new construction homes must employ photovoltaic generation starting in 2020.

However, this continued increase in photovoltaics is putting immense strains on California’s electrical grid. The now well-known ‘Duck Curve’ depicts this problem well, illustrating how the excess energy generated by PVs in the middle of the day is being wasted or sold to neighboring states since its generation pattern does not match consumer demand patterns. Short term battery storage could solve this issue, but companies in California should also consider diversifying and building out the grid to increase its consistency and reliability. Though floating wind energy is still in its infant stages of development, it could undoubtedly help complement California’s existing grid infrastructure.

Throughout the world, floating wind turbines have already generated interest due to a variety of factors, one being the inevitable saturation of traditional offshore wind project areas. While offshore wind is still has room for growth in all regions of the world, the continued implementation of traditional offshore wind will leave fewer sites shallow and windy enough for commercially viable wind energy projects. In California, residents likely don’t see traditional offshore wind farms off the coast for one specific reason: water depth. Traditional offshore wind farms can only be built in water depths under 20 meters for monopole foundations and 50 meters multi-leg foundations, a constraint that is somewhat incompatible with California’s deep coastal waters. This depth constraint typically limits traditional offshore wind projects to near the shoreline, a position that typically has more wind resources than land but far less than the open ocean.

 There isn’t much high resolution data on wind resources in the middle of the ocean, but velocity profile research suggests that fewer obstacles obstructing wind flow results in larger wind resources in comparison to those on land or coastlines.  Data from the global wind atlas appears to confirm this hypothesis, suggesting that if we want to maximize energy generation from offshore wind, we’ll need to employ floating wind turbines to take advantage of the massive resources far from the coast, since they are not constrained by water depth.

Beyond opening access to a greater wind resource, floating wind turbines are also ecologically favorable when compared to their fixed bottom counterparts. A growing body of research suggests that traditional, nearshore wind farms disrupt fisheries and migratory bird patterns. Additionally, the presence of nearshore wind farms has historically generated backlash from coastal communities who feel that their undisturbed oceanic horizon has been disrupted by the monolithic turbine towers. Beyond this “visual pollution”, however, nearshore wind farms truly do disrupt shipping lanes. Floating wind turbines, on the other hand, are far away from the coast and are therefore less likely to interfere with the coastal economy and the views of coastal residents. If fully realized, floating wind turbines can therefore provide abundant carbon-free energy with less societal aggravation.

Despite the promise of floating wind, it faces some serious obstacles in deployment. Floating wind would almost certainly be more difficult to maintain than near shore or onshore wind farms; the cost of getting to and servicing turbines alone would be monumental. Additionally, reports indicate that offshore wind farms appear to have significantly more drivetrain issues than their onshore counterparts due to corrosion and other environmental factors. If this problem persists, it would only add to the already high projected operational cost of a floating wind farm.  Beyond that, floating wind turbine platform and tower designs have not yet converged, signaling that the technology is still a ways away from reaching maturity. Once designs start converging and floating wind deployment increases, however, the technology will naturally fall in price and become more competitive on the energy market.

Overall, floating wind represents an innovation with an enormous untapped potential. While it has a set of hurdles to overcome before scaling, fixed offshore wind faced similar hurdles before arriving at its current prominence. In both Japan and Scotland, pilot floating wind farms are already in operation and an army of government reports and early stage companies are driving the industry forward. Because of this, floating wind will likely follow the trajectory of other renewables, which have seen costs steadily drop as their technology matures.  Aside from the technological and financial challenges, floating wind erases nearly all of the issues that people have with wind power in the current day and gives hope to California’s ambitious goal of going carbon-free by 2045.

Conor Quigley is an undergraduate student in the Department of Mechanical Engineering at Stanford University

Photograph by: Kim Hansen, (https://commons.wikimedia.org/wiki/File:Middelgrunden_wind_farm_2009-07-01_edit_filtered.jpg)