Offshore wind farms already face one of the most inhospitable environments for renewable energy – we know salt water, storms, and waves can combine to reduce output, but are inefficient turbine layouts also sapping generation?
New research from the University of Delaware suggests the existing tight grid layouts of offshore wind farms reduces wind farm power generation, but that efficiently spacing or staggering turbines significantly increases their capacity factor.
These new findings join a host of other exiting research projects exploring how turbine placement affects wind power performance, and could help engineers build offshore wind farms more efficiently to help wring as many megawatts out of each turbine and dramatically cut greenhouse gas emissions as fast as possible.
Offshore Wind Not Always Living Up To Its Potential
The team of researchers at University of Delaware’s (UD) Atmosphere and Energy Research Group based their studies on Sweden’s Lilligrund offshore wind farm. The project has a total installed capacity of 110.4 megawatts (MW), but has only produced power at a 35% capacity factor (as of 2012) – and its tightly packed rows could be the reason it performs below offshore wind’s median 43% capacity factor.
After setting their baseline, the researchers created six alternative wind farm layouts in computer simulations. Some layouts kept turbines in consistent rows spaced further apart while others staggered turbine row alignments similar to how theater seats are spaced to improve seat views as they move further back.
The computer simulations took weeks to run and focused on how the eddies, or choppy air produced by each turbine spinning, affected the output of downwind turbines in the farm.
Efficient Turbine Spacing Boosted Output 33%
So what did the simulations find? “Staggering every other row was amazingly efficient,” said Cristina Archer, associate professor at UD’s College of Earth, Ocean, and Environment. Spacing turbines farther apart and staggering rows decreased output losses from eddies 14% and improved overall performance by 33%
These results mirror onshore wind farm research being conducted at Texas Tech’s SWiFT facility, which found inefficient turbine spacing reduced power output of interior wind farm rows up to 40%
The team also found the most optimal offshore wind farm configuration had turbine rows oriented to face prevailing wind directions. However, prevailing winds change direction at most locations throughout the year, meaning turbines may need to adjust slightly on a seasonal basis to realize their highest potential output.
While that’s not technologically feasible today, knowing when turbines will be most productive could inform where and how to build future offshore wind farms. “We want to explore all these trade-offs systematically, one by one” said Archer, whose previous research found wind could meet half the world’s power demand by 2030.
Applying Lessons Learned To Future Projects
As offshore wind energy farms start sprouting up along the US East Coast, project developers have an incredible opportunity to apply lessons learned from Europe’s existing offshore wind industry.
Eight different projects totaling 2,380MW are currently under development in US waters, and higher output means these projects could become more financially viable for developers and utilities.
Offshore wind has an incredible clean tech investment outlook, with some analysts predicting an annual market value of €130 billion by 2020. With time, research like this could not only make offshore wind more productive, but help the market reach its full potential. “I’m hoping these will be tools for giving a general overview of wind at the global scale,” said Archer.
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