Interconnected Wind Farms: Distributed Harvest, Improved Consistency
Posted in Research by Kate Archdeacon on April 13th, 2010
Source: Environmental Research Web
When it comes to incorporating more wind power into electricity supply systems, a key worry is the renewable-energy source’s variability with time as wind speeds fluctuate. Now a US team has found that linking up offshore wind turbines spread over a distance of roughly 2,500 km down the eastern seaboard of the US could help smooth out this variability. “When location of wind farms and transmission are picked to make best use of large-scale meteorological patterns, there is a dramatic improvement in how steady we found the produced electric power to be,” Willett Kempton of the University of Delaware told environmentalresearchweb. “In five years of data, there was never an hour with no power production.” Not only would such wind farm interconnection reduce variability and remove periods of zero power production, it would also mean that any remaining variations in power output happened more slowly. This would give electricity suppliers more time to ramp up or down alternative sources or transmission links to meet consumer demand. Together with colleagues at Stony Brook University, US, the Delaware team analysed wind-speed data from eleven meteorological stations off the east coast, stretching from the tip of Florida in the south to Maine in the north. The researchers used this data to estimate power output from turbine arrays for the period 1998 to 2002.
Currently power supply operators use existing systems such as reserve generators and redundant power-line routes to manage the variability in wind-power output; as well as combining remote wind farms via electrical transmission, as discussed here, it’s also possible to employ energy storage, either at a central location or at distributed sites, for example through home heaters or plug-in cars, to smooth supply. There are plans for wind-turbine arrays with a total power capacity of about 2,500 MW off the eastern coast of the US. This amount, which is roughly equivalent to the output of a large coal or nuclear power plant, is only 0.1% of the available wind resource in the region. The researchers say that to connect these turbines would require 350 miles of submarine cable, which would add around $1.4 bn, less than 15%, to the estimated $10.5 bn installation costs. This supplement is roughly equivalent to levelling wind output via existing generation, which as a rule of thumb adds 10% of the wind-power cost for an electricity mix containing up to 20% wind power, and more for higher levels of wind power. And it’s much cheaper than smoothing output via energy storage schemes, such as pumping water into higher-level reservoirs – these have capital costs roughly equal to those of generation.
Read the full article on Environmental Research Web.