Maui Electric Co. dumped 7 percent of wind power produced in 2014, a significant improvement from 2013 when 17 percent of electricity generated from the three Maui wind farms went unused.
MECO filed its report on wind power use June 29 with the Public Utilities Commission, which has been critical of the utility in the past for amounts of wind power curtailed or unused. In the first few months of 2013, more than a quarter of wind power produced was being curtailed or dumped.
When it is windy outside, the utility relies more on wind energy and turns down its oil-fired generators at Kahului and Maalaea power plants, though the utility still keeps some generators running at all times to ensure that, if the wind suddenly stops blowing, customers will not lose electricity. When the amount of wind energy exceeds customers’ demand for electricity at a given time, that energy is curtailed or dumped.
MECO accepted 257.9 gigawatt hours (gwh) of wind power while curtailing 20.6 gwh in 2014. Compared to 2013, the utility accepted 27.6 gwh more wind power while dumping 26.1 gwh less. In 2013, 230.3 gwh of wind energy was accepted and 46.7 gwh was curtailed.
The utility pegged the estimated savings of using wind power, compared to the more expensive fossil fuel generated power, at $12.6 million in 2014 and $11.8 million in 2013. The utility said that the cost of wind energy in 2014 was about 19 cents per kilowatt hour (kwh), while the cost of fossil fuel generation was 22 cents per kwh.
For January to May of this year, 98.8 gwh of wind power has been accepted, which is more than the 84.3 gwh taken into the grid for the same period in 2014, but the amount of power curtailed is about the same – 12.6 gwh this year and 12.7 gwh last year.
MECO attributed the improvements in wind power use to “extensive research and analysis” in 2013 and “significant operational changes and improvements,” said Kau’i Awai-Dickson in an email.
These improvements included modifying generator control systems, reducing the use of the older generating units at the Kahului Power Plant and “changing the way we operate at Maalaea Power Plant,” she said.
The changes allowed for more room on the grid for wind power but at the cost of generating units running less efficiently, Awai-Dickson said.
“Careful and consistent 24/7 monitoring of wind output is critical to not only accepting more renewable energy on our system but controlling that output in order to maintain the stability of the grid and meet the electrical power needs of our Maui community,” she said.
Balancing the output of wind energy “on our small isolated grid” during periods of low customer demand is a challenge, she said.
The work to incorporate more renewable energy continues, Awai-Dickson said. MECO’s improvement plans call for replacing older generating units with newer, more nimble resources “capable of quicker response to accommodate variable renewable energy sources.” The utility also has plans for modernizing the grid with smart technology that will allow MECO to control demand for energy as well as the supply.
Power from renewable energy sources, including wind and solar, made up 30 percent of the electricity produced by the utility at the end of 2014, Awai-Dickson said. The report to the PUC said that the utility produced 805.9 gwh of power by fossil fuel, which was three times more than wind power production in 2014.
MECO receives power from three wind farms, Kaheawa I and II above Maalaea and Auwahi on Ulupalakua Ranch land. The 20-turbine, 30-megawatt (mw) Kaheawa I was the first wind farm on Maui, going into service in 2006, followed by the 14-turbine, 21-mw Kaheawa II in July 2012. The eight-turbine, 21-mw Auwahi went online in December 2012.
In 2014, (with figures rounded):
* Kaheawa I produced 110.1 gwh with 108.9 gwh accepted and 1.3 gwh curtailed. 110.2
* Kaheawa II produced 86.2 gwh with 69.3 gwh accepted and 16.9 gwh curtailed.
* Auwahi produced 82.2 gwh with 79.8 gwh accepted and 2.4 gwh curtailed.
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