Kaheawa Wind Power has begun preliminary work that could lead to a near doubling of its production of electricity on Maui.
If Kaheawa adds another 27 megawatts to the 30 MW it can make now, and when Shell WindEnergy Inc. completes its 40-MW wind farm at Ulupalakua, Maui conceivably could have wind capacity equal to more than a third of peak demand, now a little more than 200 MW but growing.
Most of the time, Maui Electric Co. needs much less than 200 MW, and since wind energy is unstable, electric grids have a limit to how much wind electricity they can absorb.
According to Jim Owen, communications director at the Edison Electric Institute, there is no simple number to say what proportion of wind is too much, but instability in the transmission system is a limiting factor in exploiting wind energy. The institute represents the nation’s investor-owned electric utilities.
Maui has a rich wind resource but a relatively small transmission system that limits how much wind it can use.
Oahu, which has a larger grid, could handle more wind power but probably does not have it.
Hawaiian Electric Co. considers that there are only three locations on Oahu where wind is good enough for a commercial wind farm.
One, at Kahe, has already been nixed by neighbors. Another, at Kaena Point, is a state park. That leaves Kahuku, where HECO had a small wind farm that failed. That one was designed for 12 MW but didn’t reach that.
Lynne Unemori, vice president of corporate relations at HECO, says HECO is beginning meteorological studies toward a new wind farm at Kahuku, although in a different area from previous attempts.
Because wind potential is hard to assess before detailed studies have been made, HECO is not guessing how much wind energy could be harvested at Kahuku.
Whatever the final number, it will be a small fraction of Oahu’s total demand.
Acreage is a limit on production, even where the wind blows fresh and steadily. According to the World Wind Energy Association, one of the main enemies of wind is wake-induced turbulence ““ the disturbances in the air caused by the rotation of wind rotors.
The turbulence stresses mechanical components, either shortening their life or requiring extra expense to beef up the structure.
That is one issue of the study at Kaheawa, where 20 1.5-MW towers march along a ridge from an elevation of about 2,000 feet.
Mike Gresham of UPC Hawaii Wind Partners, which operates Kaheawa, says a second line of perhaps 18 towers might be sited more or less in parallel with the existing wind farm.
It is on leased state land.
Aside from technical issues, Kaheawa will evaluate whether it has a customer. Shell will also vie to sell wind electricity to MECO, but “we don’t consider what Shell will be doing,” said Gresham.
The cost of diesel fuel ““ either petroleum or biodiesel from HECO’s co-venture refinery with BlueEarth at Waena ““ also enters into the business calculation.
The richness of the wind resource is only one of many considerations.
For example, a windy spot remote from existing transmission lines could be uneconomic because transmission lines are expensive.
Unemori says that for Oahu, HECO’s evaluation was that after the top three sites, there is a big drop-off to the next candidate spot. HECO is considering only Kahuku.
This means wind is never going to supply a very large proportion of Hawaii’s electricity needs.
Maria Tome, an alternate energy engineer in the Strategic Industries Division at the Department of Business, Economic Development and Tourism, says that if all existing and projected wind projects (excluding any expansion of Kaheawa) were online, they could provide less than 3 percent of total kilowatt-hours consumed.
According to the American Wind Energy Association, Hawaii had 49 MW of wind capacity at the end of 2006, most of it on Maui.
The rest is on the Big Island, although a farm is also projected on Kauai.
Total projected wind capacity in Hawaii is 112 MW. However, the wind blows when it chooses, so the overall output is calculated at about 35 percent of maximum instantaneous output.
Even that does not represent a complete replacement of fossil fuel.
MECO President Ed Reinhardt says MECO is still learning how to manage fluctuations in voltage due to Kaheawa’s variable output. So far, he says, the problems have not been serious.
However, on days (or nights) of fluky winds, Kaheawa may be putting out 7 or 8 MW but will drop without notice to nothing.
MECO then has to keep a diesel-fueled standby unit humming to take over.
Both HECO and MECO need permits to erect towers to take meteorological data, and the data need to be collected for at least a year, so no decisions about going ahead with a wind farm at either Kahuku or Kaheawa will be made soon.
Part of the incentive is the state’s 20-20 plan, which mandates that 20 percent of electricity will come from nonfossil sources by 2020.
MECO should make that goal, because it already gets about 16 MW of firm power from a power station operated by Hawaiian Commercial & Sugar Co. that uses bagasse for most of its fuel.
Hawaiian Electric Light Co. on the Big Island also is well on its way, with both wind and geothermal power in production.
Tome says the state law is written so that beating the goal on one island ““ for example, with wind ““ can be counted toward Oahu’s 20 percent.
Gresham notes the irony that Maui may have more wind than it can use. However, he says, “20 in 20 is a goal that should be set. Wind is a great resource, but it’s still only one of several, like solar and biomass.”
By Harry Eagar
2 April 2007
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