By Kau’i Awai-Dickson, Maui Electric Company
KAHULUI – Maui Electric Company has implemented operational improvements to increase its use of available wind energy and has plans to integrate even more. It is now using about 91 percent of available wind energy compared to an estimated 72 percent prior to making the changes. The increased use of wind energy results in estimated savings of more than $22 per year for a typical Maui residential electric bill. With additional changes, Maui Electric expects to increase the amount of wind energy used to roughly as much as 95 to 98 percent, which could save a typical residential customer another $7 to $10 per year.
“We want to make sure our customers get the maximum benefit of our abundant wind energy resources while still getting reliable service. We’ve made a lot of progress and will be making further changes to ensure our customers benefit even more,” said Sharon Suzuki, Maui Electric president.
Maui Electric’s growing use of renewable energy includes wind power, biomass energy from Hawaii’s last working sugar plantation, hydroelectric power, and energy from photovoltaic systems. As of the end of 2012, 21 percent of the electricity used by Maui Electric customers came from renewable sources.
To ensure safe, reliable electric service, Maui Electric uses some of its generators to balance the output from renewable energy sources, like wind farms and photovoltaic systems. This output varies from moment to moment depending on a number of factors including wind speeds, wind direction, cloud cover, weather conditions, and time of day.
To increase the use of wind power, Maui Electric has:
• modified some of its generator control systems
• reduced the use of the four generating units at the Kahului power plant
• fully incorporated the battery energy storage system at the Kaheawa Wind II wind farm
To integrate even more wind energy and improve the Maui system, Maui Electric is planning to:
• deactivate two of the four generating units at the Kahului power plant in 2014
• retire all four Kahului generating units by 2019
• modify the use of generating units at the Maalaea power plant
Maui Electric detailed these efforts in a report filed yesterday with the Hawaii Public Utilities Commission. The report also covered other options that will or are likely to be implemented, and others that require additional analysis before they can be implemented. These options include implementing demand response pilot programs under which customers allow selected types of electrically-powered equipment or appliances to be turned off in an emergency, installing a battery energy storage system or implementing measures to shift customer usage to certain time periods, upgrading transmission lines, and implementing Advanced Metering Infrastructure. The PUC directed Maui Electric to prepare the report when it issued a final decision for the company’s 2012 rate request in May 2013.
Electricity generation must match electricity demand (consumption by end users) at each moment. When the generation supplied to the electric system exceeds the amount of electricity being used by customers, Maui Electric first reduces output from some of its oil-fired generating units and may take some of its generating units offline. However, to maintain reliable service, there are limits on how low the output of firm generators can be turned down and constraints on whether a unit can be taken offline. After these steps are taken, if there is still more generation than demand, the amount of generation from an as-available generator, like a wind facility, may need to be lowered, or “curtailed.”