Idaho Power plans major expansion at local power plant

Idaho Power is planning a major expansion of its Evander Andrews gas turbine power plant northeast of Mountain Home.

The plant, which provides power during peak loads for the company, currently has two 45 megawatt (MW) gas turbines. Each megawatt of power can handle roughly the equivalent of 650 homes.

But beginning this summer, Idaho Power will install an additional 170 MW gas turbine at the plan, similar to the one currently operating at the Bennett Mountain plant just above The Pilot in Mountain Home.

The expansion follows a lengthy review and permitting process.

In March of 2005 Idaho Power put out a request for proposal and subsequently analyzed 31 different proposals at four sites to determine the best way to meet its power needs during high-demand "peak" periods -- such as the 4-7 p.m. time frame during the summer, when air conditioning use is at its highest, and during times when large amounts of electricity are being used for irrigation.

In December 2005 the company chose the option of installing the 170 MW gas turbine at the Evander Andrews plant, then began the lengthy regulatory process that finally concluded in December 2006 when the Idaho Public Utilities Commission issued a certificate of public convenience and necessity.

With the design and engineering process underway now, construction of the additional gas turbine facility on the existing Evander Andrews site is expected to begin this summer, with the huge turbine -- essentially a "supersized" jet engine -- expected to go on-line in 2008. The total cost of the project currently is estimated at about $60 million.

When the original 45 MW turbines were installed at the plant it was a massive undertaking. Delivered by rail to Mountain Home, a huge crane was used to load them onto special trucks that hauled them to the plant. Because of weight limits on overpasses and bridges, Idaho Power trucked them out the old Highway 30/Tipanuk road and actually had to build a special road and dig a tunnel under the interstate to get them to the plant site.

A similar process is likely to be used with the even larger turbine planned for the facility, when it arrives next fall.

The plant expansion is needed because of the rapid growth of the Idaho Power customer service area. With the two gas-fired turbine plants in Elmore County, plus 17 hydroelectric dams and parts of three coal-fired power plants, the company currently has to generate more than 3,000 MW of power during system peak times.

The gas-fired plants provide the extra power needed beyond the "base" power, and also allow the company to pull other units off-line for maintenance work, with the two local plants making up the difference. Depending on peak demand and maintenance needs, on any given day the two local plants may provide extra power ranging from nothing to full capacity at the facilities. They functionally serve as Idaho Power's "pad."

Each of the current plants employs six highly skilled operators, technicians and supervisors. The expansion project will use existing staff once it is up and running, but will require approximately 80-100 construction jobs while the new building for the turbine is being built.

Principal engineer F. Gregory Hall said he was looking forward to completing the project, and thanked the community of Mountain Home and local elected officials for all their support of the company's projects in the county.