The Minnesota Public Utilities Commission on Jan. 7 approved the latest depreciation adjustments for various Otter Tail Power assets, including a slight extension of the retirement target for the Hoot Lake coal plant.
On Sept. 1, 2015, Otter Tail Power (OTP) filed its 2015 Annual Review of Depreciation Certification petition. OTP was requesting approval of changes to the lives and salvage rates of a number of property accounts.
In a Baseload Diversification Study for the Hoot Lake Plant, completed in conjunction with Otter Tail’s 2010 Integrated Resource Plan, the commission approved an anticipated year of final retirement (AYFR) of December 2020. In its 2015 depreciation petition, OTP explained that the Midcontinent Independent System Operator (MISO) planning year runs from June 1 to May 31 of each year and there is no opportunity for part-year accreditation. The company stated that for Hoot Lake Units 2 and 3 to be accredited from June 1, 2020, to Dec. 31, 2020, the units must remain operational through the full planning year, effectively resulting in a retirement date of May 31, 2021. In the Jan. 7 order, the commission agreed to that date.
The Hoot Lake plant, located at Fergus Falls, Minnesota, has two operating units (Unit 1 was retired years ago) with a combined capacity of about 140 MW. It burns subbituminous coal from the Powder River Basin.
Otter Tail Power added significant Mercury Air and Toxics Standards (MATS) investments to Hoot Lake Units 2 and 3 in 2014, allowing the plant to keep operating until the 2021 retirement.