Effects of increased wind on Coal Creek Station generation - PowerPoint PPT Presentation

Effects of increased wind on Coal Creek Station generation Presentation for ND Energy Conference Tuesday, October 10, 2017 David Farnsworth, Great River Energy

Coal Creek Station  ND’s largest, most efficient lignite power plant (2 x 600 MW units)  Lignite supplied from Falkirk Mine  Online: U1 1979, U2 1981  Very reliable and low-cost power producer  Built for serving Great River Energy’s 28 electric coops via 500 mile DC line to Minnesota  Sells power into the MISO market

Coal Creek Station Dispatch  Great River Energy sells and buys its power in the MISO market  Coal Creek Station’s output is bid into the market based on incremental cost of production  Normally baseloaded, but low power prices can result in more frequent and deeper cycling  Coal Creek Station made changes in 2016 to allow ramping down to 30% of capacity during low prices

Coal Creek Station Dispatch  More frequent cycling driven by lower power prices  Low power prices determined by supply vs. demand  High supply for the region ■ Renewable mandates and tax credits have spurred tremendous growth in wind generation ■ Abundant low-cost natural gas has driven increased gas- fired generation at the national level  Low demand growth drivers for the region ■ Slow economic growth by historical standards ■ More efficient appliances and LED lighting

Great River Energy Generation Mix 2016 Energy Used by Generation Source • Prior to Stanton Station closure 2017 Installed Capacity by Generation Mix • Stanton retired, Genoa divested • 400 MW more wind by 2021

Wind Speed

Midwest Independent System Operator

Wind dispatch by region in MISO

MISO wind additions  MISO had 16.3 GW of wind capacity in January 2017  Projections to top 21 GW by 2020  12 GW in the interconnection queue currently

MISO wind energy production

Minimal cycling with warm weather and little wind August 2016 Events: One unit trip Coal Creek Station Generation and Cycling Profile Unit 1 Gross Output (MW) Unit 2 Gross Output (MW)

Mild temperatures, good wind. Produce frequent cycling. October 2016 Events: Low load NOx tuning, trip and repair outage; new lower load limits Coal Creek Station Generation and Cycling Profile Unit 1 Gross Output (MW) Unit 2 Gross Output (MW)

Colder temps, but very high winds (storms) December 2016 result in some cycling at nights/weekends Coal Creek Station Generation and Cycling Profile Unit 1 Gross Output (MW) Unit 2 Gross Output (MW)

Seasonably warm temperatures, moderate July 2017 wind; no plant trips or outages Coal Creek Station Generation and Cycling Profile Unit 1 Gross Output (MW) Unit 2 Gross Output (MW)

Costs to Coal Creek from Cycling  Hurts Plant Economics as Cost/MWh increases ■ Fewer MWh’s of generation ■ Plant less efficient at lower loads • More coal burned for each MWh generated • Increased operating costs per MWh ■ Increased maintenance costs • Increased thermal cycling causing metal damage of piping, supports, boiler tubes, air heater seals, etc • Starting and stopping of motors and electrical devices resulting in more failures

Example of Cycling Damage at Coal Creek Station (Unit 1, Spring 2017)

Coal Creek Station’s New Reality  Coal Creek will continue to be dispatched economically to minimize its members’ electrical rates.  Coal Creek expects to cycle more frequently as more intermittent wind comes onto the system  Coal Creek will adjust its maintenance and operating practices to minimize the costs of increased cycling  Coal Creek will look for additional revenue opportunities and efficiencies to offset increased cycling costs  As a low cost, reliable, dispatchable resource, Coal Creek expects to be a long-term generating asset for GRE