Aspen Provides Project Management Support to Repower Utility Power Plant

Modesto Irrigation District (MID) sought Aspen’s help to oversee a project to repower an existing generation station with an updated engine.  Aspen will set up the project, identify all of the steps involved, permitting and contracts needed, set up a project budget and a project schedule.  Aspen also provided the necessary CEQA support to get the project authorized by the MID Board and underway.

MID is a fully integrated publicly owned utility providing electricity to its 128,000 customers along with irrigation water to its farmers and drinking water to the city of Modesto.   MID has been providing electricity since the 1920s.

MID has numerous sources of power including hydro generation, natural gas-fired turbines, wind, and solar.  MID has a 183-megawatt (MW) natural gas-fired Woodland Generation Station (WGS) that was built in three phases.  The first phase is a 49 MW LM5000 steam-injected gas turbine called WGS1 which was commissioned 30 years ago.  The gas turbine is an aero-derivative (think jet engine) LM5000 which is coupled up to a generator to produce electricity.  The hot exhaust from the engine is routed through a heat recovery steam generator (HRSG) to produce steam and to clean up the exhaust for pollution control.  The steam is then injected into the Engine for power augmentation and nitrous oxide (NOx) reduction.

This plant has provided reliable peaking and intermediate load power to MID’s grid for the last 30 years.  The plant is key during hot summers and when the other generating units are out for maintenance.

The LM5000 engine is no longer supported by GE which means the parts and service aren’t available.  MID bought a spare engine which is presently being used.  The original engine is in disrepair and can’t be serviced.  This means that when the present engine fails, the WGS1 will no longer be available in its present configuration which will result in a loss of 50MW of generation to MID and the grid.  MID can’t afford this loss of generation and still meet the needs for its customers.

MID contracted with IEC (an engineering firm in Sacramento) to perform a study on various configurations to repower WGS1 while utilizing as much of the existing plant as possible and providing needed flexible generation.  The conclusion was to repower the plant with an LM6000 aeroderivative engine coupled to the existing generator and retrofitted into the existing turbine generator enclosure.  The scope includes removing the existing HRSG and installing pollution control equipment inside new duct work with a new exhaust stack.  The repowered WGS1 will be run as a simple cycle 49 MW plant.  This gives MID the greatest operational flexibility going forward.

Once MID staff made the decision to further investigate the feasibility of proceeding with the repowering, they approached Greg Salyer, Director of Power and Water at Aspen Environmental Group for project management support.  Greg retired from MID after holding various management roles over 30 years at MID.  Greg has extensive experience in project management including project manager in all phases for WGS1 when it was permitted and built 30 years ago.  His experience also included project manager for WGS2 which is an 83-megawatt combined cycle plant that was commissioned in 2003.  Greg was also the Generation Manager of the fleet for 14 years.

MID management stated that their goal was to complete the repowering project by May of 2023 with the plant outage starting in October 2022.  It was also MID’s goal for Aspen to provide ongoing mentoring to an MID engineer to take over the project management once the project  was kicked off with a full execution plan.  MID contracted with Aspen to set up the project, identify all of the steps involved, permitting and contracts needed, set up a project budget and a project schedule.  Aspen also provided the necessary CEQA support to get the project authorized by the MID Board and underway.

At this stage of the project, all major equipment has been ordered, the engineering contract has been signed and design is in progress.  The construction contract will be issued this fall to support meeting the completion date of May 1.  MID’s project manager Brock Costalupes is now managing the project with the ongoing mentoring and guidance from Aspen Environmental.