SOO Green, a groundbreaking underground transmission project aimed at bringing renewable energy from Iowa to Illinois, has secured its final municipal franchise agreement within the state, clearing the $3.2 billion project to proceed towards construction. Bellevue was the 24th and final municipality on the route to sign off on the project, representing a critical breakthrough for the 350-mile high-voltage direct current (HVDC) line.
The project, created through partnership among the United States’ energyRe and Denmark’s Copenhagen Infrastructure Partners, will stretch from Mason City, Iowa, to Yorkville, Illinois. Converter stations at each end will allow the line to send power in both directions. The project aims to move a mix of wind and solar energy, balanced with storage, from the Midwest to population centers in the east. Through the use of existing rail corridors as conduits for the transmission line underground, SOO Green will leave communities and landscapes intact while addressing one of the most significant challenges confronting the U.S. power market: reliably transporting low-cost renewable energy where it is needed most.
Consumers’ benefits
When operating at full capacity, SOO Green will supply 2,100 megawatts of electricity—enough to illuminate almost 1.5 million homes. Developers estimate the project will create thousands of union construction jobs, add $3.2 billion to the local economy during construction. And enhance two large power markets’ grid reliability: the Midcontinent Independent System Operator (MISO) and PJM Interconnection.
Economic studies also pinpoint consumers’ benefits. Research projects the line would save $5.8 billion net over its initial five years in operation, or average monthly residential electricity bill savings of $5.67 for Illinois Commonwealth Edison customers.
“SOO Green represents a bold new model for building the energy grid of the future,” said David Pacyna, CEO of SOO Green. “By going underground along existing rail infrastructure, we’re dramatically reducing disruption to communities and landscapes while creating a vital energy superhighway that strengthens grid reliability and resiliency, optimizes transmission efficiency, and lowers long-term energy costs.”
Attention now turns to Illinois
With approvals in place in Iowa, attention now turns to Illinois, where state legislators are being urged by project officials to pass bills making possible SOO Green’s ability to compete well in the market. Pacyna was hopeful that legislators would recognize the value of the project to help lower costs and improve Illinois’ energy competitiveness in an era of rising electricity prices. Developers also believe this project will support Illinois’ push toward clean energy.
If all of the remaining policy and regulatory steps fall into place, project work can begin as early as 2027. With commercial activities in 2031. The project has backing from a consortium of prominent energy and infrastructure companies like Siemens Energy, Jingoli Power, Prysmian Group, and PPL Corporation.
Additionally, for the developers of SOO Green, the final municipal permit in Iowa is no formality—it is a testament that the local communities support the project for rethinking the transmission and how renewable energy is sent across geography.
SOO Green Transmission Project – Fact Sheet
Project Overview
Type: High Voltage Direct Current (HVDC) underground transmission line
Length: 350 miles
Route: Mason City, Iowa → Yorkville, Illinois
Corridor: Existing railroad rights-of-way
Capacity: 2,100 megawatts (MW)
Equivalent Power: Enough to supply 1.5 million homes
Markets Connected: Midcontinent Independent System Operator (MISO) and PJM Interconnection
Latest Development
All 24 Iowa municipalities along the route have approved franchise agreements.
Bellevue, Iowa, was the final approval needed, clearing the project for construction in the state.
Economic Impact
Estimated $3.2 billion boost to the regional economy during construction
Support for thousands of union jobs
Projected consumer savings:
$5.8 billion in net savings during the first five years of operation
$5.67 average monthly bill reduction for ComEd customers
Timeline
Construction start: As early as 2027
Commercial operation: Targeted for 2031
