Historically, the South Lake Union neighborhood of Seattle, located to the north of downtown and east of the Seattle Center, was a manufacturing district whose electrical power was supplied by the Broad Street Substation.
After the failure of the Seattle Commons plan in the 1990s, which proposed a large city park over the neighborhood, the land was opened for development by Paul Allen's Vulcan Real Estate, which envisioned it as a hub for biotech and high tech firms.
Vulcan and Seattle City Light began talks of collaborating to build a $160 million substation in Interbay or South Lake Union in 2003, expecting the additional high tech firms to put a strain on the Broad Street substation and neighborhood lines laid in the early 2000s.
In 2005, Seattle City Light determined that adding capacity at the Broad Street substation through new transformer banks would be sufficient for the area's needs until the mid-2010s.

Seattle City Light proposed demolishing the Greyhound bus garage on Denny Way for its new substation in 2006, with consultants recommending that the city acquire the site for $40 million as soon as possible.
The site was purchased by Seattle City Light in October 2008 and vacated by Greyhound in 2010.
From 2012 to 2014, Seattle City Light demolished the Greyhound facility and removed contaminated soils in preparation for construction.
During the period between environmental cleanup and the start of construction, the vacant lot was used for a series of temporary public art installations collectively called All Rise.

Final approval for the project was granted in August 2015 by the Seattle City Council, who also approved the substation's unconventional design incorporating public benefits in exchange for a street vacation.
Walsh Construction was awarded the construction contract for the substation project, working alongside subcontractors Valley Electric, W.A. Chester and Transcon.
Construction of the substation began in May 2016, and by the end of the year, the first outer walls were erected.
The substation's three transformers, each weighing 6.5 short tons (5,900 kg), were installed in 2017.

The Denny Substation was energized in April 2018 and was formally opened in October, becoming the first new substation built by Seattle City Light in 30 years.
Construction of the substation required long-term closures of a westbound lane on Denny Way and postponed the installation of a bus lane on the street.
A formal opening ceremony was held on July 20, 2019, with remarks from city leaders and events sponsored by local businesses.
The substation began supplying electricity later that year and is planned to be linked to another downtown substation after 2020.
Historically, the South Lake Union neighborhood of Seattle, located to the north of downtown and east of the Seattle Center, was a manufacturing district whose electrical power was supplied by the Broad Street Substation. After the failure of the Seattle Commons plan in the 1990s, which proposed a large city park over the neighborhood, the land was opened for development by Paul Allen's Vulcan Real Estate, which envisioned it as a hub for biotech and high tech firms. Vulcan and Seattle City Light began talks of collaborating to build a $160 million substation in Interbay or South Lake Union in 2003, expecting the additional high tech firms to put a strain on the Broad Street substation and neighborhood lines laid in the early 2000s. In 2005, Seattle City Light determined that adding capacity at the Broad Street substation through new transformer banks would be sufficient for the area's needs until the mid-2010s.
Seattle City Light proposed demolishing the Greyhound bus garage on Denny Way for its new substation in 2006, with consultants recommending that the city acquire the site for $40 million as soon as possible. The site was purchased by Seattle City Light in October 2008 and vacated by Greyhound in 2010. From 2012 to 2014, Seattle City Light demolished the Greyhound facility and removed contaminated soils in preparation for construction. During the period between environmental cleanup and the start of construction, the vacant lot was used for a series of temporary public art installations collectively called All Rise.
Final approval for the project was granted in August 2015 by the Seattle City Council, who also approved the substation's unconventional design incorporating public benefits in exchange for a street vacation. Walsh Construction was awarded the construction contract for the substation project, working alongside subcontractors Valley Electric, W.A. Chester and Transcon. Construction of the substation began in May 2016, and by the end of the year, the first outer walls were erected. The substation's three transformers, each weighing 6.5 short tons (5,900 kg), were installed in 2017.
The Denny Substation was energized in April 2018 and was formally opened in October, becoming the first new substation built by Seattle City Light in 30 years. Construction of the substation required long-term closures of a westbound lane on Denny Way and postponed the installation of a bus lane on the street. A formal opening ceremony was held on July 20, 2019, with remarks from city leaders and events sponsored by local businesses. The substation began supplying electricity later that year and is planned to be linked to another downtown substation after 2020.
Denny Substation