Built in 1927 and measuring 158* feet tall at the top of its smokestacks, the Willow Street Steam Generation Plant was built by the Philadelphia Electric Company (PECO) to serve industrial sites along the Reading Railroad. Part of the third largest district steam heating system in the United States, Willow Steam burned coal that was brought by rail via the now-defunct Northern Liberties & Penn Township Branch, producing 450 degree steam that ran through a 33-mile long network of pipes underneath the sidewalks that extends as far as West Philadelphia. The closure of the plant is listed by differing sources as either the late 1970s or in 1989, and Willow Steam been left vacant since.

In 1987 Willow Steam was sold for $30 million to Philadelphia Thermal Energy Corporation, and in 1993 Philadelphia Thermal Energy’s parent company was purchased by Trigen Energy Corporation, which still uses the steam network to provide heat, cooling, and hot water for university and hospital campuses, and businesses. It was sold again to Quyen Tran, who sold it to developer John Wei, who currently owns it.

Under Wei’s ownership an asbestos removal project was undertaken and completed in 2020, though these photos were taken nearly a decade earlier in 2011. [url=hiddencityphila.org/2023/04/construction-permits-issued-for-willow-steam-plant/ target=blank]Hidden City[/url] reports that 2022 architectural sketches indicate a reuse plan leaning primarily on converting the interior into residential units with commercial space in the basement and a restaurant on the first floor. If this plan does materialize, it would be fantastic to see the distinct and historic site remain a part of Philadelphia’s architectural tapestry for generations to come.

* Other sources list Willow Steam as 163 feet tall, although I believe the architectural sketches are likely to be the most accurate.