In its letter to the LPC, the Hudson River Powerhouse Group cited the 105-year-old building’s historic significance, as the powerhouse that drove the city’s first subway lines, and its architectural merit, as a “faithful example of the City Beautiful movement,” with an exterior designed by the legendary McKim, Mead & White.

Powerhouse Group co-founders James Finn and Paul Kelterborn also described the massive powerhouse, which occupies the entire city block on 59^th Street between 11th and 12th avenues, as something of a brick bulwark against the West Side’s increasingly modern look.  “[T]he Beaux Arts Powerhouse provides a welcome contrast to a neighborhood now dominated by glass and steel,” they wrote.

The letter is accompanied by a nine-page “Vision for the IRT Powerhouse,” which charts the building’s history and imagines a number of potential civic uses, and by letters of support from a long list of civic and arts group, along with elected officials.

Powerhouse owner Con Ed has yet to file a response to the request, but the company currently uses the building for steam production, and, in a statement last week, said landmark status “could impact the reliability of steam service.” In two previous hearings, the company argued that landmarking might prevent them from making emergency safety modifications.

As The Observer reported on Monday, the LPC has already said it will hold a public hearing on the issue later this year. The building remains calendared by the LPC, after hearings were held in 1979 and 1991 to consider landmark status.

Early this week, a group of preservationists, calling themselves the Hudson River Powerhouse Group, plans to submit a request to the city’s Landmarks Preservation Commission to designate the powerhouse a historic landmark, a designation that would place new restrictions on the building and guard its exterior from alterations. Landmark status would also protect the powerhouse from demolition—either by Con Ed or by a future owner. As the group notes in its application, both the East River Powerhouse in Manhattan and the Kent Avenue Powerhouse in Williamsburg were demolished recently.

In anticipation of the request, an LPC spokesperson said Friday that the commission will hold a public hearing on the Hudson River Powerhouse later this year.

The Powerhouse Group was founded by friends James Finn and Paul Kelterborn, and though both were neophytes to preservation, they were inspired by the success of the two men, about their same age, who succeeded in protecting the High Line elevated railway. In 2007, Mr. Finn and Mr. Kelterborn met with Robert Hammond, one of the co-founders of Friends of the High Line, and Mr. Hammond has helped guide them through the preservation process. Since that meeting, the Powerhouse Group has assembled a long list of supporters, including the two community boards that border the building, State Senator Tom Duane, Assemblywoman Linda Rosenthal and City Councilwoman Gale Brewer, along with a litany of civic and arts groups.

But Con Ed, which acquired the building from the city in 1959, appears unlikely to support the request. As the company points out, the old powerhouse is, in fact, still a functioning facility. “If the building were landmarked, the permit approval process to maintain operations would be delayed and could impact the reliability of service to our steam customers,” a company spokesperson said in an email.

The building has been considered for landmark status twice before—in 1979 and 1991—and it remains calendared from the second set of hearings. Con Ed opposed the designation on both occasions, citing the potential need to make emergency modifications to the facility.

The calendar status, which has now outlasted many a calendar, appears to have been something of a compromise. Being calendared allows Con Ed more freedom to make changes to the building, but also requires that the changes be approved by the Landmarks Commission.

That status came under attack recently when residents noticed that Con Ed was removing stack five—believed to be the last original smokestack—from the powerhouse roof. “The stack has not been in use for 16 years. Its condition is deteriorating and that is a safety issue for the community,” said a Con Ed spokesperson. The company submitted the change to LPC, per the requirements of the building’s calendared status, and the commission approved the stack’s removal.

“[Con Ed] hasn’t done a bad job of maintaining it, but when they see something like that, their engineers just say, ‘Let’s make it safe,’” says Ed Kirkland, who chairs the landmarks committee of Community Board 4, and testified in favor of landmarking the powerhouse at each of its previous hearings. Mr. Kirkland has been passing by the powerhouse for 40 years, and remembers, in particular, the view coming south on the West Side Highway. “At evening rush hour, there was smoke coming from every smokestack.  It was beautiful,” Mr. Kirkland says.

Those who have been inside the building say its two towering halls are equally impressive. “It takes your breath away. It’s huge and it’s incredibly gorgeous,” said Ms. Brewer, the local council member.

The sheer size of the interior has proponents salivating at what the hall could become: a public market, an events center, a Tate Modern–esque museum, or some combination of public uses. Con Ed declined to discuss the building’s interior, but several people who previously toured the facility said one hall is nearly empty, and the other contains a mock-up of a suburban house, where the company trains meter-readers. Six Columbia grad students have spent the spring semester re-imagining the space, and the Hudson River Powerhouse Group hopes to host a design competition this summer.

“We don’t want to put the cart ahead of the horse,” said Mr. Finn, who admits all those plans depend on Con Ed decommissioning its steam production on the site, and the city somehow taking possession of the property after that—a process that could be decades in the future, if it happens at all. But he believes the long-term future should be with the city. “We’re trying to landmark it because we think, eventually, there’s no way that a modern-day power company is going to make use of a building like this for the next 100 years.”