The turbine rooms they plan on saving have only north and south walls with any architectural features as the long sides were butted up against other structures. What I am interested in saving are two partial walls of the boiler rooms and the original Boston Electric Light Plant.
The Boston Electric Light Plant consists of a relatively small dark red brick structure on the east side of the building cluster. Internally it is two large voids about three stories tall lined with white enameled bricks the east section was the engine room and the west side was the boiler room. Either one of them could function quite well as a summer market, beer hall, performance space. A steel frame of floors set away from the exterior walls with a center atrium and sky light would make a unique office space.
On the west side of the site are the boiler rooms. (in spite of the image I posted, there's more than one window. I would save that wall and build a copy of it with similar but closer spaced windows along E 1st St. I would mimic the smaller windows that flank the larger windows on Summer St. for more fenestration. I would also save at least part of C 12, that large chimney, maybe put an observatory on top of it. You could then build just about anything behind those two walls. I was thinking you could set back the floors from the Summer St. facade creating balconied halls inside with living/working space behind that.
On the north side the remains of the original boiler room has four tall segmental arch windows close together, again anything could be put behind those windows.
Not being an architect, I'm not quite sure of the architectural style of the Summer St Generating plant, I think it's Beaux-Arts? I find something classic eminently preferable to bland grey boxes. That look like dozens of other developments that have gone up all over the city. There is nothing original or distinctive about it, it could be anywhere (and it is). There's a lot of history on that site and it'd be a shame to sweep it all away.