The Sheridan Avenue steam plant, at somewhere north of 100 years in service, is one of the older bits of civil infrastructure around. @willwaldron from the Times-Union posted a photo of the original dynamos inside the plant, with the notation that they were DC, which led to conjecture that perhaps they were used solely to drive DC devices around the Capitol (elevators in particular), which made no sense to us. In addition, every reference we'd ever seen referred to it as a steam plant, with electrical generation as a nice byproduct but by no means the primary purpose of the original installation. Took a while, but we finally found some specs of sorts.
Back in the March 23, 1911 edition of Electrical World (and thank goodness for Google Books, because I'm not sure I could have found this in the garage), there was a notice that "Sealed proposals will be received by the Secretary of the Trustees of Public Buildings, Executive Chamber, Capitol, Albany, N.Y., until April as for equipment of the Capitol power house and conduits, located on the corner of Sheridan Avenue and North Hawk Street, Albany. Separate proposals will be required as follows: 1. For steam power equipment. 2. For electrical equipment." There were plans and specifications, which required a deposit of $25; they could still be buried somewhere in the offices of Franklin B. Ware, state architect.
The contracts for the building itself, which is really quite elegant in the style of electric generating houses of the day, had already been let, and the announcement in "Engineering Contracting" of Dec. 28, 1910 provides some detail as to what might have been in the plans in Franklin Ware's office:
"Bids were opened Dec. 21 at the State Capitol, Albany, by George A. Glynn, secretary Trustees Public Buildings [sic], for the construction of the new power house which is to supply the capitol and the new state education building with heat and light. For this building and its equipment the Legislature appropriated $500,000. The proposals received were for the plumbing work and for the construction of the concrete conduit, as well as the erection of the building. The bids received were as follows: R.T. Ford Co., Rochester, $346,287; Raymond A. Booth, Albany, $382,800; Feeney & Sheehan Building Co., Albany, $413,000; Morris Kantrowitz, Albany, $414,000; A. Pasquini, Albany, $366,888; Peter Keeler Building Co., Albany, $426,399; Hudson Valley Construction Co., Troy, $387,400; Conners Brothers Co., Lowell, Mass., $394,300; Luke A. Burke & Sons, New York, $439,750. The new power house will have a boiler room of sufficient size for 10 380-H.P. boilers, and an engine room of sufficient size to contain five engines and dynamos of 1,7000 K.W. capacity. Only eight boilers and four engines and dynamos will be installed at present. Coal will be contained in vaults on either side of the boiler room, having a capacity of 7,000 tons. The plans also call for an overhead coal pocket containing 1,000 tons. The building will be of face brick with stone base and terra cotta trim, the roof work being of tile and copper. The vaults will be of reinforced concrete, the top being paved for driveways. A concrete conduit approximately 8 ft. square on the inside will be carried under Hawk St., Albany, from the corner of Sheridan avenue to a point opposite the present power house where it will connect with the present conduit. The conduit will be carried under the roadway and between the abutments of the Hawk Street viaduct. The specifications require that the building shall be ready in all its parts for the installation of apparatus by Nov. 1, 1911. Contracts for equipment probably will be awarded early next year."
We later learn from "Domestic Engineering and the Journal of Mechanical Contracting," July 29, 1911, that:
The state trustees of public buildings have awarded the following contracts:
The contract for the steam equipment of the capitol power-house now in course of erection on Sheridan avenue, Hawk and Orange streets, in Albany, N.Y. Also the steam and return connection between the power-house and the capitol and education building on Washington avenue, to Gillis & Geoghegan, New York City, for $202,053.
The contract for the electrical equipment of the said power-house, and the electrical connections between the power-house and the education-building, was awarded to the Lord Electrical Co., New York City, for $95,700.
Dynamos certainly connote DC power, and what we're seeing in the picture are some lovely examples of DC dynamos. But the conclusion that the Capitol would then continue to draw on that as DC power, for which there were and are few ideal applications (super-heavy motors, electric trains, and steel production come to mind), runs afoul of the timeline. By this time conversion to AC (or the other way around) was a simple matter for a rotary converter (Steinmetz wrote on the topic at least as early as 1897), AC was the way the world was wired for the most part, and it's hard to imagine the dynamos were going directly to any DC load. It may have been more convenient to carry the current to the buildings as DC, and convert it there; it's possible the conversion then was part of the "electrical connections" at the State Education Building.
The boilers that provided steam heat to the Capitol and the State Education building are not in evidence in this photo; I'd guess they were on the level below. At the right side of each machine you can see the engine, presumably driven by steam from the boilers, which in turn turned the dynamo wheel, which would have created AC power that commutators made into DC. (The problem of the commutator was the problem solved by Nikola Tesla. Pre-Tesla, they tended to be more than a bit sparky.) The steam was also used then, as now, to heat the buildings. It sounds like they would have had to replace the conduit at the time the Hawk Street Viaduct was torn down, or perhaps before.
All this was years and years before the boilers, by then apparently running primarily on oil, were adapted to burn shredded solid waste as part of the "solution" to the area's solid waste problem. (No one should confuse this arrangement with an actual solid waste incinerator; you may as well compare an ox-cart to a modern bus, in that they both kinda do the same thing.)