Four smaller gas turbine peaking generators remain in operation, as does the Y-50 Cable connection across Long Island Sound.

It was designed in an industrial Beaux-Arts style, with large arched windows and stringcourse intended to prevent it from becoming an eyesore given its proximity to affluent communities.

[3] The building was divided into three sections: a narrow four-story administration section to the north containing offices; a five-story turbine room containing a large open space with decorated glazed buff brick walls; and a six-story boiler house mainly filled with equipment, topped by six 140-foot smoke stacks (ultimately reaching 265 feet above the floor slab).

[1][2] The extra generating capacity was needed due to a sixfold increase in Long Island's electricity demand from 1910 to 1925.

[1][2] In 1942, a 3-hour power outage caused by testing of new distribution circuits affected seven major factories producing material for World War II.

[5] Although sabotage was not suspected, it caused the colonel in charge of civilian protection for Nassau County to request that the Army guard the power station.

[8] In 1967, a 15 MW GE Frame 5 gas turbine generator was constructed for black start, peaking, and emergency purposes.

[9] In 1972, the Town of Oyster Bay board unanimously denied LILCO a permit to further expand the plant with five 50 MW gas turbines, citing air-quality concerns and the effects of the 1970s energy crisis.

[9] In 1978, the Y-50 Cable was constructed between Westchester County's Dunwoodie North Substation and the Glenwood Generating Station, via the Long Island Sound.

[18] In 2001, LIPA proposed building two mini-turbines at Glenwood Landing as part of a plan to build ten such plants across Long Island to avoid the risk of rolling blackouts in the face of increased demand like those experienced in California the previous year, given strain on the system from a heat wave in 2001.

[25] Despite collecting 780 signatures for a petition, this was rejected due to the excessive cost of renovating the building given its poor condition.

[1][14] In 2017, National Grid proposed raising the legal power output limit of the two 2002 peaking plants from 79.9 MW to 94 megawatts.