Ultimo Power Station
Ultimo Power Station, also known as Ultimo Powerhouse, was a major electricity plant in the inner-city Sydney suburb of Ultimo. It opened in 1899 and was the city’s first large power station, built mainly to supply power for the electric tram network. Before Ultimo, there was a small plant in Regent Street (in use from 1882) and occasional experimental electric tram operations powered by small generators since 1890.
The station began with a mix of equipment: American-made steam engines driving direct‑current generators, later joined by British-made turbo-alternators for alternating current. Most of the early AC equipment operated at 6,600 volts and 25 cycles per second. The original plant had four cross‑compound steam engines, each about 1,250 hp, connected to GE DC generators around 850 kW at 550 volts. They could be pushed to about 1,600 hp to meet peak tram demand.
Initially, steam was produced by 14 Hoskins boilers, each about 300 hp, operating at 140 psi. The boilers were hand-fired and used a single chimney. As tram demand grew, the plant expanded. In 1902, three large 1,500 kW alternators were added to fix voltage drops on the George Street tram line; these were powered by 2,500 hp engines and ran at 6.6 kV and 25 Hz. The boiler house was enlarged, and more boilers were added over the years, with the total reaching 32 by 1904.
From 1905 onward, turbo-alternators began replacing some of the original engines. The first turbo-alternator (No. 6) was brought into use in January 1905, a 3,000 hp turbine driving a 1,875 kW alternator at 50 Hz. Over the next years, additional turbo-alternators were installed, and more boilers were added to handle the higher output. By 1921, Ultimo shifted to generating at 25 Hz only, and the remaining 50 Hz units were removed by 1928.
A major modernization started in 1929, with six large pulverized coal boilers and two 20 MW turbo-alternators. This work, completed by 1931, increased the plant’s capacity substantially. In 1941–42, more boilers and another turbo-alternator were added, and in 1949 an English Electric unit of 18.75 MW replaced some older machinery, bringing the total output to about 79.5 MW at its peak. During coal shortages in 1948–49, some boilers were converted to burn furnace oil.
Control of Ultimo passed from the Department of Railways to the Electricity Commission of New South Wales on 1 January 1953. The Sydney railway and tram power grid used Ultimo and White Bay power stations, linked by a 6,600 V transmission network. Trams ran on 600 V DC supplied through rotary converters from the 6.6 kV AC, while heavy rail electrification used 1,500 V DC (begun in 1926). A 25–50 Hz frequency changer at White Bay (introduced in 1939) allowed power from the railway stations to feed Sydney’s 50 Hz grid as needed. As electric trams declined, 25 Hz generation was gradually abandoned, and the tram network closed in 1961.
Ultimo Power Station was decommissioned in 1963 and the site was later used as a wing of the Powerhouse Museum. It has been recognized with an Historic Engineering Marker by Engineers Australia.
This page was last edited on 3 February 2026, at 20:23 (CET).