The Big-T Pumped Hydro Energy Storage (PHES) is being built around 50 kilometers northeast of the city of Toowoomba in the state of Queensland. The project uses two vertically staggered water reservoirs: while the upper reservoir is newly added, the lower one is the already existing Lake Cressbrook reservoir.
When electricity prices are low, the power plant pumps water into the higher reservoir. This typically occurs during times of excess solar power generation. Conversely, when electricity prices rise, the water from the upper reservoir is released to generate additional electricity.
Big-T consists of an underground power plant complex connected with hydraulic tunnels, various pressure shafts, and an access tunnel. The pumped storage power plant will eventually have the capacity to generate 400 megawatts of electricity for up to 10 hours.
In planning the project, led by Lombardi, Lombardi works closely with Tractebel. The two engineering firms combine their expertise in hydropower and underground projects for Big-T. The partnership has already proven successful in previous construction projects, such as the realization of the Australian pumped storage power plant Snowy 2.0, where Lombardi and Tractebel collaborated.
Lombardi is responsible for the planning and supervision of the project configuration, waterways, inlets, shafts and surface infrastructure. In addition, Tractebel plays an important role in planning the power plant complex and the access tunnels.