Flagship Projects

Big-T: A major project for Australia's energy transition

Hydropower for a sustainable future

«The Big-T pumped storage power plant contributes to grid stability in the state of Queensland and helps to reduce electricity prices in the region.»
Big-T has been designed to minimize environmental impacts and maximize benefits for the general public. The construction includes, among other things, an underground power plant and underground high-voltage lines leading to distribution centers. This combination minimizes deforestation and also reduces the risk of bushfires.

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.

Learn more

  • Cavern and shaft construction
  • Underground facilities and systems
  • Ventilation
  • Operating and safety systems
  • Technical buildings
  • Mining
  • Excavation support and ground improvement
  • Hydroelectric power plants
  • Surface and underground powerhouses
  • Hydraulic tunnels and shafts
  • Penstocks and steel lining
  • Hydromechanical equipment
  • Electromechanical equipment
  • Balance of Plant
  • Dams and retention structures
  • Water transfer systems and pumping stations
  • Green Energy
  • Hydrology and watershed modelling
  • Geo-Engineering
  • Monitoring
  • Operation & Maintenance
  • Risk Analysis
  • Engineering for net-zero future
  • Material Management
  • Special geotechnical works 

Megawatt - Maximum power output of the pumped-storage power plant.


Meters - Length of the hydraulic tunnels connecting the water reservoirs.


million tonnes of potential reduction in CO2 emissions per annum


million tonnes of potential reduction in CO2 emissions during the project's lifetime

Lat: -27.2612578
Lng: 152.2081242

Lake Cressbrook

Cavia Diego edited
«Pumped-storage power plants are gaining increasing importance worldwide. We are very pleased that with the Big-T PHES project, we can make another contribution to the energy transition in Australia.» Diego Cavia