Australia’s national science agency, CSIRO, says a next generation supercritical carbon dioxide (sCO2) powerplant could help accelerate mining operations to low emission outputs and meet large renewable energy targets.
Constructed by the Gas Technologies Institute (GTI), General Electric and other industry partners in the United States, these sCO2 powerplants are being explored in a collaborative program involving CSIRO.
The 10 MW-electric sCO2 pilot plant, currently being constructed in Texas, USA, will demonstrate a fully integrated power cycle that can be easily configured to operation on renewable energy, CSIRO says. When completed in June 2021, it will be the largest sCO2 powerplant demonstration facility of its kind in the world and will represent a significant step toward sCO2 technology commercialisation, it added.
While most powerplants use steam turbines to produce electricity, sCO2 powerplants use high temperature CO2 instead. By avoiding the use of water, advanced sCO2 power plants using renewable energy inputs have significant potential to transition mining operations to a low emission future, CSIRO says.
“The advantage is that sCO2 is a higher density working fluid, which means sCO2 power plants can be smaller, more efficient and not reliant on water for steam and cooling,” it said. “sCO2 powerplants can also be autonomous and operate using a wide range of heat sources.”
This makes such powerplants an ideal candidate to replace diesel generation in off-grid mining operations, as renewable energy can be used to power their operations for longer periods of time.
Many mining companies are committed to transitioning to low emissions technologies and widespread implementation of sCO2 power generation technologies could be a game changer for the mining industry globally and help accelerate the world’s transition to a low carbon future, according to CSIRO.
CSIRO’s partnership in the Gas Technologies Institute Program will improve understanding of how sCO2 powerplants can enable lower and zero emission technology solutions, and how they might be used in remote off-grid mining and community locations as a low-cost alternative to diesel fuel power generation, it said.
The powerplants also provide a potential future replacement for large grid-connected electricity generation.
A renewable energy solution
For CSIRO, the use of concentrated solar thermal (CST) technologies to provide the renewable energy solution for these sCO2 power plants is also a focus. CST technologies capture and store heat, which make it an ideal solution for a sCO2 powerplant. The Australian Solar Thermal Research Institute (ASTRI), which is managed by CSIRO, is leading efforts in this area.
For mining operations, the use of portable, scalable and low-cost thermal energy storage (TES) will be a critical enabler for sCO2 power plants. TES can be used to store heat, which can then be used day or night to run a sCO2 power plant.
The addition of TES can make 24/7 renewable mining operations a reality, CSIRO says. Australia’s TES efforts under the GTI Program will be delivered in partnership with Graphite Energy.
Keith Vining, Research Group Leader for Carbon Steel Materials, CSIRO Mineral Resources, said taking advantage of Australia’s solar resource to operate sCO2 powerplants for the purposes of mineral processing is a positive development.
“Metal production is highly energy intensive,” Vining said. “In most cases metal production from Australia’s mineral resources is performed overseas using traditional fossil fuel energy sources.
“In a low carbon world, there is an opportunity to perform more on-shore processing and replace traditional fossil fuel energy sources with renewable energy resources in the commodity value chain. The use of sCO2 powerplants operating on renewable energy could make this opportunity a reality.”
This research is part of the Joint Industry Partnership of the Supercritical Transformational Electric Power (STEP) project known as STEP Demo.
The construction of the STEP project demonstration plant is nearing completion, with equipment installation underway in San Antonio, Texas. It is expected to be operational in mid-2021.
The site will be able to demonstrate performance over a range of operating conditions and allows flexibility to be reconfigured to accommodate ongoing testing and technology optimisation, according to CSIRO.
The supercritical CO2 cycles will be able to operate using a wide range of heat sources, including fossil fuel (natural gas), renewables (concentrated solar, biomass, geothermal), next-generation nuclear, industrial waste heat recovery, and ship-board propulsion.
