560MW of molten salt energy storage to replace coal-fired power plant in Chile

AES Andes operates in mountainous regions including Chile, Argentina and Colombia. Photo: Stephan Bachenheimer/World Bank

AES Andes, the utility company operating in South America under the AES Group, has revealed plans to convert a 560MW coal-fired power plant in Chile into a molten salt energy storage plant.

The company has submitted documents outlining the plan to the website of Chile's national Environmental Impact Assessment (SEIA) agency.

The project, called Project Alba, will see AES Andes convert the Angamos coal-fired power plant (Central Termoeléctrica Angamos, CTA) in northern Chile into a 560MW energy storage facility.

The energy storage device will use a molten salt system heated to 310-560°C, which then enters a water/salt heat exchanger to release the stored heat energy, generating steam to drive a steam turbine generator. The resulting electricity will be injected into the country's national power system.

The company's environmental impact report said the project would require a total investment of $450 million.

It mentions a 10-hour "cycle" of heating the salts, but it's unclear if that means the system will also have a 10-hour discharge duration. That would put the total storage capacity at 5.6GWh.

The plant will require 700MW of energy to heat the salt to the required temperature, with this heat to come from renewable energy delivered from the nearby Angamos substation.

The company said the project would reduce plant emissions by 50%, contributing to the decarbonization of Chile's energy system.

AES owns more than 98% of AES Andes and, together with Siemens, owns a majority stake in Fluence, the largest battery energy storage system integrator. Fluence deploys all of AES' projects in the Americas, but has not yet ventured into areas other than battery energy storage, so its potential role in the project is unclear. It is reported that the company can provide a renewable energy optimization software platform.

Companies such as Malta Inc and SaltX have developed energy storage solutions using molten salt.

German international cooperation agency GIZ and Siemens Energy are supporting the project, according to local media reports.

AES Andes is currently working on a 112MW/560MWh battery energy storage project in Chile, matched to 253MW of renewable generation from solar PV and wind. Fluence will provide the battery energy storage equipment and integration services to the company.

Parent company AES Group signed a cooperation agreement with the country's government during the 2021 COP26 climate negotiations to invest approximately $400 million. An interesting fact is that AES deployed the world's first megawatt-scale lithium-ion battery energy storage system (BESS) at a coal-fired power plant in Chile in the late 2000s.

AES Andes’ submission of project documents comes as the Chilean government considers passing major legislation to encourage energy storage deployment.

(Source: AES Andes Global Energy Storage Network, New Energy Network Comprehensive)