Tesco also has plans for Newtown, Llandrindod Machynlleth and Welshpool
Tesco has announced plans for a fifth store in Powys which it hopes will create 180 jobs.
The company says the multimillion-pound development at Ystradgynlais will be one of a new generation of environmentally-friendly supermarkets.
A public exhibition has already been held by the firm to discuss the proposals with the local community.
Tesco has announced plans to open other Powys stores at Newtown, Machynlleth, Welshpool and Llandrindod Wells.
Felix Gummer of Tesco said the store's carbon footprint would be 70% less than a supermarket built in 2006.
He added: "The new Tesco environmental stores are an exciting development in Tesco's long-term plans to reduce significantly the carbon footprint of its stores by 2020."
Tesco confirmed it planned to create 180 jobs.
Plans for the 30,000 sq foot (2,787 sq m) development have been submitted to Powys council.