BIG STONE CITY, SD (KELO.com) — Sioux Falls based POET is teaming up with California company Antora, and Minnesota-based Otter Tail Power to launch a new clean energy project near the Big Stone City power plant. The plan uses thermal batteries to store heat, which is used to generate steam piped into the ethanol plant. That cuts emissions and helps POET qualify for federal tax credits. The project is seen as an alternative to CO2 pipelines, which were stripped of eminent domain rights by the South Dakota legislature this year.