A renewable energy system includes a digester assembly having an outer tube with an input region and a digestion region. The input region extends above grade and is configured to receive liquid waste. At least a portion of the digestion region is positioned below grade and configured to receive the liquid waste and to anaerobically digest the liquid waste with microorganisms to supply renewable byproducts, such as methane, hydrogen, carbon dioxide, and/or carbon dioxide-rich water. The digester assembly can include two or more deformable tubes that are configured to move liquid through the outer tube by alternatingly compressing one another. In one embodiment, the deformable tubes are configured to replenish waste liquid and to deliver liquid byproducts. In another embodiment, the deformable tubes are configured to exhaust air, such as for delivery of gas byproducts and fostering an anaerobic environment.