Abstract: A gasifier may include a chamber wall defining a gasification chamber configured to allow gasification of feedstock material. The gasifier may also include an ash grate disposed in the gasification chamber. The gasifier may further include a rotary crusher disposed in the gasification chamber above the ash grate. The rotary crusher may include at least one crushing element. The rotary crusher may be configured to break apart, between the at least one crushing element and an opposing surface, the feedstock material responsive to rotation of the rotary crusher.