Texas Microbial Applications has several in-vessel composters, including portable systems. They work on many types of waste, including animal parts, and are powered by small motors.
In-vessel composting is done by feeding organic materials into a drum, silo, tunnel or similar structure where temperatures, moisture and aeration are controlled and the materials are mechanically agitated while the composting process takes place. In-vessel composting requires less space for operating than traditional outdoor windrow/pile composting, is not disrupted by weather changes, eliminates odor issues, eliminates liquid rill-off from composting site, reducing fire danger and greatly accelerates the composting process.