Processes and systems are disclosed for converting animal manure into useful energy and materials. Some variations provide a process for converting animal manure into a purified thermal gas, comprising: drying a starting animal manure in a manure dryer; pelletizing the dried animal manure to generate manure pellets; thermally reacting the manure pellets in a thermal reactor to generate an intermediate thermal gas and a solid biochar; separating out the solid biochar; condensing the intermediate thermal gas to generate a cooled thermal gas; compressing the cooled thermal gas to generate a compressed thermal gas; catalytically reacting the compressed thermal gas in a water-gas shift reactor to generate a shifted thermal gas having an adjusted H.sub.2/CO ratio; treating the shifted thermal gas using an acid-gas removal unit to generate a purified thermal gas; removing water and/or light gases from the purified thermal gas; and recovering or further processing the purified thermal gas.