A reduced emission kiln is described. In some embodiments, the kiln includes a combustion zone for generating heat energy. The combustion zone includes an oxygen inlet and a fuel inlet. In some embodiments, the kiln also includes a calcination zone for converting limestone into lime and carbon dioxide in response to the heat energy from the combustion zone. The calcination zone includes an inlet for limestone, a conduit for directing the carbon dioxide to the combustion zone for use as a flood gas to control the heat energy, an outlet for directing the lime to a hydration chamber, and a carbon dioxide permeable membrane for separating the carbon dioxide in the calcination zone from other materials in the calcination zone and preventing the other materials from entering the conduit for directing the carbon dioxide.