In Table the in-and outgoing (negative sign) heat flow rates of all unit operations with the according temperature levels are given for the SPO and the RO setup. The operating conditions are chosen according to the previous section: 𝑛̇C O 2 ,in = 0.91 kmol d -1 , 𝑟 in,SPO = 4.7, 𝑟 in,RO = 4.09. There are no noteworthy differences in the heat flow rates and temperature levels between the both setups. However, due to the recycle in the RO setup, there are some additional unit operations, namely TURB2 and HX4. Due to the recycling stream preheating in HX4 prior to the reactor, the overall energy demand is higher for the RO setup. The excess heat of the unit operations could be used either to provide heat in process steps with heat demand, like the preheating in HX4, or to heat other systems possibly like the electrolyser or the human habitat. The preceding section illustrates that downstream processing can be minimized by employing excess hydrogen at the reactor feed for both the SPO and RO configurations. In the SPO configuration, an inlet ratio of 𝑟 in,SPO = 4.7 is to achieve the set objectives for purity as well as production rate, while 𝑟 in,RO = 4.09 is sufficient for the RO. Due to the different H2 demand of the two suggested setups, the availability of hydrogen at a given landing site may determine whether a recycle is necessary or not.