In the lunar environment, solar energy is almost half again as intense as typical terrestrial levels (1350 W/m2 versus about 900 W/m2) and nearly constant during the 2-week-long “lunar day.” Of course, accommodation of the lunar night will preclude long-term, continuous solar-driven production and, lacking some kind of long-term thermal storage, will require some kind of two-phased monthly cycle. However, the energy requirements for processing lunar materials into cement are such that abundant long-term average production can easily be maintained. In particular, 1 kg of cement requires an input of about 1000 kcal. This means that even with a 50% duty cycle for the full lunar day and night, more than 100 tons of cement could be produced annually with a relatively modest solar furnace of roughly the scale we describe subsequently. Larger production would require either more or bigger furnaces.