Release of Oxygen from Lunar Regolite using concentrated solar energy. ORESOL

Participants: CIEMAT-PSA (Spain).
Contacts: Thorsten Denk;
Funding agency: European Commission 6th Framework Programme ERA-STAR Regions (ERA – Space Technologies Applications & Research for the Regions and Medium-Sized Countries - CA-515793- ERA-STAR REGIONS), ESP2007-29981-E.

Background: The project Oresol originates from the "ERA-STAR Regions" program, where it was part of a joint initiative between Andalusia and Bremen/Germany. PSA continued the activity due to the unique possibility to investigate a promising type of solar chemical reactor for reactions that need the processing of large quantities of solids.

Objectives: The principal goal of the project is the development and testing of a solar powered fluidized bed reactor for the extraction of oxygen from lunar regolith. This is done by the reduction of one constituent of lunar soil, ilmenite (FeTiO3), with hydrogen, and the subsequent electrolysis of the obtained water.

Achievements in 2015:
After finishing the assembly in 2014, the behaviour of the solar reactor and the peripheral components was thoroughly tested under non-solar conditions. This included especially the operation of the reactor with the window installed to determine the pressure losses of all upstream and downstream elements. Finally, an important milestone was the relocation of the system from the laboratory (where the assembly and cold pre-tests were done) to the experimental platform of the Plataforma Solar’s big Solar Furnace SF60. Presently, a major modification of this platform is under way. When finished, the solar test campaign can start.

Besides the work on the hardware of the reactor, a study was done with the goal to simplify the concentrator system for the operation on the lunar surface. While a conventional Solar Furnace (fig.1 left) consists of a flat heliostat (1), a building for weather protection, an attenuator (2) to compensate for the varying solar radiation flux, the concentrator (3), an additional, water cooled diagonal mirror (5) to achieve a vertical beam, and the reactor (4) on an elevated working platform, the simplified and especially lightweight version (fig. 3, right) uses an off-axis concentrator that allows to leave the reactor on the ground. The hardware can be reduced to the flat heliostat (1), the off-axis concentrator (3), and the reactor (4). The performance, especially the achievable peak flux, is slightly reduced, but this is not relevant for this application. Due to its appearance, the concentrator was dubbed "mussel-concentrator" [1].

Fig.1: Left: Conventional Solar Furnace. Right: Off-axes ("mussel") concentrator.

A proposal has been presented within the Horizon 2020 Call: H2020-FETOPEN-2014-2015-RIA called “SOLUNOX”. SOLUNOX aims to set a solid scientific and technological basis for the first feasible approach of oxygen (O2) production from lunar regolith. The target is to demonstrate the Proof-of-Principle sustainable operation of an integrated lunar O2 production plant towards the direction of Moon Industrialization. This proposal has been prepared in collaboration with the following institutions: APTL (Greece), DLR (Germany),), Hygear (Netherlands) and CIEMAT-PSA (Spain).

 [1]  A novel off-axis solar concentrator providing a vertical beam. Aurelio González-Pardo and Thorsten Denk.  21st SolarPACES Conference, 13 - 16 October 2015, Cape Town, South Africa.