Leonard David's INSIDE OUTER SPACE

An artistic rendering of what a resilient microgrid for a lunar base camp might look like. Sandia engineers are working with NASA to design the system controller for the microgrid. Credit: Illustration by Eric Lundin

Engineers at Sandia National Laboratories in New Mexico are working with NASA and the Department of Energy to design a resilient microgrid electrical system for the Moon.

NASA’s plan for a conceptual Artemis lunar base consists of a habitation unit — complete with room for up to four astronauts — as well as the potential for separate mining and fuel processing facilities.

Early Artemis missions will include short stays at the base camp with the goal to enhance stay times of crews for two months.

Utilizing lunar resources, mining and processing facilities could churn out rocket fuel, water, oxygen and other materials needed for extended exploration of the Moon’s surface while decreasing supply needs from Earth.

Resiliency and robustness

These type facilities would be located far away from the base camp — so other science and technology activities conducted there won’t be disrupted — but the electrical grid for the two units will be connected during emergencies for resiliency and robustness.

There are some very important differences between something like an International Space Station-type microgrid to something that has the extent of a future lunar base, said Jack Flicker, a Sandia electrical engineer.

Credit: NASA

“One of those differences is the geographic size, which can be problematic, especially when running at low DC voltages,” Jack said in a Sandia press statement. “Another is that when you start to extend these systems, there will be a lot more power electronics as well as a lot more distributed energy resources that will exist throughout the base. Sandia has been looking at microgrids with a lot of distributed energy resources for quite a long time.”

Voltage level

Also in work is designing the software to regulate the electricity of the mining and processing center, underway since early summer 2021. That controller can be contrasted to cruise control in a standard automobile in that it maintains an even voltage level on the grid, despite changing external situations.

A Secure Scalable Microgrid Testbed is a unique Sandia research facility that researchers will use to fine-tune their control system. They will also use the testbed to study questions about power system controllers and the interactions between distributed energy resources, energy storage and power electronics on a DC microgrid that is a scaled and simplified representation of the eventual lunar microgrid. Most terrestrial microgrids, and terrestrial electrical grids in general, run on alternating-current power.

Sandia electrical engineers Rachid Darbali-Zamora, front, and Lee Raskin test an algorithm on a hardware-in-the-loop setup at the Distributed Energy Technologies Laboratory.
Credit: Rebecca Gustaf

Variety of situations

“With this DC power-hardware-in-the-loop setup that we’re building in the lab, we can test power converters, the impedance of electrical lines between lunar facilities, we could also test actual energy generation and storage devices,” said Rachid Darbali-Zamora. “Basically, we can use it to study a variety of situations so we can design a system that is self-sustaining and can continue operating even if a solar panel array goes down.”

While this work is for a microgrid on the Moon, the research is also relevant to creating resiliency for communities on Earth, Rachid said. Sandia has a history in designing reliable and resilient microgrids for military bases and vital city services.

This project is funded by the Department of Energy’s (DOE) Office of Electricity as part of a DOE-NASA partnership to combine the expertise, experience and research facilities of both federal agencies.