Given Mars’ history of global dust storms, who would have thought that solar power would ever be competitive with nuclear in providing surface energy for future human settlements on the red planet? But that’s what a new paper authored by researchers at the University of California, Berkeley (UC Berkeley) and just published in the journal Frontiers in Astronomy and Space Sciences now indicates.
Solar’s rise as a Mars power contender is directly related to revolutionary improvements in the efficiencies at which photovoltaics convert sunlight into electricity. And if solar photovoltaics prove to be viable on Mars in real life, the decades-old debate about how to scale up Martian exploration without resorting to nuclear power will finally subside. And, in turn, this new solar impetus might help spawn new means of generating more efficient solar power here on Earth.
The high efficiency, lightweight and flexibility of the latest solar cell technology means photovoltaics could provide all the power needed for an extended mission to Mars, or even a permanent settlement there, say researchers at UC Berkeley.
The team’s approach was to compare these two technologies head-to-head for a six-person extended mission to Mars involving a 480-day stay on the planet’s surface before returning to Earth, says the university.
Their analysis found that for settlement sites over nearly half the Martian surface, solar is comparable or better than nuclear, if you consider the weight of the solar panels and their efficiency, says UC Berkeley. That is, as long as some daytime energy is used to produce hydrogen gas for use in fuel cells to power the colony at night or during sandstorms, says the university.
“Photovoltaic energy generation coupled to certain energy storage configurations in molecular hydrogen outperforms nuclear fusion reactors over 50% of the planet’s surface, mainly within those regions around the equatorial band,” UC Berkeley bioengineering doctoral student Aaron Berliner, one of two first authors of the paper, said in a statement.
But only photovoltaic power with electrolysis — using electricity to split water into hydrogen and oxygen — was competitive with nuclear power: It proved more cost-effective per kilogram than nuclear over nearly half the planet’s surface, reports UC Berkeley.
Heretofore, it was assumed that given Mars’ distance from the Sun and its problems with dust in its atmosphere that nuclear power would ultimately need to become the primary power source to provide early long-term Mars colonies with adequate power.
But the authors found otherwise.
“We show that photovoltaics-based power systems would be adequate and practical to sustain a crewed outpost for an extended period over a large fraction of the planet’s surface,” they write.
None of this would be possible if there hadn’t been a sea change in solar cell photovoltaic technology over the last two decades.
A big innovation in the last decade or so has been the development of lightweight, flexible solar panels, co-first author Anthony Abel, a graduate student in the Department of Chemical and Biomolecular Engineering, told me. Using these newer technologies, the mass of solar panels decreases a lot, so you end up being competitive with nuclear.
What part of the Martian surface is optimal for solar?
“The overall result was that nearer the equator, solar was better than nuclear, while nearer the poles, nuclear was better than solar,” Berliner told me.
Jezero and Gale Craters —- the landing sites of the Mars Perseverance and Curiosity rovers —- fall within latitudes in which solar technology has an advantage, says Berliner.
For a landing site near the equator, for example, they estimated that the weight of solar panels plus hydrogen storage would be about 8.3 tons, versus 9.5 tons for a kilo-power nuclear reactor system, notes UC Berkeley.
How would future Mars solar power stations mitigate dust storms?
That remains an issue, Berliner concedes. But our study here provides a picture of power availability for average climate conditions on Mars, he says. Yet moving forward, our methods could be very easily applied in consideration of a number of dust conditions, says Berliner.
Is there synergy between Mars solar photovoltaics and its application here on Earth?
High efficiency solar panel cells are typically “grown” on elemental semiconductor materials like Germanium wafers, which cost somewhere around $10,000 per square meter, says Abel. Scientists have been developing ways to grow the solar cell device, remove it and then re-use the wafers, which would be the process for making lightweight solar panels for Mars, he says.
“That innovation could drive costs down for Earth applications as well,” said Abel.