Francis Himsworth looks at the viability of using algae as a renewable biofuel for extra-planetary missions and potentially as one when they land.
To date, the most commonly used biofuels are derived from sugarcane and corn. However, with trips to Mars and the Moon on the horizon (no pun intended), it’s worth looking into sustainable fuel alternatives that can be grown on the go. That’s where algae come in handy!
Fuel alternatives need to be easily harvestable and processable. Unfortunately, the most widespread agricultural technologies we have today certainly don’t fit the criteria for space fuel. They need sunlight, soil, fertilisers, and optimal weather conditions, all of which are certainly not guaranteed on either the Moon or Mars!
With algae’s growth harvest cycle of around 4 weeks, or about 30 days, not only are they an extraordinarily fast-growing plant, they’re also the fastest growing biofuel head and shoulders above their alternatives. Corn sits at an average harvest cycle of 84 days, whilst sugarcane pulls in at a lengthy 12 months, allowing multiple cycles of algae to be produced before even one cycle from the others.
However, don’t just take my word on this. The likes of the Royal Society of Biology have cottoned on and quoted prominent researcher Professor Rod Scott on the matter: “To provide 50% of the USA's fuel requirements with corn oil, you'd need 846% of the available crop area in the US, which is clearly impossible. That falls to just 2.5% with microalgae.”
Now, the real question isn’t so much whether algae can serve as a biofuel - for they have already been tested to the extents that they need to be - but rather how would growing algae on space ships or other planets work? So what does it look like and what equipment do you need?
Well, it turns out that growing algae is impressively space efficient. In the diagram shown, algae are compactly organised into rows of glass capsules where once fully grown, they are harvested and siphoned off to processing. It could theoretically be put onto a slidable rack and simply slid into a spacecraft, and there’s no reason why the glass couldn’t just be a transparent plastic instead.
Thanks to Dr Aled Robert’s presentation with AstroSoc, we’re now also aware of how the use of algae delivers other benefits, such as making oxygen, pharmaceuticals, and most recently, Dr Robert’s novel regolith biocomposites. These fabulous materials are mixtures of endemic rock samples from different planets (currently only tested with Mars) mashed together with other materials like our algae, proteins from blood or urea, and finally fired like any ordinary brick.
From all of this, we can conclude that as we delve into a more achievable idea of space travel, we should look for appropriate technologies alongside it. As such, it is no stretch to say that (as far as fuel goes) algae could be the future of space!
4) Roberts, A.D., Whittall, D.R., Breitling, R., Takano, E., Blaker, J.J., Hay, S. & Scrutton, N.S. (2021) ‘Blood, sweat, and tears: extraterrestrial regolith biocomposites with in vivo binders’, Materials Today Bio, 12, 100136. https://doi.org/10.1016/j.mtbio.2021.100136
This article was written by Francis Himsworth.