The Problems with Fictional Space Ship Engines from a Mechanic’s Perspective

by Joanna Byrne
June 22, 2019

I had a Professor in a writing workshop ask me if I incorporated my knowledge as a mechanic in my fiction writing when she found out my trade. I was baffled and blurted out ‘no, no one would understand any of it,’ which I think insulted her, but is probably also true. If you’ve never had the experience of hearing me go full diesel-geek, then you might not understand. That comment, however, made me very self-aware of if I was dipping into my experience and knowledge when I write.

I can’t say for sure I do, but it creates a huge issue when I read.

My nephew (IG: @shadetreechef) is not a huge science fiction fan, though I am trying to corrupt him, but he loaned me Becky Chamber’s The Long way to a Small and Angry Planet, lauding it as a ‘good read’ and I don’t think he understood what he would do to me.

The ship, Wayfarer, burns algae as its fuel source for its primary engine.

These are the things that keep me awake at night.

As a diesel mechanic who specializes in engines and fuel systems, and has been disappointed by the loss of quality fuel mileage that my older trucks had before they began mixing biodiesel into petroleum diesel this caught my attention. In the real world, a great deal of biodiesel is produced from algae and is the primary source of biodiesel in the area of the USA where I live. In short terms it is impractically inefficient to produce, is frequently contaminated with emulsified water (water particles are bonded to the burnable fuel particles, rendering them useless, and creating damage to delicate fuel system components), and has a high rate of bacteria infestation. Since its phasing in my 7.3l Powerstroke engines with the HEUI fuel system have dropped from consistently making 18/20 mpg to struggling to make 10/12 mpg.

I warned you I would go all diesel geek.

The thing is my knowledge of real-world fuel produced from algae has created this huge question in my mind that is often overlooked in science fiction.

What do the ships run on?

I know its fiction. They could run on unicorn farts, and it wouldn’t matter, but it bothers me.

An algae fuel-powered space ship engine would require tremendous power to produce its own fuel (as Wayfarer does), Chamber’s does an admirable job at addressing the issue, and in her first and second books (fixing to read the third) she touches on there being more that one type of engine and fuel source. I love that she spends time on the little details.

So I put my nephew, and my mechanic boyfriend, through individual lectures on the theory of science fiction fuel sources, and the logistical problems that the main drive engine powered by ship-grown algae would present.

I have fished through my mind for answers to fuel issues like availability, mining, transport, primary versus secondary, low fuel light, stranded because ran out of fuel, sourcing fuel from common space items but that is just the start. Is it a combustion ignition engine? Or does it have to have a spark? Does it have an alternator? Giant solar panels and massive banks of batteries? How stable is the fuel?

I really could go on.

My point, primarily, is that it’s in the details. Fuel is an issue in space. If you are going into the far reaches of nowhere you better be able to get home, and if you don’t think about that along the way, either your reader will be confused, or your crew will find themselves stranded.

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