How would a bioengineered warbeast get energy from fossil fuel products?

Question

In the somewhat far future, mankind has become fairly adept at wet nanotechnology and synthetic biology. Allowing them to not just modify what exists in nature, but build beyond it with almost anything organic.

When I say organic, I mean organic, there are more than a few organisms that incorporate what we'd recognize as plastics and synthetic fibers into their biology. They're also far better at precipitating metal than real life organisms. Which is kind of why I felt this belonged with a xenobiology tag. So naturally gladiatorial arenas are in vogue to pit fantastic beasts against each other.

No expense is spared in creating these masterworks of bioengineering. Bio-electronics, optics, synthetic muscles far stronger than anything in nature could evolve. Their size varies as well from being between the size of a wolf to being no bigger than a Siberian Tiger.

However one major problem is that these organisms need a lot of calories to fight and perform for their owners. But I've also read once that a gallon of gasoline contains 31,000 calories.

Is there any plausible mechanism to get these organisms to digest and breakdown fossil fuel products such as gasoline or kerosene for energy?

Answer 1

I mean - you've already said 'In the Far Future' - so you've got license for pretty much anything you want.

To answer your question though - in terms of pure chemistry, it's pretty plausible.

Petrol and other fossil fuels are mainly various Hydrocarbons (Carbon and Hydrogen atoms joined in various lengths), whereas Carbohydrates (pasta, bread etc.) are various combinations of Hydrogen, Carbon and Oxygen.

Fats likewise are a combination of Hydrogen, Carbon and Oxygen.

So - assuming you get Oxygen from the air and a way to combine it into something useable by an organic entity - you are sorted.

You could do this via having a specially designed digestive system that reconstitutes petrol into something approaching a natural substance. You could have super-advanced bacteria that do this. You could use some form of catalytic conversion etc.

The only issue you might have is your body needs other minerals apart from Carbon, Hydrogen and Oxygen to live. Things like Calcium and Iron.

This could be solved by simply having those as additives in a special petrol mix or by having them 'eat' normal food to supplement their fuel-based diet.

Answer 2

Sure, but why?

A gallon of gas contains about 28K nutritional Calories (which are each 1000 chemistry calories, note the change in the initial 'C'),

A gallon of butter contains about 25K nutritional calories. Even granola is something between 9K and 10K calories per gallon.

So, while gas is indeed an energy dense food, it's not much denser than regular food. Food also provides other nutrition (vitamins, protein, etc.) that alive things are likely to need.

So, why do you hear about energy density in petro-products? Likely because that energy is much easier to use: You can access the calories in gasoline by lighting it on fire, getting at the calories in granola takes an elaborate bioreactor.