Some fuels are easier to access than others. Biomass, for instance, represents a great deal of potential energy that’s tied up in very strong chains of molecules, such as cellulose. To get access to that energy, what you need is a molecular wood chipper: something that can break down tough chains into molecules we CAN use, like ethanol.
The problem: breaking down tough, energy-containing compounds into useable fuel sources.
The solution: microbes (bacteria, yeast, algae, etc.)
You may be asking yourself: why use microbes to break these things down? Don’t we have chemicals that can do the same thing?
I’d answer your question with another question:
Why do we use microbes for making beer, or cheese? Why didn’t your grandma wheel in a tank of gas to bubble into the bread dough and make it rise? You’d probably say “because it’s easier” and you’d be right. She’d sprinkle in some yeast (microbes) to get the dough to rise. Humans and microbes have a rich, delicious history together when it comes to food, but the idea of using microbes to process biomass into biofuels is, by comparison, quite new.
Microbes are tiny toolkits that can break down molecules or build new ones—often more efficiently than a chemist in a lab can. A microbe’s toolkit has developed over endless generations to be as cheap and effective as it can be. So why reinvent the wheel? Just as silk worms were harnessed by humans to create raw silk for fabrics, we can use microbes to perform complicated processes under simple conditions.