Deep-sea mussels are living hydrogen fuel cells

We're still trying to figure out how to properly harness the power of hydrogen as a clean energy source — and now we might be able to pick up some unexpected pointers from some bizarre symbiotic bacteria found at the ocean depths.

Many mussels found around hydrothermal vents live in a symbiotic relationship with bacteria, which handle key biological functions for their host. In one instance, the bacteria serve as the powerhouse for the mussels, processing materials around them into usable energy. Intriguingly, these bacteria are actually taking in hydrogen as their power source, making them the natural equivalent of the hydrogen fuel cells we're currently working to build.

Hydrothermal vents shoot out a steady stream of inorganic chemicals such as hydrogen sulfide, ammonium, methane, iron and, crucially, hydrogen. Since the bottom of the ocean is about as far away from sunlight as it's possible to get, the energy producers that live around these vents cannot make use of photosynthesis like their counterparts on land. Instead, they have to harvest the inorganic chemicals to produce energy, in a process known as chemosynthesis.

Until now, researchers were only aware of two broad types of chemosynthetic microbes - ones that processed hydrogen sulfide for their host, and ones that processed methane. But now researchers at the Max Planck Institute have discovered a third, and it's the hydrogen-harvest bacteria of the Logatchev hydrothermal vent field deep beneath the middle of the Atlantic Ocean.

It makes sense that the bacteria at this particular vent would look to hydrogen as an energy source. Logatchev has the highest known hydrogen concentrations in its plumes of any vent, and the researchers calculate that microbes could harvest seven times as much energy using hydrogen as they could with methane, and eighteen times what they could hope to get from hydrogen sulfide.

It appears that these mussels and their symbiotic partners are far from the only organisms to make use of hydrogen as an energy source, but this is the first time that we've actually observed this particular process. Now the only real question is whether there's any chance we can throw some hydrogen and some deep-sea mussels into a car engine, and just sort of see what happens next...

Via the Max Planck Institute. Image by MARUM.