Oceans May Be Large, Overlooked Source of Hydrogen Gas

[caraher]

1. Not a very big source, it would appear

The paper talks about something on the order of 10^12 mol of H2 per year. From the abstract:

It has recently been estimated that serpentinization within continental lithosphere produces H2 at rates comparable to oceanic lithosphere (both are ~10^11?mol?H2/yr). Here we present a simple model that suggests that H2 production rates along the mid-oceanic ridge alone (i.e., excluding other marine settings) may exceed continental production by an order of magnitude (~10^12?mol?H2/yr).

Suppose one captures all of it and uses it in fuel cells. You'll yield electrical energy at a rate of something like 250 kJ/mol of H2 that way, so the total annual energy harvested would be 250 trillion kJ, or about 70 million kWh. Dividing by the number of hours in a year yields about 8000 kW, or 8 MW, as the effective average electrical power.

So we could engage in a heroic effort to investigate this theory, find ways to harvest the hydrogen, etc. Or build a wind farm or solar PV array of modest size to generate the same amount of electricity.

Even if the theory pans out, the challenge of capturing this small resources strikes me as far greater than, say, capturing the methane we know is bubbling into the atmosphere - and the latter would be a far greater energy source (not carbon-free, of course, but to the degree that methane is a more potent greenhouse gas than CO2, a net positive in limiting climate change).