There are a variety of schemes for using electricity from intermittent sources. They usually end up being convoluted contraptions that have dual power systems - one for use when the sun shines (or wind blows or whatever) and another for use at other (most?) times. One ot the sillier ones I've heard of burns biomass part time and captures sunlight at others. I've argued that a more appropriate use for intermittent power would be for interruptible applications, for example using remote wind and solar systems to produce hydrogen through electrolysis. There seems to be a better way.

"We were studying making hydrogen in microbial electrolysis cells and we kept getting all this methane," . . .

Microbial electrolysis cells do require an electrical voltage to be added to the voltage that is produced by bacteria using organic materials to produce current that evolves into hydrogen. The researchers found that the Archaea, using about the same electrical input, could use the current to convert carbon dioxide and water to methane without any organic material, bacteria or hydrogen usually found in microbial electrolysis cells. . .

The researchers created a two-chambered cell with an anode immersed in water on one side of the chamber and a cathode in water, inorganic nutrients and carbon dioxide on the other side of the chamber. They applied a voltage, but recorded only a minute current. The researchers then coated the cathode with the biofilm of Archaea and not only did current flow in the circuit, but the cell produced methane.

"The only way to get current at the voltage we used was if the microbes were directly accepting electrons," said Logan. He notes that the electrochemical reaction takes place without any precious metal catalysts and at a lower energy level than converting carbon dioxide to methane using conventional, non-biological methods.

The cells are about 80 percent efficient in converting electricity to methane and because they use carbon dioxide as feed stock, would be carbon neutral if the electricity comes from a non-carbon source such as solar or wind power. . .

Logan suggests the method for off peak capture of renewable energy in a portable fuel. Methane is preferred over hydrogen because a large portion of the U.S. infrastructure is already set up to easily transport and deliver methane.

True. We know how to handle methane, and it has so many uses. One that I've talked about many times is that it is a feedstock for nitrogen fertilizer production. It's really just the hydrogen in the CH4 that is of value for producing NH3, but if methane is easier to make than hydrogen that seems as good since we already do it that way.