Freshwater Plus Seawater Plus Microbes Equals Hydrogen

class="wp-caption aligncenter" style="width: 465px"> title="RED stack" src="" alt="RED stack" width="455" height="333" />
class="wp-caption-text">RED stack

Now, I’ve talked before about using title="microbes" href="" target="_blank">microbes to treat wastewater and create hydrogen. There have usually been some complications with this process such as the need to add electricity in order to start and maintain the process.

Penn State researchers have solved this issue by introducing fresh water and seawater into the process.

According to title="PNAS" href="" target="_blank">PNAS, “There is a tremendous source of entropic energy available from the salinity difference between river water and seawater, but this energy has yet to be efficiently captured and stored. Here we demonstrate that H2 can be produced in a single process by capturing the salinity driven energy along with organic matter degradation using exoelectrogenic bacteria. Only five pairs of seawater and river water cells were sandwiched between an anode, containing exoelectrogenic bacteria, and a cathode, forming a microbial reverse-electrodialysis electrolysis cell.”

The press release goes on to title="say" href="" target="_blank">say, “The key to these microbial electrolysis cells is reverse-electrodialysis or RED that extracts energy from the ionic differences between salt water and fresh water. A RED stack consists of alternating ion exchange membranes — positive and negative — with each RED contributing additively to the electrical output.”

So, what this means is that by adding the right amounts of freshwater and saltwater to wastewater and by using the right microbes, the process of producing H2 can be endless. Of course this study still has a few steps to go before it can be commercialized but the results so far sound promising.

If we as a nation can find a way to avoid steam reforming of natural gas (the current most popular method of producing hydrogen) or even brute force electrolysis of water, then we’ll have many more options on how and where hydrogen is produced in large enough quantities to run our emerging transportation system. And unlike seawater, this would actually leave a good taste in one’s mouth.

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