Microbes Churn Out Hydrogen at Record Rate

FiReaNGeL writes to mention that Penn State Researchers have improved on their original microbial electrolysis cell design bringing the resulting system up to better than 80 percent efficiency when considering all energy inputs and outputs. "By tweaking their design, improving conditions for the bacteria, and adding a small jolt of electricity, they increased the hydrogen yield to a new record for this type of system. 'We achieved the highest hydrogen yields ever obtained with this approach from different sources of organic matter, such as yields of 91 percent using vinegar (acetic acid) and 68 percent using cellulose,' said Logan. In certain configurations, nearly all of the hydrogen contained in the molecules of source material converted to usable hydrogen gas, an efficiency that could eventually open the door to bacterial hydrogen production on a larger scale."

Re:288 percent increase over electricity input

[pushing-robot]

Yes, but the bacteria are producing it from decaying plant material. You'd have to see how much greenhouse gases are being produced by the bacteria as they decompose the vinegar/cellulose/whatever before calling this a better solution than conventional electrolysis.

A good step... but not carbon neutral.

[compumike]

The 80% figure is impressive. But beware of the efficiency numbers they quote. This isn't the full fuel cycle. You've still got to compress and distribute hydrogen, which takes a lot (gases take lots of work to compress). For a vehicle, burning it isn't too efficient maybe 30-40%, and fuel cells aren't quite there yet.

Additionally, with any kind of electrolytically-driven process like this one, there's a HUGE efficiency penalty once you increase the flow rates to be anything substantial. And you need to, because otherwise the amount of hydrogen produced per fuel cell area would be tiny. And then, at that point, you've got the problem of lots of carbon to dispose of. Guess what -- this working microbial fuel cell takes C,H,O in as vinegar or cellulose, and outputs H2 and CO2! Do you really call that 'carbon neutral' as a fuel source? It's still dumping CO2 into the atmosphere, just less of it per Joule of useful energy.

Still, this is a great direction for them to keep going... there are very interesting things you can do with hydrogen, even to extend existing liquid fuel stocks (i.e. crude oil to gasoline) by hydrogenation. (Much cheaper than building lots of fuel cells... but not carbon-neutral.)

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Educational microcontroller kits for the digital generation. [nerdkits.com]

Re:288 percent increase over electricity input

[Angstroem]

Uhm, but you are aware that the decaying plant material can't give off more CO2 or other Carbon-based greenhouse gases than it originally consisted of. Close cycle and such.

Grow a tree. Burn a tree. No increase in greenhouse gas.

As long as you don't use your conventional gas-powered buzz saw to bring it down and an F350 to haul it to your place...

Re:A good step... but not carbon neutral.

[HTH NE1]

Yes, I do call it carbon neutral. The plants take in CO2, H2O and E to create vinegar and cellulose, and due to thermodynamics, plants can't create more H2O and CO2 than they take in; so by definition it's carbon neutral.

Except that CO2 is now airborne again instead of locked inside the plants, when they could have carried it deep into the soil and become fossil fuels.

By your logic, the planet as a whole is carbon neutral as nothing from the outside is adding carbon. Indeed, putting stuff into orbit and on interplanetary and interstellar probes is carbon negative (the carbon put into the atmosphere from the combustion during launch was already here).

With that mindset, it sounds like the only solutions for a carbon negative process would be to either perfect alchemy or disperse the planet. "Disperse the Earth" would make a nice bumper sticker.

Re:A good step... but not carbon neutral.

[Anonymous Coward]

Well .. better for carbon that was already circulating in the ecosystem to
be emitted as CO2 than for carbon from fossil fuels - that was previous sequestered - to be emitted. This is recirculation of carbon, rather than injection of new supplies..

Re:Uhm

[jchernia]

Keep in mind that septic tanks work on this principle, just drop new tablets of the bacteria in every once in a while and processing resumes, clear water leeches out and there is a ready supply of food for them. Been in use on small scale for a very long time. Composting also works with a constant supply of food on a small scale.

As for eating your roof, there are already bacteria that do that, but they have to be in the belly of a termite to survive, likewise if some of these were to get out, I don't imagine they would last long.

Re:Uhm

[Firethorn]

although depending on their metabolism they may see the production of hydrogen as inefficient way of reproducing themselves and switch to a different by-product that works faster

That's indeed part of the problem from what I've heard for using bacteria to produce stuff.

Likely any home user would have to 'scrub' his system every so often as non-hydrogen producing bacteria start emerging and taking over. Hopefully the fix would be equivalent as opening a yeast packet for making bread is today.

Still, I don't see home fuel production spreading much further than it has today. It's always going to be a niche market - most people just aren't going to want to go through the hassle, no matter how simple you make it. Plugging in at night is about as far as I'll give them.

An idea of what do with the CO2

[Radon360]

Here's one possible solution:

Bubble it into water in which you release into shallow man-made ponds in order to accelerate algae growth. Harvest the resultant algae, squeeze the oil out of it and make biodiesel. Put the leftovers from that into a fermenter and get what amount of ethanol you can from it. Then dump whatever is leftover from that onto fields to decompose and enrich the soil.

Yes, you are eventually liberating the carbon again in multiple paths, but it comes down to whether you want to actually sequester the carbon, or are willing to recycle it through a number of diversified fuels as many times as possible.

Re:scared of hydrogen

[Copid]

My guess is that we have enough H in our oceans to keep us going for quite a while. If somebody asked me which molecules I'd be happiest "wasting" in the pursuit of energy, I'd probably go for H2O. We have lots of it, as long as whatever we're doing with it also provides us enough energy to efficiently extract it from sea water.

Anybody want to run the numbers to figure out what percentage of our water we'd be losing per year to sustain our current level of energy use assuming the efficiencies quoted in the article and JimboFBX's suggested 1% hydrogen loss?

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