Bio-batteries, Bio-Generation, and Pervasive Energy
Thursday, December 24, 2009 at 10:22AM
Toby Considine

I am always intrigued by bio-batteries and bio-generation. Every now and then, I read a report, or talk to someone in passing, whose work is far off the beaten electrical engineering path. I am always especially interested when I learn that one of these companies has been funded, meaning they have been able to demonstrate something working, even if only once for one person. Most of them will never be able to provide grid-scale energy; but I think that will not be able to solve our energy problems at grid scale, unless we change our policies that guide our energy choices, and are policies that constrain our siting and construction.

Coal-based algal diesel was our best shot at grid-scale bio-energy. The process feeds nearly-pure oxygen into a high efficiency coal plant, produce nearly pure carbon dioxide as waste. This carbon dioxide then supercharges the growth of enhanced algae that produce compounds that can be made into biodiesel. The carbon would be captured into the fuel, the algae would release oxygen. The first scale trial of this approach was shouted down by the no-coal sloganistas and the anti-genetic engineering luddites. So much for reliable clean generation and energy independence.

I am more interested in local bio-generation and bio-storage. To me, pervasive energy is the natural outcome of smart energy. Pervasive energy achieves stability through diversity of technology as well as of location. Bio-energy adds another source of technology diversity.

A year ago, I ate breakfast with an electrical engineer who had flown in to meet his venture funding, and to review his progress. He was working with a biologist to coax electrons off of bacteria. Many of the most essential activities of bacteria involve electron pumps across cell membranes. Many processes are an attempt to get rid of excess electrons. The smell of swamp gasses in in part due to the ability of sulfur to accept easily another electron. We experience the strong odors of sulfur compounds in the strong smell of onions and garlic, due to compounds (mercaptans) that use sulfur to scoop up electrons and keep their sweet flesh from rotting. Bacterial generation convinces soil bacteria to get rid of electrons onto special electrodes to generate a current that can power low power lights., Bacterial generation is not grid scale; you will not use it to light up your town. If you have damp soil, you might use it to light your front walk, or to power emergency lights in stairwells.

Down east here in Carolina, a hog farmer has created a bio-based district energy plant. He tented his waste lagoon to capture the methane gas. He uses the methane to heat greenhouses of winter tomatoes. He cools the flue gases and pipes the carbon-dioxide rich mix into the greenhouses to accelerate tomato growth. The use of this energy on his micro-district is more valuable than selling to the grid.

I recently read a report of a battery "based on the biology of electric eels". The report claimed that a new company is within a year of commercial batteries for cell phones. I have no idea what process these batteries are based on; I suspect that the publicist-author did not understand it either. For now, I have to be content thinking about, as William Cox quipped, a cell phone that re-charges when dropped in the toilet.

Speaking of toilets, humans produce large amounts of materials of use for the energy engineer. By happy chance, these materials are already located where we can use them for distributed energy. I have written before about the report from Ohio University of using full strength human urine as a source of hydrogen for fuel cells. The cartoons, of course, suggest of unconventional attempts to fill a car's gas tank in the middle of the night. The reality suggests an efficient material to use converting local generation, whether solar or wind, to hydrogen for later use.

The North American grid used to be reliable. We have used up its safety margins. We are, by policy, replacing reliable generation (coal, nuclear) with un-reliable generation (wind, solar, et al.). We cannot solve those problems within the grid. The North American Power Grid will probably never be as reliable again.

We will supplement that reliability, though, with a diverse set of energy sources and energy storage systems in our homes and offices. Some of these storage systems will be metal-acid batteries, and thermal storage, and even compressed air. But some of these supplements will be strictly biological.

Article originally appeared on New Daedalus (http://www.newdaedalus.com/).
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