Lately I’ve been working on my presentation for the 10th anniversary of the North American Passive House Conference. It’s on the global warming impact of insulation, a followup to my latest article about Alex Wilson’s work on that subject.
The world of electricity is changing quickly. With all the photovoltaic(PV) Generation of electricity directly from sunlight. A photovoltaic cell has no moving parts; electrons are energized by sunlight and result in current flow. modules out there generating solar power and the advent of the smart meter, there’s a revolution going on within the electric utility industry.
I wrote a little bit about this revolution recently when I discussed the duck curve. Near the end of that article, I mentioned that Matt Golden said something about the “new world where EE [energy efficiency] is dead.” So I spoke with Matt last week, and here’s some of what he said.
You may think there’s no more boring topic than electric utilities. Power plants. Transmission lines. Engineers with flat top haircuts and pocket protectors full of pens in their white short-sleeved shirts.
Well, let me tell you two words that might help make them more interesting: duck curve. If you haven’t heard this term yet, you’re not alone.
Scientists at Stanford University produced a battery that generates electricity from an unlikely resource—sewage.
Their microbial battery won’t be powering neighborhoods, but they believe it could aid the power used to treat wastewater, which accounts for about 3 percent of energy in developed nations like the U.S. The researchers hope the prototype, which is about the size of a D-battery, will be used in sewage plants as well as to break down organic pollutants in the dead zones of lakes and coastal waters where fertilizer runoff and other organic waste can deplete oxygen levels and suffocate marine habitants.
According to a research paper published in Proceedings of the National Academy of Sciences, the prototype is visually nothing more than one positive electrode and one negative, stuffed in a bottle of wastewater. Bacteria are attached to the negative electrode and feed on organic waste particles and produce electricity that is captured by the battery’s positive electrode.
Craig Criddle, the paper’s co-author, an environmental engineer and Stanford Woods Institute senior fellow, referred to the practice as “fishing for electrons.”
The Stanford engineers believe the battery can extract about 30 percent of the potential energy locked in wastewater. They estimate that percentage is nearly equal to the efficiency of the market’s best solar cells when they convert sunlight into electricity.
The Stanford team says it will be a while before the product is fully developed, let alone used at treatments plants. The fellows continue to look for inexpensive and efficient material for the battery’s positive node.
“We demonstrated the principle using silver oxide, but silver is too expensive for use at large scale,” said Yi Cui, a materials scientist and associate professor of materials science and engineering. “Though the search is under way for a more practical material, finding a substitute will take time.”
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