Algae cultivation (and lipid extraction) has been the holy grail of the biofuels industry. Now these aquatic organisms – specifically their ability to give off tiny bursts of electrical current – could become the savior of dirty utilities as well.
The vision of huge tubs of algae consuming CO2 and nutrients from wastewater to produce biodiesel and bio-gasoline has drawn scores of scientists to experiment with the notoriously capricious plant.
The fact that algae are difficult to farm hasn’t kept the money from flowing. ExxonMobil last year poured $300 million into joint research with scientist Craig Venter’s Synthetic Genomics. Several months later, Sapphire Energy won $104.5 million in federal loan guarantees and grants from the Agricultural and Energy departments for a demonstration refinery in New Mexico. The Department of Energy earmarked another $44 million a month later in January for nationwide university and other research.
The current harvested so far is tiny, but the potential for bioelectricity from algae is compelling
Now a team of Stanford University researchers is exploring an alternative to the biofuels route. Their work is at an early stage. But its concept is startling: plant-based energy generated without the release of carbon.
The researchers, led by WonHyoung Ryu, now a professor in Korea, pierced each algae cell with a sharp nano-electrode probe made of gold. The probe collected electrons produced during photosynthesis, channeling a small current.
So far, the current from each cell is tiny, just one picoampere. (A trillion cells would be needed to equal the energy stored in a AA battery.) Still, the breakthrough is compelling.
“We believe we are the first to extract electrons out of a living plant cell,” Ryu said in a Stanford release. “This is potentially one of the cleanest energy sources for energy production.”
But it is not without difficulties. Most importantly, the cells died within one hour. Ryu theorizes they may have developed leaks where the probe punctured their membranes. They alternately may have run out of gas after their energy was stolen. The electrons transfer energy from the sun to protein inside the cells.
The research team, which published its work in the journal Nano Letters and included two members from the Carnegie Institution, hopes to change the design of the electrode to lengthen the life of the cells. It also conceives of using larger electrodes and bigger plants with larger chloroplasts, the area of the cell where photosynthesis takes place and water is split into oxygen, protons and electrons. That way, more electrons might be captured.
“We’re still in the scientific stage of the research,” says Ryu. But the potential is great. Electron harvesting has a 20 percent energy efficiency. Plants burned for fuel store only 3 to 6 percent of the sun’s solar energy.
While the work is at an early stage, perhaps it is time to coin the term “bioelectricity.”
Posted by Mark Boslet 
