Engineers Tap Algae Cells for Electricity

With the help of photosynthesis plants convert light energy to chemical energy. This chemical energy is stored in the bonds of sugars they use for food. Photosynthesis happens inside a chloroplast. Chloroplasts are considered as the cellular powerhouses that make sugars and impart leaves and algae a green hue. During photosynthesis water is split into oxygen, protons and electrons. When sunrays fall on the leaves and reach the chloroplast, electrons get excited and attain higher energy level. These excited electrons are caught by proteins. The electrons are passed through a series of proteins. These proteins utilize more of the electrons’ energy to synthesize sugars until the entire electron’s energy is exhausted.

Now researchers at Stanford are inspired by a new idea. They intercepted the electrons just after they had been excited by light and were at their highest energy levels. They put the gold electrodes inside the chloroplasts of algae cells, and tapped the electrons to create a tiny electrical current. It may be the beginning of the production of “high efficiency” bioelectricity. This will be a clean and green source of energy but minus carbon dioxide.

Stanford University researchers got their work published in the journal Nano Letters (March, 2010). WonHyoung Ryu is the main author of this work. He says, “We believe we are the first to extract electrons out of living plant cells.” The Stanford research team created an exclusive, ultra-sharp gold nanoelectrode for this project.

They inserted the electrodes inside the algal cell membranes. The cell remains alive throughout the whole process. When cells start the photosynthesis, the electrodes attract electrons and produce tiny electric current. Ryu tells us, “We’re still in the scientific stages of the research. We were dealing with single cells to prove we can harvest the electrons.” The byproducts of such electricity production are protons and oxygen. Ryu says, “This is potentially one of the cleanest energy sources for energy generation. But the question is, is it economically feasible?”

Ryu himself provides the answer. He explained that they were able to extract just one picoampere from each cell. This quantity is so little that they would require a trillion cells photosynthesizing for one hour just to get the same amount of energy in a AA battery.

Another drawback of such an experiment is that the cells die after an hour. It might be the small trickles in the membrane around the electrode could be killing the cells. Or cells may be dying because they’re not storing the energy for their own vital functions necessary to sustain life. To attain commercial viability researchers have to overcome these hurdles.

They should go for a plant with larger chloroplasts for a larger collecting area. For such experiment they will also need a bigger electrode that could tap more electrons. With a longer-surviving plant and superior collecting ability, they could harness more electricity in terms of power.


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