From February 2021 to August 2021, a computer device was placed near the window of the home of Paolo Bombelli, a biochemist at the University of Cambridge, but unlike a common computer, the drive of this device was not the electricity delivered by the power grid, but It is a battery made of algae.
This particular biophotovoltaic cell has a plastic and steel casing, about the size of an AA battery, and an aluminum anode. Responsible for generating electricity is an alga called "Synechocystis sp. PCC 6803" in the shell, a cyanobacteria belonging to the genus Synechocystis.
▲ Picture from: ScienceDirect
The characteristic of this cyanobacteria is that it can rely on photosynthesis to produce during the light period, and when there is light, it will produce excess nutrients, and when the environment becomes dark, it will continue to maintain its own operation through these excess nutrients.
The "cyanobacteria battery" is connected to the Arm Cortex-M0+ microprocessor. The extremely small silicon area, low power consumption and minimal code footprint allow developers to achieve 32-bit performance at the price of 8. The processor itself It's quite energy efficient.
▲ Picture from: Engadget
The processor, which was programmed to check its own work after a series of calculations, used the cyanobacterial device as its sole power source for months on end. The processor runs for 45 minutes computing consecutive integer sums to simulate a computing workload, requiring 0.3 microwatts of power; the subsequent 15 minutes of standby time requires 0.24 microwatts of power.
As for why the "cyanobacterial battery" produces electric current, the research team including Paolo Bombelli has two hypotheses. One is the "electrochemical model", in which microorganisms create suitable conditions for aluminum anodization or release electrons, and then generate electricity; the other One is the "bioelectrochemical model", in which the cyanobacteria themselves generate electrons, and the electrons are transferred to the aluminum anode through the bacterial membrane, thereby generating an electric current.
▲ Picture from: Paolo Bombelli
Since the researchers found that the aluminum anode did not change significantly in the experiment, it is believed that the "bioelectrochemical model" is more likely. That is, the current is produced by the cyanobacteria themselves.
Although the processor did not require much energy, the "cyanobacteria battery" also maintained it without power loss for six months of the experiment, and when the microprocessor was disconnected after the experiment, the cyanobacteria also continue to generate electricity.
▲Chris Howe (left) and Paolo Bombelli (right) of the research team, picture from: Cambridge University
The microprocessor Arm Cortex M0+ has a wide range of applications, ranging from processors in IoT, artificial intelligence or machine learning, to sensors in wearables…
Of course, "cyanobacterial batteries" can't provide a lot of power, but they have a "useful place" in scenarios that only require a small amount of power, such as in sensors or charging mobile phones. For people in rural areas or low-income countries, this could be another source of electricity.
▲ Picture from: "Energy & Environmental Science"
More importantly, the simple structure and environmentally sustainable characteristics of this bio-based battery provide a new direction for the development of electricity, without the need for resources such as rare earth elements and lithium that are facing shortages in most power supply equipment today, as long as sunlight. And water, it continuously generates electricity on the energy source.
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