How Chinese scientists used algae in seawater battery to make clean power from the sun
- Team puts four types of microorganism into miniaturised bionic ocean battery that proved stable and suitable for very low power applications
- Author says efficiency is limited by cyanobacteria activity but it could be boosted with genetic engineering
A new technology could use the ocean as a green, living battery, according to the Chinese scientists behind the innovation.
The researchers put four types of microorganism, including algae, into a battery-like device filled with seawater. The microorganisms converted sunlight to sugar and then used the sugar to produce clean electricity.
The battery put out a maximum 380 microwatts in power and operated stably for more than a month, making it suitable for ultralow-power facilities, according to the researchers.
The research group in eastern China reported their development of the world’s first biophotovoltaics device using a vast army of microbes in 2019. The power density of the new system has increased by an order of magnitude.
For now, the battery performance cannot match that of semiconductor-based photovoltaics but it reveals a more environmentally compatible and potentially more cost-effective way of generating electricity directly from light, according to the researchers.
The work was published in Nature Communications on September 24 by researchers with the State Key Laboratory of Microbial Resources, Qingdao Institute of Bioenergy and Bioprocess Technology and Tianjin Institute of Industrial Biotechnology under the Chinese Academy of Sciences.
“The miniaturised bionic ocean battery was inspired by marine microbial ecosystems,” lead author Zhu Huawei, of the State Key Laboratory of Microbial Resources, said.
After breaking down, some organic matter is deposited onto the seabed sediment where they become nutrition for microorganisms and have a role in their metabolism.
Solar energy is the main driving force in these biogeochemical cycles. To increase performance and improve efficiency, researchers built a special device to realise the cycle in one battery.
The battery’s four-species microbial community mimics the ecological structure of marine microbial ecosystems: a primary producer, a primary degrader and two ultimate consumers.
The primary producer first yields sucrose through photosynthesis, the primary degrader breaks the sucrose down to lactate, the two ultimate consumers further decompose lactate and generate electricity.
Together the four microbial species with different functions achieve photoelectric conversion.
“It not only proves that the four-species system is optimal in terms of power density and stability, but also shows that maintaining a complete three-level ecological structure is an efficient way for bio-photoelectric conversion,” Zhu said.
“The battery could serve as an alternative electrical energy source for ultralow-power facilities, such as environmental sensors of the Internet of Things. A single miniaturised bionic ocean-battery generating hundreds of microwatts is sufficient to support these small facilities.”
With solar energy as the sole input, this bionic battery even has the potential to operate on Mars, as long as water, carbon dioxide and minerals are available.
The team is looking for effective ways to boost the power output. As with widely used solar cells, one strategy is to stack bio-solar cells to achieve greater voltage and current output for higher powered facilities.
“Three of the four species are engineered strains. Current efficiency is limited by the activity of cyanobacteria, and with genetic engineering there is hope to increase it by 2-3 times,” Zhu said.
“The battery construction is relatively complicated at present. We are considering automating this process by using 3D printing technology.”