Electricity generation in rice paddies: the potential of microbial fuel cells

During photosynthesis, rice releases sugars, acids, and other carbon compounds through its root system. In waterlogged soil conditions, where oxygen levels are extremely low, bacteria use these substances for metabolism. By creating an electrochemical circuit with an anode submerged in the soil and a second electrode in oxygen-rich water, microorganisms transfer electrons, generating an electric current.

In 2020, a research group led by Mostofa Mujtahid Al Hussain conducted tests in a greenhouse, using activated biochar as an anode. According to data published in the journal Energy Conversion and Management, the peak power of such a system reached 106.67 milliwatts per square meter of anode. Simultaneously with current generation, a reduction in methane emissions by 27.1–38% was observed, with no significant changes in the harvest volume recorded.

Earlier, in 2008, Kazuya Watanabe's team achieved figures of up to 6 milliwatts per square meter using graphite felt. Other studies, including the work of Atsushi Kouzuma, Nobuo Kaku, and Kazuya Watanabe, demonstrated results of around 80 milliwatts. Practical application of the technology has already been tested: for instance, Yu Lu and colleagues used energy from soil cells to power an electronic timer, and Emilius Sudirjo from Wageningen University used tubular elements in active fields, recording an average daily power of up to 9.6 milliwatts per square meter.

Nevertheless, the question of widespread implementation remains open. Scientists note that with a high content of organic matter in the soil, the methane suppression effect decreases. Issues of economic efficiency also remain unresolved: the use of expensive catalysts and graphite materials is not cost-effective for large-scale agriculture. The potential of the method depends on the cost of electrodes, labor costs for their installation in the soil, and the need to confirm the stability of the effect across different types of soil and in various climatic zones.