○Electricity Generation and Storage [2]

    Microbial power generation involves inserting two electrodes into the ground to harness weak electric currents. However, these currents are very small, producing around 1.5 volts per electrode, necessitating numerous connections in series. There have been experiments connecting 100 of these cells, generating over 100 volts for household power. This experiment involved a box measuring 15cm wide, 15cm deep, and 30cm high filled with soil, with electrodes inserted. When 100 of these cells were connected, they generated around 140 volts. With dimensions of 150cm width, 150cm depth, and 30cm height for 100 cells, it's a size suitable for installation in multiple units within a residence.

    Electrode combinations include magnesium (negative) and charcoal (positive), zinc plate (negative) and copper plate (positive), among others. Titanium, stainless steel, nickel, iron, and other materials are also used as conductors. Weak electrical currents can be extracted not only from soil but also from water, garden soil, or soaking aluminum and charcoal in saline water. However, considering the limited resources like rare metals, the primary choice often leans towards magnesium and charcoal.

    There's a readily available type of battery known as a carbon battery. Its advantages lie in its fast charging capability, long-term usability, resilience to moisture, suitability in freezing temperatures or even in fire, making it suitable for permanent outdoor installations. However, these batteries have very small storage capacities, necessitating an increase in their quantity.

    Carbon batteries are already in practical use. As an example, one carbon battery weighing 12 kg can charge up to 25Wh. It measures approximately 33cm in width, 22cm in depth, and 45cm in height. To provide an estimate, using a 7W LED bulb for 3 hours requires 21Wh of power. For a laptop consuming 20-30W, an hour of usage would require 20-30Wh.

    According to a survey by Japan's Ministry of the Environment in the 2020 fiscal year, the average energy consumption per household annually in Japan was 4258 kWh, roughly 12 kWh per day, including single-person households to large families. Another study suggests around 7.3 kWh for a single-person household and 14.6 kWh for a family of four.