*2.3. DMFC Power Station*

Figure 6a shows the front view of the portable DMFC power station. Its dimension is 26 <sup>×</sup> <sup>22</sup> <sup>×</sup> 22 cm3, and it weighs approximately 2 kg. A fuel injection port is located at the left of the front cover, a heat sink was attached on the right side cover, and vent holes were provided on the top and side for good air circulation.

Figure 6b shows the rear view of the inside. A 4 L fuel tank approximately half of the height of the power station was placed at the bottom providing 1.5 to 2 kWh energy generation capacity to last longer than 20 days of continuous operation. DMFC stack module sockets to accept four stack modules were placed on the upper left side. The number of modules to be plugged in can be determined by the power demand of the targeted application. The EMS control board is located on the upper right. The Li-ion batteries are placed at the right front of the fuel tank. The installation and replacement of the DMFC stack modules are simple and quick, connecting the dosing pump to the fuel tank with a hose, plugging electronic signal and power cables into the corresponding EMS sockets, and it is done. The power station is easy to assemble, to maintain, and portable. We conducted a long-term field test to demonstrate its feasibility for IoT applications in outdoor environments.

**Figure 6.** Portable DMFC power station. (**a**) Front view; (**b**) rear view internal configuration
