Abstract
Objective. In recent years, hydrogen fuel is extremely expected as one of solution for global warming protection. Especially, in the near future, the bio-hydrogen fuel (Bio-H2) due to biomass feedstock which is carbon-neutral would be promising as an eco-friendly fuel. Also, the Bio-H2 production system through the biomass gasification process of Blue Tower process was developed as the commercial plant (15 t-dry/d) in Fukuoka, Japan. That is, it might be close for the eco-friendly fuel to be marketed. On the other hand, the market of smartphone grew and the annual sales recorded around 0.3 billion units. Thus, as one candidate of the device for which Bio-H2 would be available, we focused on the smartphone with a PEFC (Polymer Electrolyte Fuel Cell) unit as an alternative to a Li-ion battery, and estimated the primary energy consumption and/or the direct and indirect CO2 emissions using LCA methodology. In this paper, we investigated the influences of duration time and/or electricity consumption for each functional operation including the effect of exchange from a conventional cell phone to a smartphone. For instance, using the questionnaire on the usability of smartphone, we investigated the user condition in each generation which covered under 20’s to over 50’s. In comparison to the previous study, we clearly confirmed that the duration time was expanded. Also, we measured the operating electricity consumption of smartphone by the power meter, and investigated the PEFC performance through the basic experiments. Using the above research results, our purpose is to analyze the CO2 abatement benefit of the smartphone with a PEFC unit fueled by Bio-H2 against the conventional one with a Li-ion battery.
Results and Discussion. We evaluated the electricity consumption of talking, music, SMS (Short Mail Service), e-mail and internet access, which we intended in our study, and estimated the Bio-H2 consumption for every operating period (OP) and for users categorized by each generation. For instance, the electricity consumption of under 20’s which is the largest value is 2.63 kWh/OP of OP=2.6 years and 3.74 kWh/OP of OP=3.7 years, respectively. Based on these results, on the Bio-H2 consumptions in the cases of OP=2.7 years and OP=3.6 years, we estimated 0.98 to 1.49 Nm3/OP and 1.39 to 2.12 Nm3/OP, respectively.On the other hand, assuming the specific CO2 emission of Bio-H2 was 34.7 to 90.4 g-CO2/MJ, the CO2 abatement on direct emission would be approximately 60.4% to 86.8% in comparison to the conventional smartphone. In addition, we have a potential to obtain CO2 reduction benefit in the total CO2 emissions including the indirect one, even if the operating period is shorter. This would be due to the expansion of operating time for internet access and the higher efficiency of PEFC performance.
Conclusions. Due to the increase in energy consumption due to more convenient operations of a smartphone such as internet access and a higher performance of PEFC unit, the CO2 reduction benefit against a conventional phone would be significantly obtained by the PEFC smartphone fueled by Bio-H2.
