DEVELOPMENT AND PERFORMANCE ANALYSIS OF A GREEN HYDROGEN PRODUCTION SYSTEM FOR HYDROGEN DEMAND OF BANGLADESH BY 2040

Abstract

Nowadays, green hydrogen production through electrolysis of water, using renewable energy sources like solar, wind is increasing worldwide, as it leaves no emission behind. This work is intended to identify the diversified applications of hydrogen in different sectors in Bangladesh like the chemical, food and metal industries, fuel cells, bio-gas, heating applications, etc. In this research, a green hydrogen production system has been developed using locally available materials and technologies. An electrolyzer is the central part of this system. It has two cells connected in parallel and has bipolar electrode configuration. Each cell has 4 individual electrodes and one shared electrode. Total 9 electrodes have been used. Each electrode is positioned having an equal separation from each other so that each electrode gets equal potential difference across them. Here, 10.6 volt is applied to the assembly, and hence, each pair gets 2.65 volt. NaOH solutions of different molarity are used to optimize the gas production rate. Performance analysis of developed system shows that it can produce 92.5% pure hydrogen with 30.62% efficiency and the production rate is 206 mL/min or 1.104 g/h or 0.0123 Nm 3 /h. A practical study on different electrolysis conditions are tested before developing the electrolyzer. The study concludes that the solar photovoltaic panels and wind turbines are technically feasible for water electrolysis. Wind speed data was collected for one year (July, 2015 to June, 2016 and July, 2016 to June, 2017) at two sites in Chattogram and Dhaka, two busy metropolitan cities in Bangladesh. The Weibull distribution of data shows that the shape factor of the wind data in Dhaka (Lat: 23.7390° N, Long: 90.3831° E) is 1.42 and scale factor is 1.96 ms -1 at measured height of 27 meters from sea level. The shape factor for Chattogram (Lat: 22.2877° N, Long: 91.7751° E) site is 1.8 and the scale factor is 2.2 ms -1 at the height of 59 meters from sea level. It is found that the scale factor significantly improves with the increase of hub heights. For Chattogram site, scale factor is around 3.68 ms -1 at a height of 130 meter, and for the Dhaka site it is nearly 4.17 ms -1 at 200 meters. At measured height the yearly average energy density would be 7800 Whm for Dhaka site and for Chattogram site it would be around 12300 Whm . The site specific wind characteristics suggest that the turbines having 2 ms -1 cut-in-speed and 10 ms -1 rated speed would produce energy with 30% capacity factor, from the month of April to September, for both the sites. For the urban building rooftops, lightweight small capacity (~1kW) wind turbines with mentioned characteristics are most suitable. DB 400 and AWM-1500 model turbines have the similar characteristics and were chosen for the further simulation.

The values of the global solar radiation (taken from NASA for July 1983 to June 2005) are 4.59 kWh/m 2 /day and 4.76 kWh/m 2 /day for Dhaka, and Chattogram, respectively. The average sunshine hour for both the cities are about 4.5 hours/day. The economic feasibility, especially the Levelized Cost of hydrogen, produced from PV and wind based power options, have been determined. Life-cyclecost analysis shows that, the production cost of hydrogen of a plant using Solar PV

power is about BDT 859.77/Nm 3 or BDT 9.56/g. The electricity consumption of the developed hydrogen plant is 3897.6 kWh/year and the energy requirement for hydrogen production is about 108.72 kWh/kg. The amount of hydrogen yield is 35.85 kg or 398.56 Nm 3 per year. Sensitivity analysis based on different parameters finds that the production cost of hydrogen using solar power varies from BDT 7.99/g to BDT 10.93/g or BDT 718.85/Nm 3 to BDT 982.99/Nm 3 . The cost includes lead acid battery cost, replacement cost and maintenance costs. On the other hand, for wind power scheme, the production cost is about BDT 10.30/g or BDT 926.66/Nm . For wind-solar hybrid model, the production cost of hydrogen would be BDT 7.47/g or BDT 671.71/Nm 3 with reduced number of battery usage. Sensitivity could impact the cost to vary between BDT 7.28/g or BDT 654.50/Nm 3 to BDT 10.11/g or BDT 909.64/Nm 3 . Based on the simulated results, it is found that the solar-wind hybrid model would be the most effective for green hydrogen production in Bangladesh. Demand potential of hydrogen is estimated to cope with the targets of Bangladesh Government by 2040. The demand potential analysis is based on the methods and criteria adopted by the several international agencies, research institutes and laboratories. Out of several methods and assumptions, three scenarios, each having a specific percentage of different fuel mix are selected, modified and set for Bangladesh. For Scenario-1, the least GDP growth case, Bangladesh would require about 2.98 MTOE of hydrogen in 2040. The Scenario-2, set for the moderate GDP growth case would require about 6.05 MTOE and for Scenario-3 which is the maximum expected GDP growth case, the hydrogen requirement would be 9.12 MTOE. The power sector would consume about 70% whereas industries and transport would consume 23% and 6%, respectively. However, considering the socio-economic conditions of Bangladesh, Scenario-1 could be achieved easily with the projected time period to enter in the world hydrogen economy. In comparison to the current international cost of hydrogen, the developed electrolyzer shows higher production cost. The developed unit is a small capacity electrolyzer and works properly to produce green hydrogen. Research should be conducted to develop large scale electrolyzer in Bangladesh to evaluate the cost from large scale production unit. Technology transfer may also help to establish green hydrogen economy. Due to the availability of solar and wind resources, solar PV and wind turbine technology would largely contribute to the green hydrogen production in Bangladesh.