Modeling of Hydrogen Infrastructure for Fuel Cell Applications and Its Impact on Hydrogen Economic Era, Case Study in Semarang

The current global trend is a shift in the use of fossil energy to hydrogen, known as the "hydrogen economy". At present transportation (automotive) is looking for alternative fuels as a substitute for fuel oil. In addition to using electricity as a driving force, hydrogen fuel is used as one of the fuels which can also be considered an option. This study seeks to determine the profile of energy consumption in Semarang district starting from the transportation to a certain year. The output of this research is about hydrogen infrastructure and making possible steps for a decission by knowing the profile of energy consumption in Semarang. Finally it will be known the potential of hydrogen infrastructure development which can become a guideline in determining the right policy in carrying out hydrogen infrastructure development in Semarang. The capacity of hydrogen production in Semarang is approximately 1,000 m3 / hour. The production breakdown per day is : 550m3 / hour x 24 = 13,200m3. It can be maximized the production of hydrogen for 360 days per year is 4,752,000m3. The prediction of the hydrogen needs of 2020 in Semarang is 1,955,780 m3. Thus the production of hydrogen in Semarang can be fulfilled.


INTRODUCTION
Background research because air pollution has worsened in major cities around the world, so the use of car transportation must be limited and measures introduced to encourage clean vehicles [1]. The transportation sector is a major contributor to the emergence of global warming around 20% of greenhouse gas emissions caused by the transportation sector [2]. Hydrogen is an energy storage medium for electricity produced from renewable energy sources that makes important connections in the sustainable and emission-free energy chain from start to finish. Unlike fossil energy, hydrogen will not run out because hydrogen is the most common element found in nature. Hydrogen can be used both to produce electricity and as a fuel which makes it very suitable for stationary and mobile applications [1]. The current global trend is a shift in the use of fossil energy to hydrogen, known as the "hydrogen economy" [1]. One key to expanding alternative energy is to produce and introduce vehicles driven by energy sources other than petroleum fuels, such as hydrogen gas, so that each energy source is converted into electrical energy to drive a vehicle. Developing alternative energy diversification at the consumer level will prevent price increases and dependence on one fuel can be reduced [3].

Basic theory
Fuel cells are electrochemical cells that are similar to batteries, the difference is that the reactants consumed by fuel cells can be replenished continuously. Fuel cells produce electricity from outside hydrogen and oxygen supplies. Fuel cells are different from batteries where electricity is produced from internal energy. The electrodes in the battery react and change when the battery is charged or discharged, while the fuel cell electrode is catalytic and relatively stable [4]. Hydrogen needs infrastructure for distribution. [5].

RESEARCH METHODOLOGI
Case study was taken in Semarang. Semarang is also known as one of the metropolitan cities in Indonesia, where traffic congestion has always been a major problem in metropolitan cities. Based on data from DPAAD Semarang in 2014, the number of vehicles in Semarang reached 1,305,636. The number of vehicles in Semarang has also caused traffic jams in Semarang. The most prominent impact of the increasing number of vehicles in Semarang is increased air pollution..

RESULTS AND DISCUSSION
In 2014, energy consumption (Gj) in Semarang was calculated by the calculation below. We can see the calorie equation for joules can be written as: The calculation of energy in Gj in Semarang can be written as:  12.7 MJ / m3 [6]. can be written as: 12.7 MJ/m3 = 12,700 KJ/m3 (20) 1 m3 = 12.7 MJ = 0.0127 GJ (21) With mathematical equations, the calculation will be obtained in Table 2. The relationship between energy needs in Semarang throughout the year is changed to m3, with 1 m3 = 12.7 MJ = 0.0127 GJ. can be written as table 2 below. Table 2. Energy demand conversion in Semarang throughout the year

Comparison of fuel and hydrogen costs
In 2014, diesel fuel consumption in Semarang was = 187,495 kl of diesel fuel. In 2014, the use of premium in Semarang was 349,448 kl Premium. In 2014, the use of Pertamax in Semarang was = 16,804 kl Pertamax, then the total cost is as follows: From