1. Optimizing The Process The economic implications of this process require a systematic optimization. The major variable in the process is the number of compressors in series. Described below is the process of minimizing the cost of hydrogen compression. The first thing to take into account is the initial cost of the compressors. Equation 1 calculates the cost of a single compressor where F gas is the flow rate of hydrogen gas, r is the compression ratio, and η is the efficiency of the compressor. Equation 2 calculates the power required to operate N compressors in series, where K is the heat capacity ratio of the species, T is the inlet temperature, and r n is the compression ratio. The largest cost in the compression process is the cost of operating the compressors. The annual operation cost is found by multiplying the power calculated in Equation 2 by the electrical cost described in Equation 3. The temperature rise can be used in Equation 4 to calculate the maximum outlet pressure a compressor can achieve without exceeding a temperature of 150°C, which will overheat the compressor. Optimization of Hydrogen Compression for Use as Vehicle Fuel Group 12: Jade Bates, Brandon Burns, Trung Dong, Janna Foret, Ramzy Muhsen Unprecedented Challenges [7] A hydrogen delivery system must be established. Each point along this network would need to be physically, chemically and mechanically secure. First responders will have to develop new processes and responses for car accidents that involve a hydrogen fuel cell-powered vehicle. Any incident at any point in the hydrogen network will require a specific safety plan that deals with hydrogen explosions. Safety Considerations Equipment and Material Recommendations By examining the compression ratio equation, you can see that raising the inlet pressure of the compressor will lower the compression ratio. Being that this ratio is multiplied throughout the work and cost equations, lowering it will lower the work of the compressor which ultimately lowers the cost of compressing hydrogen gas. References [1] “Alternative Fuels and Advanced Vehicles,” U.S. Department of Energy, http://www.afdc.energy.gov/fuels/. [2] “Aluminum 7075-T6 Tubing” available via http://www.seamlessaluminiumtube.com/china- 7075_aluminum_tubing_t6_aluminium_tube_round_7_9_x_0_72_mm-1267054.html. [Accessed 4/27/2014]. [3] “Development of a Centrifugal Hydrogen Pipeline Gas Compressor,” (Department of Energy 2008) available via http://www.hydrogen.energy.gov/pdfs/progress13/iii_10_dibella_2013.pdf. [4] “Explosion Hazards of Hydrogen-Air Mixtures” available via http://www.hysafe.org/science/eAcademy/docs/1stesshs/presentations/Ireland_hydrogen_safety.pdf. [Accessed 4/27/2014]. [5] “Flow Diagram,” available via http://www.kakoki.co.jp/english/products/p-004/index.html. [Accessed 4/26/2014]. [6] “Material Safety Data Sheet-Hydrogen,” BOC Gases, (January 2004). [7] “What are the safety concerns of fuel cells?,” available via http://auto.howstuffworks.com/fuel- efficiency/alternative-fuels/safety-concerns-of-fuel-cells.htm. [Accessed 4/28/2014]. Abstract Hydrogen is believed to be an alternative to gasoline for vehicle fuel. In order to use hydrogen as a fuel source, the gas must be compressed and stored in fuel tanks. Described is the optimization of this compression process. The economic model is designed to minimize the total cost of compressing the gas to its effective pressure. Background Information Figure 1. Hydrogen delivery system flow diagram [5]. Hydrogen [6] Colorless, odorless, lightweight, extremely flammable gas. Skin and eye irritation not typical Can cause asphyxia if released into a confined area No effect on wildlife or environment. Comparison of Hydrogen to Methane Methane is much cheaper to compress than hydrogen. Methane fuel has less emissions than gasoline. Hydrogen fuel emits only water and nitrogen oxides and thus leaves no carbon footprint. Hythane (80% methane, 20% hydrogen) has a higher combustion rate than methane. Infrastructure for all three fuel alternatives is currently limited [1]. Figures 2 and 3. Hydrogen explosion and structural damage [4]. Lessons Learned [4] Keep hydrogen equipment far away from ignition sources such as heat, flames, and sparks High occupancy areas and machinery congested areas should be distanced from hydrogen equipment as well Check hydrogen’s compatibility with compressor material to avoid embrittlement (1) (2) (3) Gasoline ProblemHydrogen Solution Increasingly scarce fossil fuel Most abundant element in the universe Environmentally invasive harvesting methods Environmentally friendly collection options Harmful, toxic emissionsNo dangerous emissions Low yield energy density Highest energy density among gasoline and alternative fuels Hydrogen fuel has the potential to become an excellent alternative vehicle fuel source. When compared to gasoline, hydrogen offers many environmental and economic benefits. History Optimized Solution (4) Figure 4. Aluminum alloy 7075-T6 [2]. Aluminum alloy 7075-T6 was chosen by the Department of Energy as the material used for a hydrogen pipeline compressor’s rotor and volute [3].