A Life Cycle Assessment of the PureCell Stationary Fuel Cell System ...

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Chapter 1 – Introduction More people are becoming conscious of the fact that our non-renewable energy resources are declining, and that we therefore have to switch to (more) renewable resources to satisfy our energy demand. In 2003 only 8% of the world primary energy production came from renewable sources [1]. A technology that is currently seen as a possible contribution to solve this problem and that has been subject to increasing support is fuel cell technology. Fuel cells have the potential to cover a large market, since the opportunities include stationary, mobile and portable applications. Fuel cell stacks generally use hydrogen as a fuel (although there also exist other possible fuel types), which is at present produced through steam reforming of natural gas. Since natural gas is a non-renewable energy resource – with the exception of small volumes harvested from landfills and anaerobic digesters – one should realize that today’s fuel cells are non-renewable energy systems. However, they still have a better environmental performance when compared with conventional power plants [2]. Furthermore, both the promise of steam reforming of natural gas with carbon sequestration and of an emerging hydrogen economy in which an increasing share of the hydrogen is produced by renewable resources will only enhance the environmental performance of fuel cells. The fuel cell system that is assessed in this report is UTC Power’s PureCell Model 200 Power Solution system (formerly the PC25), a 200 kW stationary phosphoric acid fuel cell. The PureCell system has an internal natural gas steam reforming system. Since 1991, more than 275 PureCell power systems have been sold, with various applications including a New York City police station and a major postal facility in Alaska. The standard PureCell system is a grid-connected unit that operates in parallel with the electric utility grid. The unit can also be purchased to operate either in grid-connected or grid-independent mode switching between modes automatically or on command. The PureCell system is a source of reliable and assured power, and it can therefore be used as a back-up power system or as a power source for remote locations. PureCell power systems also have the option of heat recovery. A standard PureCell power system is equipped with a thermal management system that provides up to 925,000 Btu/hr at 140 degrees Fahrenheit (equal to 271 kW at 60 degrees Celsius). There is also a high grade heat recovery option that provides up to 475,000 Btu/hr at up to 250 degrees Fahrenheit (equal to 139 kW at 121 degrees Celsius) [3]. Whereas the electrical efficiency of the PureCell system is close to 40% based on lower heating value (LHV), the total efficiency with heat recovery exceeds 80%. UTC is in the process of redesigning the system and would value having a Life Cycle Assessment (LCA) highlight opportunities for improvement when regarding its environmental performance. LCA is a systematic analysis of product life cycles from an environmental point of view. It was developed into an ISO-standard (the ISO 14040- series) in the late 1990’s [4]. An LCA can clarify which stages in the product life cycle 11
and which elements of the product cause the most environmental pressure. Product development and improvement is therefore one of its direct applications. In addition to the actual LCA of the PureCell system this report also describes two potential changes in the product system’s life cycle which lead to an improvement in its environmental performance. These two alternatives are: using renewable hydrogen from wind power and improving the end-of-life scenario from an environmental perspective by reusing components and maximizing platinum recycling. Each of these changes has been separately included in the LCA model in order to quantify the potential environmental improvement relative to the current PureCell system. Chapter 2 discusses the procedures that are followed in order to provide a consistent LCA. These procedures include data collection, data allocation and impact assessment. In Chapter 3 the goal and scope of this research are defined, including a specification of the functional unit and the system boundaries. Chapter 4 provides the inventory analysis, describing how the LCA is modeled, which data are used and which calculations and assumptions were necessary for the inventory modeling. In Chapter 5 the impact assessment step in LCA is explained, and results are shown followed by an interpretation of these results. Also a contribution and sensitivity analysis is performed. Two opportunities for environmental improvement are analyzed in Chapter 6, including LCA results and interpretation. Chapter 7 provides the final conclusions of this research project. 12
Page 1 and 2: Report No. CSS06-09 June 30, 2006 A
Page 3 and 4: Document Description A Life Cycle A
Page 5 and 6: Acknowledgements This research was
Page 7 and 8: Use Phase .........................
Page 9 and 10: List of Figures Figure 3-1: Manufac
Page 11 and 12: List of Tables Table 4-1: Air blowe
Page 13: Table 0-12: Semiconductor chip Pure
Page 17 and 18: determining the facility area relat
Page 19 and 20: System Boundaries Ideally an LCA in
Page 21 and 22: Most of these data were obtained fr
Page 23 and 24: Chapter 4 - Inventory Analysis This
Page 25 and 26: Figure 4-2: PureCell subsystem and
Page 27 and 28: Air valve subassembly The air valve
Page 29 and 30: water and can be recovered in order
Page 31 and 32: Power data for 2005 value, which wa
Page 33 and 34: Enclosure The enclosure shelters th
Page 35 and 36: • The ‘PET ETH U, adapted to US
Page 37 and 38: Power Conditioning System (PCS) The
Page 39 and 40: Steam ejector The steam ejector is
Page 41 and 42: Steel scrap The scrap rate that was
Page 43 and 44: Use Phase In SimaPro, the use phase
Page 45 and 46: The specific gravity of natural gas
Page 47 and 48: End-of-Life Phase For every PureCel
Page 49 and 50: Chapter 5 - Impact Assessment and I
Page 51 and 52: indicator 99 uses European normaliz
Page 53 and 54: In Figures 5-3 and 5-4 a more direc
Page 55 and 56: Due to the extremely high contribut
Page 57 and 58: Figure 5-9: PureCell System manufac
Page 59 and 60: From Figure 5-10 it becomes clear t
Page 61 and 62: Figure 5-14: PureCell system CSA, w
Page 63 and 64: esponsible for 72% of the CSA total
Page 65 and 66:
It is obvious that the attention no
Page 67 and 68:
Figure 5-22 shows the impact per ma
Page 69 and 70:
Table 5-3 shows the manufacturing p
Page 71 and 72:
perturbation is also evaluated by l
Page 73 and 74:
are the main opportunities for redu
Page 75 and 76:
A 3% decrease in the platinum recyc
Page 77 and 78:
Material Waste treatment Percentage
Page 79 and 80:
(or at least achieve the assumed 98
Page 81 and 82:
Figure 6-1: Wind/electrolysis syste
Page 83 and 84:
subassemblies that make up the fuel
Page 85 and 86:
For the 100 miles scenario, this th
Page 87 and 88:
Resp. organics 1.41E+03 1.23E+02 8.
Page 89 and 90:
1000 Miles Transport Scenario Figur
Page 91 and 92:
ILS and steam ejector subassemblies
Page 93 and 94:
PCS waste scenario 1 kg Separated w
Page 95 and 96:
The 98% recycling of ILS platinum a
Page 97 and 98:
Table 6-14 shows a comparison of ag
Page 100 and 101:
The goal of this part of the resear
Page 102 and 103:
References 1. Energy Information Ad
Page 104 and 105:
Appendices 101
Page 106 and 107:
Cold transforming steel PureCell sy
Page 108 and 109:
Table 0-4: PureCell system maintena
Page 110 and 111:
NH4+ 0.043917 g NH3 (as N) 0.04 g C
Page 112 and 113:
Stainless Steel 316 2B IISI [8] Pro
Page 114 and 115:
Electric Components PureCell system
Page 116 and 117:
dioxin (TEQ) 9.99E-12 g ethane 0.03
Page 118 and 119:
Mg 10.4668 g Mn 5.42E-05 g Hg 0.001
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adioactive substance to water 1.82E
Page 122 and 123:
Silicon wafer PureCell system [17]
Page 124 and 125:
particulates (unspecified) 17.5 lb
Page 126 and 127:
Appendix E: PureCell System Life Cy
Page 128 and 129:
Appendix G: Calculations for the Pu
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