PhD Thesis - Energy Systems Research Unit - University of Strathclyde

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2.5.9 Electrolysis The principle behind the production of hydrogen via electrolysis was discussed in Section 2.4.1. As well as providing a use for excess electricity in a system, electrolysers may also be attached to dedicated wind and PV supplies, where all of the electricity output is used for hydrogen production. 2.6 Summary • There are a number of different processes available that allow the total energy needs of an area to be met in a sustainable manner, and those chosen will depend on a range of area-specific factors. • The production of fuels from biomass and waste sources is an important source of sustainable fuel for transportation, heat and electricity production, and provides a good waste management solution for unavoidable wastes. • When designing systems with a large amount of intermittent electricity generation, or systems where generators are run continuously to produce electricity and/or heat, it is important to seek as close a match between the demand and supply profiles as possible. • This may be done by varying the types and locations of the generators being used, and employing various storage and/or load following generating plant. • Any excess electricity or heat generated in the system should be put to good use to help meet the demands for different energy types, or stored, in some form, for later use. 58
• Where CHP is used, the balance between the heat and electricity demand should be maintained as close as possible to the heat to electricity output ratio, to avoid wastage. • As there are many factors to be considered in the design of sustainable energy supply systems, the interrelationship between the various components can be complicated. This will vary with each different situation considered, which highlights the need for a decision support framework where different supply scenarios may be quickly and easily tried, in order to gain an understanding of these balances, and find the most technically suitable system design for a specific situation. This chapter discussed the various components that could be used to create a sustainable energy supply system, and how they could be combined to create an efficient and reliable system. As there are many complex operational factors to be taken into consideration when designing integrated systems to supply the electricity, heat, hot water and transportation needs of an area, the creation of a generic framework that would aid informed decisions would be valuable. Chapter 3 describes the various ways in which the design of sustainable energy systems has been approached. 2.7 References [1] F.J. Born, “Aiding renewable energy integration through complementary demand-supply matching”, PhD Thesis, University of Strathclyde, 2001, www.esru.strath.ac.uk [2] M. J. Grubb, ‘The integration of renewable electricity sources’, Energy Policy, 1991, Vol. 19, No. 7, pp 670-688 [3] A. Mourelatos, D. Assimacopoulos, L. Papagainnakis, A. Zevros, ‘Large scale integration of renewable energy sources an action plan for Crete’, Energy Policy, 1998, Vol. 26, No. 10, pp 751-763 59
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Decision Support for New and Renewa
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Abstract The global requirement for
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CONTENTS 1 ENERGY SYSTEMS FOR SUSTA
Page 7 and 8: 5.5 Steam Turbine Model 149 5.6 Fue
Page 9 and 10: FIGURES Figure 1.1 Final Energy Con
Page 11 and 12: Figure 7.30 Following Electricity a
Page 13 and 14: on the use of fossil fuels, energy
Page 15 and 16: The general increase in energy cons
Page 17 and 18: supply is reduced or eliminated, lo
Page 19 and 20: Figure 1.3 The Electricity Supply G
Page 21 and 22: on different generation mixes depen
Page 23 and 24: Various studies have been carried o
Page 25 and 26: provision for smaller areas, and he
Page 27 and 28: 1.7 References [1] The Internationa
Page 29 and 30: 2 Options for New and Renewable Ene
Page 31 and 32: the amount of usable heat that is g
Page 33 and 34: the conversion of petrol cars; howe
Page 35 and 36: set times, producing a constant ele
Page 37 and 38: partial load. Fast response and sta
Page 39 and 40: 2.3 The Production and Storage of H
Page 41 and 42: dedicated boiler, which runs contin
Page 43 and 44: Figure 2.3 A Typical Hydrogen Filli
Page 45 and 46: part of the natural carbon cycle (a
Page 47 and 48: Figure 2.4 Layout of a Gasification
Page 49 and 50: met by process integration and the
Page 51 and 52: Figure 2.5 The Inputs and Outputs o
Page 53 and 54: 1. Scale for measuring out lye and
Page 55 and 56: feedstock being used. Sugary feedst
Page 57: carbon dioxide via steam reforming.
Page 61 and 62: [22] Vehicle Certification Agency (
Page 63 and 64: [55] M. A. Paisley, J. M. Irving, R
Page 65 and 66: 3 Approaches to Renewable Energy Sy
Page 67 and 68: Because of the intermittent nature
Page 69 and 70: A renewable energy supply evaluatio
Page 71 and 72: the system are kept. The output of
Page 73 and 74: There are various models available
Page 75 and 76: When the use of climate dependant i
Page 77 and 78: 3.5 References [1] M. Muselli, G. N
Page 79 and 80: 4 A Procedure for Demand and Supply
Page 81 and 82: pumped storage and flywheels), a ba
Page 83 and 84: for the agricultural vehicle use re
Page 85 and 86: Figure 4.4 Combining Demands to Tak
Page 87 and 88: ates for vehicles, engines and othe
Page 89 and 90: Figure 4.5 Derived Fuel Production
Page 91 and 92: together if desired, and taken forw
Page 93 and 94: profiles are output from this part
Page 95 and 96: dividing the production rate at eac
Page 97 and 98: As it would be too confusing to sho
Page 99 and 100: Figure 4.12 Output of the Matching
Page 101 and 102: However, when more than one transpo
Page 103 and 104: considered, this amount is added to
Page 105 and 106: users are alerted if there is not e
Page 107 and 108: at the matching stage, along with t
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vehicles if they are increased by 1
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If biogas is being considered, the
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The number of timesteps per hour wi
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After the algorithm has been follow
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• Float Charge - once the battery
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Discharge No tank = tank fuel used
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equired (kW) = maxkWh x bulk% (5.16
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An example of the output graph prod
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5.2.1 Required Power Specifically d
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5.2.3 Engine Performance in the Con
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used for gas powered ICEs, but the
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and five times, depending on the nu
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Is PL < Min ? No Is PL = 0 ? No Is
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where Max = maximum energy availabl
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where Ratiopart = heat to electrici
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(including following heat demand wh
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where SFC = specific fuel consumpti
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engines running respectively). If t
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(continued) Is Fuel Available > (4
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of the definition window for a Stir
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and continuous operation. Again, mu
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The performance of a fuel cell is n
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percentage loading, rather than usi
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Is Min = 0 ? No Is Min = PC1 ? No I
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5.6.4 If Fuel Availability is Less
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5.7 Electrolyser Model An electroly
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original calculation of the amount
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5.8 Regenerative Fuel Cell Model A
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following the heat demand. To follo
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C:\ My Documents\ Nic\ Thesis\ Old\
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As 1 kWh = 3610.3 kJ, and using lit
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Add Heat to Water Storage Tank Usin
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Use Stored Hot Water to Supply Heat
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information is given about the over
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[23] K. Foger, B. Godfrey, “Syste
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the gasification and pyrolysis defi
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eing used each day for a continuous
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Where Biogas = Biogas production ra
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6.1.3 Use of Biogas Various options
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The amount of hydrogen that can be
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direct proportion, and the weight o
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produce in total (Nm 3 per tonne fe
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Electricity (kW) = Elec x Feed (6.1
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3. Make hydrogen via steam reformin
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Where Methane = Methane Production
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(continued) Keep as medium heating
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Yes Feed1 = Yield1 x Land1 / No. of
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production and energy use profiles
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If it is the last timestep of the p
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For each process, the process chara
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At the end of the simulation, graph
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As the time required for one batch
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Ethanol = Factor1 x Eth x Timesteps
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6.5 Electrolysis As it is sometimes
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6.7 Landfill Gas Processing As the
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Demand Profile Design & Profile Dat
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Figure 7.2 Degree-Days Versus Month
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Stage 1 - Sustainable Fuel Supply S
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The different profile of use graphs
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Figure 7.3 Fermentation System Inpu
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Figure 7.7 Fermentation System Info
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Figure 7.10 Fermentation System Out
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The output obtained when a second h
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Figure 7.16 Anaerobic Digestion Par
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Figure 7.19 Fermentation System Inp
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clarity. A constant supply rate of
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Figure 7.25 Heat Demand Profile Fig
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Figure 7.28 Effect of Minimum Load
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esidual heat demand as this would r
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Figure 7.35 Second Engine: Followin
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This chapter described how the over
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heat and electricity during the tou
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Figure 8.2: Overall Yearly Heat Dem
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to allow for efficient operation du
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would be incurred, and the scale of
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Figure 8.5: Electricity Supply and
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heat demand or both, or run at cons
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ut with 30% less land being require
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9 Conclusions and Recommendations T
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through these, technically viable p
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considered. The introduction of coo
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When considering larger geographica
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Appendix 1: Program Windows Figure
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Figure A1.5 CreateClimate.exe Figur
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Figure A1.9: Demand Profile Designe
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Figure A1.13: Derived Fuel Supply W
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Figure A1.17: Fermentation System D
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Figure A1.21: PV Electrolysis Syste
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Figure A1.25: Fuel Supply Profile D
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Figure A1.29: Auxilliary Supply Def
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Figure A1.33: Stirling Engine Syste
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Figure A1.37: Fuel Cell System Defi
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Figure A1.41: Electric Vehicle Syst
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Figure A1.45: Vehicle Conversion Fa
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Figure A1.49: Heating System Defini
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Figure A1.53: Pumped Hydro System D
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Figure A1.57: Auto Search Evaluatio
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PhD Thesis - Energy Systems Research Unit - University of Strathclyde

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