PhD Thesis - Energy Systems Research Unit - University of Strathclyde

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No (Figure 6.7) No No No No Yes Is anaerobic digestion being used ? Wet Animal Feed to anaerobic digester ? Dry Animal Feed to anaerobic digester ? No Crop Residue to anaerobic digester ? Crop Residue to Gasifier ? Dry Animal Feed to Gasifier ? No Crop Residue as 'Other' fuel ? Dry Animal Feed as 'Other' fuel ? Yes Is j = 0 ? No Is Batch > 24 ? Yes Yes Send WAFDayOld to Figure 6.4 as the available feedstock. Yes Is j = 0 ? No Yes No z = 2 Is Batch > 48 ? Yes WAFDay = WAFDay + Wet AF / Timest eps Yes Send DAFDayOld to Figure 6.4 as the available feedstock. Yes Yes Yes Yes Is DayCount1 > 0 ? Yes DAFDay = DAFDay + DryAF / Timesteps Is DayCount2 > 0 ? Yes No z = 3 214 No Is Batch > 72 ? Yes a = z / FermNo DayCount1 = DayCount1 + 1 No z = 4 Is DayCount1 > z ? Yes WAFDayOld = WAFDay / a WAFDay = 0 No DayCount2 = DayCount2 + 1 Is DayCount2 > z ? Yes DAFDayOld = DAFDay / a DAFDay = 0 Send Residue amount to Figure 6.4 Is Batch > 96 ? Yes No No z = 5 DayCount1 = 0 Is Batch > 120 ? Yes Is WAFDay > 0 ? No DayCount1 = 1 No No DayCount2 = 0 No DayCount2 = 1 Outputs as calculated throughout process No z = 6 Yes Is DayCount1 = 0 ? Yes Is DAFDay > 0 ? Yes Send Residue to Figure 6.1 . This amount is put into storage and the outputs produced and energy required are calculated as described in Figure 6.3. Send DryAF to Figure 6.1 . This amount is put into storage and the outputs produced and energy required are calculated as described in Figure 6.3. Assign Residue amount to chosen 'Other' category Assign DryAF amount to chosen 'Other' category Figure 6.8 Fermentation Use of Residues Algorithm WAFDayOld = 0 Yes DAFDayOld = 0 Yes No Is DayCount1 = 0 ? Is DayCount2 = 0 ? Is DayCount2 = 0 ? Yes No No
6.5 Electrolysis As it is sometimes preferable to convert the entire output of a PV or wind farm to hydrogen via electrolysis, rather than just the excess electricity left after some has been used to meet demand, a dedicated supply can be defined. The halfhourly output of a specified PV array or wind turbine set is calculated using the algorithm described by Born [9], and this electricity output, for each timestep, is fed directly into an electrolyser. The electrolyser is defined, and its output is calculated as described in Section 5.7. Information about the amount of electricity used, and the electricity that was wasted due to lack of capacity of the electrolyser is given along with the half-hourly hydrogen production graph. Information is also given about the overall amount of water required and hydrogen made. Examples of the PV and wind electrolysis system definition windows are given in Appendix 1, Figures A1.21 and A1.22. This modelling method, however, is only suitable if a small number of timesteps per hour has been specified, as it does not account for the response time of the electrolyser to high frequency wind power outputs. If the program was to be used with a larger number of timesteps per hour, this model would require further refinement. 6.6 Waste and Biomass Processing Technologies To allow the modelling of the output and energy use of various waste processing technologies, (e.g. pelletising, shredding, briquetting, chipping, wood or sewage drying), a generic process is defined. The feedstock availability is defined by the amount available (tonnes/day), and the percentage by weight of this feedstock that is output. Different feedstocks may be used at different times of the year, and varying amounts of the same feedstock may be defined. This feedstock is put into a store at each timestep it is available, and is used from that store at a specified feed rate (tonnes/hr). The electricity and heat requirements for the process (kWh/tonne feedstock), and the times over which it is operational are defined, and the output is assigned as RDF or one of the ‘other’ categories. The temporal fuel production and energy use graphs are then created as described in previous examples, with the process only working between operating times and if sufficient fuel is available. This process is shown in 215
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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
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5.5 Steam Turbine Model 149 5.6 Fue
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FIGURES Figure 1.1 Final Energy Con
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Figure 7.30 Following Electricity a
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on the use of fossil fuels, energy
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The general increase in energy cons
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supply is reduced or eliminated, lo
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Figure 1.3 The Electricity Supply G
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on different generation mixes depen
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Various studies have been carried o
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provision for smaller areas, and he
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1.7 References [1] The Internationa
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2 Options for New and Renewable Ene
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the amount of usable heat that is g
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the conversion of petrol cars; howe
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set times, producing a constant ele
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partial load. Fast response and sta
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2.3 The Production and Storage of H
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dedicated boiler, which runs contin
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Figure 2.3 A Typical Hydrogen Filli
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part of the natural carbon cycle (a
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Figure 2.4 Layout of a Gasification
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met by process integration and the
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Figure 2.5 The Inputs and Outputs o
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1. Scale for measuring out lye and
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feedstock being used. Sugary feedst
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carbon dioxide via steam reforming.
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• Where CHP is used, the balance
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[22] Vehicle Certification Agency (
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[55] M. A. Paisley, J. M. Irving, R
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3 Approaches to Renewable Energy Sy
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Because of the intermittent nature
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A renewable energy supply evaluatio
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the system are kept. The output of
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There are various models available
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When the use of climate dependant i
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3.5 References [1] M. Muselli, G. N
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4 A Procedure for Demand and Supply
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pumped storage and flywheels), a ba
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for the agricultural vehicle use re
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Figure 4.4 Combining Demands to Tak
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ates for vehicles, engines and othe
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Figure 4.5 Derived Fuel Production
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together if desired, and taken forw
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profiles are output from this part
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dividing the production rate at eac
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As it would be too confusing to sho
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Figure 4.12 Output of the Matching
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However, when more than one transpo
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considered, this amount is added to
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users are alerted if there is not e
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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
Page 163 and 164: 5.8 Regenerative Fuel Cell Model A
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Page 169 and 170: As 1 kWh = 3610.3 kJ, and using lit
Page 171 and 172: Add Heat to Water Storage Tank Usin
Page 173 and 174: Use Stored Hot Water to Supply Heat
Page 175 and 176: information is given about the over
Page 177 and 178: [23] K. Foger, B. Godfrey, “Syste
Page 179 and 180: the gasification and pyrolysis defi
Page 181 and 182: eing used each day for a continuous
Page 183 and 184: Where Biogas = Biogas production ra
Page 185 and 186: 6.1.3 Use of Biogas Various options
Page 187 and 188: The amount of hydrogen that can be
Page 189 and 190: direct proportion, and the weight o
Page 191 and 192: produce in total (Nm 3 per tonne fe
Page 193 and 194: Electricity (kW) = Elec x Feed (6.1
Page 195 and 196: 3. Make hydrogen via steam reformin
Page 197 and 198: Where Methane = Methane Production
Page 199 and 200: (continued) Keep as medium heating
Page 201 and 202: Yes Feed1 = Yield1 x Land1 / No. of
Page 203 and 204: production and energy use profiles
Page 205 and 206: If it is the last timestep of the p
Page 207 and 208: For each process, the process chara
Page 209 and 210: At the end of the simulation, graph
Page 211 and 212: As the time required for one batch
Page 213: Ethanol = Factor1 x Eth x Timesteps
Page 217 and 218: 6.7 Landfill Gas Processing As the
Page 219 and 220: Demand Profile Design & Profile Dat
Page 221 and 222: Figure 7.2 Degree-Days Versus Month
Page 223 and 224: Stage 1 - Sustainable Fuel Supply S
Page 225 and 226: The different profile of use graphs
Page 227 and 228: Figure 7.3 Fermentation System Inpu
Page 229 and 230: Figure 7.7 Fermentation System Info
Page 231 and 232: Figure 7.10 Fermentation System Out
Page 233 and 234: The output obtained when a second h
Page 235 and 236: Figure 7.16 Anaerobic Digestion Par
Page 237 and 238: Figure 7.19 Fermentation System Inp
Page 239 and 240: clarity. A constant supply rate of
Page 241 and 242: Figure 7.25 Heat Demand Profile Fig
Page 243 and 244: Figure 7.28 Effect of Minimum Load
Page 245 and 246: esidual heat demand as this would r
Page 247 and 248: Figure 7.35 Second Engine: Followin
Page 249 and 250: This chapter described how the over
Page 251 and 252: heat and electricity during the tou
Page 253 and 254: Figure 8.2: Overall Yearly Heat Dem
Page 255 and 256: to allow for efficient operation du
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Page 259 and 260: Figure 8.5: Electricity Supply and
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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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