PhD Thesis - Energy Systems Research Unit - University of Strathclyde

More documents

Recommendations

Info

As the lower heating value of the pyrolysis oil produced from the pyrolysis of plastic and tyres is significantly higher than that of the oil produced from wood, the option is available to change the pyrolysis oil type to one of the ‘other’ categories for the occasion where these two different pyrolysis feedstock types are desired. 6.2 Anaerobic Digestion Existing models are available which predict the output of anaerobic digestion systems. These, however, either require substantial amounts of complex, proprietary, and not easily available information, or look only at the overall production for a year, not taking into account possible changes in feedstock type and amount [4]. Therefore, a more generic and flexible approach has again been taken, which is based on basic process parameters and typical feedstock performances. An example of the anaerobic digestion definition window is given in Appendix 1, Figure A1.15. A graphical representation of the algorithm described in this section can be seen in Figure 6.4, where each timestep value is input in turn. 6.2.1 Process Characteristics The anaerobic digestion process is, by its nature, a continuous process, where feedstock is introduced periodically (generally daily) and resides in the digester for 10 to 40 days while the digestion process takes place. Over this retention time, biogas is given off at a steady rate, which is defined by the volume of biogas given off during this period per tonne of feedstock. The required retention time varies with the operating temperature of the digester, but the overall amount of gas that is produced per tonne of feedstock will remain the same, though this will vary with different feedstock types [5]. As the digester should remain active where possible, and as different types and amounts of feed may be available at different times of the year, up to five different feedstock supplies may be specified. These are defined by how much feedstock is available (tonnes per day), how much biogas the feedstock will 190
produce in total (Nm 3 per tonne feedstock), and what dates it is available between. The required retention time, and either the percentage of methane in the biogas produced, or the lower heating value of the biogas (kJ/Nm 3 ) must also be given. Feedstock cannot be kept in store for times of low or no production, as it will degrade too quickly. For each feedstock availability time period specified, if the digester has been running with the same level of input, for that particular feedstock, for longer than the retention time, then the volume of biogas produced at a particular timestep may be calculated using Equation 6.13. Biogas Produced (Nm 3 ) = Biogas x Feed (6.13) 24 x TS Where Biogas = Biogas produced (Nm 3 /tonne feedstock) Feed = Feedstock available (tonnes per day) TS = Number of timesteps per hour If it is the first timestep introducing the new feedstock, the amount of biogas produced is zero, and the amount of biogas produced at each subsequent timestep, until the retention time is reached, is equal to the previous timestep production value from that feedstock, plus the following incremental production increase, Production = Biogas x Feed (6.14) Increase (Nm 3 ) 24 x TS x 24 x TS x Retention Where Retention = Retention time (days). When the end of the specific feedstock availability time has been reached, the amount of biogas produced is decreased incrementally, at each timestep, by the same amount, until the retention time is reached. If the first day of feedstock availability is the first day of the year, or fuel availability has been specified as continuous, then it is assumed that full 191
Page 1 and 2:
Decision Support for New and Renewa
Page 3 and 4:
Abstract The global requirement for
Page 5 and 6:
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 and 58:
carbon dioxide via steam reforming.
Page 59 and 60:
• Where CHP is used, the balance
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
Page 109 and 110:
vehicles if they are increased by 1
Page 111 and 112:
If biogas is being considered, the
Page 113 and 114:
The number of timesteps per hour wi
Page 115 and 116:
After the algorithm has been follow
Page 117 and 118:
• Float Charge - once the battery
Page 119 and 120:
Discharge No tank = tank fuel used
Page 121 and 122:
equired (kW) = maxkWh x bulk% (5.16
Page 123 and 124:
An example of the output graph prod
Page 125 and 126:
5.2.1 Required Power Specifically d
Page 127 and 128:
5.2.3 Engine Performance in the Con
Page 129 and 130:
used for gas powered ICEs, but the
Page 131 and 132:
and five times, depending on the nu
Page 133 and 134:
Is PL < Min ? No Is PL = 0 ? No Is
Page 135 and 136:
where Max = maximum energy availabl
Page 137 and 138:
where Ratiopart = heat to electrici
Page 139 and 140: (including following heat demand wh
Page 141 and 142: where SFC = specific fuel consumpti
Page 143 and 144: engines running respectively). If t
Page 145 and 146: (continued) Is Fuel Available > (4
Page 147 and 148: of the definition window for a Stir
Page 149 and 150: and continuous operation. Again, mu
Page 151 and 152: The performance of a fuel cell is n
Page 153 and 154: percentage loading, rather than usi
Page 155 and 156: Is Min = 0 ? No Is Min = PC1 ? No I
Page 157 and 158: 5.6.4 If Fuel Availability is Less
Page 159 and 160: 5.7 Electrolyser Model An electroly
Page 161 and 162: original calculation of the amount
Page 163 and 164: 5.8 Regenerative Fuel Cell Model A
Page 165 and 166: following the heat demand. To follo
Page 167 and 168: C:\ My Documents\ Nic\ Thesis\ Old\
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: direct proportion, and the weight o
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 and 214: Ethanol = Factor1 x Eth x Timesteps
Page 215 and 216: 6.5 Electrolysis As it is sometimes
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
Page 257 and 258:
would be incurred, and the scale of
Page 259 and 260:
Figure 8.5: Electricity Supply and
Page 261 and 262:
heat demand or both, or run at cons
Page 263 and 264:
ut with 30% less land being require
Page 265 and 266:
9 Conclusions and Recommendations T
Page 267 and 268:
through these, technically viable p
Page 269 and 270:
considered. The introduction of coo
Page 271 and 272:
When considering larger geographica
Page 273 and 274:
Appendix 1: Program Windows Figure
Page 275 and 276:
Figure A1.5 CreateClimate.exe Figur
Page 277 and 278:
Figure A1.9: Demand Profile Designe
Page 279 and 280:
Figure A1.13: Derived Fuel Supply W
Page 281 and 282:
Figure A1.17: Fermentation System D
Page 283 and 284:
Figure A1.21: PV Electrolysis Syste
Page 285 and 286:
Figure A1.25: Fuel Supply Profile D
Page 287 and 288:
Figure A1.29: Auxilliary Supply Def
Page 289 and 290:
Figure A1.33: Stirling Engine Syste
Page 291 and 292:
Figure A1.37: Fuel Cell System Defi
Page 293 and 294:
Figure A1.41: Electric Vehicle Syst
Page 295 and 296:
Figure A1.45: Vehicle Conversion Fa
Page 297 and 298:
Figure A1.49: Heating System Defini
Page 299 and 300:
Figure A1.53: Pumped Hydro System D
Page 301:
Figure A1.57: Auto Search Evaluatio
show all

PhD Thesis - Energy Systems Research Unit - University of Strathclyde

Create successful ePaper yourself

Delete template?

Save as template?