PhD Thesis - Energy Systems Research Unit - University of Strathclyde

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9.2.1 Desalination Plant and Clean Water Demand The demand for clean drinking water could also be considered in MERIT as, although it is not an energy demand, desalination plant are being increasingly used as a useful outlet for excess electricity from intermittent renewable or other supplies, especially on islands where clean drinking water is scarce and there is an abundant supply of sea water [1,2]. The inclusion of clean water demand and desalination plant definition would allow the sizing of desalination plant and water storage tanks, to ensure that the demand for clean drinking water can be met in areas where clean water supply is a significant problem. Also, for the fuel production technologies that require substantial amounts of water (e.g. fermentation, electrolysis), water demands could also be produced along with the energy demand profiles attached to these processes, where necessary, and added to the demands on matching in the same manner as the energy demand profiles. Excess electricity would be used to make clean water, and the amount being produced would be compared with the clean water demand. If extra water was available it would be added to a storage profile similar to that for the derived fuel storage, if there was not enough to meet the demand the excess needed would be subtracted from the profile. The option could be given to use all excess electricity to produce water, with unlimited storage (to allow the necessary storage tank size to be ascertained), or to use the excess electricity to keep a certain size of tank full if possible. The stored contents and new production would be used to meet demand where possible. 9.2.2 Further Demand Development To allow the analysis of demand sets that include industrial processes, it would be useful to be able to specify demands for process steam (or high-grade heat and low-grade heat), and mechanical work. This would be particularly useful in the analysis of buildings or communities where excess heat from CHP generation is to be used for a particular industrial process, or where the analysis of energy use in integrated industrial processes and buildings is being 268
considered. The introduction of cooling demands, and suitable auxiliary plant to meet these requirements, may also be a useful addition to the program. This would allow the analysis of air conditioning needs in hot climates, and in buildings where large numbers of computers require constant cooling. The introduction of demand side management measures in order to improve the match between the demand and supply profiles would be of benefit [3]. Methods of using excess electricity in a useful manner, other than the use of storage devices, have already been considered for the heating and storage of hot water, and by the use of electric storage heaters. Further measures to enable demand reduction and load levelling could also be introduced, including, for example, the use of load-shedding of interruptible supplies. A method for quantifying demand reduction measures in new buildings, and the effect of retrofitted measures on existing buildings, would also be useful. This could take the form of load profile reduction at the demand definition stage. 9.2.3 Further Supply Development Further intermittent supply technologies could be incorporated into the program, including wave, tidal, and run-of-the river hydroelectric power generation. The modelling of a solar thermal Stirling engine would also be an interesting addition for the analysis of areas with high insolation. The use of heat pumps as a method for meeting heat demands is enjoying increased interest. These act in the same way as a refrigerator, with the cold side being placed outside, or in an area requiring cooling, and the hot side (heat exchanger) placed in the area to be heated [4]. The performance of heat pumps is affected by ambient temperature, and they work best in colder climates. Another useful addition to the program would be a model for the Regenesys energy storage system, recently developed by National Power, which is effectively a cross between battery and regenerative electrolyser/fuel cell technology [5]. Using low cost and environmentally benign materials, it combines the high efficiencies of batteries with the separate storage of a hydrogen production and storage system. The result is a system with a fast 269
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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
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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
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
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Page 241 and 242: Figure 7.25 Heat Demand Profile Fig
Page 243 and 244: Figure 7.28 Effect of Minimum Load
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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
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Page 265 and 266: 9 Conclusions and Recommendations T
Page 267: through these, technically viable p
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
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PhD Thesis - Energy Systems Research Unit - University of Strathclyde

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