PhD Thesis - Energy Systems Research Unit - University of Strathclyde

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Total Energy = Max x Fuel Used x Percentage (5.27) 100 where Total Energy = total useful energy available from partial load fuel use (kW) Max = maximum energy available from the fuel (kWh/kg) Fuel Used = partial load fuel use (kg/h) Percentage = percentage of energy available for use at 100% loading. The part of this total useful energy that is available as heat is the total amount minus the electrical output, and the heat to electricity ratio may then be calculated from these two figures. This whole process may be reduced to Equation 5.28. Ratiopart = SFCpart ( 1 + Ratio100% ) - 1 (5.28) SFC100% where Ratio100% = heat to electricity ratio at 100% load Ratiopart = heat to electricity ratio at partial load SFC100% = Specific Fuel Consumption at 100% load SFCpart = Specific Fuel Consumption at partial load If efficiency values are being used (gaseous fuels), the overall efficiency may be defined as Overall Efficiency = Efficiency x (Ratio + 1) (5.29) where Overall Efficiency = total heat and electrical efficiency Efficiency = electrical efficiency at 100% load Ratio = heat to electricity ratio at 100% load. Assuming the overall efficiency is constant, the heat to electricity ratio at partial load may be calculated using Ratiopart = (Overall Efficiency – Efficiencypart) (5.30) Efficiencypart 136
where Ratiopart = heat to electricity ratio at partial load Overall Efficiency = total heat and electrical efficiency Efficiencypart = electrical efficiency at partial load. Substituting for the overall efficiency gives Ratiopart = Efficiency100% ( 1 + Ratio100% ) - 1 (5.31) Efficiency part where Ratio1100% = heat to electricity ratio at 100% load Ratiopart = heat to electricity ratio at partial load Efficiency 100% = Specific Fuel Consumption at 100% load Efficiency part = Specific Fuel Consumption at partial load Therefore, if estimating the heat to electricity ratio at partial loads, Equation 5.28 is used if specific fuel consumption is being considered, and Equation 5.31 is used if efficiency values are being considered. The process of determining the heat to electricity ratio at different loads is outlined in Figure 5.11. If the engine is following the heat demand, it is necessary to recalculate the required engine power. This is because the original calculation of the electrical load required to produce the desired amount of heat relied on the heat to electricity ratio at 100% loading. However, this ratio will increase at partial loading, decreasing the required engine power to meet the heat demand. Also, if the engine is following both electricity and heat demand, and the heat demand is currently being followed, this must, again, be recalculated. However, if the electricity demand is currently being followed, there is no need to recalculate as, if the electricity demand was more than the heat demand originally, the heat supply will only increase with decreased efficiency, therefore it will still require to follow the electricity demand. This process is shown in Figure 5.12. 137
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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
Page 85 and 86: Figure 4.4 Combining Demands to Tak
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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: where Max = maximum energy availabl
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
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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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