PhD Thesis - Energy Systems Research Unit - University of Strathclyde

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In general, the bulk charge phase for an electric vehicle takes half of the recharging time, recharging the battery to around 70%, and the absorption charge phase uses the second half of the recharge time [5]. The float charge phase is not considered here as this is designed mainly to limit battery damage due to overcharging, which this model will not allow. The initial state of charge of the vehicle battery is defined with the vehicle characteristics, along with the time to start the slow recharge, and whether or not to allow fast recharges (although the number of fast recharges a vehicle undergoes should be limited as this affects the battery life). The time taken for a full slow recharge, the maximum bulk charge percentage, and the percentage of the charge time this takes, also need to be input in order to define the recharge curve. This allows the algorithm shown in Figure 5.3, for charging and discharging the electric vehicles, to be used at the matching stage. Discharging is similar to the other vehicles, except that no recharging takes place if the level falls below 0, unless fast recharging has been allowed. The efficiency of the battery must also be taken into consideration, as more energy is required to recharge the battery than will be available from the battery after recharging. This efficiency is generally around 85%, and is taken into account when recharging the battery, by increasing the amount necessary for recharging. This procedure is slightly different than for the other vehicles as, although the demand is still in storage units (kWh), the supply profile is a supply rate (kW) rather than an available amount. This must, therefore, be taken into consideration throughout the procedure. Firstly, the maximum storage capacity (maxkWh) must be calculated using Equation 5.12, and this should then be used in Equation 5.7 to calculate the initial fuel level (tank). Timesteps per day, start time1, and start time2, should be calculated as before. Then, for each timestep, the residual electricity supply should be read in as the fuel supply, and i is equal to the current timestep value. 118
Discharge No tank = tank fuel used = 0 residual = 0 i = i - timesteps per day charge = 0 fuel demand (kWh) = (transport demand x fuel consumption) / timesteps per hour tank = tank - fuel demand is tank < 0 ? Yes No required (kW) = ((max - tank) x timesteps per hour x 100) / Battery Efficiency) is fuel supply < required ? Yes tank (kWh) = tank + (( fuel supply x Battery Efficiency) / ( 100 x timesteps per hour) is tank < 0 ? Yes fuel used = fuel supply residual = (-tank x timesteps per hour) / fuel consumption tank = 0 fuel consumption (kWh/ km) Yes Yes is fast refuel allowed? is i > timesteps per day? No is i = start time1 or start time2 ? is transport demand = 0 and charge = 1 ? fuel used =fuel demand + tank residual = (-tank x timesteps per hour) / fuel consumption tank = 0 No No 119 transport demand (km/ h) Yes Yes Recharge No required (kW) = required x ((max% - current% ) / (max% - bulk%)) No tank = maxkWh fuel used = required residual = 0 tank = tank fuel used = fuel supply residual = 0 Figure 5.3 Electric Vehicle Fuel Use Algorithm No charge = 1 required (kW) = (maxkWh x bulk% x 100) / (time x time% x Battery Efficiency) is current% < bulk% ? Yes tank (kWh) = tank + ((fuel supply x Battery Efficiency) / (100 x timesteps per hour)) fuel used = fuel supply Yes is tank >= 100 % No is fuel supply < required ? Yes is tank >= 100 % No Yes No charge = 0 excess = ((tank - maxkWh) x timesteps per hour x 100) / Battery Efficiency) fuel used = fuel used - excess residual = transport demand k kWh charge = 0 tank = tank fuel used = 0 residual = transport demand tank (kWh) = tank + ((required x Battery Efficiency) / (100 x timesteps per hour)) fuel used = required tank = tank fuel used = fuel used residual = transport demand
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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
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: • Float Charge - once the battery
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
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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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