PhD Thesis - Energy Systems Research Unit - University of Strathclyde

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with this new required engine power. This process is repeated continuously using the recalculated heat to power ratio to determine the required engine power in order to satisfy the heat demand, until the difference between the last calculated ratio and the current calculated ratio is plus or minus 0.0001. If the engine is following both heat and electricity demand, once the final heat to electricity ratio has been determined, it is necessary to check if it is still better to be following the heat demand rather than the electricity demand. Again, the required generator powers to meet either demand are determined, and whichever value is highest is used in Equation 5.22 to find the required engine power. The percentage load, specific fuel consumption or efficiency and heat to electricity ratio are then calculated as before. 5.2.7 Actual Fuel Consumption Once the final values for the percentage load, specific fuel consumption or efficiency, heat to electricity ratio and number of engines running have been determined, it is necessary to calculate the actual fuel consumption required. This can be done using Equations 5.32 to 5.36. The equation used depends on the desired unit for the fuel (kWh for gas, litres for liquid and kg for solid fuels), and whether specific fuel consumption or efficiency values are being used. Although solid fuels may not be used in either of these types of engine, they may be used in Stirling engines, which will be considered later in this chapter. Consumption (litres) = SFC x Power (5.32) Density x Timesteps Consumption (litres) = 3610.3 x 100 x 1000 x Power (5.33) Efficiency x CV x Density x Timesteps Consumption (kg) = SFC x Power (5.34) 1000 x Timesteps Consumption (kg) = 3610.3 x 100 x Power (5.35) Efficiency x CV x Timesteps Consumption (kWh) = 100 x Power (5.36) Efficiency x Timesteps 140
where SFC = specific fuel consumption at partial load (g/kWh) Power = required engine power (kW) Density = density of the fuel (kg/m 3 ) Timesteps = number of timesteps per hour Efficiency = engine efficiency at partial load (%) CV = calorific value of the fuel (kJ/kg) 1 kWh = 3610.3 kJ. Once the actual fuel required has been calculated, this is multiplied by the number of engines being used, and this is checked against the amount of fuel available. If there is not enough fuel, a warning is given, and the percentage load at which the engine or engines are able to run with the available fuel is calculated. Although the generating set would not actually work in this way, this has been designed to give an idea of what would be available in a given circumstance, so the user can make a decision about either increasing the fuel production rate, or providing other means of supply to reduce reliance on the engine. If the specific fuel consumption is being used, the algorithm for determining the fuel consumption and finding the percentage load that is possible with the available fuel as necessary is shown in Figure 5.13. The possible engine power achievable with the fuel available, and hence the percentage load, are determined using the current specific fuel consumption. This may be done by rearranging Equation 5.32 or 5.34 as appropriate. If more than one engine set is available, and the possible percentage load is above 100%, the number of engines that may be run, and the percentage at which they may be run, are calculated, while not allowing them to go below minimum load. If the possible percentage load is above 400%, this is divided by 5, and, if this is not below the minimum load level, this is used as the percentage load for all five engines. If it is below minimum load, four engines are run at full power. This is repeated for above 300%, 200% and 100% (dividing by 4, 3 or 2, and with 4, 3 or 2 141
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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
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: (including following heat demand wh
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 and 190: 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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