Energy Systems and Technologies for the Coming Century ...

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Virtual Power PlantAggregatorSupermarketrefrigeration systemsHeat pumpsElectric VehiclesFig. 1.Sketch illustrating a Virtual Power Plant (VPP).2) Price based control. The individual units compute a schedule for the consumptionbased on dynamic price information given by the VPP. This enables the consumerto shift its load to times with low electricity price. It requires a communicationinfrastructure between VPP and heat pump/supermarket systems. The drawback ofthis control strategy is that it is relatively complex and that the VPP does not haveany control of the actual load response but merely sends out a guideline in the formof price signals. How to calculate optimal price signals is still an open research issue.In this paper we use the electricity spot price to illustrate such a signal.3) Frequency based control. The consumer measures the grid frequency, which in Europehas the nominal value of 50 Hz. When demand exceeds supply, the frequency falls.When supply exceeds demand, the frequency increases. One way of using frequencyactivation to change demand is demonstrated for residential fridges in [16]. Theadvantage of this type of control is the low price of the controller, because nocommunication is necessary. However the consumer does not have any economicalincentives to do this unless the enabling of flexible consumption can make the fridgeless expensive to buy. Another possibility of frequency activation is to sign a contractwhere each player participates with a power amount (MW) specified on an hourly basis.The consumer is paid for being at the disposal of the grid (DKK/MW) regardless ofthe actual activation. Activation is automatic and linearly frequency dependent in therange 50 Hz ± 200 mHz.The authors have previously demonstrated some of these strategies in suitable scenarios[17]–[19]. Results and comparisons are provided in this paper.Note that the two consumers studied in this paper both act as thermal storage to the VPP andthe consumed electric energy can not be retrieved as electric energy again. It can only beconsumed at the right times. On the contrary electric vehicles are in reality electric batteriesable to store electricity when connected to the grid and can thus be used as both a consumerand a producer to the grid.3 Models and Economic MPC formulation3.1 Supermarket Refrigeration SystemsThe supermarket refrigeration systems we consider utilize a vapor compression cycle wherea refrigerant is circulated in a closed loop consisting of a compressor, an expansion valveand two heat exchangers, an evaporator in the cold storage room and a condenser/gas coolerlocated in the surroundings. When the refrigerant evaporates it absorbs heat from the coldreservoir which is rejected to the hot reservoir. The setup is sketched in Fig. 2 with onecold storage room and one frost room connected to the system. Usually several cold storagerooms, e.g. display cases, are connected to a common compressor rack and condensing unit.The dynamics in the cold room can be described by the simple energy balance:{dT cr˙Qmc p = ˙Q load − ˙Q e , with: load =(UA) amb−cr·(T amb − T cr )dt˙Q e =(UA) cr−e·(T cr − T e )where UA is the heat transfer coefficient and m and c p are the mass and the specific heatcapacity of the refrigerated goods, respectively. T amb is the temperature of the ambient air(1)Risø International Energy Conference 2011 Proceedings Page 166
. .WcFWcTeFTeFrostCompressorsCompressorsLTPCPC.QeF.QeMTTCEvaporatorsTCCondensor.QcTcrFFrost roomTambHeat loadTcrCold roomTaSurroundingsFig. 2.Schematic layout of basic refrigeration system.which puts the heat load on the refrigeration system. The states and control variables of thesystem are limited by the following constraints:T cr,min ≤ T cr ≤ T cr,max0≤T cr − T e ≤ ∞0≤ ˙Q e ≤(UA) cr−e,max·(T cr − T e )The work done by the compressor dominates the power consumption in the system and canbe expressed by the mass flow of refrigerant (m re f ) and the change in energy content of therefrigerant. Energy content is described by enthalpy of the refrigerant at the inlet and at theoutlet of the compressor (h ic and h oc respectively). Hereby the expression in Eq. (3) is given.Ẇ c = m re f ·(h oc (T e ,P c )−h ic (T e ))η is (P c /P e )where the enthalpies depend on the evaporation temperature and the condensing pressure asstated. The mass flow can be determined as the ratio between cooling capacity and changeof enthalpy over the evaporator:m re f =˙Q eh oe (T e )−h ie (P c )All the enthalpies given here as functions of (T e , P c ) or both are non-linear refrigerantdependent functions which can be calculated e.g. by the software package ”RefEqns” [20].For the studies in section 4.1 we have assumed that the work done in the compressor isdirectly proportional with the delivered cooling capacity while we in section 4.3 use the realnon-linear description of Ẇ c described in [21] where polynomials are fitted for the enthalpydifferences. For the latter we have furthermore collected data from several supermarkets inreal operation in Denmark. From these data typical parameters such as time constants, heatloads, temperature ranges and capacities in both individual display cases and for the overallsystem have been estimated. The running compressor capacity have been monitored and fromthe data sheets the relation to energy consumption has been found.3.2 Building with Heat PumpHeat dynamics of a buildingIn this section, we develop a model of the heat dynamics of a house floor heating systemconnected to a geothermal heat pump. The system is illustrated in Fig. 3. The model isbased on the energy balances for the air in the room, the floor and the water in the floorheating pipes and condenser water tank. The house is considered to be one big room with thefollowing simplifying assumptions: 1) One uniform air temperature, 2) no ventilation, 3) noinfluence from humidity of the air, 4) no influence from the heat released from people in theroom, 5) no influence from wind. In our model two heat accumulating media are included(2a)(2b)(2c)(3)(4)Risø International Energy Conference 2011 Proceedings Page 167
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Energy Systems and Technologies for
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ContentsSessions overview 1Programm
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sessions overview08:00-09:00Coffee
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11:00 - 12:30 session 6A - Bioenerg
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ContactSustainable Energy, Technica
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Penetration of new energy technolog
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how decisions are made and by whom
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(9) is the logaritimic expansion of
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(16)we may finally write Eq(14) in
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Table 1: Fast track cases for new r
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Peterka V. Macrodynamics of technol
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Growth in clean and reliable energy
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Conclusion - an ambitious vision an
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"Spurring investments in renewable
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Integrating climate change adaptati
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transport, and finance. Energy prov
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northern South America, the Caribbe
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Table 1: Energy system adaptation s
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More generally, a number of no- or
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6 ReferencesADB, 2005. Climate proo
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Sailor, D.J., Smith, M., Hart, M.,
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Factors affecting stakeholder perce
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Another study conducted in Japan wa
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4 The effect of information on stak
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Furthermore, communication to stake
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Shackley S, McLachlan C, Gough C (2
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Figure 1: Potential CO 2 storage si
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The Upper Jurassic - Lower Cretaceo
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The majority of the individual stru
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Development. Project no. ENK6-CT-19
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Section 5 summarises the key issue
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Table 1. Efficiencies for new large
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In addition, district heating syste
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6.4 Model results from EFDA-TIMESIn
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Maisonnier, D., et al. (2007), Powe
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1Efficiency and effectiveness of pr
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3Stromerzeugung [TWh/a]250200150100
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54 Country-specific Lessons learned
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7100%90%80%quota fullfilment (%)70%
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[5] Haas R., et al: Efficiency and
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The development and diffusion of re
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a. Offshore wind in DenmarkDenmark
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applicants are invited to submit a
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nies that provide upstream and down
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for both technology users and produ
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Trade Disputes over Renewable Energ
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treatment to imported renewable ene
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In Canada, the federal government i
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grid access, subsidies and land off
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In 2010, China’s total wind insta
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Source: Renewables 2010 Global Stat
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Source: REN 21, Renewables 2010 Glo
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Source: adapted from REN21, 2010It
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their precise scope and nature diff
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60 daysBy 2 nd DSBmeetingConsultati
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discriminatory manner on domestic a
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the European Union, the North Ameri
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ended. China lost this case because
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As most countries in the world are
Page 120 and 121: Session 3A - Energy SystemsRisø In
Page 122 and 123: 1 IntroductionWith the introduction
Page 124 and 125: occur. This is an undesirably burea
Page 126 and 127: This curve could be used as a new t
Page 128 and 129: ut for the total consumption, and i
Page 130 and 131: This gives the LBR an opportunity t
Page 132 and 133: concludes that the subsurface conta
Page 134 and 135: to constrain the evaluation. In add
Page 136 and 137: Fig. 2 SW-NE trending seismic profi
Page 138 and 139: Fig. 5. Petrophysical evaluation of
Page 140 and 141: ConclusionsThe Danish subsurface co
Page 142 and 143: Performance of Space Heating in aMo
Page 144 and 145: [5],[10],[11],[16],[18],[20],[26].
Page 146 and 147: 2/3 Sun1 Coal1/3 ElPower plantHP1 H
Page 148 and 149: 25002000Surplus(min(wind,prod-cons)
Page 150 and 151: 160CO 2 emission per unit heat prod
Page 152 and 153: The calculations have been based on
Page 154 and 155: Session 3B - smart gridsRisø Inter
Page 156 and 157: 2 Myopic Investments2.1 The Balmore
Page 158 and 159: Moreover, this model is formulated
Page 160 and 161: Reducing Electricity Demand Peaks b
Page 162 and 163: 3 Event Driven Scheduling Algorithm
Page 164 and 165: 5 Mapping Teletraffic Theory to Ene
Page 166 and 167: 6.2 Results and Performance Metrics
Page 168 and 169: Energy Efficient Refrigeration and
Page 172 and 173: C p,rC p,fT rT fW cφ sT a(UA) raHe
Page 174 and 175: Total PowerP.G. #1P.G. #2C.R. #1201
Page 176 and 177: the availability payment.Simulation
Page 178 and 179: The constraint in Eq. (16) has the
Page 180 and 181: The FlexControl concept - a vision,
Page 182 and 183: can react on requests for power reg
Page 184 and 185: 3 ControlThe concept is based solel
Page 186 and 187: one hour to the next - correspondin
Page 188 and 189: 4 ProtectionThe protection of the p
Page 190 and 191: Session 4 - Efficiency Improvements
Page 192 and 193: the product portfolio point of view
Page 194 and 195: Figure 4: Principle flow sheet of t
Page 196 and 197: process information needed are seld
Page 198 and 199: AIRFINE®(Reference)MEROS®Ca(OH)2M
Page 200 and 201: 4 Conclusion & DiscussionThe Eco-Ca
Page 202 and 203: 1 Energy policy and EU directivesTh
Page 204 and 205: iomass CHP, heat pumps, electric bo
Page 206 and 207: Fig. 1: How to supply a growing hea
Page 208 and 209: Session 5A - Wind Energy IRisø Int
Page 210 and 211: The average cumulative growth rate
Page 212 and 213: turbines is expected to create a st
Page 214 and 215: O&MGridWindturbineSubstructureFigur
Page 216 and 217: Another idea is to harvest energy f
Page 218 and 219: 9. Shimon Awerbuch, Determining the
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engaged in wind energy assessment,
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treated in such a way to make them
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Figure 5: Map showing the estimated
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Figure 9: The annual mean power den
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mix is required. For example diurna
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Session 5B - Wind Energy IIRisø In
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TABLE ISOME OF THE WIND TURBINE MAN
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China, has prompted all parties, in
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to the high shaft speed. Furthermor
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Superconductors must be kept cold b
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an annual increase in demand of 6%,
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Improved High Temperature Supercond
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our study to a single set of deposi
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3.2 Yttrium-enriched YBCO thin film
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Fig. 5. AC-susceptibility dependenc
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The j C (B) dependence at 50 K for
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Session 6A - Bioenergy IRisø Inter
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The European politicians are faced
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The fast growing demand for biomass
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Figure 2: Avedøre Power Plant in C
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Figure 5: Concept for a sustainable
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The role of biomass and CCS in Chin
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2.2.1 CCS Potential for ChinaCCS is
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80%70%60%China's share ofglobal CO
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In general, if the CCS technology d
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with high implementation of CCS Chi
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The European Biofuels Policy: from
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aimed to promote agriculture-based
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(EC, 2009b), and internationally vi
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Session 6B - Bio Energy IIRisø Int
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The commercial scale production of
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the production process parameters,
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NutrientWaterAlgal cultureproductio
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Schenk, P.M., Thomas-Hall, S.R., St
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Liquid biofuels from blue biomassZs
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Even though final ethanol yields we
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Integrated Gasification SOFC Plant
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2.1 Modelling of SOFCThe SOFC model
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where g 0 , R an T are the specific
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hand side y-axis corresponds to eff
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The moister content for these three
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Use of Methanation for Optimization
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power production from utilizing the
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2.1 Model DescriptionThe developed
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Figure 3: Flow sheet of methanation
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efficiency and turbine inlet temper
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[14] DNA - A Thermal Energy System
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On the effectiveness of standards v
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educing new car emissions to 120 g
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In addition energy consumption E an
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coefficient γ for the impact of fu
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400200Change in energy (PJ)01980 19
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Figure 9 depict scenarios for the f
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What are customers willing to pay f
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Randomly, continuous up to ±50%Acc
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The likelihood for the model is giv
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eally means that this factor and no
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Table 5-1 Parameter estimates from
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Table 6-2 Willingness to pay for 10
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Session 12 - Energy for Developing
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Risø International Energy Conferen
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existing renewable energy technolog
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useful energyend energysecondary en
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parts or the means of enforcing war
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The development of micro-hydro proj
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Table 1. Electric power generation
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5 ReferencesBajgain, S., Shakya, I.
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IntroductionElectricity has become
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of 2008, 43.6% of the total populat
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Hilmand provinces have comparativel
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….. eq. 5LCOE is the net present
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case of Nepal, it is 5% (Trading ec
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ing down the cost of solar PV modul
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3.3 Serving the rural areas with na
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The levelized costs of electricity
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Figure 4. Variation in LCOE with si
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The analysis reveals that fuel cost
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In case of DG, we have looked with
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Gross, R., Blyth, W., Heptonstall,
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Mode of Transport to Work, Car Owne
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power parity (PPP) basis, GDP per c
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83,385 to 109,108 while the number
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other purposes so that reduced fare
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emissions studies is that they were
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where I (·) is the indicator funct
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increases, individuals acquire more
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while that of other means of transp
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into CO 2 . For all oil and oil pro
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impact. In general, income is found
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7 ReferenceAlperovich, G., Deutsch,
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Table 1: Definitions of Variables a
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Session 13 - Energy StorageRisø In
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2 Storage demand and resulting stor
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compressed air storages, demand sit
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Fig. 3: Options for underground sto
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3.5 Geological potential in EuropeF
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Sensitivity on Battery Prices and C
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3.1 Base caseA northern European en
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4 ResultsThe model is run on a comp
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Furthermore, a slight decrease in t
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Night time charging increases with
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Lithuanian Energy Institute, PSE In
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atteries, Compressed Air Energy Sto
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negative net load, can be expected
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25%Pct. of the year20%15%10%5%0.5-0
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800006000040000MWh200000Netload-200
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[4] B. V. Mathiesen and H. Lund, "C
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Compressed Air Energy Storage in Of
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compressed air caverns, corrosion-r
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Figure 3: Distribution of salt depo
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Figure 6: EWEA's 20 year Offshore N
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spinning reserves can be provided b
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7 Discussion and conclusionsThis pa
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Risø DTU is the National Laborator
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