Energy Systems and Technologies for the Coming Century ...

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C p,rC p,fT rT fW cφ sT a(UA) raHeat pumpCondensertank(UA) faT ′ aFig. 3. House and heat pump floor heating system and its thermal properties. The dashed line represents the floorheating pipes that has heat conductivity (UA) w f and contains water with heat capacity C p,w .with heat capacities C p,r and C p, f , to capture the short-term and long-term variations of theroom air and floor heat dynamics [22]. The resulting energy balances areC p,r Ṫ r = Q f r − Q ra +(1− p)φ s (5)C p, f Ṫ f = Q w f − Q f r + pφ s (6)The disturbances influencing the room air and floor temperature, T r and T f , are the ambienttemperature, T a , and the solar radiation, φ s , through a window with fraction p of the incidentradiation on the floor. The energy balance for the water circulating in the floor heating pipescan be stated asC p,w Ṫ w = Q c − Q w f (7)in which Q c is the heat transferred to the water from the condenser in the heat pump. Q w fis the heat transferred from the water to the floor. The conductive heat transfer rates areQ ra =(UA) ra (T r − T a ), Q f r =(UA) f r (T f − T r ), Q w f =(UA) w f (T w − T f ) (8)Q ra is the heat transferred from the air in the room to the surroundings, Q f r is the heattransferred from the floor to the air in the room, and Q w f is the heat transferred from thewater in the floor heating pipes to the floor. The term U·A is a product of the heat conductivityand the surface area of the layer between two heat exchanging media. Its reciprocal valueR=1/(UA) is often used since it can be interpreted as a resistance against heat flow.Heat PumpA heat pump is a device that transfers heat from a low temperature zone to a highertemperature zone using mechanical work. Heat pumps normally draw heat from the air orfrom the ground and uses a vapor compression refrigeration cycle. This cycle is also used inthe supermarket refrigeration system studied in section 3.1. In order to take advantage of theheat produced in the cycle instead of the cooling, the condenser and evaporator functions areswitched such that the condenser is inside the house. As the heat pump dynamics is muchfaster than the thermodynamics of the building, we can assume a static model for the heatpump. The amount of heat transferred from the condenser to the water, Q cw , is related to thework of the compressor, W c , using the coefficient of performanceQ cw = ηW c (9)The coefficient of performance η for heat pumps varies with type, outdoor ground temperature,and the condenser temperature. As these two temperatures are approximately constant,we can assume that the coefficient of performance is also constant.3.3 Economic Optimizing MPCOur systems are influenced by a number of disturbances that can be predicted to somedegree of certainty over a time horizon into the future. These must to be handled by thecontroller that also has to obey certain constraints for the systems while minimizing the costof operation. Thus, we find it reasonable to aim at formulating our controller as an economicRisø International Energy Conference 2011 Proceedings Page 168
optimizing MPC problem. Whereas the cost function in MPC traditionally penalizes adeviation from a set-point our proposed economic MPC directly reflects the actual costsof operating the plant. This formulation is tractable for refrigeration and heating systemswhere we are interested in keeping the outputs (temperatures) within certain ranges whileminimizing the cost of doing so.The models described in the previous sections are converted to their discrete-time state spaceformulations using zero-order-hold sampling of the input signalsx k+1 = Ax k + Bu k + Ed ky k = Cx k + Du k + Fd k(10a)(10b)defining x as the states, the manipulable variable u, disturbances d and outputs y. Using thismodel to predict the future outputs, we may formulate a linear program that minimizes theelectricity cost for operating the system while keeping the temperatures within prespecifiedintervalsmin φ = ∑ c T y,k y k+ c T u,k u k+ ρv T v k(11a){x,u,y}k∈Ns.t. x k+1 = Ax k + Bu k + Ed k k∈N (11b)y k = Cx k + Du k + Fd k k∈N (11c)u min ≤ u k ≤ u max k∈N (11d)∆u min ≤ ∆u k ≤ ∆u max k∈N (11e)y min ≤ y k + v k k∈N (11f)y max ≥ y k − v k k∈N (11g)v k ≥ 0 k∈N (11h)N ∈{0,1,...,N} and N is the prediction horizon. The electricity prices enter the optimizationproblem as the cost coefficients c u,k . The output cost on temperature is zero, c y,k = 0. Itmay not always be possible to meet the temperature demand. Therefore, the MPC problem isrelaxed by introduction of a slack variable v k and the associated penalty cost ρ v . The penaltiescan be set sufficiently large, such that the output constraints are met whenever possible. TheEconomic MPC also contains bound constraints and rate-of-movement constraints on thecontrol variables. The prediction horizon, N, is normally selected large to avoid discrepanciesbetween open-loop and closed-loop profiles. At each sampling time, we solve the linearprogram (11) to obtain {u ∗ k }N−1 k=0 . We implement u∗ 0 on the process. As new informationbecomes available at the next sampling time, we redo the process of solving the linearprogram using a moving horizon and implementing the first part, u ∗ 0 , of the solution. Theelectricity prices, {c u,k } N−1k=0 , as well as the disturbances, {d k} N−1k=0, must be forecasted. In thispaper, we assume that the forecasts are perfect.4 Results and Discussions4.1 Direct Control of Cold RoomThe Economic MPC has been implemented in Matlab and simulations are presented in thissection [17]. We have included two conventional power generators and one large coolinghouse (or an aggregation of several supermarkets). Direct control, i.e. total collaboration andcommunication between power producers and consumers is assumed. The production by thepower generators, y 1,k + y 2,k , must exceed the demand for power by the cooling house andthe demand from the external signal r ky 1,k + y 2,k ≥ y 3,k + r k k∈N (12)We model farms of wind turbines as instantaneously changing systems and include theeffect of their power production together with all non-controllable power consumers in theexogenous net power demand signal, r k .Fig. 4 visualizes a simulation. In this scenario, the power demand from all other consumersthan the cold room increases slowly, then stays at a steady level and eventually dropsRisø International Energy Conference 2011 Proceedings Page 169
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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
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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 170 and 171: Virtual Power PlantAggregatorSuperm
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
Page 220 and 221: 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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