The Energy Supply of Campus using Exergy Approach

Transcription

1 SUSB Journal Title No. SUSB-2011/015 Technical Paper DOI: /SUSB The Energy Supply of Campus using Exergy Approach Leo Gommans* Abstract Xperience Parkstad is a district in Heerlen (The Netherlands) where several schools are located; the campus. This district consumes a considerable amount of energy and wants to reduce 80% of the CO 2 -emissions by The easy to implement measures to reduce the CO 2 -emission have already taken place, meaning that more drastic measures are necessary, while the solutions are not only found within the buildings themselves. Besides reduction of the energy demand, 10 percent of the electricity production will be realised with photovoltaic cells and small wind turbines. The remaining electricity and heat demand will be generated from biomass. The plans for the energy supply of XperienceParkstad are elaborated in an energy vision for the district [2]. Further research into the possibilities for a CO 2 -neutral energy supply with biomass, Combined Heat and Power (CHP) is done by Cauberg-Huygen Consulting Engineers in Maastricht [3]. Although we try to solve the energy supply CO 2 -neutral, this does not mean that it is an optimal solution from an exergetic point of view. Biomass resources are limited and should be used as effectively as possible. Exergetic considerations play an important role in the search for optimal solutions of the energy supply for the Xperience Parkstad district. The idea behind the exergy approach is to use the available energy flow as effectively as possible, by matching the quality of the required energy, as much as possible to the quality of energy available. To maximise the use of biomass i.e. apart from energy conversion, energy storage and transport is an important aspect for the design of the energy supply, as will be explained subsequently in the paper. By taking advantage of the local potentials, existing energy networks in the area and the old mine galleries can be developed, optimising the use of biomass as an energy source. The local situation provides old mine shafts that are filled with water. They could be used for cooling and storage of residual heat. This paper describes the plan and considerations invoved in the search for exergetic design solutions for a sustainable energy supply in the region Parkstad, which goes beyond solutions on the building level and the district Xperience Parkstad. Keywords: Energy system, Exergy, Region, Local potentials, Bio-CHP, Energy transport, Energy storage, Minewater, Geothermal, Heat grid, Absorbtion cooling 1. INTRODUCTION Currently the reduction of energy related CO 2 -emissions through energy conservation and the use of renewable energy, is deployed globally. Far-reaching plans towards energy and CO 2 -neutral buildings are being developed as well as districts and regions. Xperience Parkstad is a campus in Heerlen, where several schools are located and where prospective plans are developed to provide this district with CO 2 -neutral energy. The gross total floor area of the buildings is 85,536 m 2 (this includes buildings that are yet to be constructed), divided into four educational institutions (Fig.1) (Table 1). Energy consumption and related CO 2 emissions are determined for the current situation (with estimates for new constructions) and for the year The focus of the current CO 2 emissions is on the emphasis of electricity usage (approximately 66% of current consumption) and thus the measures should lie on the reduction of CO 2 -emissions, * Corresponding author. address: l.j.j.h.m.gommans@tudelft.nl Article history Received February17, 2011 Accepted May 15, SUSB Press. All rights reserved. caused by the demand of electricity. It is forecasted that by 2025 there will be more demand for cooling, as will be reflected in the increase of the electricity consumption. The educational institutions are expected to reduce energy consumption by applying energy efficiency measures. Furthermore through innovations in technology, performance of equipment will improve. Eventually there is an ambition to generate 10% of the electricity demand by the use of photovoltaic cells and wind generators. Estimates for these reductions are reflected in the energy demand for the year 2025 (Table 2). The energy demand consists of electricity, heat and cooling (cooling is currently generated by electricity). The planned construction of the Arcus College will be conducted using concrete core activation, that uses low temperature heat and high-temperature cooling, coming from the flooded mine shafts which are located 500 meters underneath the city of Heerlen; the minewater (Fig.1). There is almost no difference in the electricity demand during the seasons. However, there is a difference between demand of electricity during day and night time; office-hours i.e. between 8.00 and hours, shows that the electricity consumption is twice as high compared to the night. The largest heat and cooling demand also takes place during the day, the peak International Journal of Sustainable Building Technology and Urban Development / June

2 Leo Gommans is an assistant professor at Delft University of Technology faculty of Architecture, chair Climate Design and Sustainability [1]. In his PhD-research Exergetic System analyses on regional scale he is developing concepts for optimal energy systems for the region, based on exergy principles. The energy system for the campus in Heerlen (NL) which will be discussed in this paper, is a case study in the research. Gommans also works at Zuyd University in Heerlen as a lecturer at the faculty Built Environment and as a researcher for the research group RiBuilT ( for heating being between 7.00 and 8.00 am. Over the years the largest heat demand is obviously in the winter period and the largest cooling demand in the summer period. The remaining demand for electricity, heat and cooling will be generated by the planned Combined Heat and Power biofuel plant (Bio-CHP). The generation is based on the combustion of biomass. The electricity demand determines the dimensions of the Bio-CHP because the dimensioning for heat would result in a shortage of electricity production, which accounts for the largest CO 2 -emisssion. Dimensioning for electricity demand will entail a heat surplus, especially in summertime. Zero energy, energy- and CO 2 -neutral means that we are compensating our energy- or CO 2 -emissions with sustainable methods of energy generation or energy conservation. Although it is sustainable energy, this does not mean that we can use as much as we want. The measures for generating and saving energy also cost scarce resources and energy and often scarce space of which biodiversity may decrease [4]. From an exergetic perspective, we need to look for an optimal utilization of locally available renewable energy sources and the most appropriate energy system. The methodology to achieve an optimal regional energy system, to be based on exergy principles and thus the optimal utilization of potential energy, is also based on the shape, Fig.1 Plan for campus Xperience Parkstad with a local distribution network for heat and cooling - Cauberg-Huygen consulting engineers, Maastricht (Roijen& van Hooijdonk 2010) [3] location and time aspects of energy demand and supply. Besides the quantity of energy, the quality of energy is important, as well as the method by which we link this quality demand to the supply. A well balanced selection of techniques for conversion, transport and storage of energy is of crucial importance for the efficiency of the total energy system [5]. High temperature heating with bio-chp was chosen because changes to the heating system and the building, to realize low temperature heating, would be too radical for a part of the existing buildings. Table 1 Information on the different educational institutes in the Xperience Parkstad area - Cauberg-Huygen consulting engineers, Maastricht (Roijen& van Hooijdonk 2010) [3] Educational institutions Gross Floor area. Year built / to be built Remarks Arcus college (planned) 8,760 m New building with concrete core heating and cooling University Zuyd 36,041 m High + middle temperature heating, low temperature cooling Open University (existing) 20,385 m High + middle temperature heating, low temperature cooling Open University (planned) 10,000 m Not yet decided Sintermeerten college 10,350 m High temperature heating, no cooling Total m 2 Table 2 Current and future (2025) energy demand (natural gas and electricity) for the educational institutions in XperienceParkstad - Cauberg-Huygen consulting engineers, Maastricht (Roijen& van Hooijdonk 2010) [3] Current situation Situation by 2025 (estimation) Educational institution Electricity Natural gas [m 3 /year] Electricity Natural gas [m 3 /year] Total CO 2 -emission [tons / year] Arcus college 2,129 37,136 1,673 37,136 1,013 HogeschoolZuyd 2, ,952 2, ,952 2,027 Open Universiteit 1, ,000 1, , Sintermeertens college , , Total 7, ,088 5, ,093 4, SUSB Vol.2 No.2 Jun.2011 L. Gommans

3 Although the new energy system of the Campus in Heerlen provides an efficient and sustainable energy supply, there is more possible by using the local potential and improving the use of the energy qualities. From an exergetic approach where the potential of the old coal mines are used for storage of energy, the plan is further analyzed. The exergy and energy flows are identified then there is examined how residual energy flows can be used better, to achieve an optimal energy system for the campus. As you will see, this approach can lead to surprising solutions that are not often to is not often used on a regional scale. The solutions are so specific for the situation that there is not much comparason with other project around the world. Further research and monitoring should show whether the assumptions for energy efficiency can be realized 2. ENERGY LOSS DUE TO CONVERSION, TRANSPORT AND STORAGE OF ENERGY To determine the efficiency of the total energy system and to optimize the system we should look at all the exergy that is lost and the extra energy that is needed in the total chain from supply to demand. This method is part of my PhD-research Exergy analysis on the regional scale1 and Xperience Parkstad is one of the case-studies in this research. I used the planned energy plan of Xperience Parkstad, to investigate where there are opportunities to optimize the energy system, regarding the regional potentials. In this section, the losses of the chosen energy system, and its efficiency is identified. In the next section, alternatives that can improve the efficiency of the energy system are considered, using potential off-site and exergetic principles, thus the optimal use of the quality of energy. The whole chain from the supply to the demand of energy will be examined. The starting point for a more CO2-neutral Xperience Parkstad school campus, is an energy system based on the combined generation of heat, electricity and cooling from locally available biofuel residues. Some residues were eligible for this biofuel, and are investigated [3], namely: - Wood residues (from wood waste or waste wood) - Methane (from anaerobic digestion produced from manure or organic waste) - Bio-oil from a local producer (BiPoTec), from local green residues (straw). The choice for wood residual as fuel, has primarily not been based on an energy optimization, but on practical and economic grounds: The wood residual has a relatively high energy content, as such the storage space and transportation load of the wood residual is limited. Besides, these flows do not require prior preparations, thus can be used immediately. Sufficient wood waste is collected by RD4 (waste collection, disposal and cleaning in the region of South Limburg) and is available for a reasonable price also anticipated in the future. The choice for CO2-reduction in Xperience Parkstad results in the application of renewable energy (biomass) at a district level to effect savings, and more optimal use of fuel by CHP. Fig.2 Wood, in the form of natural firewood, compares favorably with all other energy sources in the amount of net energy realized after processing and transportation (Lighter colors indicate a range of possible EROI due to varying conditions and uncertain data).(hall & Day 2009) [6]. Where energetic considerations are the base for a selected fuel, the energy required to produce this fuel is important. The conversion of the fuel for electricity (and residual heat) via CHP, also provides an energy efficiency, that depends on the applied technique. Four variants are calculated for Xperience parkstad, based on an electricity production at 80% of the total electricity demand. In conjunction with the energy demand for the fuel production that follows the ERoEI2, the electricity production and the amount of heat is determined for each Bio-CHP technique (Table 3). The chosen CHP on wood chips, will run almost continuously day and night, due to economic considerations, which means that there will be a continuous residual heat supply. Over a year, the heat demand of Xperience Parkstad, will be just over half the residual heat from the plant. In summer there will be a surplus and at peak loads 1 The research Exergy-analysis on a regional scale will be implemented within a government funded project EOS LT (NL Agency): Synergy between Regional Planning and Exergy (SREX), involving multiple disciplines and universities working together and have their contibutions in the research. ( 2 ERoEI of EREI stands for Energy Returned on Energy Invested. De ERoEI has to be larger than 1, inorder to be profitable. If the ERoEI is less than 1, more energy is put into production then it yields. ERoEI is also known as EPR (Energy Production Ratio). Energiebalans_(natuurkunde) International Journal of Sustainable Building Technology and Urban Development / June

4 Table 3 Energy demand for fuel production that follows the ERoEI, Electricity production and residual heat for the Bio-CHP variants Description Bio-CHP and biofuel ERoEI factor [-] Energy con-tents. [MJ/kg or MJ/m 3 ] Fuel demand [kg or m 3 ] Energy demand for fuel prod. Nel [%] Nth [%] Electricity production Residual heat production CHP on wood chips ,574, ,645 9,289 ORC 3 on wood pellets ,193,000 2, ,645 21,675 CHP on Bio-oil ,000 5, ,645 5,161 CHP on biogas* ,229,408 1, , * Units in m 3 in winter a shortage of heat. To find out how large this deficit is, a calculation based on the daily heat demand, must be made. A conservative estimate is that 20% of the heat demand cannot be covered and not all the heat can be used to heat the buildings. An important part of the surplus in summer will be used for cooling, by applying absorption cooling technique 4. The remaining surplus of residual heat has to be removed via cooling towers. This cooling will cost extra electricity for fans and pumps 5. The choice for centralized CHP and absorption cooling, leads to the application of a heating and cooling grid, this grid creates additional heat losses in the pipes, has an extra electricity demand for pumps [7] and will cost extra material and energy for the construction of the network. Based on data for steel pipes with insulation [8] and an amortization period of 30 years, the annual primary energy consumption for material and construction of the heating network, additional heat losses and electricity consumption of the pumps is calculated. Table 4 gives an overview of the energy losses and auxiliary energy demand for the whole chain from energy supply to energy demand of the energy system for Xperience Parkstad. From the whole range of organic residue to the supply of useful heat, cooling and electricity, there are a number of steps related to the techniques of conversion and transport of energy. This leads to losses in extra energy - These losses can be translated into primary energy consumption 6. Table 5 gives an overview of the yearly primary energy demand. If the supply of the produced energy (heat, cold and electricity) has been done in a usual way, this would result in a primary energy demand of 66,640 GJ primary /year (Table 6). A comment about this primary energy demand is that it concerns the calorific value. The energy needed for transportation and extraction is not yet taken into account. Oil, coal and gas also have additional energy demand for transportation and extraction. This energy is included in Table 4 Energy losses and auxiliary energy demand for the whole chain from energy supply to energy demand of the energy system for Xperience Parkstad Available residual heat (90 o C) Available heat for XperienceParkstad (80% of heat demand) Available heat for 2,527 MWhabsorbtion cooling (75% efficiency) Conductor losses in the heat grid, due to transmission (20%) Conductor losses in the cooling grid, due to transmission (10%) Remaining residual heat (to the cooling tower) Electricity demand for pumps and ventilators in the cooling towers Electricity demand for absorption cooling Electricity demand of thepumps for cold transport Electricity demand of the pumps for heat transport Total auxiliary electricity demand Primary energy demand for materials and construction of the cooling heat grid Additional natural gas demand for heating in winter period (estimated on 20%) +9,289 MWh th /year - 4,190 MWh th /year - 3,369 MWh th /year -1,047 MWh th /year MWh th /year +1,393 MWh th /year 41.8 MWh e /year MWh e /year 37.9 MWh e /year 37.7 MWh e /year MWh e /year 125 GJ/year 119,000 m 3 /year 3 Organic Rankin-Cycle (ORC) makes it possible to generate electricity with temperatures from 80 o C. 4 Absorption cooling makes it possible to generate temperatures from approximately 10 o C with temperatures above 80 o C. 5 Measurements from Johan Desmedt s presentation (Energietechnologie, VITO, Mol - Belgie) during Dag van de duurzamekoude, 11 th June 2009 in Amsterdam (The Netherlands): The use of residual heat for cooling; Results of measurement for a year taken from the Academic Hospital Sint Jan in Brugge (Belgium). 6 The conversion of electricity to primary energy is based on the average performance of a power plant in the Netherlands, namely39%, accordingnen5128-nen (2004). Energy performance of residential buildings determination method NEN SUSB Vol.2 No.2 Jun.2011 L. Gommans

5 Table 5 Total primary energy supply for the energy system of Xperience Parkstad Additional natural gas demand for heating in winter: 119, = 4,185 GJ primary /year Energy for transport and conversion of wood residuals to wood chips 2,229 GJ primary /year Energy for construction of heating and cooling network 125 GJ primary /year Electricity demand for pumps for heat transport: 37.7 MWh e / = 348 GJ primary /year Electricity demand for pumps for cooling transport: 37.9 MWh e / = 350 GJ primary /year Electricity demand for absorption cooling: 386 MWh e / = 3,563 GJ primary /year Electricity demand pumps/fans of cooling towers: 41.8 MWh e / = 386 GJ primary /year Total primary energy supply for the energy system of Xperience Parkstad 11,186 GJ primary /year Table 6 Primary energy demand for the energy system of Xperience Parkstad when supplied in the usual way. Electricity with an average efficiency from a plant (39%) = 4,665 MWh / = Heat from a High efficiency gas heater (85%) = 4,190 MWh / = Cooling with a heatpump using electricity (COP 7 = 4) = 2,527 MWh/ 4 / = Total primary energy demand Xperience Parkstad when supplied in the usual way 43,062 GJ primary /yr 17,746 GJ primary /yr 5,832 GJ primary /yr 66,640 GJ primary /yr the sustainable variant with biomass-chp. Therefore the energy demands of the variant with fossil fuels, would increase by5to 10% (see ENROI in Fig.2). The annual saved primary energy is 66,640 GJ 11,186 GJ =55,454 GJ primary which is 83% of the primary energy demand. This meets the CO 2 -reduction goal of Xperience Parkstad. 3. OPTIMIZING THE EFFICIENCY OF THE ENERGY SYSTEM, USING THE MINEWATER Despite the fact that we use a CO 2 -neutral fuel, we still have to improve the energy performance of the energy system; the supply of biomass residues in the region is limited and the remaining energy still has to be covered by fossil fuels. To optimize the energy system, there are certainly possibilities when investigating the energy losses within the system itself, and looking beyond the boundaries of the district Xperience Parkstad. The main loss of energy for Xperience Parkstad is because not all available residual heat can be used immediately (especially in the summer). Therefore, this heat is used to produce cooling with an absorption cooling process. Otherwise, we have to lose this residual heat with the help of cooling towers. As such the cooling is a substantial part of the energy demand. Investigating the possibilities to Fig.3 Energy losses and auxiliary energy demand for the whole chain from energy supply of wood residual to the energy demand for the energy system for Xperience Parkstad 7 COP = Coefficient of performance and indicates the delivered amount of thermal energy, relative to the (electric) drive power that is required to deliver this thermal energy. International Journal of Sustainable Building Technology and Urban Development / June

6 Fig.4 Cascaded cooling in summer via the minewater in XperienceParkstad ensures a much higher efficiency connect to the minewater-plant8 via the connection that is planned for the new Arcus College, may offer interesting solutions (Fig.4). The municipality of Heerlen has placed the minewater at the disposal of the Arcus College; 122 m3/h minewater with a temperature of 15oC for cooling and 59 m3/h with a temperature of 28oC for heating. The minewater supply for cooling in the summer is 15oC and returns to the mine at 20oC, which is a cooling power of over 700 kw. Based on measurements done in the minewater-project, it is expected that the supply of cooling costs approximately 70 kw electricity to circulate the minewater9, i.e. a COP of 10. That is better than absorption cooling, citing a COP of Although the cooling temperature using absorption cooling, (6-10oC) is lower than cooling with minewater (15oC). However, the minewater of 20oC, can still take the heat from the absorption cooling machines before the minewater returns to the mines. Now the temperature of the minewater is approximately 30oC. This cascading does not take extra pump energy into the mine water circuit and provides a substantial savings in the cooling circuit of the absorption cooling. An initial assessment is that approximately 80% this energy is saved. Subsequently the minewater can also drain the heat of the Bio-CHP, which means that there are no cooling towers required, as well as no energy and water supply for these towers. Thus the minewater can return to the mines with a temperature of 50oC. In this way we can provide eight times as much cooling with the same electricity for the pumps, circulating the minewater; 5,600 kw cooling instead of the initial 700 kw! Another interesting point of this alternative for cooling, is that the heat from the cooling process is stored in the mines in summer and can be used in winter for heating. Fig.5 Schematic section of the Heerlen underground with mine galleries where the heat and cold is extracted en infiltrated again 8 9 For more information on the minewater project see: Measurements by Cauberg-Huygen, Maastricht within the research Concerto: Remining Lowex. This concerns the electricity demand for cooling towers and pumps SUSB Vol.2 No.2 Jun.2011 L. Gommans

7 Table 7 Total primary energy supply for the energy system of Xperience Parkstad using minewater Heat provided by the minewater (119,000 m3a.e): 49.5 MWh e / = Cooling provided by the minewater (estimated 25%) 84,2 MWh e / = Energy for transport and conversion of wood residuals to wood chips Energy for construction of heating and cooling network (embodied energy) Electricity demand for pumps for heat transport: 37.7 MWh e / = Electricity demand for pumps for cooling transport: 37.9 MWh e / = Electricity demand for absorption cooling: 60 MWh e / = Total primary energy supply for the energy system of Xperience Parkstad 457 GJ primary /year 777 GJ primary /year 2,229 GJ primary /year 125 GJ primary /year 348 GJ primary /year 350 GJ primary /year 554 GJ primary /year 4,840 GJ primary /year The question is how much the temperature will decrease, and how the heat will flow in the mine galleries. In view of the high temperatures down in the mine (approximately 30 o C), the temperature doesn t decrease rapidly. That could cause a higher temperature from the mines in winter - higher than the initial 28 o C. If, for example the temperature in winter is 40 o C, then this means that the energy for the pumps that circulates the minewater, is reduced more than half. At the same time the heat power in the winter multiplies and can be directly used, without a Heatpump. The result is that no electricity is needed for the heatpumps which all together can yield a large profit in the winter as well. The energy needed for the pumps to circulate the minewater is approximately 1 kwh of electricity per 20 kwh supplied heat, i.e. a COP of 20. However, when a higher temperature is required, e.g. 35 o C, then the electricity demand of the heatpump has to be included to realize this temperature. If this heat pump would work with a COP of 5 (which is a reasonable assumption), then the combined COP (heat pump and minewater included) is 4. The heatpump is not necessary anymore when the temperature of the minewater is higher because of the stored heat in the mines (in summer). Besides this, the same amount of energy is delivered with half the amount of electricity for the minewater circulation pumps - at least when the return temperature to the mines remains low in winter. The efficiency improvement for space heating via minewater can be applied for heating the new buildings of Arcus College and Open University, but also for other buildings with low-temperature heating, that are connected to the minewater system. When these new buildings are heated with the minewater in the winter (by stored heat from cooling in the summer), additional gas heaters may be redundant as well as the natural gas. The cooling towers may be redundant as well, and so the energy and water demand of these cooling towers. Then the cooling for Arcus college is done with the minewater as well as the cooling for the absorption cooling process. If the supply of the energy produced (heat, cold and electricity) is done including energy delivery from the minewater as described above, this would result in a primary energy demand of 4,840 GJ primary /year (Table 7). The annual saved primary energy is 66,640 GJ 4,840 GJ =61,800 GJ primary which is 93% of the primary energy demand that is required when the energy demand is provided as usual. This reduction of more than half, compared to the energy system without minewater is a significant improvement, taking into account that the same amount of residual biomass is used. 4. CONCLUSION The analysis of the energy system for the campus Xperience Parkstad illustrates the energy flow, losses and the auxiliary energy demand. It demonstrates that, even though there is a CO 2 -neutral energy source, a considerable part of the energy is lost and extra energy is required to operate the energy system. It also illustrates the opportunities for optimizations of this system. The use of minewater can reduce the CO 2 -emissions in Xperience Parkstad with a further 55% compared to the previous planned energy system with Bio-CHP and absorption cooling. The use of minewater can also decrease the CO 2 -emission outside the Xperience Parkstad district by providing heat with a higher temperature in winter to all the buildings connected to the minewater network. Thus, the connection with the minewater and the optimal use of the different qualities of energy demand and supply, places the Xperience Parkstad area in a different perspective that goes beyond the local scale and improves the efficiency of the local energy system as well: In summer the minewater can improve the energy system for Xperience Parkstad by cascaded cooling. Meanwhile, the heat is stored in the mine galleries and there will be some seasonal heat storage to use the heat in winter. Further research on the aspect of heat storage in the mines is promising because of the efficiency improvement that can be realized in the winter period, especially when a heatpump is not essential anymore, due to a higher temperature of the supplied water from the mines. This efficiency in heating can also be achieved for other buildings outside the Xperience Parkstad area, connected to the minewater. The mine galleries underneath the Parkstad region may be an immense storage for residual heat, not only for the Bio- CHP but also for other residual heat, e.g. from industrial processes: Regenerating the heat in summer and regenerating the cold in winter; Not a finite source for heating and cooling, but an infinite storage of heat and cooling. The local coal mines in South Limburg have a high storage capacity of heat in the water of the mine galleries. The reservoir volume of the Oranje Nassau mines in Heerlen, have an estimate of 10.8 million m 3 of minewater [9]. If we International Journal of Sustainable Building Technology and Urban Development / June

8 assume a supply temperature of 40 o C and a return temperature of 20 o C, then the heat capacity for this mine is 250 million kwh of heat, which is equivalent to approximately 25 million m 3 of natural gas - the energy consumption for heating 25,000 new built houses. In the Parkstad Limburg region there are next to the Oranje Nassau mines, several other mines where heat and cooling could be stored. The concept for the optimized energy system of Xperience Parkstad, based on the exergetic principle of cascaded energy flows and the use of minewater, could be expanded to a regional network across the region of Parkstad Limburg, using only 7% of the primary energy and reducing approximately 93% of the CO 2 -emissions, compared to the usual situation. The ideas of such a regional network would be consistent with the plans of the SREX study for South Limburg, where industrial and residential areas of Parkstad Limburg are linked by a network of heat and cold 11. Prior to these plans, the energy system of Xperience Parkstad first needs to be optimized by the removal of heat with the minewater in the summer. The profit we can achieve by cooling with the mine water is already gained. The next promising step which requires further research is energy storage in the mines combined with a regional thermal network! REFERENCES [1] aa58-8c1a95604ee4&lang=en. [2] Roijen, E. J. A., Fijlstra, T., Plas, R. van der, Knecht, J. de., Energievisie Onderwijscampus Heerlen, (Written in Dutch), [3] Roijen, E. J. A., Hooijdonk, R. van., Exergiecentrale Xperience Parkstad / Onderwijscampus te Heerlen - Concept energiecentrale en keuze BioWKK, (Written in Dutch), [4] Gommans, L. J. J. H. M., The use of material, space and energy from an exergetic perspective, Proceedings Sasbe 2009 Conference on Smart and Sustainable Built Environments, Delft, The Netherlands, [5] Gommans, L., Dobbelsteen, A. van de, Synergy between exergy and regional planning, Proceedings Energy 2007, First international conference on energy and sustainability, Wessex Institute of Technology, The New Forest, UK, [6] Hall, C., Day Jr, J., Revisiting the limits to growth after peak oil. American Scientist, Vol. 97, No. 3, [7] Bussel, F. J. M. v., Warmtedistributie basisgegevens, (Written in Dutch), [8] Steenderen, P. v. L., A.B.K., Exergie-economie van afstandverwarming, Universiteit van Twente, Faculteit werktuigbouw, leerstoel energietechnologie. (Written in Dutch), [9] Gommans, L. J. J. H. M., Kempen, G.W.P.J., Tongeren, P.C.H. van., Schone energie uit vertrouwde bron, Onderzoek naar de haalbaarheid van het benutten van aardwarmte uit het mijnwater voor het Stadspark Oranje Nassau, Heerlen (NL). (Written in Dutch). 11 SREX - Research report : Energy transition in South Limburgwww.energieplanning.nl 184 SUSB Vol.2 No.2 Jun.2011 L. Gommans