orc analysis

8/10/2019 Orc Analysis

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NARUITELJ

Regionalna energetska agencija sjever,

Miroslava Krlee 81, Koprivnica

VEZA

Ugovor o usluzi tehnike ekspertize u sklopu projekta Inovativno

iskoritavanje nisko-temperaturnih geotermalnih izvora u jugoistonojEuropi, datum 30. rujan 2013.

Analysis of Organic Rankine Cycle technology applied for

electric and heat energy production using renewable energy

from geothermal wells

IZDAVA:

North-west Croatia Regional Energy Agency

Andrije aje 1010 000 Zagreb

http://www.regea.org

AUTORI: Dr. sc. Julije DomacMr. sc. Velimir egonAdam Babi, mag. Ing. mech.

VODITELJ PROJEKTA: Mr. sc. Velimir egon

ODOBIO VODITELJ PROJEKTA:

Mr. sc. Velimir egon

ODOBRIO RAVNATELJ

Dr.sc. Julije Domac

Zagreb, prosinac 2013


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Analysis of Organic Rankine Cycle technology applied for electric and heat energy production usingrenewable energy from geothermal wells

Table of Contents

Summary ................................................................................................................................................. 1

1. Introduction ..................................................................................................................................... 22. ORC systems - technical data .......................................................................................................... 3

2.1. Organic Rankine cycle systems (ORC systems)........................................................................ 3

2.2. ORC system powered by geothermal energy .......................................................................... 7

2.3. ORC system powered by biomass ......................................................................................... 10

3. Geothermal wells Ka-1 and Mol-32 ............................................................................................. 11

3.1. ORC system application - only geothermal energy ............................................................... 13

3.1.1. Investment costs of geothermal plant .......................................................................... 14

3.2. ORC system application - geothermal and biomass energy .................................................. 15

3.2.1. Investment costs of combined geothermal and energy plant ...................................... 17

4. Conclusion ..................................................................................................................................... 18

5. Literature ....................................................................................................................................... 19


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Summary

Organic Rankine Cycle (ORC) technology is modern and highly energy efficient. It allows electric

energy production from renewable sources like geothermal wells, biomass, Sun and waste heat

energy. Organic Rankine Cycle technology is based on Rankine cycle with high-molecular-mass

organic fluid. Key is in organic fluid which evaporates on significantly lower temperature andpressure than water in classic Rankine cycle. This system is described in first part of study with accent

on biomass and geothermal ORC systems.

Second part of study is based on two Croatian wells and finding solutions how to apply ORC

technology for electric energy production. However both wells are characterized by low geothermal

water temperature (about 60 C) and small heat power. ORC technology demands at least 100 C ofgeothermal water temperature.

This study offers two solutions. First one is based on drilling the well hole deeper, this procedure

provides higher geothermal water temperature and more heat power. Other solution is based on

second energy source. More heat power and higher temperature of organic fluid can be achieved byincluding biomass boiler in system. Furthermore, heat pump is also required. It lifts heat energy from

geothermal well on higher temperature level. With biomass boiler and heat pump in system, deeper

drilling of well is not required.

Investment costs of proposed solutions are high. Plant with overall thermal power 1,000 kW and

electric power about 200 kW cost approximately 3,180,000.00. One third of investment costs is forreinject drillhole and completion of production drillhole, that is the main reason for so high

investment costs. Many parts of plant have to be custom made and there is a lot of special work so it

is very difficult to estimate costs precisely.


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1. Introduction

Croatia has many geothermal wells, mostly with temperatures below 100 C and this is the mainimpeller for this study. Namely, goal of this analysis is to find a way how to use heat energy from

geothermal energy sources for electric energy production through Organic Rankine Cycle (ORC)

technology. Nowadays, ORC systems are cutting edge technology in world, but in Croatia are knownonly two implementations (in city of Novska and city of Udbina) and both are in pellet industry. This

technology is based on thermodynamic process of Rankine Cycle but instead of water, working fluid

is organic liquid with low vaporization temperature. Technology is described more detail in second

chapter.

In the third chapter are given parameters about two real geothermal wells in city of Krievci andvillage of Molve. These wells are characterized by low geothermal water temperature and small

power. Despite that, in the same chapter possibilities of using ORC technology on mentioned wells

are presented. The two solutions are given for each well. First one is based on geothermal energy

only, but with some changes on drillholes. Second solution includes biomass energy. With biomass as

heat energy source much larger power plant can be planned without any big changes on drillholes.Estimated investment costs are given after presented solutions.

In last part of this paper is given conclusion with recommendations for further steps about these two

wells and ORC technology.


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2. ORC systems - technical data

2.1. Organic Rankine cycle systems (ORC systems)

The Organic Rankine Cycle's principle is based on a turbogenerator working as a normal steam

turbine to transform thermal energy into mechanical energy and finally into electric energy throughan electric generator. Instead of the water steam, the ORC system vaporizes an organic fluid,

characterized by a molecular mass higher than water. Vaporization and condensation in ORC is on

lower pressure and lower temperature than standard water cycle. Thermodynamic cycle of ORC

system is shown inFigure 2.1 by temperature-entropy diagram and scheme.

Figure 2.1 Organic Rankine cycle

By courtesy of Turboden srl www.turboden.it

A heat source heats liquid (water or thermal oil) to a high temperature, typically a bout 300C, in aclosed circuit. The hot liquid passes through heat exchanger in ORC module (pre-heater and

evaporator). In heat exchanger heat is transferred from hot liquid to organic working fluid in ORC

system and consequently organic working fluid evaporates (from point 3 to point 4). Then organic

vapor expands in the turbine (from point 4 to point 5), producing mechanical energy, further

transformed into electric energy through a generator. Turbine is directly coupled to the electric

generator through an elastic coupling. The vapor is then cooled, first in regenerator and then in

condenser. Regenerator is not obligatory part of the ORC system but it increases energy efficiency ofsuch systems. Condenser in scheme has water as a cooling fluid, but organic working fluid can be

cooled by air also. In water condenser, water warms up at about 80 - 90C and can be used fordifferent applications requiring heat, for example district heating, wood drier or something else.

Finally, condensed organic fluid is pumped back into the regenerator to close the circuit and restart

the cycle.

In next table are compared main characteristics of water and high molecular mass organic fluid as a

working fluid in Rankine cycle.


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Table 2.1 Comparison of water and organic fluid as a working medium

Water High molecular mass organic fluid

small, fast-moving molecules very large flow rate

metal parts and blade erosion larger-diameter turbine

multistage turbine and high mechancal stress no wear of blades and metal parts


ORC unit with main parts can be seen in next figure. Blue arrows mark cooling water inlet and outlet

while yellow arrows mean hot liquid inlet and outlet.

Figure 2.2 Components of an ORC unit


The ORC system has high overall energy efficiency: 98% of incoming thermal power in the thermal oil

or water is transformed into electric energy (around 20%) and heat (78%), with low thermal leaks, 2

% due to thermal isolation, radiance and losses in the generator (Figure 2.3). These data are provided

by producing company of ORC systems Turboden srl. Electric efficiency of ORC systems can be higher

(around 24% and more) in non cogenerative cases.

Figure 2.3 Energy distribution



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Except high overall energy efficiency, ORC system has next advantages:

Very high turbine efficiency (up to 90%);

Low mechanical stress of the turbine (low peripheral speed);

Direct drive of turbine to the electric generator without reduction gear (low RPM of the

turbine);

No erosion of the turbine blades (absence of moisture in the vapor nozzles); Low mechanical stress of the cycle (much lower pressure than steam cycle);

Very long operational life of the machine (designed for 20+ years)

Automatic operation of plants without need of onsite attendance by licensed operators;

High availability (greater than 98 %);

Partial load operation down to 10 % of nominal power (Figure 2.4);

Low Observations&Measurements requirements (O&M) - about 3 to 5 hours per week.

Partial load efficiency curve is shown inFigure 2.4.ORC system can operate down to 10 % of nominal

load with 45 % of the cycle efficiency. ORC system has 90 % of efficiency down to 50 % loading.

Figure 2.4 ORC partial load efficiency


Earlier in the text is mentioned Turboden srl as an ORC system producer. This producer is dominant

in Europe by number of installed ORC unit. Company ORMAT is dominant in North America. These

and other producers and characteristics of their product are described inTable 2.2.

Table 2.2 List of world main ORC system producer

ProducerElectric power

(kW)

Electric efficiency

(%)

Temperature of hot

liquid (C)

Ormat 2007,500 - 150 to 300

Turboden srl 3002,000 16 to 20 100 to 300

HMK GmbH 502,000 9 to 21 120 to 350

Khler und Ziegler AnlagentechnikGmbH 70 - 200 11 100

Ergion GmbH 4 - 300 13 to 16 120 to 300

Adoratec GmbH 3001,750 15 to 18 300

WSK Energie und Umwelttechnik

GmbH 52 - 65 ~16,3 -

Source: Bian D. (2012), Optimization of middle-temperature waste heat utilization by means of ORC process,

Thesis, Faculty of Engineering Rijeka


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As a heat source can be used biomass, heat waste, geothermal and solar energy. Biomass as a heat

source for ORC unit is the most popular, second place hold heat waste energy, geothermal energy is

third and solar energy is the rarest. These renewable heat sources are true value of ORC systems,

namely ORC technology is not about the lowest price per kWel possible, but about sustainable

investments in renewable energy and energy efficiency. Payback period of investment depend on the

specific application and local market, according to producer information payback period is about 4 to5 year.


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2.2. ORC system powered by geothermal energy

In cases when geothermal energy is used as heat source in ORC system, there is no unique solution.

Every ORC system for geothermal energy is custom made. Hot water resource should be between

100 C and 200 C.ORC unit size could be up to 15 MWel and have a high efficiency cycle. Efficiency

can be enhanced with two-level cycles. During designing, it has to be pay attention on some specificpotential problems.

Main issues to consider:

Corrosionspecial and costly materials for the heat exchangers, great influence on the costof the unit and longer delivery period;

Scalinglimits in cooling the geothermal brine;

Foulingremovable covers and straight cleanable tubes;

Working fluid flammability, critical in urban areas and for insurance cost;

Vapor plume and need for makeup water in case of evaporative devices;

Larger footprint and noise emissions from the fans in case of air cooling.

ORC systems with geothermal energy can be cooled by evaporative towers or air condensers. Their

characteristics are shown in next table.

Table 2.3 Characteristics of cooling devices

Evaporative towers Air condensers

Smaller footprint Larger footprint

Efficient in hot dry climate Efficient in cold climate

Higher own-consumption Lower own consumption

Fresh water consumption No water needed

Chemical water treatment Virtually no environmental impact and operating costs


Other important decision to make is choosing of optimal organic fluid in ORC system. Decision

making parameters are:

Cost;

Enthalpy drop & flow rate;

Pressure levels;

Environmental friendliness;

Heat input curve;

Cooling system.

Thermodynamic process of Rankine Cycle with isopentane as a working fluid is shown in next figure.


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Figure 2.5 Rankine Cycle with organic working fluid isopentaneSource: Short Course on Geothermal Drilling, Resource Development and Power Plants,

organized by UNU-GTP and LaGeo, in Santa Tecla, El Salvador, January 16-22, 2011. Dr. Pll Valdimarsson,University of Iceland

In next figures can be seen one real geothermal plant with ORC unit. On photos is Hochtief plant

located near Mnchen. Hochtief plant is made for electric energy production only and its electricpower is 5 MW.

More geothermal plants are listed in table on next page. It is important to notice that minimal

geothermal water temperature is 106 C in plant in Austria and that was the first Turboden

geothermal plant, after that, all plants have higher geothermal water temperature.

Figure 2.6Geothermal plant near MnchenBy courtesy of Turboden srl www.turboden.it


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Table 2.4 European geothermal ORC systems

Start-up

dateCustomer/end user City Country Description

Power

(kW)

Geothermal water

temperature (C)

03/2001Marktgemeinde

Altheim GmbHAltheim Austria

Heat &

power1000 106

06/2008

GEIE-Groupement

Europeenne d'Interet

Economique

Soultz-sous-Forets

France Power only 1500 175

12/2012 Karl Lausser GmbHSauerlach

(Munich)Germany

Heat &

Power5000 140

03/2012 Enel Livorno ItalySupercritical

prototype500 150

12/2012 Hochtief EMDuermhaar

(Munich)Germany Power only 5600 138

03/2013 Hochtief EMKirchstockach

(Munich)Germany Power only 5600 138

UC*

Geothermische

Kraftweksgesellschaft

Traunreut GmbH

Traunreut GermanyHeat &

power

4100 118

*Under construction



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2.3. ORC system powered by biomass

The most common type of ORC systems is type with biomass as energy source. Such systems can

produce heat and electrical power with high efficiency and user friendly operation. The generated

power usually ranges between 200 kW and 5 MW electric. Heat energy can be used in many various

applications like: District heating networks;

Timber drying in sawmills;

Sawdust drying in wood pellet factories;

Greenhouses;

Swimming pools;

Trigeneration.

In combustion chamber of boiler can burn forestry residues, sawdust, wood chips, bark, treated

wood, dried sewage sludge, straw, green cuttings, waste material etc.

Scheme of real ORC system with all main parts is shown inFigure 2.7.Thermal power of that plant is2,220 kW. Flow rate is about 16 kg/s and temperature change is about 50 C, from 300 C to 250 C.ORC unit has electric power output 400 kW and thermal power is around 1,780 kW. Only 40 kW of

power is thermal loss. District heating is good way to use thermal power, but beside that it has to be

installed additional coolers in system for cases when district heating is turned off or below nominal

capacity. In presented example (Figure 2.7) district heating water flow rate is 14,2 kg/s with

temperatures 60/90 C.

Figure 2.7 Scheme of ORC system powered by biomass fuel



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3. Geothermal wells Ka-1 and Mol-32

Geothermal wells Ka-1 and Mol-32 are in central focus of this study. It has to be found solution howto use effective their thermal energy by ORC technology. Main results of conducted measurements

are given inTable 3.1.

Table 3.1 Characteristics of geothermal wells Ka-1 i Mol-32Location Krievci Molve

Name of well Ka-1 Mol-32

Temperature of geothermal water on the ground (C) 68 60

Thermal potential (kW) 750* 300*

Corrosive characteristics of geothermal water

Yes (too much sulfate,

chloride and gasses

CO and HS)No**

Flow rate (m/day) 390 150

Temperature on the bottom of the well (C) 83,9 97,8

Well depth (m) 1,496 1,623

*In case when outlet temperature of geothermal water is 20 C.

**Required detailed analysis.

Source: INA (2009), Izvjetaj o rezultatima proizvodnog ispitivanja i hidrodinamikog mjerenja u buotini

Krievanka-1 (Ka-1), SD Naftaplin, Sektor proizvodnje nafte i plina

INA (2005), Izvjee o obavljenim radovima na geotermalnoj buotini Molve-32, Sektro proizvodnje nafte i plina,

Okrug Podravina

Thermal potential is 300 kW in Mol-32 and 750 kW in Ka-1 but this worth in case when geothermal

water is cooled on 20 C. These wells are very small by its power size and they have low t emperature

of geothermal water. For Ka-1 were made some studies of how to utilize heat energy from

geothermal well. Heat energy could be used for heating of nearby schools and school hall and it is

estimated currently is required about 425 kW of heat power. Near the well are located two

swimming pools. Swimming pools are used only in summer because then they are heated by solar

energy. In case they will be heated, it is required 225 kW of heat power for small pool and 1,000 kW

for big pool. If swimming pools will be heated then is required to build building for pools or for one of

them. Overall heat power is 1650 kW.


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Figure 3.1 Landscape around Ka-1Source: Google Earth

Heat energy demands of surrounding buildings of well Mol-32 are not yet investigate (Figure 3.2).

Assumption is that this heat energy will be optimally used by cooperation with some industry.

Currently there is not any satisfied industry but this will be ideal for pellet industry, greenhouses,

sawmills or something similar where is required big amount of heat energy. Very positive

characteristic of this well is good chemical quality of water so water is not corrosive. This property

influence significantly on capital costs of power plant because there is no need for special stainless

material.

Figure 3.2 Landscape around Mol-32

Source: Google Earth


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3.1. ORC system application - only geothermal energy

Wells Ka-1 and Mol-32 with current parameter are not satisfied for commercial production of heat

and electric energy through ORC system. It has to be higher geothermal water temperature and

higher heat power. In the winter will be primary to satisfied heat demand of local building, industryor something else. All excess of heat energy will be used through ORC unit for electric energy

production. Of course, during summer when heat demand will be low, electric energy production will

be the highest. Also, higher power size gives shorter payback period of investment.

Wells could be improved by deeper drilling and by more drillholes. Deeper well will be result with

higher geothermal water temperature and probably by increasing of heat power. More drillholes will

give more power.

Scheme of complete system is shown on Figure 3.3.Except production well there is also injection

well because geothermal water on temperature 60 C has to be return. Other solution is cooling

water on temperature below 30 C(according the current law about waste water). This solution can

be implemented in well Mol-32, but it is not satisfied for well Ka-1 because of problematic water

chemical properties.

Figure 3.3 Scheme of geothermal plant

Source: North-West Croatia Regional Energy Agency, own drawing

Well Ka-1 and Mol-32 should be improved according to Table 3.2 and Table 3.3. Further analysis is

made with assumption goal state of wells will not change during exploitation. Exact way of goal state

achievement has to be determinate after detail analysis.


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Table 3.2 Current and goal state of well Ka-1

Current state Goal state

Geothermal water temperature (C) 68 100

Heat power (kW) 750 1,000

Water flow rate (l/s) 4.5 6.0

According Geothermal well preliminary testing procedure Krizevci Croatiamade by company EFLA it

can be expected higher geothermal water temperature and increasing of its flow capacity. That will

be result with heat power about 1,000 kW (in case water is cooled on 20 C).

In well Ka-1 heat exchanger, pipeline and pump have to be made from special stainless materialbecause water is corrosive. 1000 kW heat power will satisfied heat demand of local schools, school

hall and smaller swimming pool. When heat energy is not required ORC unit will work full capacity.

Its electric power should be approximately 200 kW.

Table 3.3 Current and goal state of well Mol-32

Current state Goal stateGeothermal water temperature (C) 60 100

Heat power (kW) 300 1,000

Water flow rate (l/s) 1.7 6.0

In well Mol-32 has to be significantly increased flow rate of geothermal water to achieved better

economic aspects of investment into ORC technology. Currently there is not any serious industry or

heating network so this system can be made for electric power production only (200 kWel). Other

possibility is to install this system together with some heat energy consumer like greenhouses. Excess

of heat energy then could be used for electric power production.

3.1.1.

Investment costs of geothermal plant

Precise investment cost of geothermal plant is very difficult to give because there is a lot of custom

made parts and there is no standard prices. In table below are given cost estimations based on costs

of other geothermal plants.

Table 3.4 Investment costs*

Mol-32 Ka-1

ORC unit with all associated parts 850,000.00 1,100,000.00

Completion of current drillhole 1,000,000.00 600,000.00

New production drillhole 2,000,000.00 -

Reinject drillhole 1,000,000.00 1,000,000.00District heating system 60,000.00 180,000.00

Other expenses 200,000.00 200,000.00

Total expenses 5,110,000.00 3,080,000.00

*Estimated, without VAT


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3.2. ORC system application - geothermal and biomass energy

Other possibility of using geothermal heat energy without any huge changes on current well is to

connect well system with biomass boiler system. In that case, plant power can be significantly

increased, depend about boiler power. This solution include heat pump into the whole system, this is

presented in next figure (Figure 3.4). Current geothermal water temperature is lower than minimalrequired temperature for ORC unit. This is the reason for including high temperature heat pump into

the system. After temperature is increased liquid goes to heat exchanger with organic working fluid.

Appropriate organic fluid will be determinate by ORC unit producer. After first heat exchanger

working fluid goes to evaporator. Evaporator is connected to the biomass boiler through pipeline

with thermal oil. After that, organic vapor propel turbine and consequently generator produce

electric energy. Cooling of organic vapor is made in two steps. First, vapor goes into heat exchanger

where water is heated. This water is used for fulfilling building or industry heating demand. Second

step is complete condensation of organic vapor in air condensers. If there is no any heating demand,

organic vapor goes directly into condensers. Then pump push liquid into the cycle again.

Figure 3.4 Scheme of plant based on geothermal and biomass energy

Source: North-West Croatia Regional Energy Agency, own drawing


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All main parts are shown in upper scheme and power of them is given in next table.

Table 3.5 Power of main parts

Mol-32 Ka-1

Rated heating output of heat pump (kW) 350 850

Heat power of biomass boiler (kW) 650 600Overall heat power (kW) 1,000 1,450

Potential heat power of district heating (kW)* 780 1,140

Electric power of ORC unit (kW) 200 290

*Included thermal losses of 2%

Heat pump has to be for high temperature sources. Electric power of compressor for Mol-32 will be

around 50 kW and for Ka-1 around 100 kW. Electric power of ORC unit in both cases is below 300kW because of current national tariff system for electric energy from renewable sources. Electric

power of ORC unit in Molve is only 200 kW. Reason for that is very small thermal power of

geothermal well. Such system can be economically payable very hard. In both cases boiler should be

powered by woodchips so it have to be planed woodchips storage and associated equipment.

Heat energy of plant in city of Krievci can be efficiently used for heating of school buildings, schoolhall and smaller swimming pool. Also, there is capacity for even more building or factory which can

be include into the heating network. On the other hand, plant in village of Molve is great for

connecting with some industry. Possible solution for sawmill and pellet factory are given in next two

figures (Figure 3.5 andFigure 3.6). Also, similar industry can be made in city of Krievci near Ka-1.

Figure 3.5 Scheme of sawmill with ORC unit



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Figure 3.6 Scheme of pellet factory with ORC unit


There is second option for using of heat energy from geothermal well with combination of heat

energy from biomass. In that case have to be achieved goal state of wells shown in Table 3.2 and

Table 3.3 and then is not required heat pump. Instead of heat pump geothermal water is pumped

directly into heat exchanger with organic fluid. Then organic vapor condensate at low temperature

(below 80 C) and cannot be made district heating network.

3.2.1. Investment costs of combined geothermal and energy plant

Like in chapter3.1.1 precise investment cost of this plant is very difficult to give because there are a

lot of custom made parts so there are not standard prices. In this case is not required to build any

new drillholes except reinject drillhole, but significant costs are now biomass boiler and heat pump.

Table 3.6 Investment costs*

Mol-32 Ka-1

ORC unit with all associated parts 850,000.00 1,350,000.00

Biomass boiler with biomass storage and equipment 700,000.00 700,000.00

Reinject drillhole and completion production drillhole 1,200,000.00 1,200,000.00

Heat pump and required equipment 100,000.00 200,000.00

District heating system 30,000.00 150,000.00

Other expenses 300,000.00 300,000.00

Total expenses 3,180,000.00 3,900,000.00

*Estimated, without VAT


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4. Conclusion

ORC technology and its possibilities are quite unknown in Croatia so in first part of this paper

principles of technology and its main parts are presented. ORC systems powered by geothermal and

biomass energy are more detailed elaborated.

Further research of ORC technology is made based on two Croatian wells. Both wells have low

geothermal water temperature (about 60 C) and this is a big lack for ORC technology. Namely, forORC technology, temperature of geothermal water should be at least 100 C. Other problem is smallheat power of wells. Geothermal well with more power is more suitable for investment in ORC

system because payback period is shorter.

In this paper two different solutions are given, both based on increasing of temperature and heat

power. That can be achieved by drilling holes deeper or by including another source of energy like

biomass. Goal state of wells is geothermal water temperature of 100 C and overall heat powerabout 1,000 kW. Primary this heat power will be used for local buildings heating or potential industry

heating. Excess of heat energy will be introduced in ORC unit and it will serve for electric energyproduction. Simple scheme of whole system is shown on Figure 3.3. ORC unit will work with full

capacity in summer when building heating demands are low. In village of Molve good option is to

install ORC unit made only for electric energy production because nearby well has no serious heat

energy demands. Other solution is more complex and includes biomass boiler and heat pump.

Scheme of this system is given inFigure 3.4.In this case it is not necessary to make huge changes on

wells therefore heat pump and biomass boiler are included in system. Heat pump gives temperature

above lower limit for ORC system and biomass boiler increases thermal power of system.

Next step should be making of detail economic analysis of these projects, but it has to be said wells

Ka-1 and Mol-32 are not in optimal conditions for ORC technology. This is the main reason for high

investment costs shown in chapters 3.1.1 and 3.2.1.However, ORC technology has definitely hugepotential in Croatia because of renewable sources usage and high energy efficiency.


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5. Literature

Bini R., Di Prima M., Guercio A. (2010), Organic Rankine Cycle (ORC) in biomass plants: an overview

on different applications, available at:

http://www.turboden.eu/en/public/downloads/10A02943_paper_marco.pdf,Turboden Srl

Bian D. (2012), Optimization of middle-temperature waste heat utilization by means of ORCprocess, Thesis, Faculty of Engineering Rijeka

Bundesverband Geothermie, The Altheim Rankine cycle turbogenerator, available at:

http://www.geothermie.de/wissenswelt/archiv/englisch/the-altheim-rankine-cycle-

turbogenerator.html

Duvia A., Guercio A., Rossi di Schio C. (2009), Technical and economic aspects of Biomass fuelled CHP

plants based on ORC turbogenerators feeding existing district heating networks, available at:

http://www.turboden.eu/en/public/downloads/09A06400_paper_orc_turboden_clotilde.pdf,Turboden srl

Duvia A., Tavolo S. (2008),Application of ORC units in the pellet production field: technical-economic

considerations and overview of the operational results of an ORC plant in the industry installed in

Mudau (Germany), available at:

http://www.turboden.eu/en/public/downloads/Turboden_Paper_on_ORC_application_in_the_pelle

t_production.pdf,Turboden srl

EFLA Orkuverk Itd., (2009), Implementation of energy efficiency measures with district geothermal

heating in city of Krizevci, preliminary report

EIHP (2012), Razvojna studija i studija izvodljivosti grijanja javnih objekata geotermalnom energijom

u Gradu Krievcima, Zagreb

INA (2009), Izvjetaj o rezultatima proizvodnog ispitivanja i hidrodinamikog mjerenja u buotini

Krievanka-1 (Ka-1), SD Naftaplin, Sektor proizvodnje nafte i plina

INA (2005), Izvjee o obavljenim radovima na geotermalnoj buotini Molve-32, Sektro proizvodnje

nafte i plina, Okrug Podravina

Ministry of Economy (2013); Pravilnik o istraivanju i eksploataciji mineralnih sirovina, Croatia

Peretti I. (2008),Application of ORC units in sawmills. technical-economic considerations, available at:

http://www.turboden.eu/en/public/downloads/08A03722_paper_turboden_segherie.pdf, Turboden

srl

Pernecker G., Uhlig S. (2002), Low-enthalpy power generation with ORC-turbogenerator the Altheim

project, Upper Austria

Turboden srl (2013), ORC Brochure, available at:

http://www.turboden.eu/en/public/downloads/ORC%20Brochure%20leaflet.pdf

Turboden srl (2013), The Company and the Geothermal Applications, available at:http://www.turboden.eu/en/public/downloads/12-COM.P-22-rev.9.pdf
http://www.turboden.eu/en/public/downloads/10A02943_paper_marco.pdfhttp://www.turboden.eu/en/public/downloads/10A02943_paper_marco.pdfhttp://www.geothermie.de/wissenswelt/archiv/englisch/the-altheim-rankine-cycle-turbogenerator.htmlhttp://www.geothermie.de/wissenswelt/archiv/englisch/the-altheim-rankine-cycle-turbogenerator.htmlhttp://www.geothermie.de/wissenswelt/archiv/englisch/the-altheim-rankine-cycle-turbogenerator.htmlhttp://www.turboden.eu/en/public/downloads/09A06400_paper_orc_turboden_clotilde.pdfhttp://www.turboden.eu/en/public/downloads/09A06400_paper_orc_turboden_clotilde.pdfhttp://www.turboden.eu/en/public/downloads/Turboden_Paper_on_ORC_application_in_the_pellet_production.pdfhttp://www.turboden.eu/en/public/downloads/Turboden_Paper_on_ORC_application_in_the_pellet_production.pdfhttp://www.turboden.eu/en/public/downloads/Turboden_Paper_on_ORC_application_in_the_pellet_production.pdfhttp://www.turboden.eu/en/public/downloads/08A03722_paper_turboden_segherie.pdfhttp://www.turboden.eu/en/public/downloads/08A03722_paper_turboden_segherie.pdfhttp://www.turboden.eu/en/public/downloads/ORC%20Brochure%20leaflet.pdfhttp://www.turboden.eu/en/public/downloads/ORC%20Brochure%20leaflet.pdfhttp://www.turboden.eu/en/public/downloads/12-COM.P-22-rev.9.pdfhttp://www.turboden.eu/en/public/downloads/12-COM.P-22-rev.9.pdfhttp://www.turboden.eu/en/public/downloads/12-COM.P-22-rev.9.pdfhttp://www.turboden.eu/en/public/downloads/ORC%20Brochure%20leaflet.pdfhttp://www.turboden.eu/en/public/downloads/08A03722_paper_turboden_segherie.pdfhttp://www.turboden.eu/en/public/downloads/Turboden_Paper_on_ORC_application_in_the_pellet_production.pdfhttp://www.turboden.eu/en/public/downloads/Turboden_Paper_on_ORC_application_in_the_pellet_production.pdfhttp://www.turboden.eu/en/public/downloads/09A06400_paper_orc_turboden_clotilde.pdfhttp://www.geothermie.de/wissenswelt/archiv/englisch/the-altheim-rankine-cycle-turbogenerator.htmlhttp://www.geothermie.de/wissenswelt/archiv/englisch/the-altheim-rankine-cycle-turbogenerator.htmlhttp://www.turboden.eu/en/public/downloads/10A02943_paper_marco.pdf


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Turboden srl (2013), Turboden Biomass solutions, available at:

http://www.turboden.eu/en/public/downloads/12-COM.P-18-rev.8.pdf

Valdimarsson P. (2011), Short Course on Geothermal Drilling, Resource Development and Power

Plants,organized by UNU-GTP and LaGeo, in Santa Tecla, El Salvador, January 16-22, University ofIceland
http://www.turboden.eu/en/public/downloads/12-COM.P-18-rev.8.pdfhttp://www.turboden.eu/en/public/downloads/12-COM.P-18-rev.8.pdfhttp://www.turboden.eu/en/public/downloads/12-COM.P-18-rev.8.pdf

orc analysis

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