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GIS-based analysis of hydrogen production from geothermal electricity using CO2 as working fluid in Algeria
i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y x x x ( 2 0 1 5 ) 1 e1 0
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GIS-based analysis of hydrogen production from geothermal electricity using CO2 as working fluid in Algeria Abderrahmane Gouareh a,*, Noureddine Settou b, Ali Khalfi a, Bakhta Recioui a, Belkhir Negrou b, Soumia Rahmouni b, Boubekeur Dokkar b Univ Sidi Bel Abbes, Fac. Technology, Dept. Mechanical Engineering, Lab. Materiaux et Systemes Reactifs (LMSR), BP89, Sidi Bel Abbes 22000, Algeria b Univ Ouargla, Fac. Des sciences appliquees, Lab. Promotion et valorisation des ressources sahariennes, Ouargla 30000, Algeria a
article info
abstract
Article history:
Large reductions in carbon dioxide (CO2) emissions are needed to mitigate the impacts of
Received 11 January 2015
climate change. Electric power plants and refineries were the largest CO2 emission sources
Received in revised form
in Algeria. One option to reduce CO2 emissions is carbon dioxide capture and storage (CCS),
11 May 2015
which can be used to generate electricity with processes of geothermal heat extraction.
Accepted 15 May 2015
The objective of this study is to analyse the spatial distribution of CO2 emission sources,
Available online xxx
and to identify the most suitable locations for integrating this technology. For these suitable locations, dioxide carbon emissions were quantified. This quantification is used to
Keywords:
evaluate the potential for both electric and hydrogen production and to estimate the lev-
Hydrogen production
elized cost of electrolytic hydrogen. For this reason, Geographical Information System (GIS)
Geothermal energy
based methodology with combining several criteria is used. These criteria include spatially
Electricity production
varied CO2 emission sources, potential geothermic and demand of electrical energy
CO2
(considering the existing production sources and the consumption of electrical energy for
GIS
each city). GIS is used for creating new multi-layer information. It also offers a highly
Algeria
flexible, easily updateable database and display tool that facilitates the spatial analyses. As a result, the most suitable areas were located extensively in northeast and southwest part of Algeria. The northeast site was characterised by geothermal gradient of 6 C/100 m and has the most important electric and hydrogen potential, while in the second site the electric and hydrogen production is low than the first. In addition, the cost of hydrogen production at the northeast site is more competitive. Copyright © 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
* Corresponding author. Tel.: þ213 697290606. E-mail address: [email protected] (A. Gouareh). http://dx.doi.org/10.1016/j.ijhydene.2015.05.105 0360-3199/Copyright © 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: Gouareh A, et al., GIS-based analysis of hydrogen production from geothermal electricity using CO2 as working fluid in Algeria, International Journal of Hydrogen Energy (2015), http://dx.doi.org/10.1016/ j.ijhydene.2015.05.105
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Introduction Energy is a key element required for sustainable development and prosperity of a society [1]. Around 80% of the world's primary energy comes from fossil fuels [2]. The combustion of fossil fuels for power generation is one of the most important sources of global carbon dioxide emissions. Power plants contribute to over 37% of the worldwide CO2 emissions [3]. Algeria's energy sector was responsible for 123.47 thousand metric tons of carbon dioxide emissions during 2011 [4], with 20% of that figure coming from the refineries by production, processing and transport of hydrocarbons, and 47% from the electricity generation [5]. Currently, more than 99% of Algeria's electricity generation comes from fossil-fuel sources [6], the remaining share 0.8% comes from renewable energies and in particular hydropower. Over 98% of the electricity production is based on natural gas [7], which has detrimental impacts on the environment. Algeria generated 56.16 TWh of power in 2013 that is an evolution rate of 4.1% compared to 2012 [8]. This rise of electricity production is due to population growth and the increase in energy requirement. The electrical energy consumption and population in Algeria from 1980 to 2013 are illustrated in Fig. 1, where the number of population reached from 19.5 million in 1980 to 39.31million in the year 2013, while the electricity consumption reached 45.05 TWh in 2013 from 5.39 TWh in 1980. The above increases can be attributed to rapid growth in residential, commercial, and industrial sectors. This reflects a rise in CO2 emissions in a long-term; the increase requirements for climate protection are a great challenge for the power producers. Currently, there is also a strong policy (as required by the Kyoto Protocol signed on December 1997) [9] that is required in the global, national and regional level. This policy addresses the effects of energy based Greenhouse Gas (GHG), particularly CO2 emissions, as it relate to global warming and climate change [10]. With the decrease in the amount of fossil fuels, such as oil and gas and the increasing concerns over the environmental problems they cause. It is essential to find out new energy solutions that can help reduce GHG emissions and replace these fuels as soon as possible [11]. Renewable energy resources will be the
most attractive alternative resources [12]. Many governments and researchers around the world have lanced many researches to develop secure and environmental friendly resources. Thus to achieve the global drivers for a sustainable vision of our future energy market. Hydrogen appears to be one of the most effective solutions and it can play an important role in providing better environment and sustainability [13] if it is produced through renewable energy sources. Many research studies e.g, [14,15] have reported the water electrolysis process for hydrogen's potential production from renewable energy resources, such as solar and wind. Geothermal based hydrogen production and heat generation using different technologies have suggested and investigated in various studies e.g, Refs. [11e16]. Hydrogen production from CO2-based geothermal systems through water electrolysis [17] have expounded on a few papers, the process consists of taking CO2 from large stationary sources and stores it in deep geological layers to prevent its release into the atmosphere. The sequestration of carbon is applied in the electricity generation; this electricity could then be used for hydrogen production using water electrolysis [9]. Chennouf et al. [18] have estimated geothermal electricity production using carbon dioxide as working fluid in the south of Algeria the result show that an important electrical energy can be produced; the electricity generated can then be used for hydrogen production. As continuity of this work, Rahmouni et al. [9] studied a technical, economic and environmental analysis of combining geothermal energy with carbon sequestration for hydrogen production in In Salah region (south of Algeria) where the process has a good potential for geothermal hydrogen production. Other report of Rahmouni et al. [19] investigate the system of hydrogen production through water electrolysis using different renewable energy sources (solar PV, solar chimney power plant (SCPP) and geothermal energy), a technical and economic analysis of hydrogen production was conducted in this study, the result showed a high potential hydrogen in the studied region, where the geothermal based hydrogen station is classified in the second place after SCPP according to the high cost of electrolytic hydrogen. The aim of our study is to analyse the spatial distribution of CO2 emission sources, and identification of the most suitable locations to integrate carbon dioxide capture and storage (CCS) by using geographical information system. For these locations, dioxide carbon emissions are quantified in order to evaluate the potential for both electric and hydrogen production and to estimate the cost of electrolytic hydrogen.
Energy supplies of Algeria
Fig. 1 e Electricity consumption and population growth in Algeria from 1980 to 2013.
Algeria is the largest natural gas producer and second largest oil producer, after Nigeria, in Africa. It became a member of the Organization of the Petroleum Exporting Countries (OPEC) in 1969 [6]. Algeria's proven gas reserves were estimated at about 4.5 billion cubic metre in 2012. According to the BP statistical 2012 [20], Algeria's oil reserves amounted to 12.2 billion barrels by January 2012. It was the third-largest oil reserves in Africa (after Libya and Nigeria). These reserves are mainly in the south-eastern part of the country, particularly in Hassi Messaoud Basin, with over 60% of Algeria's proven
Please cite this article in press as: Gouareh A, et al., GIS-based analysis of hydrogen production from geothermal electricity using CO2 as working fluid in Algeria, International Journal of Hydrogen Energy (2015), http://dx.doi.org/10.1016/ j.ijhydene.2015.05.105
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reserves and Ourhoud field which is located in the Berkine Basin and it is the second-largest oil field after Hassi Messaoud Basin in Algeria [21].
Electricity generation in Algeria The global energy consumption is likely to grow faster than the population growth across the world. Like any other energy sectors, electricity demand has significantly increased in Algeria over the past years. Algeria's total installed power capacity and electricity production in 2013 reached the levels of 14.95 GW and 56.16 TWh respectively [22]. Through a large interconnected system in the north of the country and some isolated grids in the South, 99% of its population was connected to electricity at the end of 2013 [23]. At present, most of Algerian power plants are using nonrenewable sources such as natural gas, fuel oil to generate electricity. The important Algerian power plants are located in the north of Algeria and distributed over three poles; Eastern, Western and Centre, presented in a descending order of capacity. In the south, there is a low installed capacity that uses diesel generators. Currently, gas turbine power plants (GT) without steam cycle are the major technology used to generate electricity in the country. This type of power plants in Algeria has 6727.5 MW total capacity and produce 45% of total electricity generated. Steam power plants (ST) have 2990 MW, equivalent to 20% of total nominal capacities. 32% for a combined cycle power plant (CC) with a capacity of 4784 MW and diesel engine power plants also uses to electrified houses for remote areas in the county. Today diesel engine power plants represent 1% of the total installed capacity [8]. The remaining share 2% that comes from hydropower and hybrid station, as it is presented in Fig. 2. The hybrid solar-gas power station of Hassi R'mel is the first integrated solar combined cycle power station in Algeria (established in July 2011). It is situated in the south of Algeria around 531 km away from the capital Algiers, with a total power capacity of 150 MW. The plant combines a 25 MW
Fig. 2 e Electricity production by technology in Algeria for 2013, [23].
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parabolic trough concentrating solar power array, covering an area of over 180,000 m2, in conjunction with a 125 MW combined cycle gas turbine plant [24]. The plant contributes to around 1% of Algeria's total installed power capacity (Fig. 2) and it can reduce reliance on fossil fuels as well as greenhouse gas emissions. In order to diversify electricity production system and contribute to sustainable development, the Algerian government is trying to harness the enormous renewable energy potential. In 2011, an ambitious renewable energy and energy efficiency program was adopted. The Minister of Energy and Mines (MEM) [8] aims to achieve 40% of national electricity production from renewable energy sources by 2030 [25]. The program consists of generating 22,000 MW of power from renewable sources, 12,000 MW will be meant for domestic consumption and leave the amount of (10,000 MW) for exportation. Around 60 solar photovoltaic plants, concentrating solar power plants, wind farms as well as hybrid power plants are to be constructed between 2011 and 2030, as presented in Fig. 3. In addition to Hassi R'mel station, many other projects are under implementation such as wind farm of Adrar (located in the southwest of Algeria, around 1431 Km away from the capital) with a total capacity of 10 MW in 2013, electrification of 16 villages with individual PV kits, with a total capacity of 5 MW. Local fabrication of PV modules with a total production capacity of 116 MWp/year started in 2014 [26]. Algeria's renewable energy program is one of the most progressive in the MENA region and the government is making all efforts to secure investments and reliable technology partners for ongoing and upcoming projects. It is expected that the country will emerge as a major player in international renewable energy in the future.
Electric power plants and refineries emissions In general, thermal power plants operated by fossil fuels produce huge amounts of air pollutants. The pollutants
Fig. 3 e Contribution of renewable energy by type from 2011 to 2030.
Please cite this article in press as: Gouareh A, et al., GIS-based analysis of hydrogen production from geothermal electricity using CO2 as working fluid in Algeria, International Journal of Hydrogen Energy (2015), http://dx.doi.org/10.1016/ j.ijhydene.2015.05.105
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Table 1 e Refineries and electric power plants emissions for each technology in 2011.
Materials and methods
Sources
Site description (Algeria)
Refineries Electric power plants
Industrial power plants Total
Technology e CC GT ST e
Units Emission number (MtCO2/year) 6 4 29 6 15 45
7.34 13.86 6.8 7.4 0.5 35.9
considered in this study are carbon dioxide (CO2). The majority of energy sources used in Algerian power plants is fossil fuels. Based on data presented in Ref. [27], the total emission due to electricity generation is estimated. The total CO2 emissions of electric power plants are illustrated in Table 1. Algeria has six refineries with a combined processing capacity of 30.69 million tones/year. The major refinery is of Skikda (in the north east of Algeria, around 469 km away from the capital) with a capacity of 16.5 million tones/year, and the small one is the refinery of Adrar with capacity of 0.6 million tones/year. The total CO2 emissions of these refineries are shown in Table 1. A major development program was initiated to increase the capacity of the refineries by constructing five new refineries with a total capacity of 30 million tones/year, (four refineries with a processing capacity of 5 million tons/ year and a refinery with a heavy crude processing capacity of 10 million tons/year). This development program will boost its crude processing capacity of 30.69 million tons/year at present to 60 million tons/year in long term [8].
Geothermal energy potential and its usage in Algeria Algeria is divided into two regions by the South Atlas Fault with Alpine in the north and the Saharan Platform in the south [28]. The geothermal resources are of low-enthalpy type [25], more than 200 hot springs mainly located in the NorthEast and the North-West regions of the country. The onethird's temperatures of these springs are superior to 45 C [28]. Where the natural out flow of the existing reservoirs is over 2 m3/s. This represents only a very small part of the production possibilities of the reservoirs. Deeper in the South, geothermal reservoir called the albian platform is found at 1000e2700 m depth [29], the hot water of this reservoir has an average temperature of 57 C [28]. The northeastern zone of the country, covering an area of 15,000 km2, remains potentially the most interesting geothermal area, where the temperature reach 98 C at Hammam Meskhoutine, 68 C for the western area, 80 C for the central area [29]. With a large potential for low-geothermal temperature, the existing resources such as thermal springs and wells are used only for space heating like greenhouse heating at Hammam Maskhoutine, Touggourt and Ghardaia. A residential heating system, fed by 69 C geothermal water, is also planned for Hammam Righa. There are non-electric applications of geothermal heat. In spite of that, a project was envisaged for installation of a small power plant in the Bouhadjar zone, in the east of Algeria [28].
Algeria is geographically situated in northern Africa, between the 35 and 38 north latitudes and 8 and 12 east longitudes, bordering the Mediterranean Sea, between Morocco and Tunisia (see Fig. 4), and it is the largest country of Africa with 2,381,741 km2 [28] and a population of 39.31million of inhabitants in 2013 [4].
Data collection and assumptions Data required for input into the GIS model depend on data source and its availability; it can be collected from different sources. Table 2 illustrates the type of data, which has been collected. In this study, three criteria were selected for evaluating the most suitable locations, in the first step, maps and data sets (Administrative division of the case study, spatially varied of CO2 emission sources, geothermal potential, electrical energy demand) of study area were prepared based on different sources, administrative division of the country is prepared in Arc-map basing in ESRI world map, CO2 emission sources were prepared based on the data collected from CARMA site prepared in excel table, then added as XY Data to Arcgis, potential geothermic maps were digitized and converted to raster and vector files. All of the digitization, conversion and analysis processes of the maps were performed using GIS software; Arc GIS Desktop 9.3 (see Fig. 5).
Criteria description The following factors were considered in the site selection for electricity geothermal generation process for this study: emitted quantity of CO2, the availability of important geothermic gradient and the need for electrical energy. Each criterion is explained below.
Fig. 4 e The geographical position of study site.
Please cite this article in press as: Gouareh A, et al., GIS-based analysis of hydrogen production from geothermal electricity using CO2 as working fluid in Algeria, International Journal of Hydrogen Energy (2015), http://dx.doi.org/10.1016/ j.ijhydene.2015.05.105
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Table 2 e Example of input data for Arc GIS. Data group Administrative division Major CO2 emission source Electrical energy demand Geothermal potential
Individual layers Cities Refineries Electric power plant Electricity production by city Electricity consumption by city Geothermic gradient
Type of data Vector Vector Vector Vector Vector Vector
polygon point point polygon polygon polygon
Data sources ESRI world map data with own processing in Arcgis 9.3 MEM and CARMA data with Own processing in Arcgis Sonelgaz data with own processing [8] Sonelgaz data with own processing [8] Data gathering from Ref. [29] and processing in Arcgis
Mapping of CO2 sources In order to visualize the spatial distribution of CO2 sources and their associated potential for electricity geothermal production, each power plant and Refinery was stored in a georeferenced database with attributes indicating the type of technology, annual capacity and quantity of CO2 emitted (Fig. 6).
The availability of important geothermic gradient The geothermic gradient is one of the important criteria to find the suitable location for integration of carbon dioxide utilization and storage technology. Based on geographical information system and data presented in Ref. [22] (which includes some thematic maps that show depth, temperature and geothermal gradient), digitalized map of geothermic gradient in Algeria is developed. Fig. 7 shows the distribution of geothermal gradient in Algeria.
Electrical energy demand The electrical energy demand for each city was presented by the difference between the total energy product by electric power plants located in a city and the electrical energy consumed there too. Fig. 8 illustrates the electrical energy demand for 48 cities in Algeria.
Fig. 6 e Map of large stationary point CO2 emission sources in Algeria.
Fig. 5 e Description of general methodology and case study. Please cite this article in press as: Gouareh A, et al., GIS-based analysis of hydrogen production from geothermal electricity using CO2 as working fluid in Algeria, International Journal of Hydrogen Energy (2015), http://dx.doi.org/10.1016/ j.ijhydene.2015.05.105
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Applying this methodology using available GIS data, exclusion criteria method and spatial analysis tools yielded two important zones presented in Fig. 9. The detailed information of resulting sites is shown in Table 3.
Estimation of hydrogen production from geothermal power plant Numerical simulation is used to estimate the potential of electric and hydrogen production for the two suitable locations. In this study, industrial system of hydrogen production is investigated. This system is mainly composed of two subsystems: the first is for electricity production and the second is an electrolysis system. Fig. 10 illustrates the schematic diagram of hydrogen production system.
Estimation of the electricity generation Fig. 7 e Map of distribution of geothermic gradient in Algeria.
Results and discussion Suitable locations for geothermal-based hydrogen production The most suitable location to integrate carbon dioxide utilization and storage technology was performed using the methodology and the GIS database outlined in this study.
There are many types of geothermal power plants that depend on the state of the fluid (steam or water) and its temperature [30]. In this study, our interest is to combine the geothermal energy extraction and CO2 sequestration to produce electricity (Fig. 11). The system pumps CO2 into geothermal reservoirs as depleted gas and oil fields or saline aquifers through an injection well, where the carbon dioxide is trapped in an existing geologic formation, heated and put under high pressures. The high temperature CO2 then rises through a recovery well to drive a turbine that is connected to a power generator. After passing through the turbine, the carbon dioxide is reinserted into the cycle, forming a closed-loop system [31]. The flowing equation Eq. (1) is used to calculate the total energy being extracted per year.
Fig. 8 e Map of electrical energy demand by cities. Please cite this article in press as: Gouareh A, et al., GIS-based analysis of hydrogen production from geothermal electricity using CO2 as working fluid in Algeria, International Journal of Hydrogen Energy (2015), http://dx.doi.org/10.1016/ j.ijhydene.2015.05.105
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Fig. 9 e The most suitable location.
Table 3 e The Detailed information of resulting sites. Zones Northeast zone Southwest zone
Sources of CO2
Production capacity (MW or Mt/year)
6 electric power plants 2 refineries 3 electric power plants One refinery
2703.4 21.5 238 0.6
EEGS ¼ QV $tf $ DT $Cpf
13.5 0.52
(1)
where EEGS [kWh] is the energy extracted per year, QV [m3/h] is the volumetric flow rate, tf [h] is the equivalent running hours, DT is the temperature difference between injected carbon dioxide and initial reservoir temperature and Cpf [kJ/m3K] is the volume related heat capacity working fluid. For the northeast zone 13.5 million tons per year of CO2 can be removed, compressed and injected at a depth of
Fig. 10 e Schematic diagram of hydrogen production system.
Quantity of CO2 (Mt/year) (Kg/s) 428 16.6
Geothermic gradient ( C/100 m)
Electrical energy demand in GWh
6 5.5
5243.1 871.8
2000 m [9]. The total amount of CO2 injected into the geothermal well is 428 kg/s. The thermal gradient in the geothermal well is assumed to be 60 C/km. For the Southwest zone, the total amount of CO2 that can be injected into the geothermal well is 16.6 kg/s and the thermal gradient in the geothermal well is assumed to be 55 C/km. Table 4 below illustrates the calorific, electric energy and the annual electrical energy produced by the system with a runtime of 7750 h per year for each zone.
Fig. 11 e System description.
Please cite this article in press as: Gouareh A, et al., GIS-based analysis of hydrogen production from geothermal electricity using CO2 as working fluid in Algeria, International Journal of Hydrogen Energy (2015), http://dx.doi.org/10.1016/ j.ijhydene.2015.05.105
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Table 4 e The calorific, electric capacity and annual electrical energy of resulting sites. Zones
Calorific capacity (MWth)
Electric capacity (MWe)
Annual electrical energy (GWh)
105.2 3.8
14.7 0.6
113.9 4.6
Northeast zone Southwest zone
Hydrogen production through electrolyser The electrolysis of water is one option to produce sustainable hydrogen, where the electricity generated by geothermal power plant is used to operate electrolyser to split the water molecules into their elements hydrogen and oxygen. The anode and the cathode reactions are described below: Anode 2OH /ð1=2Þ O2 þ H2 O þ 2e
(2)
Cathode 2 H2 O þ 2e / H2 þ 2OH
(3)
PT CATH2 ¼
t t¼0 ½CEL þ CEGS ð1 þ tÞ i PT h t t¼0 MH2 ;t ð1 þ tÞ
(5)
where t is the discount rate and sets as 6%, and T is the plant life time and sets as 50 years [9]. The equation terms are determined as below: Investment cost of electrolyser, CEL
With different kinds of water electrolyser, an alkaline electrolyser has been used in this case. Alkaline electrolyser is one of the easiest methods for hydrogen production, offering the advantage of simplicity. The challenges for widespread use of water electrolysis are to reduce energy consumption, cost and maintenance and to increase energy efficiency, safety, durability and reliability [17,32]. The hydrogen produced with high purity can then be used for later purposes. In this analysis, an electrolyser with power capacity of 52.5 kWh/kg is considered (which is equivalent to about 75% in efficiency) [9]. The computation of the hydrogen mass produced from geothermal energy is described as follows: MH2 ¼ EEL LHVH2 ¼ hEL $EEGS LHVH2
(4)
where EEL is the energy required for electrolyser and hEL is the efficiency of the electrolyser. The lower heating value LHV of the produced hydrogen is taken as 33.31 kWh/kg [9]. Based on numerical simulation, the results show that the hydrogen production for the Northeast zone is 3.4 Mkg/year, for the second zone in the Southwest part of the country the hydrogen production is less and it is 0.14 Mkg/year.
Economic analysis In order to evaluate the economic performance of geothermal based hydrogen system for the resulting locations. A technoeconomic model was developed by using the levelized cost of hydrogen production method [33]. The model equation is an evaluation of the total life cycle cost and total lifetime hydrogen production, considering the capital costs and any on-going costs associated with each component. The total cost of producing hydrogen ($/kg H2) is expressed with the following formula:
The total investment of electrolyser depends on the size of the hydrogen production facility. The electrolyser capital cost is determined by the required maximum hydrogen production rate, the effective electrolyser efficiency and the estimated specific capital cost per kWe at nominal production [34]. CEL ¼ CEL;u
MH2 KEL;th 8760 hEL
(6)
where CEL [$] is the capital cost of electrolyser, CEL,u [$/kWe] is the unit cost of electrolyser and kEl,th [kWh/kg] is the theoretical specific energy required by the electrolyser. In this study an electrolyser unit cost of 368 $/kWe is considered, which corresponds to target values established by Ref. [35]. The replacement costs and annual operating costs were assumed equal to 25% and 2%, respectively, of the first cells investment. Investment cost of geothermal power plant, CEGS The total capital cost of geothermal power plant with CO2 sequestration can be divided into many costs of capture, compression, pipeline transport, injection and storage of carbon dioxide (CO2) and the cost of the energy conversion system. The cost of the capture range from 15 to 75 $/tCO2 net captured from a coal or gas fired power plant and from 25 to 115 $/tCO2 net captured from other industrial sources. The injection equipment costs include supply wells, plants, distribution lines and electrical services. The O&M costs include normal daily expenses, and surface and subsurface maintenance costs. The annual operating cost of the sequestration project can be approximated at 5e10% of the total capital cost [36,37]. The cost of the energy conversion system is estimated from Ref. [38]. Eq. (7) has been formed to calculate the price per kWe, which is formed using turbines up to 20 MW. While this
Table 5 e The detailed cost of the installation. Zones Northeast Southwest
Geothermal system cost, M$
Electrolyser cost, M$
Installation (geothermic/H2) cost, M$
LEC,$/kWhe
Hydrogen cost, $/kg
167.7 14.57
21.2 0.873
188.9 15.45
0.107 0.235
4.679 8.706
Please cite this article in press as: Gouareh A, et al., GIS-based analysis of hydrogen production from geothermal electricity using CO2 as working fluid in Algeria, International Journal of Hydrogen Energy (2015), http://dx.doi.org/10.1016/ j.ijhydene.2015.05.105
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data contains only prices for gas turbines it is assumed that carbon dioxide turbines have similar costs. CPCU ¼ 0; 0004 kWe þ 0; 4137
(7)
The denominator of the function (5) is the annual net hydrogen production (kgH2/year). The detailed costs of the installation are presented in Table 5. The results show that more than 90% of the cost is from the cost of the electricity needed and all the costs of electrolyser account less than12% of the hydrogen production cost. The hydrogen cost for the Northeast zone is 4.7 $/kgH2 and the hydrogen cost for the Southwest zone represents the double of the first with 8.7 $/kgH2.
Conclusion In this study the Geographical Information System (GIS) based methodology, combining several criteria was used to analyse the spatial distribution of CO2 emission sources, and identification of the most suitable locations to integrate geothermal heat extraction processes. Production of hydrogen from geothermal energy with capture and sequestration of CO2 offers a route toward near zero emissions in production. In the present study, two suitable locations resulted where the potential of power and hydrogen production from geothermal energy using carbon dioxide as working fluid coupled with electrolysis system were estimated for each location. Based on Numerical simulation the results presented in this paper confirm that the installation is capable to produce about 3.4 million kg/year of electrolytic hydrogen for the geothermal source of carbon dioxide mass flow rate of 428 kg/s and the thermal gradient equals 60 C/km in the northeast zone. For the second zone in the southwest part of the country, the hydrogen production is less and it has 0.14 million kg/year. The estimated cost of hydrogen is 4.7 $/kgH2 in northeast location and almost double cost in the southwest (8.7 $/kgH2). There is a clear evidence that geothermal based hydrogen production system is one of the most environmentally forms of energy available. It should be given much higher priority for future hydrogen production. The results of evaluating the technical hydrogen production potential showed a high potential of hydrogen in the northeast region, where the application should be considered. The results of a cost analysis have indicated that the electricity costs contributes significantly to the total project investment and have a major impact on the produced hydrogen price via water electrolysis process. The conclusion is that even stronger development of renewable energies would be required in the future to satisfy both electricity and hydrogen production and contribute as an opportunity to support economic growth and energetic transition in Algeria.
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[2] Boudghene Stambouli A, Khiat Z, Flazi S, Kitamura Y. A review on the renewable energy development in Algeria: current perspective, energy scenario and sustainability issues. Renew Sustain Energy Rev 2012;16:4445e60. [3] World Nuclear Association Report. Comparison of lifecycle greenhouse gas emissions of various electricity generation sources. July 2011. [4] The World Bank, http://data.worldbank.org, accessed December.2014. [5] Projet 00039149/GEF/PNUD. Inventaire national des missions de gaz a effet de serre. Fe vrier 2010:38. e [6] Report Algeria. U.S. energy information administration. May 2013. [7] Bulletin N 19 research and development. Systems integration renewable sources energy for electricity generation in Algeria. 2011. [8] Ministry of Energy and Mines (MEM), http://www.memalgeria.org, accessed December 2014. [9] Rahmouni S, Settou N, Chennouf N, Negrou B, Houari M. A technical, economic and environmental analysis of combining geothermal energy with carbon sequestration for hydrogen production. Energy Proc 2014;50:263e9. [10] Kurka T, Jefferies C, Blackwood D. GIS-based location suitability of decentralized, medium scale bioenergy developments to estimate transport CO2 emissions and costs. Biomass Bioenergy 2012;46:366e79. [11] Tolga Balta M, Dincer I, Hepbasli A. Potential methods for geothermal-based hydrogen production. Int J Hydrogen Energy 2010;35:4949e61. [12] Kanoglu M, Bolatturk A, Yilmaz C. Thermodynamic analysis of models used in hydrogen production by geothermal energy. Int J Hydrogen Energy 2010;35:8783e91. [13] Dincer I. Green methods for hydrogen production. Int J Hydrogen Energy 2012;37:1954e71. [14] Gibson TL, Kelly NA. Optimization of solar powered hydrogen production using photovoltaic electrolysis devices. Int J Hydrogen Energy 2008;33:5931e40. [15] Zhifanga S, Shijieb F, Cunman Z. Wind farm combined with hydrogen production system evaluation. Energy Proc 2012;14:160e6. [16] Tolga Balta M, Dincer I, Hepbasli A. Thermodynamic assessment of geothermal energy use in hydrogen production. Int J Hydrogen Energy 2009;34:2925e39. [17] AlZaharani A, Dincer I, Naterer GF. Performance evaluation of a geothermal based integrated system for power, hydrogen and heat generation. Int J Hydrogen Energy 2013;38:14505e11. [18] Chennouf N, Negrou B, Dokkar B, Settou N. Valuation and estimation of geothermal electricity production using carbon dioxide as working fluid in the south of Algeria. Energy Proc 2013;36:967e76. [19] Rahmouni S, Settou N, Negrou B, Chennouf N, Ghedamsi R. Prospects and analysis of hydrogen production from renewable electricity sources in Algeria. In: Progress in Clean Energyvol. 2. Switzerland: Springer International Publishing; 2015. [20] BP Statistical Review of World Energy June 2013, http://www. bp.com/statisticalreview, accessed December 2014. [21] Hafner M, Tagliapietra S, Elandaloussi EH. Outlook for oil and gas in Southern and Eastern Mediterranean ountries. MEDPRO technical report no. 18. October 2012. se des bilans d’activite s et Comptes [22] Mekideche MA. Synthe s 2013 des socie te s du Groupe Sonelgaz sociaux consolide Juin. 2014. Newsletter presse n 29. [23] Michaut S. Market analysis for gas engine technology in Algeria. KTH School of Industrial Engineering and Management; 2013. 06e04.
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[24] Mahmah B, Harouadi F, Benmoussa H, Chader S, Belhamel M, M'Raoui A, et al. MedHySol: future federator project of massive production of solar hydrogen. Int J Hydrogen Energy 2009;34:4922e33. nergies renouvelables. [25] Report 2011, Observatoire des e [26] Renewable Energies Development Centre (CDER), http:// portail.cder.dz/spip.php?article4343, accessed December 2014. [27] Carbon Monitoring for Action (CARMA), http://carma.org, accessed December 2014. [28] Himri Y, Malik AS, Boudghene Stambouli A, Himri S, Draoui B. Review and use of the Algerian renewable energy for sustainable development. Renew Sustain Energy Rev 2008;13:1584e91. [29] Kedaid F. Database on the geothermal resources of Algeria. Geothermics 2007;36:265e75. [30] Gallup DL. Production engineering in geothermal technology: a review. Geothermics 2009;38:326e34. [31] Randolph JB, Saar MO. Coupling carbon dioxide sequestration with geothermal energy capture in naturally permeable, porous geologic formations: implications for CO2 sequestration. Energy Proc 2011;4:2206e13.
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GIS-based analysis of hydrogen production from geothermal electricity using CO2 as working fluid in Algeria Abderrahmane Gouareh a,*, Noureddine Settou b, Ali Khalfi a, Bakhta Recioui a, Belkhir Negrou b, Soumia Rahmouni b, Boubekeur Dokkar b Univ Sidi Bel Abbes, Fac. Technology, Dept. Mechanical Engineering, Lab. Materiaux et Systemes Reactifs (LMSR), BP89, Sidi Bel Abbes 22000, Algeria b Univ Ouargla, Fac. Des sciences appliquees, Lab. Promotion et valorisation des ressources sahariennes, Ouargla 30000, Algeria a
article info
abstract
Article history:
Large reductions in carbon dioxide (CO2) emissions are needed to mitigate the impacts of
Received 11 January 2015
climate change. Electric power plants and refineries were the largest CO2 emission sources
Received in revised form
in Algeria. One option to reduce CO2 emissions is carbon dioxide capture and storage (CCS),
11 May 2015
which can be used to generate electricity with processes of geothermal heat extraction.
Accepted 15 May 2015
The objective of this study is to analyse the spatial distribution of CO2 emission sources,
Available online xxx
and to identify the most suitable locations for integrating this technology. For these suitable locations, dioxide carbon emissions were quantified. This quantification is used to
Keywords:
evaluate the potential for both electric and hydrogen production and to estimate the lev-
Hydrogen production
elized cost of electrolytic hydrogen. For this reason, Geographical Information System (GIS)
Geothermal energy
based methodology with combining several criteria is used. These criteria include spatially
Electricity production
varied CO2 emission sources, potential geothermic and demand of electrical energy
CO2
(considering the existing production sources and the consumption of electrical energy for
GIS
each city). GIS is used for creating new multi-layer information. It also offers a highly
Algeria
flexible, easily updateable database and display tool that facilitates the spatial analyses. As a result, the most suitable areas were located extensively in northeast and southwest part of Algeria. The northeast site was characterised by geothermal gradient of 6 C/100 m and has the most important electric and hydrogen potential, while in the second site the electric and hydrogen production is low than the first. In addition, the cost of hydrogen production at the northeast site is more competitive. Copyright © 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
* Corresponding author. Tel.: þ213 697290606. E-mail address: [email protected] (A. Gouareh). http://dx.doi.org/10.1016/j.ijhydene.2015.05.105 0360-3199/Copyright © 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
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Introduction Energy is a key element required for sustainable development and prosperity of a society [1]. Around 80% of the world's primary energy comes from fossil fuels [2]. The combustion of fossil fuels for power generation is one of the most important sources of global carbon dioxide emissions. Power plants contribute to over 37% of the worldwide CO2 emissions [3]. Algeria's energy sector was responsible for 123.47 thousand metric tons of carbon dioxide emissions during 2011 [4], with 20% of that figure coming from the refineries by production, processing and transport of hydrocarbons, and 47% from the electricity generation [5]. Currently, more than 99% of Algeria's electricity generation comes from fossil-fuel sources [6], the remaining share 0.8% comes from renewable energies and in particular hydropower. Over 98% of the electricity production is based on natural gas [7], which has detrimental impacts on the environment. Algeria generated 56.16 TWh of power in 2013 that is an evolution rate of 4.1% compared to 2012 [8]. This rise of electricity production is due to population growth and the increase in energy requirement. The electrical energy consumption and population in Algeria from 1980 to 2013 are illustrated in Fig. 1, where the number of population reached from 19.5 million in 1980 to 39.31million in the year 2013, while the electricity consumption reached 45.05 TWh in 2013 from 5.39 TWh in 1980. The above increases can be attributed to rapid growth in residential, commercial, and industrial sectors. This reflects a rise in CO2 emissions in a long-term; the increase requirements for climate protection are a great challenge for the power producers. Currently, there is also a strong policy (as required by the Kyoto Protocol signed on December 1997) [9] that is required in the global, national and regional level. This policy addresses the effects of energy based Greenhouse Gas (GHG), particularly CO2 emissions, as it relate to global warming and climate change [10]. With the decrease in the amount of fossil fuels, such as oil and gas and the increasing concerns over the environmental problems they cause. It is essential to find out new energy solutions that can help reduce GHG emissions and replace these fuels as soon as possible [11]. Renewable energy resources will be the
most attractive alternative resources [12]. Many governments and researchers around the world have lanced many researches to develop secure and environmental friendly resources. Thus to achieve the global drivers for a sustainable vision of our future energy market. Hydrogen appears to be one of the most effective solutions and it can play an important role in providing better environment and sustainability [13] if it is produced through renewable energy sources. Many research studies e.g, [14,15] have reported the water electrolysis process for hydrogen's potential production from renewable energy resources, such as solar and wind. Geothermal based hydrogen production and heat generation using different technologies have suggested and investigated in various studies e.g, Refs. [11e16]. Hydrogen production from CO2-based geothermal systems through water electrolysis [17] have expounded on a few papers, the process consists of taking CO2 from large stationary sources and stores it in deep geological layers to prevent its release into the atmosphere. The sequestration of carbon is applied in the electricity generation; this electricity could then be used for hydrogen production using water electrolysis [9]. Chennouf et al. [18] have estimated geothermal electricity production using carbon dioxide as working fluid in the south of Algeria the result show that an important electrical energy can be produced; the electricity generated can then be used for hydrogen production. As continuity of this work, Rahmouni et al. [9] studied a technical, economic and environmental analysis of combining geothermal energy with carbon sequestration for hydrogen production in In Salah region (south of Algeria) where the process has a good potential for geothermal hydrogen production. Other report of Rahmouni et al. [19] investigate the system of hydrogen production through water electrolysis using different renewable energy sources (solar PV, solar chimney power plant (SCPP) and geothermal energy), a technical and economic analysis of hydrogen production was conducted in this study, the result showed a high potential hydrogen in the studied region, where the geothermal based hydrogen station is classified in the second place after SCPP according to the high cost of electrolytic hydrogen. The aim of our study is to analyse the spatial distribution of CO2 emission sources, and identification of the most suitable locations to integrate carbon dioxide capture and storage (CCS) by using geographical information system. For these locations, dioxide carbon emissions are quantified in order to evaluate the potential for both electric and hydrogen production and to estimate the cost of electrolytic hydrogen.
Energy supplies of Algeria
Fig. 1 e Electricity consumption and population growth in Algeria from 1980 to 2013.
Algeria is the largest natural gas producer and second largest oil producer, after Nigeria, in Africa. It became a member of the Organization of the Petroleum Exporting Countries (OPEC) in 1969 [6]. Algeria's proven gas reserves were estimated at about 4.5 billion cubic metre in 2012. According to the BP statistical 2012 [20], Algeria's oil reserves amounted to 12.2 billion barrels by January 2012. It was the third-largest oil reserves in Africa (after Libya and Nigeria). These reserves are mainly in the south-eastern part of the country, particularly in Hassi Messaoud Basin, with over 60% of Algeria's proven
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reserves and Ourhoud field which is located in the Berkine Basin and it is the second-largest oil field after Hassi Messaoud Basin in Algeria [21].
Electricity generation in Algeria The global energy consumption is likely to grow faster than the population growth across the world. Like any other energy sectors, electricity demand has significantly increased in Algeria over the past years. Algeria's total installed power capacity and electricity production in 2013 reached the levels of 14.95 GW and 56.16 TWh respectively [22]. Through a large interconnected system in the north of the country and some isolated grids in the South, 99% of its population was connected to electricity at the end of 2013 [23]. At present, most of Algerian power plants are using nonrenewable sources such as natural gas, fuel oil to generate electricity. The important Algerian power plants are located in the north of Algeria and distributed over three poles; Eastern, Western and Centre, presented in a descending order of capacity. In the south, there is a low installed capacity that uses diesel generators. Currently, gas turbine power plants (GT) without steam cycle are the major technology used to generate electricity in the country. This type of power plants in Algeria has 6727.5 MW total capacity and produce 45% of total electricity generated. Steam power plants (ST) have 2990 MW, equivalent to 20% of total nominal capacities. 32% for a combined cycle power plant (CC) with a capacity of 4784 MW and diesel engine power plants also uses to electrified houses for remote areas in the county. Today diesel engine power plants represent 1% of the total installed capacity [8]. The remaining share 2% that comes from hydropower and hybrid station, as it is presented in Fig. 2. The hybrid solar-gas power station of Hassi R'mel is the first integrated solar combined cycle power station in Algeria (established in July 2011). It is situated in the south of Algeria around 531 km away from the capital Algiers, with a total power capacity of 150 MW. The plant combines a 25 MW
Fig. 2 e Electricity production by technology in Algeria for 2013, [23].
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parabolic trough concentrating solar power array, covering an area of over 180,000 m2, in conjunction with a 125 MW combined cycle gas turbine plant [24]. The plant contributes to around 1% of Algeria's total installed power capacity (Fig. 2) and it can reduce reliance on fossil fuels as well as greenhouse gas emissions. In order to diversify electricity production system and contribute to sustainable development, the Algerian government is trying to harness the enormous renewable energy potential. In 2011, an ambitious renewable energy and energy efficiency program was adopted. The Minister of Energy and Mines (MEM) [8] aims to achieve 40% of national electricity production from renewable energy sources by 2030 [25]. The program consists of generating 22,000 MW of power from renewable sources, 12,000 MW will be meant for domestic consumption and leave the amount of (10,000 MW) for exportation. Around 60 solar photovoltaic plants, concentrating solar power plants, wind farms as well as hybrid power plants are to be constructed between 2011 and 2030, as presented in Fig. 3. In addition to Hassi R'mel station, many other projects are under implementation such as wind farm of Adrar (located in the southwest of Algeria, around 1431 Km away from the capital) with a total capacity of 10 MW in 2013, electrification of 16 villages with individual PV kits, with a total capacity of 5 MW. Local fabrication of PV modules with a total production capacity of 116 MWp/year started in 2014 [26]. Algeria's renewable energy program is one of the most progressive in the MENA region and the government is making all efforts to secure investments and reliable technology partners for ongoing and upcoming projects. It is expected that the country will emerge as a major player in international renewable energy in the future.
Electric power plants and refineries emissions In general, thermal power plants operated by fossil fuels produce huge amounts of air pollutants. The pollutants
Fig. 3 e Contribution of renewable energy by type from 2011 to 2030.
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Table 1 e Refineries and electric power plants emissions for each technology in 2011.
Materials and methods
Sources
Site description (Algeria)
Refineries Electric power plants
Industrial power plants Total
Technology e CC GT ST e
Units Emission number (MtCO2/year) 6 4 29 6 15 45
7.34 13.86 6.8 7.4 0.5 35.9
considered in this study are carbon dioxide (CO2). The majority of energy sources used in Algerian power plants is fossil fuels. Based on data presented in Ref. [27], the total emission due to electricity generation is estimated. The total CO2 emissions of electric power plants are illustrated in Table 1. Algeria has six refineries with a combined processing capacity of 30.69 million tones/year. The major refinery is of Skikda (in the north east of Algeria, around 469 km away from the capital) with a capacity of 16.5 million tones/year, and the small one is the refinery of Adrar with capacity of 0.6 million tones/year. The total CO2 emissions of these refineries are shown in Table 1. A major development program was initiated to increase the capacity of the refineries by constructing five new refineries with a total capacity of 30 million tones/year, (four refineries with a processing capacity of 5 million tons/ year and a refinery with a heavy crude processing capacity of 10 million tons/year). This development program will boost its crude processing capacity of 30.69 million tons/year at present to 60 million tons/year in long term [8].
Geothermal energy potential and its usage in Algeria Algeria is divided into two regions by the South Atlas Fault with Alpine in the north and the Saharan Platform in the south [28]. The geothermal resources are of low-enthalpy type [25], more than 200 hot springs mainly located in the NorthEast and the North-West regions of the country. The onethird's temperatures of these springs are superior to 45 C [28]. Where the natural out flow of the existing reservoirs is over 2 m3/s. This represents only a very small part of the production possibilities of the reservoirs. Deeper in the South, geothermal reservoir called the albian platform is found at 1000e2700 m depth [29], the hot water of this reservoir has an average temperature of 57 C [28]. The northeastern zone of the country, covering an area of 15,000 km2, remains potentially the most interesting geothermal area, where the temperature reach 98 C at Hammam Meskhoutine, 68 C for the western area, 80 C for the central area [29]. With a large potential for low-geothermal temperature, the existing resources such as thermal springs and wells are used only for space heating like greenhouse heating at Hammam Maskhoutine, Touggourt and Ghardaia. A residential heating system, fed by 69 C geothermal water, is also planned for Hammam Righa. There are non-electric applications of geothermal heat. In spite of that, a project was envisaged for installation of a small power plant in the Bouhadjar zone, in the east of Algeria [28].
Algeria is geographically situated in northern Africa, between the 35 and 38 north latitudes and 8 and 12 east longitudes, bordering the Mediterranean Sea, between Morocco and Tunisia (see Fig. 4), and it is the largest country of Africa with 2,381,741 km2 [28] and a population of 39.31million of inhabitants in 2013 [4].
Data collection and assumptions Data required for input into the GIS model depend on data source and its availability; it can be collected from different sources. Table 2 illustrates the type of data, which has been collected. In this study, three criteria were selected for evaluating the most suitable locations, in the first step, maps and data sets (Administrative division of the case study, spatially varied of CO2 emission sources, geothermal potential, electrical energy demand) of study area were prepared based on different sources, administrative division of the country is prepared in Arc-map basing in ESRI world map, CO2 emission sources were prepared based on the data collected from CARMA site prepared in excel table, then added as XY Data to Arcgis, potential geothermic maps were digitized and converted to raster and vector files. All of the digitization, conversion and analysis processes of the maps were performed using GIS software; Arc GIS Desktop 9.3 (see Fig. 5).
Criteria description The following factors were considered in the site selection for electricity geothermal generation process for this study: emitted quantity of CO2, the availability of important geothermic gradient and the need for electrical energy. Each criterion is explained below.
Fig. 4 e The geographical position of study site.
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Table 2 e Example of input data for Arc GIS. Data group Administrative division Major CO2 emission source Electrical energy demand Geothermal potential
Individual layers Cities Refineries Electric power plant Electricity production by city Electricity consumption by city Geothermic gradient
Type of data Vector Vector Vector Vector Vector Vector
polygon point point polygon polygon polygon
Data sources ESRI world map data with own processing in Arcgis 9.3 MEM and CARMA data with Own processing in Arcgis Sonelgaz data with own processing [8] Sonelgaz data with own processing [8] Data gathering from Ref. [29] and processing in Arcgis
Mapping of CO2 sources In order to visualize the spatial distribution of CO2 sources and their associated potential for electricity geothermal production, each power plant and Refinery was stored in a georeferenced database with attributes indicating the type of technology, annual capacity and quantity of CO2 emitted (Fig. 6).
The availability of important geothermic gradient The geothermic gradient is one of the important criteria to find the suitable location for integration of carbon dioxide utilization and storage technology. Based on geographical information system and data presented in Ref. [22] (which includes some thematic maps that show depth, temperature and geothermal gradient), digitalized map of geothermic gradient in Algeria is developed. Fig. 7 shows the distribution of geothermal gradient in Algeria.
Electrical energy demand The electrical energy demand for each city was presented by the difference between the total energy product by electric power plants located in a city and the electrical energy consumed there too. Fig. 8 illustrates the electrical energy demand for 48 cities in Algeria.
Fig. 6 e Map of large stationary point CO2 emission sources in Algeria.
Fig. 5 e Description of general methodology and case study. Please cite this article in press as: Gouareh A, et al., GIS-based analysis of hydrogen production from geothermal electricity using CO2 as working fluid in Algeria, International Journal of Hydrogen Energy (2015), http://dx.doi.org/10.1016/ j.ijhydene.2015.05.105
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Applying this methodology using available GIS data, exclusion criteria method and spatial analysis tools yielded two important zones presented in Fig. 9. The detailed information of resulting sites is shown in Table 3.
Estimation of hydrogen production from geothermal power plant Numerical simulation is used to estimate the potential of electric and hydrogen production for the two suitable locations. In this study, industrial system of hydrogen production is investigated. This system is mainly composed of two subsystems: the first is for electricity production and the second is an electrolysis system. Fig. 10 illustrates the schematic diagram of hydrogen production system.
Estimation of the electricity generation Fig. 7 e Map of distribution of geothermic gradient in Algeria.
Results and discussion Suitable locations for geothermal-based hydrogen production The most suitable location to integrate carbon dioxide utilization and storage technology was performed using the methodology and the GIS database outlined in this study.
There are many types of geothermal power plants that depend on the state of the fluid (steam or water) and its temperature [30]. In this study, our interest is to combine the geothermal energy extraction and CO2 sequestration to produce electricity (Fig. 11). The system pumps CO2 into geothermal reservoirs as depleted gas and oil fields or saline aquifers through an injection well, where the carbon dioxide is trapped in an existing geologic formation, heated and put under high pressures. The high temperature CO2 then rises through a recovery well to drive a turbine that is connected to a power generator. After passing through the turbine, the carbon dioxide is reinserted into the cycle, forming a closed-loop system [31]. The flowing equation Eq. (1) is used to calculate the total energy being extracted per year.
Fig. 8 e Map of electrical energy demand by cities. Please cite this article in press as: Gouareh A, et al., GIS-based analysis of hydrogen production from geothermal electricity using CO2 as working fluid in Algeria, International Journal of Hydrogen Energy (2015), http://dx.doi.org/10.1016/ j.ijhydene.2015.05.105
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Fig. 9 e The most suitable location.
Table 3 e The Detailed information of resulting sites. Zones Northeast zone Southwest zone
Sources of CO2
Production capacity (MW or Mt/year)
6 electric power plants 2 refineries 3 electric power plants One refinery
2703.4 21.5 238 0.6
EEGS ¼ QV $tf $ DT $Cpf
13.5 0.52
(1)
where EEGS [kWh] is the energy extracted per year, QV [m3/h] is the volumetric flow rate, tf [h] is the equivalent running hours, DT is the temperature difference between injected carbon dioxide and initial reservoir temperature and Cpf [kJ/m3K] is the volume related heat capacity working fluid. For the northeast zone 13.5 million tons per year of CO2 can be removed, compressed and injected at a depth of
Fig. 10 e Schematic diagram of hydrogen production system.
Quantity of CO2 (Mt/year) (Kg/s) 428 16.6
Geothermic gradient ( C/100 m)
Electrical energy demand in GWh
6 5.5
5243.1 871.8
2000 m [9]. The total amount of CO2 injected into the geothermal well is 428 kg/s. The thermal gradient in the geothermal well is assumed to be 60 C/km. For the Southwest zone, the total amount of CO2 that can be injected into the geothermal well is 16.6 kg/s and the thermal gradient in the geothermal well is assumed to be 55 C/km. Table 4 below illustrates the calorific, electric energy and the annual electrical energy produced by the system with a runtime of 7750 h per year for each zone.
Fig. 11 e System description.
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Table 4 e The calorific, electric capacity and annual electrical energy of resulting sites. Zones
Calorific capacity (MWth)
Electric capacity (MWe)
Annual electrical energy (GWh)
105.2 3.8
14.7 0.6
113.9 4.6
Northeast zone Southwest zone
Hydrogen production through electrolyser The electrolysis of water is one option to produce sustainable hydrogen, where the electricity generated by geothermal power plant is used to operate electrolyser to split the water molecules into their elements hydrogen and oxygen. The anode and the cathode reactions are described below: Anode 2OH /ð1=2Þ O2 þ H2 O þ 2e
(2)
Cathode 2 H2 O þ 2e / H2 þ 2OH
(3)
PT CATH2 ¼
t t¼0 ½CEL þ CEGS ð1 þ tÞ i PT h t t¼0 MH2 ;t ð1 þ tÞ
(5)
where t is the discount rate and sets as 6%, and T is the plant life time and sets as 50 years [9]. The equation terms are determined as below: Investment cost of electrolyser, CEL
With different kinds of water electrolyser, an alkaline electrolyser has been used in this case. Alkaline electrolyser is one of the easiest methods for hydrogen production, offering the advantage of simplicity. The challenges for widespread use of water electrolysis are to reduce energy consumption, cost and maintenance and to increase energy efficiency, safety, durability and reliability [17,32]. The hydrogen produced with high purity can then be used for later purposes. In this analysis, an electrolyser with power capacity of 52.5 kWh/kg is considered (which is equivalent to about 75% in efficiency) [9]. The computation of the hydrogen mass produced from geothermal energy is described as follows: MH2 ¼ EEL LHVH2 ¼ hEL $EEGS LHVH2
(4)
where EEL is the energy required for electrolyser and hEL is the efficiency of the electrolyser. The lower heating value LHV of the produced hydrogen is taken as 33.31 kWh/kg [9]. Based on numerical simulation, the results show that the hydrogen production for the Northeast zone is 3.4 Mkg/year, for the second zone in the Southwest part of the country the hydrogen production is less and it is 0.14 Mkg/year.
Economic analysis In order to evaluate the economic performance of geothermal based hydrogen system for the resulting locations. A technoeconomic model was developed by using the levelized cost of hydrogen production method [33]. The model equation is an evaluation of the total life cycle cost and total lifetime hydrogen production, considering the capital costs and any on-going costs associated with each component. The total cost of producing hydrogen ($/kg H2) is expressed with the following formula:
The total investment of electrolyser depends on the size of the hydrogen production facility. The electrolyser capital cost is determined by the required maximum hydrogen production rate, the effective electrolyser efficiency and the estimated specific capital cost per kWe at nominal production [34]. CEL ¼ CEL;u
MH2 KEL;th 8760 hEL
(6)
where CEL [$] is the capital cost of electrolyser, CEL,u [$/kWe] is the unit cost of electrolyser and kEl,th [kWh/kg] is the theoretical specific energy required by the electrolyser. In this study an electrolyser unit cost of 368 $/kWe is considered, which corresponds to target values established by Ref. [35]. The replacement costs and annual operating costs were assumed equal to 25% and 2%, respectively, of the first cells investment. Investment cost of geothermal power plant, CEGS The total capital cost of geothermal power plant with CO2 sequestration can be divided into many costs of capture, compression, pipeline transport, injection and storage of carbon dioxide (CO2) and the cost of the energy conversion system. The cost of the capture range from 15 to 75 $/tCO2 net captured from a coal or gas fired power plant and from 25 to 115 $/tCO2 net captured from other industrial sources. The injection equipment costs include supply wells, plants, distribution lines and electrical services. The O&M costs include normal daily expenses, and surface and subsurface maintenance costs. The annual operating cost of the sequestration project can be approximated at 5e10% of the total capital cost [36,37]. The cost of the energy conversion system is estimated from Ref. [38]. Eq. (7) has been formed to calculate the price per kWe, which is formed using turbines up to 20 MW. While this
Table 5 e The detailed cost of the installation. Zones Northeast Southwest
Geothermal system cost, M$
Electrolyser cost, M$
Installation (geothermic/H2) cost, M$
LEC,$/kWhe
Hydrogen cost, $/kg
167.7 14.57
21.2 0.873
188.9 15.45
0.107 0.235
4.679 8.706
Please cite this article in press as: Gouareh A, et al., GIS-based analysis of hydrogen production from geothermal electricity using CO2 as working fluid in Algeria, International Journal of Hydrogen Energy (2015), http://dx.doi.org/10.1016/ j.ijhydene.2015.05.105
i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y x x x ( 2 0 1 5 ) 1 e1 0
data contains only prices for gas turbines it is assumed that carbon dioxide turbines have similar costs. CPCU ¼ 0; 0004 kWe þ 0; 4137
(7)
The denominator of the function (5) is the annual net hydrogen production (kgH2/year). The detailed costs of the installation are presented in Table 5. The results show that more than 90% of the cost is from the cost of the electricity needed and all the costs of electrolyser account less than12% of the hydrogen production cost. The hydrogen cost for the Northeast zone is 4.7 $/kgH2 and the hydrogen cost for the Southwest zone represents the double of the first with 8.7 $/kgH2.
Conclusion In this study the Geographical Information System (GIS) based methodology, combining several criteria was used to analyse the spatial distribution of CO2 emission sources, and identification of the most suitable locations to integrate geothermal heat extraction processes. Production of hydrogen from geothermal energy with capture and sequestration of CO2 offers a route toward near zero emissions in production. In the present study, two suitable locations resulted where the potential of power and hydrogen production from geothermal energy using carbon dioxide as working fluid coupled with electrolysis system were estimated for each location. Based on Numerical simulation the results presented in this paper confirm that the installation is capable to produce about 3.4 million kg/year of electrolytic hydrogen for the geothermal source of carbon dioxide mass flow rate of 428 kg/s and the thermal gradient equals 60 C/km in the northeast zone. For the second zone in the southwest part of the country, the hydrogen production is less and it has 0.14 million kg/year. The estimated cost of hydrogen is 4.7 $/kgH2 in northeast location and almost double cost in the southwest (8.7 $/kgH2). There is a clear evidence that geothermal based hydrogen production system is one of the most environmentally forms of energy available. It should be given much higher priority for future hydrogen production. The results of evaluating the technical hydrogen production potential showed a high potential of hydrogen in the northeast region, where the application should be considered. The results of a cost analysis have indicated that the electricity costs contributes significantly to the total project investment and have a major impact on the produced hydrogen price via water electrolysis process. The conclusion is that even stronger development of renewable energies would be required in the future to satisfy both electricity and hydrogen production and contribute as an opportunity to support economic growth and energetic transition in Algeria.
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Please cite this article in press as: Gouareh A, et al., GIS-based analysis of hydrogen production from geothermal electricity using CO2 as working fluid in Algeria, International Journal of Hydrogen Energy (2015), http://dx.doi.org/10.1016/ j.ijhydene.2015.05.105