International Congress Energy and Environment 2006, 2006
Development trend of the energy sector nowadays are more and more under the strong influence of t... more Development trend of the energy sector nowadays are more and more under the strong influence of three kinds of problems: security of energy supply, unpredictability of energy market and influence of production and consumption of energy on the environment. In such conditions decentralized production of usable form of energy using primary renewable and unrenewable energy sources appears as one of the most important direction in the future. Regarding that in developed contries around 40 % of energy is used in households, 30% in transport and 30% in production, micro-cogeneration unit for households become more important. Micro-cogeneration unit is in fact made up of an assembly for production of usable form of heat (for example warm water or warm air) and an assembly for production of electric energy. Here, electric energy can be produced in different ways, for example by using a microturbine generator, Stirling´s engine generators, fuel cell systems etc. In this work there are two directions of the development of micro-cogeneration units shown, which comply with the definition of micro-CHP unit according to European cogeneration directive 2004/8/ES (electric power < 50 kW). The difference between described directions are made regarding primary energy, ie. CO2 emission: the first direction uses natural gas and during the work emits CO2, and the second direction uses solar energy and does not emit CO2 during the work. Within the first direction, only systems with fuel cells as generators of electric energy are considered. Concerning the type of fuel cell used, only PEMFC (polymer electrolyte fuel cell) and SOFC (solid oxide fuel cell) systems are considered. Within the second direction solar photovoltaic systems with cogeneration of heat are considered (solar photovoltaic/thermal or PV/T) which have the ability of using electrolyser/hydrogen storage/fuel cell subsystem as energy storage. A new concept of micro-cogeneration unit is also shown, the one which, besides the heat and electric energy for household usage, covers energy for driving the personel car, i.e. personal transport, so it should be called "micro-combined heat and power and transport unit". A review of efficiency of units of some leading producers according to mentioned directions is given. It is concluded that in transition period, when the prices of hydrocarbon fuels are still relatively low, efficiency of solar cells small, and lack of respect on restriction of CO2 emission is not sanctioned enough, development of micro-cogeneration units, based on fuel cells with natural gas as a fuel, dominates.
Within the next 10 to 20 years world and Croatian inland economy will be faced with the transitio... more Within the next 10 to 20 years world and Croatian inland economy will be faced with the transition from classic primary energy sources (as fossil fuels) to renewable energy sources, first of all wind and solar energy. At the same time scale, hydrogen as a new fuel will rise up to the stage. That is the reason why already today many people talk about forthcoming „ Hydrogen Economy", i.e. global hydrogen based economy. Anticipating forecasted development there is a question when and how will Croatia start to keep along with this global scenario? One of the possible answers to this question is discussed in the presented paper. It starts with the fact that Croatia is an important European tourist destination which is yearly visited by 10 millions, mostly motorized, foreign tourists. WTO, World Tourism Organization, predicts that foreign arrivals to Croatia will grow by 8.4% annually up to the year 2020. More than 90% of all foreign tourists spend their holidays on the Adriatic cost...
Round parabolic solar mirror is of ten called the solar or sun dish. Even when the dish is facete... more Round parabolic solar mirror is of ten called the solar or sun dish. Even when the dish is faceted into several smaller dishes (facets) which are all focusing the sunlight in the single point (focus), it is called a solar dish. When solar radiation to electricity converter is mounted into the dish focus and the sun-tracking system is provided, it could be named solar dish/converter system. Depending on the sort of the converter, two promising systems which are approaching the commercialization could be mentioned. These are solar dish/Sterling system and solar dish/photo voltaic system. In this paper, majority of the technical and economical aspects of the two systems are examined and compared. Two systems are chosen to represent this: SAIC/STM Sun Dish TM, solar dish with Sterling heat engine/generator, and Solar Systems SS20TM representing solar dish with concentrating photovoltaic converter. It is concluded that solar dish with concentrated photovoltaic converter can have much bet...
In investigation of different materials for electrodes used in electrolysers for hydrogen product... more In investigation of different materials for electrodes used in electrolysers for hydrogen production, nickel foam shows wide interests in hydrogen scientific community. This paper brings novel results of performed experiments on pure nickel foam and nickel foam silver coated. The electrochemical behavior of chosen material in high concentrated alkaline media was studied using potentiostatic and potentiodynamic DC and AC electrochemical methods: linear polarization, electrochemical impedance spectroscopy. It was shown that using silver coatings enable higher hydrogen generation. There is defined linear region of the hydrogen production with evidence that an increasing of the electrodes overvoltage decreases the resistance to the charge transfer.
ABSTRACT The paper describes a prototype of the membrane pressure gauge with optoelectronic conve... more ABSTRACT The paper describes a prototype of the membrane pressure gauge with optoelectronic conversion. The main parts of the system are a polished metal membrane of 8 mm diameter, plastic 3 m long optical fibers, and a box containing the optoelectronic components (laser diode module, photodetectors and operational amplifiers). Pressure changes causing membrane displacement modulate the laser beam conducted by the incoming optical-fiber. The modulated and reflected beam is conducted through two outgoing optical fibers to the optoelectronic assembly, where the ratio of the outputs from the two fibers is converted into a voltage proprotional to the pressure. The important influence of the arrangement of the fiber ending above the membrane has been investigated. By changing the environmental temperature for 20 s up to approximately 350 K the laser diode has been pointed out as, by far, to be the most responsible electronic part for output signal deviation. The calibration characteristics using a reference manometer in the range from 5 to 15.5 MPa were recorded.
The experimental research on hydrogen production by water electrochemical splitting is presented ... more The experimental research on hydrogen production by water electrochemical splitting is presented in the article. In the study low temperature electrolytic unit with 26 th % KOH liquid solution and small-scale photovoltaic module (PV-module) were used to convert solar energy into molecular hydrogen. Speeds and volumes of average monthly hydrogen production are defined for Kyiv insolation using experimental facilities. The method applied can be proposed to estimate hydrogen amount generated when combining the conventional electrolysis process and photovoltaic module for compensating the long term fluctuations of solar photovoltaics.
Croatian Solar House (CSH) is basically an energy-ecological project with the main goal reduction... more Croatian Solar House (CSH) is basically an energy-ecological project with the main goal reduction of energy consumption, its production by renewable energy sources, having as a consequence benefical lowering in CO2 emission. It follows the “ Green paper” of European Commission 2000, and its concept is in full accordance with current European trends, described in the program called “ Intelligent Energy for Europe” . As 32% of total final consumption in Croatia corresponds to households, they will be in focus of our interest. In this sense, we shall apply new approaches for energy efficiency in households (like in the European program SAVE) which can save substantially energy in our country. Additionally, in CSH we will also use new technologies for energy production, using renewable energy sources (as in the European program ALTENER), namely photovoltaic and renewable energy sources (based on our own patents) as well as hydrogen fuel cells (from electrolytic and/or reformed hydrogen)...
Izgrađen je eksperimentalni uređaj za istraživanje termohidraulicnih fenomena kod prisilnog dijab... more Izgrađen je eksperimentalni uređaj za istraživanje termohidraulicnih fenomena kod prisilnog dijabatskog dvofaznog strujanja vode. U osnovi, to je elektricno zagrijavana vertikalna isparivacka cijev duzine 1890 mm, vanjskog i unutrasnjeg promjera 10 i 7 mm. Moguc je radni tlak do 20 MPa, protok vode do 4*10-2 kg/s i radna temperatura stijenke do 650 °C. Maksimalna je elektricna snaga zagrijavanja 100 kW. Kompjutorski nadzirana mjerna centrala istovremeno prihvaca dvadesetcetiri temperature uzduž stijenke cijevi, tlak u sistemu, volumni protok, elektricnu snagu grijanja, ulaznu i izlaznu temperaturu radnog medija. Prikazano je i analizirano nekoliko scenarija postizanja krize kipljenja i promjene temperature uzduž stijenke cijevi, koja je njezina posljedica. Pomocu termoparova pricvrscenih u stijenci cijevi samo 1 mm od isparivacke povrsine detektirano je osciliranje tone isusenja po duzini cijevi. Posljedica su tog pomicanja gradijenti temperature stijenke kod hlađenja 700 °C/s i kod...
International Congress Energy and Environment 2006, 2006
Development trend of the energy sector nowadays are more and more under the strong influence of t... more Development trend of the energy sector nowadays are more and more under the strong influence of three kinds of problems: security of energy supply, unpredictability of energy market and influence of production and consumption of energy on the environment. In such conditions decentralized production of usable form of energy using primary renewable and unrenewable energy sources appears as one of the most important direction in the future. Regarding that in developed contries around 40 % of energy is used in households, 30% in transport and 30% in production, micro-cogeneration unit for households become more important. Micro-cogeneration unit is in fact made up of an assembly for production of usable form of heat (for example warm water or warm air) and an assembly for production of electric energy. Here, electric energy can be produced in different ways, for example by using a microturbine generator, Stirling´s engine generators, fuel cell systems etc. In this work there are two directions of the development of micro-cogeneration units shown, which comply with the definition of micro-CHP unit according to European cogeneration directive 2004/8/ES (electric power < 50 kW). The difference between described directions are made regarding primary energy, ie. CO2 emission: the first direction uses natural gas and during the work emits CO2, and the second direction uses solar energy and does not emit CO2 during the work. Within the first direction, only systems with fuel cells as generators of electric energy are considered. Concerning the type of fuel cell used, only PEMFC (polymer electrolyte fuel cell) and SOFC (solid oxide fuel cell) systems are considered. Within the second direction solar photovoltaic systems with cogeneration of heat are considered (solar photovoltaic/thermal or PV/T) which have the ability of using electrolyser/hydrogen storage/fuel cell subsystem as energy storage. A new concept of micro-cogeneration unit is also shown, the one which, besides the heat and electric energy for household usage, covers energy for driving the personel car, i.e. personal transport, so it should be called "micro-combined heat and power and transport unit". A review of efficiency of units of some leading producers according to mentioned directions is given. It is concluded that in transition period, when the prices of hydrocarbon fuels are still relatively low, efficiency of solar cells small, and lack of respect on restriction of CO2 emission is not sanctioned enough, development of micro-cogeneration units, based on fuel cells with natural gas as a fuel, dominates.
Within the next 10 to 20 years world and Croatian inland economy will be faced with the transitio... more Within the next 10 to 20 years world and Croatian inland economy will be faced with the transition from classic primary energy sources (as fossil fuels) to renewable energy sources, first of all wind and solar energy. At the same time scale, hydrogen as a new fuel will rise up to the stage. That is the reason why already today many people talk about forthcoming „ Hydrogen Economy", i.e. global hydrogen based economy. Anticipating forecasted development there is a question when and how will Croatia start to keep along with this global scenario? One of the possible answers to this question is discussed in the presented paper. It starts with the fact that Croatia is an important European tourist destination which is yearly visited by 10 millions, mostly motorized, foreign tourists. WTO, World Tourism Organization, predicts that foreign arrivals to Croatia will grow by 8.4% annually up to the year 2020. More than 90% of all foreign tourists spend their holidays on the Adriatic cost...
Round parabolic solar mirror is of ten called the solar or sun dish. Even when the dish is facete... more Round parabolic solar mirror is of ten called the solar or sun dish. Even when the dish is faceted into several smaller dishes (facets) which are all focusing the sunlight in the single point (focus), it is called a solar dish. When solar radiation to electricity converter is mounted into the dish focus and the sun-tracking system is provided, it could be named solar dish/converter system. Depending on the sort of the converter, two promising systems which are approaching the commercialization could be mentioned. These are solar dish/Sterling system and solar dish/photo voltaic system. In this paper, majority of the technical and economical aspects of the two systems are examined and compared. Two systems are chosen to represent this: SAIC/STM Sun Dish TM, solar dish with Sterling heat engine/generator, and Solar Systems SS20TM representing solar dish with concentrating photovoltaic converter. It is concluded that solar dish with concentrated photovoltaic converter can have much bet...
In investigation of different materials for electrodes used in electrolysers for hydrogen product... more In investigation of different materials for electrodes used in electrolysers for hydrogen production, nickel foam shows wide interests in hydrogen scientific community. This paper brings novel results of performed experiments on pure nickel foam and nickel foam silver coated. The electrochemical behavior of chosen material in high concentrated alkaline media was studied using potentiostatic and potentiodynamic DC and AC electrochemical methods: linear polarization, electrochemical impedance spectroscopy. It was shown that using silver coatings enable higher hydrogen generation. There is defined linear region of the hydrogen production with evidence that an increasing of the electrodes overvoltage decreases the resistance to the charge transfer.
ABSTRACT The paper describes a prototype of the membrane pressure gauge with optoelectronic conve... more ABSTRACT The paper describes a prototype of the membrane pressure gauge with optoelectronic conversion. The main parts of the system are a polished metal membrane of 8 mm diameter, plastic 3 m long optical fibers, and a box containing the optoelectronic components (laser diode module, photodetectors and operational amplifiers). Pressure changes causing membrane displacement modulate the laser beam conducted by the incoming optical-fiber. The modulated and reflected beam is conducted through two outgoing optical fibers to the optoelectronic assembly, where the ratio of the outputs from the two fibers is converted into a voltage proprotional to the pressure. The important influence of the arrangement of the fiber ending above the membrane has been investigated. By changing the environmental temperature for 20 s up to approximately 350 K the laser diode has been pointed out as, by far, to be the most responsible electronic part for output signal deviation. The calibration characteristics using a reference manometer in the range from 5 to 15.5 MPa were recorded.
The experimental research on hydrogen production by water electrochemical splitting is presented ... more The experimental research on hydrogen production by water electrochemical splitting is presented in the article. In the study low temperature electrolytic unit with 26 th % KOH liquid solution and small-scale photovoltaic module (PV-module) were used to convert solar energy into molecular hydrogen. Speeds and volumes of average monthly hydrogen production are defined for Kyiv insolation using experimental facilities. The method applied can be proposed to estimate hydrogen amount generated when combining the conventional electrolysis process and photovoltaic module for compensating the long term fluctuations of solar photovoltaics.
Croatian Solar House (CSH) is basically an energy-ecological project with the main goal reduction... more Croatian Solar House (CSH) is basically an energy-ecological project with the main goal reduction of energy consumption, its production by renewable energy sources, having as a consequence benefical lowering in CO2 emission. It follows the “ Green paper” of European Commission 2000, and its concept is in full accordance with current European trends, described in the program called “ Intelligent Energy for Europe” . As 32% of total final consumption in Croatia corresponds to households, they will be in focus of our interest. In this sense, we shall apply new approaches for energy efficiency in households (like in the European program SAVE) which can save substantially energy in our country. Additionally, in CSH we will also use new technologies for energy production, using renewable energy sources (as in the European program ALTENER), namely photovoltaic and renewable energy sources (based on our own patents) as well as hydrogen fuel cells (from electrolytic and/or reformed hydrogen)...
Izgrađen je eksperimentalni uređaj za istraživanje termohidraulicnih fenomena kod prisilnog dijab... more Izgrađen je eksperimentalni uređaj za istraživanje termohidraulicnih fenomena kod prisilnog dijabatskog dvofaznog strujanja vode. U osnovi, to je elektricno zagrijavana vertikalna isparivacka cijev duzine 1890 mm, vanjskog i unutrasnjeg promjera 10 i 7 mm. Moguc je radni tlak do 20 MPa, protok vode do 4*10-2 kg/s i radna temperatura stijenke do 650 °C. Maksimalna je elektricna snaga zagrijavanja 100 kW. Kompjutorski nadzirana mjerna centrala istovremeno prihvaca dvadesetcetiri temperature uzduž stijenke cijevi, tlak u sistemu, volumni protok, elektricnu snagu grijanja, ulaznu i izlaznu temperaturu radnog medija. Prikazano je i analizirano nekoliko scenarija postizanja krize kipljenja i promjene temperature uzduž stijenke cijevi, koja je njezina posljedica. Pomocu termoparova pricvrscenih u stijenci cijevi samo 1 mm od isparivacke povrsine detektirano je osciliranje tone isusenja po duzini cijevi. Posljedica su tog pomicanja gradijenti temperature stijenke kod hlađenja 700 °C/s i kod...
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