SURVEY ON THERMAL PHOTOVOLTAIC CELL OF SOLAR ENERGY WITH BIOMASS GASIFIER
1Ravi Vaishya,
Research Scholar, Electronics & Communication Engineering
2Prof. Dr. S.R. Nigam
3Prof. Dr. R.R.Lal
123AISECT University Bhopal , Madhya Pradesh , India
Abstract - The energy sector is in transition worldwide because of increasing demand for energy; significantly fluctuating oil prices; stronger desire for energy supply security and independence; and in response to sustainability, conservation and environmental considerations. The mass deployment of renewable and low- carbon energy technologies has the potential to make important contributions towards these goals. Biomass energy has the potential to provide a significant proportion of the renewable energy required to meet these and other national and international targets and obligations. This paper is related to the all survey of TPV and biomass gasification.
1. INTRODUCTION
The conventional resources of energy such as fuel oil, gas and coal are finite and the already depleting very rapidly, Being our country an agricultural one and more than 70 % of the Indian Population living in the villages, about 80% of their energy need is for domestic purpose (i.e. for cooking, lighting, water pumping etc.) is fulfilled by non commercial sources of energy like firewood, agricultural waste, forest waste, etc.
From times immemorial man has been dependent on Nature's bounty of forest wealth and fossil fuels to cater to his energy needs. With time and increasing sophistication in his standard of living, especially in the current century, he has become more and more dependent on electricity for running the wheels of his civilization. Most of the electricity has till now been generated from fossil fuels in huge power plants run by coal and oil or by nuclear fuels. However, the continuously increasing use of fossil fuels has dangerously depleted available natural resources of these. It has further seriously strained our national economy through recurring payments to meet the bills incurred on the import of oil and other fossil fuels required to sustain the insatiable demands for the same.
2. REVIEW OF LITERATURE
The photovoltaic thermal (PVT) system has been introduced to utilize the energy of the sun in the form of electricity as well as thermal simultaneously. Different types of hybrid PVT systems exist. The compulsions of the Kyoto protocol are forcing to minimize greenhouse-gas emission, depleting rapid rise in the fuel import bill, fuel reserves, multiplying energy demand exert irresistible pressure on India to harness renewable energy resources as the most suitable alternative to fossil fuels for electricity generation. It is high.
time for the country to change the country’s energy basket by shifting its focus on renewable energy resources from conventional fossil fuels (coal and diesel) for electricity generation. Lots of theoretical and experimental work on hybrid PVT systems is reported in the literature. These PVT systems preliminarily utilize thermal energy from the sun to produce electrical energy. A healthy research work has been done in term of the energy metrices of hybrid PVT air collector.
Many papers deal with equilibrium modelling and kinetic modelling of gas-char reactions in the reduction zone of downdraft biomass 10 gasifier. Few papers report overall modelling of biomass gasification processes involving drying, pyrolysis, oxidation, and reduction. Many reactions that occur in coal gasification also occur in biomass gasification. Due to certain commonalities between them, some literatures on coal gasification are also useful in modelling biomass gasifiation.
On the Bases of this following literature research proposed for hybrid system TPV and biomass gassifier .
NielsJungbluth et al. [8] presented The life cycle inventories of photovoltaic power plants performed for the convent data v2.0 can be assumed to be representative for photovoltaic plants and for the average photovoltaic mix in Switzerland and in other European countries in the year 2005. The analysis of the results shows that it is quite important to take the real market situation into account (raw material supply, electricity, irradiation and performance ratio, etc.). The study shows the considerable achievements in the last year for reducing the environmental impacts for the production of photovoltaic plants. But, of outermost importance for the environmental impacts are not only the impacts per kWp but also the actual performance of the plants. It seems
necessary to install future PV power plants to a larger amount in countries with higher irradiation levels. From this perspective, the present focus on the German market is not optimal.
Kensuke Nishiokaa, et. al. [10] presented The temperature dependences of the electrical characteristics of InGaP/InGaAs/ Ge triple-junction solar cells under concentration were evaluated. The temperature dependence of Z is mostly affected by the temperature dependence of Voc. Z decreased with increa sing temperature, and increased withincrea sing concentration ratio because of the increase in Voc. The normalized temperature coefficients of the conversion efficiency
((dZ/dT)/Z(25 1C)_100) of the
InGaP/InGaAs/Getriplejunction solar cell is _0.248%/1C at 1 sun and _0.098%/1C at 200 suns.
The decrease in Z withincrea sing temperature decreases with increasing concentration ratio.
These results indicate that concentration operations have beneficial effects on high-temperature operations. Moreover, the annual output of a concentrator system with a high-efficiency triple- junction cell is estimated using the experimental characteristics of solar cell obtained in this study and field-test meteorological data collected for 1 year at NAIST, and compared width at of a no concentration flat-plate system.
G. Kosmadakis⇑, et.al. [14] presented In the present study an attempt for improving the CPV system’s efficiency has been investigated, by combining the technologies of the concentrating photovoltaic and the organic Rankin cycles. The heat rejected from the concentrating PV is recovered from the ORC, in order to increase the total electric power production.
1. The results of this analysis revealed that CPV–ORC combination improves the efficiency of CPV technology from 9.81% to 11.83% in average.
2. There are more parameters to be further investigated, in order to optimize in a greater extent the system’s design, such as the condensation temperature of R-245fa, the heat transfer process at the absorber plate, the selection of more efficient solar cells etc.
3. The annual simulation, showed that the incorporation of the ORC system is responsible for the larger amount of the electric energy produced (6339.4 kWh for the ORC system instead of 3735.8 kWh for the CPV system). The annual efficiency calculated is 10.52%, which is quite high, considering that the system operates at mixed partial and full loads.
Abraham Kribus, et.al. [15] presented In this analysis, we have compared several configurations for cogeneration and polygene ration with solar thermal and PV systems. The analysis included both generation of additional electricity with the captured heat, and other options of using this energy for heating and cooling. The models have represented, as much as possible, real device efficiencies rather than upper thermodynamic limits. The results lead to several conclusions:
Polygene ration leads to increased conversion efficiency. This has been observed in all the cases presented above, but in some cases the gain was not significant: for example, a two-stage heat engine configuration has shown maximum gain of only 6%. Therefore, care must be taken to choose the more advantageous configurations, such as those with a bottoming AHP. These have shown efficiency gains of up to 50%, and overall efficiency of 43%, under the conditions investigated here.
Concentrating the solar radiation is essential to effective polygene ration. The higher the concentration, the more effective the system;
in some cases, a system without concentration is altogether impractical. This statement assumes that within the investigated range of up to C=1000, the optical efficiency does not significantly change with concentration. This can be achieved but has economic implications on the construction of the concentrator; these aspects were not treated here.
Richard B. Diver, et. al. [19] presented An innovative alignment technique based on overlaying theoretical images of a trough module onto carefully surveyed photographs has been invented and investigated. The TOP technique, as with dish optical alignment approaches, uses differences between theoretically calculated and optically measured image positions to guide mirror alignment. The TOP technique satisfies all of the requirements of an ideal alignment process.
It uses relatively low technology equipment, inherently aligns the mirrors to the HCE, and can be implemented day or night within the rows of commercial trough power plants. It is also adaptable for use in new installations, mirror replacement, and for characterizing gravity induced optical errors. Alignment accuracy should be better than the optical accuracy of the mirrors themselves, therefore enabling the best possible optical performance. The TOP alignment technique was validated on the rotating platform at the NSTTF.
EckhardLüpfert, et. al. [21] presented The precision of the concentrator shape and alignment of collectors with high concentration ratio can strongly affect the performance. Photogrammetric measurement of mirrors, modules, and collector assemblies has been used to identify specific geometric properties and compare them to specifications. High density photogrammetry results can be used to perform ray-tracing studies of geometric effects on the optical efficiency. Flux mapping is now available as the fastest method to check larger collector areas when in operation. The bundle of methods allows fast identification and quantification of collector errors. The techniques can be used for prototype evaluation as well as for solar field quality checks and acceptance tests.
C.E. Kennedy et. al. [22] presented Silvered PET with a protective alumina coating deposited by IBAD represents an advancement in solar reflector durability. Samples of the reflector have shown an initial hemispherical reflectance of 95% and outstanding optical performance in both accelerated and outdoor (Colorado) exposure testing. These results are preliminary, and further testing is ongoing. Additional issues to address include determining the minimum coating thickness needed to ensure optical durability, increasing the deposition rate, and the long-term mechanical stability of the material under biaxial strain. The material under development offers promise as a commercially viable solar reflector material.
C. E. Kennedy, et. al. [23] presented The previous best-case scenario, from the live- spreadsheet model cost analysis, was for an ASRM with 1 mm of low-purity Al2O3 deposited onto a PET substrate at a 60 nm/s rate with a $50 h machine burden @8#. Prior to this, it was thought feasible to produce an ASRM that met the cost goal with a 4 mm-thick alumina with a deposition rate of at least 60 nm/s ~based on an earlier cost analysis performed nine years prior and from early batch durability results in which the thicker ~4 mm! alumina samples performed better!.
Therefore, the alumina coating was thick for most samples produced. Based on this best-case scenario, we thought we needed to use a PET substrate, decrease the thickness, increase the rate, and decrease the purity of the alumina—all without compromising durability. Decreasing the thickness without compromising durability is feasible.
Henry Price, et. al. [24] presented The reliability, lifetime and performance of parabolic trough receivers are significant issues for both existing and future parabolic trough plants. Failure rates have
historically been unacceptably high at the SEGS plants, resulting in high O&M costs and unacceptable performance losses. The O&M companies have learned many lessons on how to operate and maintain solar fields that help to protect the receivers. This paper has shown how a detailed solar field component reliability database can provide an important tool for understanding failure trends and helping to solve key O&M issues in the solar field. Receiver vendors are developing new designs with improved performance and reliability. Field tests of the new Solel receiver have shown significant increases in performance and the latest generation of tubes appears to resolve many of the issues with G/M seal failures and coating failures. Schott has introduced a number of innovative new receiver technology elements that appear to further advance the state-of-the-art in receiver technology and, potentially more importantly, add a second potential source of supply for parabolic trough receivers.
James E. Pacheco, et. al. [27] presented A thermocline indirect storage system has been developed that is about 2/3 the cost of a two-tank molten salt system for parabolic trough power plants. Screening studies on candidate filler materials showed that silica filter sand, quartzite rock, and taconite were compatible with nitrate salts, both in isothermal and cyclic conditions. We chose quartzite and silica sand as the most practical filler materials for a small, pilot-scale test because of their availability and cost. Results from the pilot- scale test confirmed the thermal capacity of the thermocline was near the calculated value. The height of the thermal gradient corresponded to that predicted by the model. Heat losses were higher than predicted primarily due to the heat losses through pump penetrations on the top of the tank, though in a large thermal storage system (100s MWht) that effect will have a smaller ~near negligible! impact. The results of this work show that a molten-salt thermocline system is a feasible option for thermal storage in a parabolic trough plant.
Valentina A. Salomoni a, et. al. [28] presented Guidelines for designing a concrete storage module and for its integration into a solar plant, respecting constraints linked both to an adequate solar field operation and to the production system based on ORC, have been described in this paper. A series of simplified procedures have been developed to be used for a first module design and more sophisticated (even if more expensive) simulation techniques via the Finite Element Method have been checked and upgraded. Once the ongoing experimental phase on a scaled storage prototype at
the ENEA site of Casaccia has been concluded, the obtained data will be used for completing both the setup of the calculation instruments and the R&D activity dealing with the development of an appropriate concrete mixing, optimizing its chemical–physical and durability performances, and with the module integration within a CSP system.
KingaPielichowska a, et. al.[29] presented It is generally agreed that the intensive investigations undertaken in the last three decades have given latent PCMs significant advantages over sensible systems including the lower mass and volume of the system, higher storage density and lower energy losses to the surroundings. Although the physical properties of most PCMs necessitates the application of additional techniques such as microencapsulation to increase the heat transfer area, reduce reactivity with the outside environment and control volume changes during the phase transition, these materials have found numerous applications in various industrial sectors.
Inorganic compounds for energy storage have a higher latent heat per unit volume and a higher thermal conductivity than organic compounds.
However, they are more corrosive to metallic materials and supercoiling effects may adversely influence their phase change properties although the use of nucleating and thickening agents may mitigate these disadvantages.
T.E. Boukeliaa,et. al.[30] presented The parabolic trough solar thermal power plants using two different heat transfer fluid; terminal VP-1 and solar salt, with integrated thermal energy storage and fuel back-up system are designed for 50 MWe energy output. The optimization based on parametric analysis of solar multiple and full load hours is carried for the two PTSTPPs alongside Andasol 1 reference plant.
Ya-Ling He ⇑, et. al. [32] presented This paper presents an integrated model for the typical parabolic trough solar thermal power generation system with Organic Rankin Cycle. The simulation is model built within the transient energy simulation package TRNSYS. With the model, the influences of several designing and operating parameters on the performance of the collector field as well as the whole system are examined.
Jürgen Dersch, et. al. [33] presented SEGS plants are the best choice if high solar fractions or solar- only plants are desired and the load schedule is either flexible or close to matching the solar resources. A TES system can help bridge a few- hour mismatch between solar resources and load
demand that, for example, is common with air conditioning loads in developed countries. If the plant will be required to operate in base-load fashion, 24 hours per day, the ISCCS provides the best combination of LEC and carbon emission reduction.
M. Eck et. al. [34] presented Experimental results of the DISS project performed at the Platform Solar de Almeria are presented. These results show clearly the supremacy of the recirculation mode over the once-through-mode in terms of the thermo hydraulic stability and the strain of the absorber tubes. The experimental results are compared to simulation results of the steady state and transient behavior of the direct steam generation in parabolic troughs. The comparison of the results show a good agreement. These programs will be used for the controller design and assessment of the different operation modes. So far (as of Nov. 2000) no experiments in injection mode nor with an automatic temperature control have been performed, therefore a final evaluation of the three concepts is not possible. In further experimental studies the once-through-concept has to prove its controllability and the injection and recirculation- concept have to prove their potential of further improvements. An improvement of the injection mode will be the minimization of the number of injection coolers and that of the recirculation- concept will be the simplification of the separator.
Beyond it the injection-concept has to prove its thermo hydraulic stability. Suggestions for the overcoming of the main disadvantage of the recirculation-mode, the complex design, are presented. Further investigations have to show the efficiency of these simplified separator concepts.
Loreto Valenzuela a, et. al. [35] presented The DISS project has demonstrated that it is possible to produce steam at high pressure and temperature directly in the parabolic-trough solar collectors.
This paper presents the prototype plant operated and evaluated in two different modes, Recirculation and Once through. For the first experiments in the facility, control structures were mostly based on classical controllers.
L. Valenzuela a, et. al. [36] presented This paper has shown the development and implementation of control strategies to a new plant representing a breakthrough in technology for producing steam at high pressure and temperature directly in parabolic trough solar collectors. The DISS plant using this type of technology has been operated in two different modes. This paper has presented one of the plant configurations evaluated, the recirculation operation mode. With a PI control based scheme
the controllability of the plant was guaranteed during clear days and even with transients in the solar radiation. A structure based on classical controllers was chosen because the plant operators are familiar with the used PI controllers and also to try to assure a secure operation in the first tests performed in this facility.
Matthew J. Emes, et.al. [38] presented There is significant potential to lower the LCOE in windy sites by careful choice both of the design wind speed at which heliostats are parked in stow position and of the size of the heliostats. Lowering the design wind speed has the potential to reduce the LCOE of a PT plant at windy sites because of the strong dependence of the cost of the heliostat field on the design wind speed. For example, the relative cost of the structural components increases from 6% to 23% as the design wind speed is increased from 1 m/s to 15 m/s. Hence, at the three Australian sites assessed here, a significant reduction in the design wind speed is associated with only a small reduction to the capacity factor, which lowers the LCOE. For example, lowering the design wind speed by 9 m/s from the maximum 22 m/s measured wind speed at Alice Springs yields a 0.3% lower capacity factor and a 18% reduction in LCOE. The optimal size of a heliostat is also dependent on the design wind speed.
P.J. Turner et. al. [40] presented:- This paper compares the conventional single-layer tube-bank approach to this volumetric cavity receiver concept and shows that surface radiation losses are reduced by two separate mechanisms; the volumetric approach and by reducing peak radiating metal temperatures. As well as the potential to create a simple and cheap design to construct, the reduction in tube to header junctions should also reduce parasitic pumping losses while the flexible support of individual tubes may reduce thermally induced stress loading. One obvious simplification is the use of flat ―tubes‖ in the simple 1-D model.
Modeling the actual tubular surfaces will affect the results since radiation, particularly from the rear, will be at more random angles than the incoming solar flux.
Pablo Ferna´ndeza,b, et. al. [41] presented A multidisciplinary design optimization of a 5 MWth Small Particle Heat Exchange Receiver for central receiver solar power plants was presented. This new solar receiver, currently being developed under the U.S. DOE Sun Shot Program, aims to heat air to temperatures in excess of 1300 K and use this high-temperature energy to drive a Brayton cycle or a combined Brayton/Rankin cycle. The design space considered consisted of the lateral
wall angle of the receiver, the geometry of the window, and the radioactive properties of the walls.
The aluminum oxide walls, which would also serve as thermal insulation, showed the best compromise between wall temperature and thermal efficiency compared to the other three main types of radioactive properties that could be employed.
J. Spellinga, et. al. [43] presented In order to overcome the limitations of the simple-cycle HSGT layouts studied in previous works, two power plant improvements were combined to form an advanced HSGT power plant. High-temperature TES units were integrated to extend the degree of solar operation, and a conventional Rankin bottoming- cycle was added to reduce the cost of electricity.
The advanced HSGT power plant was analyzed using thermo economic tools in order to determine the performance, economic viability and environmental impact. Multi-objective optimization was used to examine the trade-offs between electricity costs and CO2 emissions and the results were compared against existing power plant concepts. The advanced combined-cycle configuration can achieve annual solar shares of over 90% while electricity costs range from a minimum of 81 USD/MWhe to a value of 105 USD/MWhe at an annual solar share of 37% and 157 USD/MWhe at an annual solar share of 76%.
Scott M. Flueckiger a, et. al. [44] presented A numerical model for molten-salt thermocline tank operation has been developed to provide accurate simulation of mass and energy transport at low computing cost and without reliance on commercial CFD software. The thermal model is integrated into a system-level simulation of a 100MWe power tower plant to assess thermocline tank performance under realistic and long-term operating conditions. Operation of the plant model is informed by a meteorological year of sunlight data recorded near Barstow, CA in 1977. The molten-salt thermocline tank, sized to provide 6 h of thermal energy storage, increased the annual plant capacity factor to 0.531 with excellent year- long storage effectiveness exceeding 99%.
Ion Iliuta, et. al. [47] presented A dynamic 1-D, multi-component, non-isothermal model was elaborated to simulate an all thermal two- compartment fluidized bed which performs alternatively, in space and time, steam biomass gasification and char combustion. The model accounts for detailed gas and solid hydrodynamics whereupon gasification/ combustion reaction kinetics, thermal effects and freeboard reactions were tied. The simulation shows that char combustion generates sufficient heat to sustain
gasification at high temperature by tolerating up to 20% heat losses. A non-diluted (N2-free) high hydrogen yield and relatively large hydrogen content could be obtained from biomass gasification in two-compartment bubbling fluidized-bed reactors. All thermal operation could be achieved with a switching periods of a minute supporting feasibility of this new concept.
Ajay Kumar 1, et. al. [48] presented Biomass gasification is a promising technology to displace use of fossil fuels and to reduce CO2 emission.
Among other alternative energy conversion pathways, it has great potential because of its flexibility to use a wide range of feedstock, and to produce energy and a wide range of fuels and chemicals. Recently, the focus of its application has changed from production of combined heat and power to production of liquid transportation fuel.
The technical challenges in commercialization of fuels and chemicals production from biomass gasification include increasing the energy efficiency of the system and developing robust and efficient technologies for cleaning the product gas and its conversion to valuable fuels and chemicals.
Brandon J. Hathaway a , et. al. [49] presented A numerical simulation based on the MCRT method is used to explore the performance of a cylindrical cavity receiver exposed to concentrated radiation with its exterior surface exposed to a convicting fluid. The results provide guidance on design of cavities for indirect solar thermal receivers. For best performance in terms of absorption efficiency, the cavity-aperture ratio D and aspect ratio L should be maximized within the confines of any restrictions on size and operating temperature. In general, cavities with aspect ratios or cavity=aperture diameter ratios less than 1.5 exceed the temperature limits of Inconel. In considering the spectral properties of the cavity, Inconel is superior to alumina.
RadeKaramarkovic, et. al. [51] presented For air gasification of biomass at a given temperature, the optimal moisture content is the one that corresponds to the moisture content in the biomass for which this is the temperature at the CBP. Only in that case does the optimal moisture content in biomass exist. If biomass is gasified above the temperature at the CBP for dry biomass, an increase of the moisture of the biomass leads to the decrease of both the energy and energy based efficiencies. Drying of biomass feedstock is beneficial for the efficiencies based on chemical energy and energy. When biomass is dried with the product gas sensible heat, the temperature difference in the dryer influences the efficiency
based on the total energy. The smaller this temperature difference is, the more energy efficient is the drying process.
K. Papadikisa, et. al. [54] presented effect of biomass shrinkage inside a bubbling fluidized was modeled and significant conclusions could be made. Shrinkage does not have a significant effect on the momentum transport from the bubbling bed to the discrete biomass particles for small sizes in the order of 500_m. The effect of shrinkage on momentum transport can be neglected when fluidisedbeds operate with such small particle sizes.
However, the same cannot be stated for shrinkage parameters that shrink the particles close to their total disintegration. The model excluded this extreme condition and studied particles that shrink until half of their initial volume. For fast pyrolysis applications in lab-scale fluidized beds, small particle sizes are necessary (350–500_m) due to feeding problems. The effect of shrinkage on the pyrolysis of thermally thin particles does not have a significant impact neither on the product yields nor the pyrolysis time.
Brandon J. Hathaway, et. al. [55], presented the primary objective of the present study was to explore the use of molten alkali carbonate salts as a means to enhance the rate of biomass gasification via the representative reactions of cellulose pyrolysis and carbon gasification. A comparison of gas product yields and a kinetic study were carried out using pure cellulose and activated charcoal in a ternary mixture of lithium, sodium, and potassium carbonate in the temperature range from 1124 K to 1235 K. The data were analyzed to provide Arrhenius rate constants for both flash pyrolysis and gasification. The key conclusion is that the molten salt increases the rate of pyrolysis by 74%
and increases gasification rates by more than an order of magnitude while promoting a product gas composition nearer to thermodynamic equilibrium predictions. Although alkali metal carbonates have been found to catalyze pyrolysis reactions in studies where there is sufficient contact time between the melt and the feedstock, catalysis was not observed in the present study in which pyrolysis was extremely rapid.
Chen Hanping, et. al. [56] presented the gasification properties of three local biomass samples were investigated using a fluidized bed reactor combined with micro-GC and GC-MS. The main conclusions can be derived as follows.
Gasification behaviors displayed a close relation with biomass type. Sawdust showed a higher combustible gas (H2, CO, and CH4) and tar yield, as the higher volatile and hydrogen and oxygen
content. The LHV order of product gas from different biomass samples can be elaborated as follow: sawdust > peanut shell > wheat straw. With ER increasing, the gas yield increased rapidly from 1.14 to 1.93 m3/kg, while the heating value was decreased largely from 7.09 to 3.26 MJ/m3, as more carbon was converted to CO2. Meanwhile, the variation of ER also had an important effect on tar yield and tar species. The amount of methylbenzene and naphthalene increased greatly with ER increasing, while that of phenol and styrene production decline obviously.
Tao Song, et. al. [57] presented the process of hydrogen production from biomass gasification in the novel interconnected fluidized beds was investigated, which separated the combustion process and gasification process. The experiments were performed in a laboratory scale apparatus of interconnected fluidized beds, and hydrogen-rich gas was produced free ofN2 dilution even when air was used to generate the gasification-required heat via in situ combustion. The effects of gasified temperature and steam/biomass ratio on hydrogen production, syngas composition, carbon gasification of biomass, carbon combustion of biomass, and carbon utilization of biomass were discussed. The results indicated that both a high hydrogen yield and a relatively great hydrogen content could be obtained from biomass gasification in the novel interconnected fluidized beds.
Jeffrey S. Dukes et. al. [60] presented Ancient organic matter generated fossil fuels through inefficient processes. Calculations in this paper suggest that the formation of coal from plants is less than 10% efficient, and the formation of oil and gas from phytoplankton is less than 0.01%
efficient. These estimates imply that the fossil fuels used by humans in 1997 were generated from ancient organic matter that contained approximately 44 × 1018g C, which is >400 times the current global NPP. As fossil fuel stores are depleted, modern solar resources are likely to supply an increasing fraction of societal energy demands.
AnastasiosMeliset. al. [64] presented theoretically maximum solar energy conversion efficiencies and productivities in oxygenic photosynthesis are contrasted with actual measurements in a variety of photosynthetic organisms, including green microalgae, cyanobacteria, C4 and C3 plants. Improvements in photosynthetic solar energy conversion efficiency and productivity can be achieved upon minimizing, or truncating, the chlorophyll antenna size of the
photosystems. Specific examples are offered on how this could be experimentally achieved.
Generation of truncated light-harvesting chlorophyll antenna size (tla) strains in all classes of photosynthetic systems will help to maximize solar-to-product energy conversion efficiency and photosynthetic productivity under high-density cultivation and bright sunlight conditions. Further, the DNA insertion mutagenesis approach, outlined in this article, can help to identify currently unknown genes that determine the development of the Chl antenna size in photosynthetic organisms, and demonstrates that a truncated Chl antenna size decreases excess absorption and wasteful dissipation of sunlight by individual cells, resulting in better light utilization efficiency and greater photosynthetic productivity under mass culture conditions.
David Alan Walker et. al. [65] examined the relevant literature confirms that there is general agreement that maximal, theoretical light utilization by C3 plants and algae is about 4.5%.
An increase in actual light utilization by crops, from present values (of about 1%) to as much as 3%, remains a goal to be aspired to rather than one which is likely to be achieved in the foreseeable future. There is no credible evidence that cultivated algae are currently able to accumulate substantially more biomass, during a period of sustained growth, than other green organisms. When comparisons of crop yields are based on their normal period of growth, theyields of biomass are relatively similar, regardless of species or locality. Intensive agricultural practice of any sort rarely uses less fossil fuel energy than the light energy that it conserves as biomass. Biofuels do not, at present, lead to any appreciable sparing of carbon dioxide emissions that could not be better accomplished by the most modest means of energy conservation.
Richard Petelaet. al. [66] presented the methodology for understanding the energy of photosynthesis outlines a preliminary study of the photosynthesis process based on the simultaneous analyses of energy, entropy and energy. The study introduces the devaluation enthalpy (for the fair comparison of energy and energy balances), the formulae for arbitrary radiation (convenient for the use of measurements of any actual radiation spectrum), and formulates the limiting diffusion range of the process. The study determines the effects of the main process input parameters and describes the model of CO2 photosynthesis. Multi- factored aspects of the problem are presented based on original computation results. However, the analyses developed here cannot be directly compared with literature data since the latter are
relatively sparse and based usually on incompatible assumptions. The interdisciplinary subject of photosynthesis is very complex and involves many areas of knowledge including thermodynamics, theory of energy, transfer of radiation energy, heat convection, gas diffusion, chemistry, thermochemistry, photochemistry, as well as data dependent on time, day, month, season, weather conditions, geometrical configuration, etc.
D. Weißbach a, et. al. [67] proposed a uniform mathematical procedure based on the energy concept makes it possible to compare all power generating systems. The results are shown in Fig. 3.
All EROIs are above the physical limit of 1 which means they all ―produce‖ more energy than they
―consume‖. Not all of them are above the economical limit of 7, though (see Sec. 6). Solar PV in Germany even with the more effective roof installation and even when not taking the needed buffering (storage and over-capacities) into account has an EROI far below the economic limit. Wind energy seems to be above the economic limit but falls below when combined even with the most effective pump storage and even when installed at the German coast. Biogas-fired plants, even though they need no buffering, have the problem of enormous fuel provisioning effort which brings them clearly below the economic limit with no potential of improvements in reach. Solar CSP is the most hopeful option among the new solar/wind technologies, in particular because of the smaller influence of the buffering. However, pump storage is often not available in regions with high solar irradiation.
Marc A. Rosen et. al. [68] revealed comparing the thermodynamic characteristics of coal-fired and nuclear electrical generating stations, several illuminating insights into the performance of such stations have been acquired. First, although energy and energy efficiencies are the same for PNGS and similar for NGS, energy analyses do not systematically identify the location and cause of process inefficiencies, and energy analyses do.
That is, energy losses are associated with emissions (mainly heat rejected by condensers), and energy losses primarily with consumptions (mainly in the reactors) and little with cooling water and stack gases. Second, since devices with the largest thermodynamic losses have the largest margins for efficiency improvement, efforts to increase the efficiencies of coalfield and nuclear electrical generating stations should focus on the combustion and nuclear reactors, respectively.
Isam H. Aljundiet. al. [70] presented an energy and energy analysis as well as the effect of varying
the reference environment temperature on the energy analysis of an actual power plant has been presented. In the considered power cycle, the maximum energy loss was found in the condenser where 66% of the input energy was lost to the environment. Next to it was the energy loss in the boiler system where it was found to be about 6%
and less than 2% for all other components. In addition, the calculated thermal efficiency of the cycle was 26%. On the other hand, the energy analysis of the plant showed that lost energy in the condenser is thermodynamically insignificant due to its low quality. In terms of energy destruction, the major loss was found in the boiler system where 77% of the fuel energy input to the cycle was destroyed. Next to it was the turbine where 20.4MW of energy was destroyed which represents 13% of the fuel energy input to the cycle.
MaríaMínguez, et. al. [73] presented on research and significant technical development are needed in order to achieve the required maturity level for industrial use, Bio IGCC technology presents some major advantages compared with other technologies for power generation from waste.
Firstly, the use of a gas turbine provides the system with a better load regulation behavior than conventional steam turbine and nuclear power plants, similar to that of a NGCC. Secondly, gasification allows the implementation of pre- combustion CO2 capture, increasing CO2 emission avoidance very significantly with lower energy consumption than post-combustion capture. For the case of biomass waste this leads to effective negative net emissions, causing a real removal of CO2 from the atmosphere if the whole carbon lifecycle is observed. Thirdly, a high overall high waste-to-power process efficiency (45–48% with no CO2 capture and 38–42% with capture, for the agricultural, wood and industrial waste examples analyzed) makes Bio IGCC one of the most promising among technologies for large-scale power generation from waste.
Matthew J. De Kam, et. al. [74]proposed technologies available which can significantly decrease the mount of fossil fuels needed to produce ethanol. 30.4 MWe of renewable power can be produced at a dry-grind ethanol facility with a capacity of 190 million liters per year while also supplying all the process heat needs using ethanol coproduces and corn cobs. The renewable energy ratio of ethanol production could be improved from a typical value of 1.7 up to 5.1 at plants using BIGCC technology. A key to the feasibility of these systems will be the cost to build and operate them. Future work is needed to evaluate the economic realities associated with BIGCC
technology applied to the ethanol industry. In states where the utilities are mandated use renewable sources of electricity perhaps partnerships between ethanol plants and utilities could be made. The heat and power generation system could be located at a separate, but nearby site and operated by the utility.
Future work in the area of public policy is needed to understand what incentives would be necessary to help the ethanol industry proceed in the direction of improved sustainability.
Krzysztof J. Ptasinski_, et. al. [75] proposed research for substitute fossil fuels by renewable fuels, solid biofuels (straw, untreated wood, treated wood, grass/ plants) or liquid biofuels (vegetable oil) could replace coal as a gasification feedstock.
The optimum gasification efficiencies of these fuels based on lower heating values are comparable, i.e., around 84%. However, if the efficiencies are based on chemical energy, the solid biofuels with high oxygen content are regarded as high-quality fuels, for which a penalty is paid when decomposing them into small gaseous components.
Also, the gas produced from solid biomass gasification has a lower temperature so that it contains less physical energy. As a result of these two factors, gasification based on chemical and physical energy shows higher efficiencies for coal than for solid biomass, i.e., almost 84% vs. 76–
78%. It is interesting to note that gasification of vegetable oils is similar to the gasification of coal, and both these fuels can be considered as high- quality fuels.
Mark J. Prins_, et. a. [76] presented the presence of kinetically limited char gasification reactions in gasifies negatively influences the efficiency of a gasified. Therefore, a relatively simple equilibrium model predicts the maximum efficiency that could be attained. In order to gasify fuels with high thermodynamic efficiency at atmospheric pressure, it is recommended to use a gasification temperature around 927 1C, and fuels with O/C ratio smaller than 0.4 (corresponding to a preferred lower heating value above 23 MJ/kg). To minimize kinetic restrictions, higher temperatures may be preferred. At a gasification temperature of 1227 1C, the recommended O/C ratio of the fuel is 0.3 or less (corresponding to a preferred lower heating value above 26MJ/kg). Fuels with higher O/C ratios, such as wood, have larger energy losses because of their high ratio of chemical energy to lower heating value. Furthermore, such fuels are over-oxidized in the gasified in order to reach the required gasification temperature. In practice, due to heat losses, the presence of ash in the fuel, and of nitrogen in the gasifying agent if air or enriched air is used, the extent of over-oxidation will be
more severe. However, for gasification at elevated pressures, the minimum temperature required for gasification increases, and the gap with kinetically preferred temperatures (i.e. the extent of over oxidation) can be reduced.
M.H. Mahfuz a, et. al. [77] presented In this study, thermodynamic performance (energy and energy analyses) of a solar power plant located in Shiraz, Iran was explored theoretically. The thermodynamic second law analysis (based on the energy concept) was executed to investigate the performance of the solar thermal power plant integrated with the PCM.
The findings from this study can be summarized into the following points:
1) The energy efficiency of parabolic trough system is around 30%, while the exegetic efficiency of the system is below 10%.
2) Collector–receiver induces the highest irreversibility in the system and should be modified to minimize the losses.
A. Baghernejad, et. al. [78] presented a comprehensive energy and energy analysis of the Integrated Solar Combined Cycle System in Yazd, Iran is conducted using the design plant data.
Performance assessment of this ISCCS is made through energy and energy efficiencies, exegetic improvement potential, as well as some other thermodynamic parameters. The energy destructions in the overall ISCCS are quantified and illustrated using an energy flow diagram along with an energy flow diagram. Concluding remarks that can be made are:
1) Energy destruction throughout the plant is quantified include: losses in combustor, collector, stack and heat exchangers, and pump & turbines are determined which accounts for 29.62, 9, 7.78 and 8% of the total energy input to the plant, respectively.
2) The values of energy and energy efficiencies for the ISCCS are found to be 46.17% and 45.6%, respectively. These efficiencies are higher than simple combined cycle power plant without solar contribution and also Rankin cycle power plants with parabolic trough technology.
Yolanda Lechón, et. al. [81] showed the LCA performed of these two hybrid operation solar thermal power plants, some important conclusion can be drawn.
First at all, both technologies show an environmental profile much better than the current mix of technologies used to produce electricity in Spain.
The cumulative energy demand of the life cycle of both plants is lower than the energy produced and the EPT calculated is around 1 yr.
ImadEddineMeriche, et. al. [83]
presentemodeled and simulated a solar gas turbine installation capable to provide an electrical production equal to 20.5 MWe in ISO condition, and then we studied the impact of adding a regenerator in the installation. The results obtained in this study show a direct impact of the regenerator in improvement of hybrid and solar- electric efficiencies, with a stable production of electrical energy, less consumption of natural gas and reduction heliostats fields’ area. The energy and the exergy balance confirm the impact of the regenerator, by a gain of 4.26 % in exergy efficiency, with high solar-electric efficiency and a cheaper electrical production due to the reduction of consumption of natural gas and heliostats field’s area. This type of installation is new and very promising especially in regions with duration of sunshine up to 3500 hours/year and a direct normal radiation greater than 2000 kWh/ 2/year, such as the south western of Algeria.
V. Siva Reddy1, et. al. [84] proposedthe energetic and exegetic analyses have been carried out for the year round operation of CTRSTPP for the selected location of Jodhpur (India). The results reveal that the main energetic loss takes place in the Rankin cycle heat engine circuit through the condenser, followed by the heliostat field-receiver system, whereas the result of the exegetic analysis shows a different behavior. In fact, the solar heliostat field- receiver assembly is the main area where the exegetic losses are the highest followed by boiler.
The monthly average electric energy generation was found to be the highest (15_103MWhe) in April, whereas it was found to be the lowest (5.4_103 MWhe) in August. This is due to the monthly variation in the available solar radiation at Jodhpur. For the Jodhpur location with 146.3-ha land area, it can produce 123.07_103MWhe at a solar radioactive energy input of 490.76_103MWh per year. The unit cost of electric energy generation was found to be about INR 10.09 for 30-year lifespan of the solar plant along with a 10% interest rate on investment. This analysis also provides a strong base and holistic approach for potential harvesting opportunities to generate power from solar energy available in India.
Niels Jungbluth, et. al. [85] worked for the life cycle inventories of photovoltaic power plants can be assumed to be representative for photovoltaic plants and for the average photovoltaic mix in
Switzerland in the year 2000. The average electricity mix considers the actual performance of the installed plants, while plant data (e.g., laminate and panel, monocrystalline or polycrystalline) can be used for comparisons of different technologies.
The analysis of the results shows that it is quite important to take the real market situation (raw material supply, electricity, etc.) into account.
Different situations in other countries in comparison with the data modeled for Switzerland are mainly due to different solar irradiation. It should be considered that the inventory may not be valid for wafers and panels produced outside Europe, because production technologies and power mix for production processes might not be the same.
For the modeling of a specific power plant or of power plant mixes outside Switzerland it is advisable to consider at least the annual yield (kW h/kWp) and if possible also the actual size of the plant in square meters. The scenario for a future technology helps to assess the potential for improvement of different production steps in the near future (until 2010). Environmental impacts in this scenario are lower by 30–50%. However, the realization of this scenario depends on the development of the market situation for electronics and photovoltaic power. The use of SoG-grade silicon instead of EG-silicon, which would be an important improvement, is possible only if the supply of silicon for photovoltaic cannot be secured in the way it is today or if subsidies are granted to increase the total production of PV panels. A direct comparison of plants with pc-Si and mc-Si cells with the herewith-inventoried data has only a limited precision. For some production stages data were available for only one of the two types (e.g., NOx emissions during wafer sawing and etching).
Yan Hu a, et. al. [88] proposed energy policies use gross energy production plus energy imports as the energy supply. However, what is important to society is the net energy available from these resources . EROI, like net energy, describes numerically how much energy is left to power the modern industrial society after extraction, processing and delivery. In this paper we present a more complete analysis than usual, using not only the production estimates, but also the net energy from conventional fossil fuels that will be available to China’s economy. Our results show that the EROI of conventional fossil fuels in China is decreasing due to progressive depletion . Additionally, earlier work also found that, in general, the energy returned to energy invested (EROI) tended to decline over time for energy resource examined because the most profitable resources are used up first [18]. The EROI of
conventional oil and natural gas extraction decreased from 14:1 in 1996 to 10:1 in 2010 and coal production from about 35:1 to about 27:1 during the same period. The net energy produced will probably increase until about 2020, but then decline. EROI and net energy give us an alternative perspective for understanding modern civilization.
Angelantonio Rafaschieri, et. al. [89] obtained, some possible issues have been identified in order to improve environmental efficiency. With reference to biomass production, the most negative environmental elects are caused by the usage of chemicals and fertilizers. Thus, improvements are necessarily based on optimization of the ratio biomass yield/applied fertilizers and on biological ant parasitic solutions. The use of Biodiesel as a fuel for agricultural machinery could further reduce CO2 emissions and the life cycle environmental impact. With reference to gasification conditions, the use of air as an oxidizers causes 2 to 7 times lower environmental elects than in the case of oxygen gasification. However, 99% of that is due to the electricity consumption to produce the oxygen. According to EEC expectations for year 2010, a 12% power mix from renewable sources scenario makes this deference not very significant.
Martin C. Heller a, et. al. [91] showed theLife cycle analysis demonstrates that electricity generation with willow energy crops, either by coffering with coal or in dedicated biomass power plants, leads to significant reductions in many of the environmental impacts of coal-based electricity production. Consumption of non-renewable resources (coal) is reduced, as are net greenhouse gas emissions and criteria a air pollutants including SO2, Hg, and likely, NOx. Coffering biomass at 10% increases the net energy ratio of producing electricity by 8.9%. Similarly, the net energy ratio for dedicated biomass gasification is estimated to be 13, indicating that 13 units of electricity are produced for every unit of fossil energy consumed across the entire system life cycle. For comparison, the net energy ratio of the current US electricity grids 0.26. This study suggests that the environmental impacts from producing electricity with willow biomass energy crops are similar to using woody residues and that the pollution prevented is comparable to other renewable energy sources (solar and wind).
Additional data and experience are needed to determine whether the small differences reported here are indeed significant. It should be noted that choice of modeling parameters and allocation procedures can have significant effects on results.
Martin C. Hellera, et. al. [92] proposed the system performance results presented here provide further evidence for the environmental benefits of dedicated biomass energy. By our estimates, willow biomass crop production in NY requires the consumption 0:018 MJ of non-renewable energy to produce 1 MJ of renewable energy in the form of wood fuel. After transportation and energy conversion eAciency estimates are included, the generation of electricity from dedicated willow biomass energy crops would consume 0:092 MJ of non-renewable energy per MJ of electricity generated (0:33 MJ kWh−1). By comparison, the generation of a composite kilowatt-hour of electricity under the current US fuel mix consumes 11:2 MJ kWh−1 . The manufacture of inorganic fertilizer accounts for nearly 40% of the energy cost of producing willow biomass. Great opportunity exists to improve the system energy performance through the use of organic waste streams such as sewage sludge bio solids as a nutrient source. Utilization of bio solids in biomass energy production can increase the net energy ratio by more than 40% and also provides a productive use for what was previously treated as a waste stream. Further efficiencies can be gained through continued research into the in9uence of fertilizer type and application rates on biomass productivity.
Inge Vande Wallea, et. al. [93] proposed energy production based on SRF biomass has a high efficiency, the total amount of electrical and thermal SRF energy that could be produced in Flanders is low. The CO2 emission reduction potential of SRF plantations in Flanders seems to be very restricted as well. Main causes of these two phenomena are the land scarcity in this region as a result of the high population density, and the low biomass production values found at the plantation studied here. The most interesting option seems to be the combination of a combined heat and power installation with a relatively small SRF plantation in the close neighborhood.
David Styles, et. al [94] presented the construction of full LCAs for Miscanthus and SRCW electricity chains confirmed that electricity produced from energy crops would be associated with a substantial (almost 90%) decrease in GHG emissions compared with conventional peat and coal electricity. In addition, GHG emissions attributable to Miscanthus and SRCW cultivation were substantially lower than those attributable to conventional agricultural systems. For example, Miscanthus and SRCW cultivation resulted in GHG emission reductions of 10,130 and 10,722 kgCO2 eq. ha_1 a_1, respectively, when replacing dairy systems, and 5821 and 4030 kgCO2 eq. ha_1
a_1, respectively, when replacing sugar-beet cultivation. To indicate the consequent potential implications for national GHG emissions, a simple scenario of 30% peat-electricity substitution with co-fired Miscanthus-electricity, and 10% coal- electricity substitution with co-fired SRCW- electricity, was developed. Miscanthus was assumed to replace sugar beet cultivation, and SRCW assumed to replace equal areas of dairy, beef and sheep farming (land uses currently under economic pressure).
PietroGoglioa, et. al. [95] illustrated the significances of some possible variations in small- scale SRC willow-to electricity energy systems. It was shown that selection of chip drying technique will have a significant impact in the net energy production; therefore, energy efficiency enhancement measures such as exhaust gas recovery are vital. It was also shown that fertilizer application technique will have significant impact on energy output–input ratio that determines the system energy efficiency. Overall, for small-scale power plants such as those considered in this study, it is important to evaluate the most suitable conversion pathway both in terms of feedstock supply logistics and efficiency in energy conversion. Whereas it is known that chips transportation distance is a key issue in biomass-to- energy systems, for the scale of energy system considered in this study, it was found that chips could be transported up to a distance of 38 km with less than 8.3% reduction in energy output–input ratio, and with a lesser variation in CO2 emission.
Chip transportation distances greater than 38 km significantly reduced the energy output–input ratio (25.9%). The impact of cultivation practices on net energy production was of less significance possibly due to the low energy cultivation. However, variation ascribed to change in type of fertilizer and fertilizer application technique strongly influenced energy efficiency. Due to large areas required for sustained electricity generation wholly supported by energy crop feedstock, complete estimation of all GHG emissions, potential impacts on biodiversity, eutrophication and acidification, should be considered in a more detailed assessment of the overall environmental compatibility.
SylvestreNjakouDjOmo, et. al. [97] illustrative the wide variation in specific numerical results among the reviewed studies, it is possible to draw the following conclusions: on average, SRWC yielded 36 times more energy than coal (ERcoal _0.9) per unit of fossil energy input, and GHG emissions were 24 times lower than those of coal (GHGcoal _96.8). Consequently SRWC provide an opportunity to reduce dependency on fossil fuels
and to mitigate GHG emissions. Harvesting and fertilization were the largest contributors to energy use across the reviewed studies, and it was found that harvesting consumed 1.2–1.3% more energy than fertilization. Despite the fact that SRWC can play an important role in mitigating GHG emissions, some uncertainties linked to evaluating the GHG emissions from individual bioenergy systems remain. N2O emissions from fertilizer application, carbon sequestration, and the reference land use (baseline) pose the major challenges to providing a high degree of confidence in the calculated emissions.
H.D. Madhawa Hettiarachchia, et. al. [98]
showed the performance of four working fluids that are suitable for low-temperature geothermal binary power cycles are investigated using an optimization criterion, ratio of heat transfer area to net power produced, which is a good measure of the total power plant cost. It was shown that the simulation converges to a minimum objective function at a particular set of operating conditions.
Results shows that the choice of working fluid can greatly affect the power plant cost, in some instances the difference could be more than twice.
Ammonia has minimum objective function and maximum geothermal water utilization, but not necessarily maximum cycle efficiency. An energy analysis reveals that the ammonia cycle efficiency has been largely compromised for the minimum plant cost. Ammonia is the preferred selection followed by HCFC 123, n-Pentane and PF5050, respectively, although the latter has most preferable physical and chemical characteristics. But the presence of wet vapor at the end of the expansion and very high evaporation pressure limits the use of ammonia in low-temperature geothermal applications.
Dongxiang Wang, et. al. [99] proposed a thermal efficiency model theoretically in an ideal ORC to analyze the influence of working fluid properties on the thermal efficiency based on thermodynamic analysis, the optimal operation condition and energy destruction for various heat source temperatures were also evaluated utilizing pinch point analysis and energy analysis method. The proposed efficiency model exhibits excellent agreements with the theoretical data and shows better performance than the existing models.
Meanwhile, the model theoretically indicates that Jacob number and the ratio of evaporating temperature and condensing temperature play essential roles in discriminating the thermal efficiency among various working fluids. It is advisable to get the most from the heat source rather than always pursuit of high thermal
