Energy Balance Of System Research Articles

Experimental determination of cold water temperature at the inlet to solar water storage tanks

In the present work, results of experimental research on the mains water temperature supplying the Solar Domestic Hot Water system in the period from 2016 to 2018 are shown. The test object is located in the Hotel for Research Assistants on Bialystok University of Technology campus in Poland. One of the elements that will guarantee the correct energy balance of a hot tap-water system is the exact determination of the cold water temperature. The aim of this study is estimation of the temperature of the mains water flowing into the district heating substation and the water feeding directly the heat storage tanks. The research results showed that the average value of the cold water was 14.09°C during the 3 years of measurements. Moreover, it was shown that this temperature increased by about 0.4°C as a result of heat exchange with the air inside the substation. In the article, the author proposed modifications of coefficients in a commonly used model developed by National Renewable Energy Laboratory for determining the temperature of mains water in energy simulations. The proposed changes allow for accurate modelling of the cold water temperature under the climate conditions of north-eastern Poland.

Modeling general energy balance of systems

Abstract Analyzing security issues in systems can depend on many parameters. The purpose of this paper is to develop a modeling that can be applied uniformly to all systems. For this purpose, a system of parameters that is found in every system is examined. The background to the research is the problem of safety. The topic is to examine the relationships between system components that determine the safety without the exact interpretation of safety. For standardization the modeling process is based on the philosophical main topics. Elements of the model can be derived from the abstract categories of human thinking. The study is based on cybernetics with energy modeling. That is, the general energy balance of the systems is tested. Further studies are based on the general system equation under the energy model thus generated. The general shape and special cases of the equation determine the types of system examinations.

A thermodynamic analysis and economic evaluation of an integrated cold-end energy utilization system in a de-carbonization coal-fired power plant

Huge amount of cold-end energy discharged from the CO2 capture/compression process is not thermodynamically satisfactory for monoethanolamine (MEA)-based de-carbonization coal-fired power plants. In this study, an improved cold-end energy utilization concept for a MEA-based de-carbonization coal-fired power plant was innovatively proposed, which highly integrates the CO2 capture/compression, steam bleeding, and boiler air pre-heating processes to cascade utilize the system cold-end energies, and beneficially supplies the heat required for solvent regeneration and air preheating. To be specific, three paths have been adopted: (1) reboiler condensate recirculation: part of the reboiler condensate is recirculated to mix with the steam bleed to provide the heat for solvent regeneration; (2) absorption heat transformer (AHT): upgrading the reboiler condensate heat for solvent regeneration; and (3) multi-stage air heating: cascade utilization of the heat discharged from coolers within CO2 capture/compression process to preheat combustion air prior to the flue gas-air preheater, saving part of the flue gas heat to be used in a more cascade way. The mass and energy balance of the proposed system and the overall system performance were determined using the process simulation. The energy saving mechanism of the adopted three paths were investigated through adopting the graphical exergy analysis for the reboiler block and air preheating process. The cost of electricity (COE) and cost of CO2 avoided (COA) of the proposed system were also determined. Results showed that the energy efficiency of the proposed system could be 3.2 percentage points higher than that of the conventional de-carbonization plant without cold-end energy utilization. The COE and COA of the proposed system were reduced by 8.0% and 22.2%, respectively.

The design of conservative finite element discretisations for the vectorial modified KdV equation

We design a consistent Galerkin scheme for the approximation of the vectorial modified Korteweg–de Vries equation with periodic boundary conditions. We demonstrate that the scheme conserves energy up to solver tolerance. In this sense the method is consistent with the energy balance of the continuous system. This energy balance ensures there is no numerical dissipation allowing for extremely accurate long time simulations free from numerical artifacts. Various numerical experiments are shown demonstrating the asymptotic convergence of the method with respect to the discretisation parameters. Some simulations are also presented that correctly capture the unusual interactions between solitons in the vectorial setting.

Starvation in the Midst of Plenty: Reflections on the History and Biology of Insulin and Leptin.

Insulin and leptin are critical metabolic hormones that play essential but distinct roles in regulating the physiologic switch between the fed and starved states. The discoveries of insulin and leptin, in 1922 and 1994, respectively, arose out of radically different scientific environments. Despite the dearth of scientific tools available in 1922, insulin’s discovery rapidly launched a life-saving therapy for what we now know to be type I diabetes, and continually enhanced insulin therapeutics are now effectively applied to both major forms of this increasingly prevalent disease. In contrast, although the discovery of leptin provided deep insights into the regulation of central nervous system energy balance circuits, as well as an effective therapy for an extremely rare form of obesity, its therapeutic impact beyond that has been surprisingly limited. Despite an enormous accumulated body of information, many important questions remain unanswered about the mechanisms of action and role in disease of both hormones. Additionally, although many decades apart, both discoveries reveal the complexities inherent to scientific collaboration and the assignment of credit, even when the efforts are spectacularly successful.

An improved supercritical coal-fired power generation system incorporating a supplementary supercritical CO2 cycle

Large superheat degree of the steam bleeds from regenerative heaters as well as the large heat transfer temperature difference during the air preheating process is not thermodynamically satisfactory in advanced supercritical power plants with the aim of high power generation efficiency. In this study, an improved supercritical coal-fired power generation system, which integrates a supercritical CO2 (S-CO2) power cycle to utilize the superheat of the steam bleeds as well as to heat the combustion air, was proposed. In the proposed system, the heat transfer temperature difference within the steam regenerative trains and air preheating process could be reduced, leading to less exergy destructions. Moreover, less required heat for flue gas air heaters makes it possible to adopt a low-temperature economizer (LTE) between the arranged two-stage flue gas air heaters, saving part of the steam bleeds, even if the exhaust flue gas temperature is kept constant. The detailed exergy distributions within the regenerative heaters and air pre-heating process were discussed using the graphical exergy analysis. The mass and energy balance of the proposed system and the overall system performance were determined using the process simulation. The economic viability and the implementation feasibility of the proposed system was also analyzed. Results showed that the exergy destruction of the regenerative heaters and air preheating process could be reduced by 4.47 MW and 11.95 MW, respectively. The gross electric power output from the proposed system was 1007.79 MW with a satisfactory energy efficiency at 46.0%, 0.4 percentage point higher than the reference power plant. The payback period of the proposed system is slightly longer than that of the reference plant at the current market condition and it will be more profitable as the S-CO2 cycle becomes more commercially mature.

Multi-Objective Control of Air Conditioning Improves Cost, Comfort and System Energy Balance

A new model predictive control (MPC) algorithm is used to select optimal air conditioning setpoints for a commercial office building, considering variable electricity prices, weather and occupancy. This algorithm, Cost-Comfort Particle Swarm Optimization (CCPSO), is the first to combine a realistic, smooth representation of occupants’ willingness to pay for thermal comfort with a bottom-up, nonlinear model of the building and air conditioning system under control. We find that using a quadratic preference function for temperature can yield solutions that are both more comfortable and lower-cost than previous work that used a “brick wall” preference function with no preference for further cooling within an allowed temperature band and infinite aversion to going outside the allowed band. Using historical pricing data for a summer month in Chicago, CCPSO provided a 1% reduction in costs vs. a similar “brick-wall” MPC approach with the same comfort and 6–11% reduction in costs vs. other control strategies in the literature. CCPSO can also be used to operate the building with much greater comfort and costs or much lower costs and comfort than the “brick-wall” approach, depending on user preferences. CCPSO also reduced peak-hours demand by 3% vs. the “brick-wall” strategy and 4–14% vs. other strategies. At the same time, the CCPSO strategy increased off-peak energy consumption by 15% or more vs. other control methods. This may be valuable for power systems integrating large amounts of renewable power, which can otherwise become uneconomic due to saturation of demand during off-peak hours.

Thermal energy balance control model of motorized spindle system enabling high-speed dry hobbing process

High-speed dry hobbing has been confirmed as a dominant advanced technique for gear machining due to its outstanding performance in terms of high productivity and environmental friendliness. The motorized spindle system is the key component of the high-speed dry hobbing machine, and its thermal stabilization is of significant importance for the machining precision. However, due to the integration of motor and spindle, the adoption of high cutting speed and the heavy cutting load, thermal energy will accumulate in the motorized spindle system and result in thermal deformation and stability degeneration, which eventually affects the consistency of hobbing accuracy. In this paper, an analytical model is proposed to control the thermal energy balance of a high-speed dry hobbing spindle system by optimizing the thermal energy accumulation with the hob rotation speed, hob axial feed rate, cooling water flow rate and the compressed air temperature. The optimal solution is obtained by solving the proposed optimization model with the simulated annealing method. A motorized spindle system is introduced as a case study and the experimental results indicate that the maximum value of the average temperature of the motorized spindle system is reduced from 39.6 °C to 35.0 °C, an 11.6% margin, and the material removal time is reduced from 2.07 min to 1.06 min, a 48.8% margin, under the optimal condition. Moreover, the average runout value of a hobbed workpiece is effectively controlled, by a 15.7% margin. Therefore, the presented optimization model can give a reference for the selection of suitable process parameters for thermal stability control and higher machining productivity and accuracy.

Thermodynamic, Economic and Environmental Evaluation of an Improved Ventilation Air Methane-Based Hot Air Power Cycle Integrated with a De-Carbonization Oxy-Coal Combustion Power Plant

Efficient utilization of ventilation air methane (VAM) as well as improving the energy efficiency of de-carbonization oxy-coal combustion power plants are intensively studied for achieving energy savings and greenhouse gas (GHG) emission control. Here, an improved VAM-coal hybrid power generation system, which integrates a VAM-based hot air power cycle with a de-carbonization oxy-coal combustion circulating fluid bed (CFB) power plant was proposed. In the proposed system, part of the boiler flue gas was bypassed to feed the VAM auto-oxidation, and the whole VAM oxidation heat was efficiently utilized to drive a hot air power cycle. Meanwhile, the turbine exhaust air was utilized to heat the feed/condensed water within the regenerative heating trains in a cascade way, which was in turn beneficial to de-carbonization oxy-coal combustion plant. The mass and energy balance of the proposed system were determined using the simulation process. The thermodynamic benefits, economic viability and the environmental impacts were discussed. Results showed that energy efficiency of the proposed system reached 27.1% with the energy saving ratio at 0.9%. The cost of electricity (COE) was $118.15/MWh with the specific CO2 emission as low as 17.46 kg CO2/MWh.

Interaction of a quantum field with a rotating heat bath

The linear coupling of a rotating heat bath to a quantum field is studied in the framework of the Markovian master equation for the field’s non-unitary time evolution. The bath’s rotation induces population inversion for the field’s low-energy modes. For bosons, this leads to superradiance, an irreversible process in which some of the bath’s kinetic energy is extracted by spontaneous and stimulated emission. We find the energy and entropy balance for such systems and apply our results to the theory of black hole radiation. We also comment on how this relates to classical self-oscillations, including shear flow instabilities in hydrodynamics.

CORRECTION OF THE TEMPERATURE EFFECT IN 1020 NM BAND OF SUN-SKY RADIOMETER

Abstract. Aerosol is an important part of the earth-atmosphere system. It can directly and indirectly influence solar radiation and then affect the energy balance of earth-atmosphere system. AERONET, as the largest ground-based observation network, provides multi-parameters of aerosol from more than 600 hundred sites using sun-sky radiometer, which contains 9 channels from 340 nm to 1640 nm. Among which, 1020 nm channel is greatly influenced by the temperature. In this paper, a new correction method of 1020 nm band is introduced. The new method transfers the temperature correction coefficient of the master radiometer to the comparative one. The filed calibration experiment shown that the temperature correction coefficient obtained by this method is close to the result from the temperature controlled chamber, and the difference is about 2.1 %. This new method is easy-to-use, and its accuracy is comparable to the standard one. It is more applicable for large-scale instrument calibration. In principle, this method is applicable to all bands of the sun-sky radiometer.

Heat Generation Measurement of Li-Ion Battery Cells Under Fast Charging Conditions By Employing Isothermal Calorimeter

Introduction Lithium-ion batteries are employed in so many applications including electric vehicles (EVs), hybrid electric vehicles (HEVs) and many consumer products such as cell phones, tablets and computers. Notwithstanding the foregoing, there are still concerns about the safety of Lithium-ion batteries. Abuse conditions such as excessing external heat, over-charging, over-discharging, nail penetration, crush, high charging currents and external and internal short-circuit can cause battery temperature to go far beyond the manufacturer ratings. If the heating rate exceeds dissipation rate for the longer time, then thermal runaway will occur. Thermal runaway leads to many unwanted accidents such as a leak, smoke, gas venting , flames and rapid battery disassembly. Several previous studies have been conducted on the thermal safety of Lithium-ion batteries. Bernardi et al. [3] constructed a heat-generation model for battery systems containing the mixing enthalpies ,electrochemical reactions and phase changes. Guo et al. [4], by employing a finite element method, developed a three-dimensional thermal model. Kim et al. [5] developed a three-dimensional thermal abuse model concerning the chemical reactions. He et al. [6] investigated the thermal management of a Li-ion battery module by employing a two-dimensional computational fluid dynamics model. Wang et al. [7] studied the thermal management of the battery module and optimum structure through employing a lumped model and three-dimensional computational fluid dynamics method. Future electric vehicles will need to be charged in time comparable to refilling time of nowadays conventional combustion vehicles. In consequence, in this work, the thermal behaviour and heat generation of different Lithium-ion battery chemistries subjected to fast charging protocols will be investigated. Heat generation of different Lithium-ion battery cells will be measured by employing isothermal calorimeter. Methodology The experiment is performed by means IBC (Isothermal Battery Calorimeter) 284 from NETZSCH, which is illustrated in Figure 1. Calibration of the IBC 284 consists in applying a controlled electrical current to a precision resistance located inside the calorimeter chamber of the IBC 284[8]. Figure 1: External system components - IBC 284 [8]. First,the calibration of the calorimeter was performed at different temperatures (from -30°C to +60°C). Results Three different chemistries (LTO, NMC and LFP) will be tested during fast charging. Heat generation will be quantified and will be compared amongst these three li-ion battery cell chemistries. Processing of the data was accomplished by means of Proteus Analysis Software (PAS). An example of standard calibration graph and calibration polynomial are shown in figure 2. Exemplary graphs for determination of different parameters are shown in figure 3. Figure 2: Standard calibration graph and calibration polynomial [8]. Figure 3: Example of the graph [8]. References 1 J. Wen, Y. Yu and C. Chen, Mater. Express, 2, 197–212(2012). 2 C.-Y. Jhu, Y.-W. Wang, C.-M. Shu, J.-C. Chang and H.-C. Wu,J. Hazard. Mater.,192, 99–107(2011). Bernardi, D.; Pawlikowski, E.; Newman, J. A general energy balance for battery systems. J. Electrochem. Soc., 132, 5–12(1985).Guo, G.F.; Long, B.; Cheng, B.; Zhou, S.Q.; Xu, P.; Cao, B.G. J. Power Sources, 195, 2393–2398(2010).Kim, G.H.; Pesaran, A.; Spotnitz, R. J. Power Sources, 170, 476–489(2007).He, F.; Li, X.; Ma, L. Int. J. Heat Mass Transf., 72, 622–629(2014).Wang, T.; Tseng, K.; Zhao, J.; Wei, Z. Appl. Energy, 134, 229–238(2014).http://www.netzsch-thermal-analysis.com.

Effects of low-strength ultrasonication on dark fermentative hydrogen production: Start-up performance and microbial community analysis

Our previous studies have demonstrated the positive impacts of low-strength (LS)-ultrasonication on biological methane production via anaerobic digestion. In this study, the effects of LS-ultrasonication and effluent recirculation on dark fermentative hydrogen production using upflow anaerobic sludge blanket reactor were investigated. Significant increase in hydrogen (H2) yield (up to 0.89 mol H2/mol hexose) was observed under LS-ultrasonication conditions. This enhanced H2 yield seems to be associated with the decrease in dissolved H2 concentration via a degassing effect, as evident from increased H2 content (up to 20%). Effluent recirculation alone led to positive effects. However, applying both LS-ultrasonication and effluent recirculation decreased H2 yield compared to the trial with only LS-ultrasonication (0.89–0.72 mol H2/mol hexose), possibly due to the cumulative shear stress and sludge bed expansion above the ultrasonication zone. Microbial community analysis revealed that the presence/absence of LS-ultrasonication and/or effluent recirculation significantly affected the microbial communities. Ethanoligenes cloacae, Aeromonas hydrophila and Clostridium pasteurianum were identified as principal H2 producers under the LS-ultrasonic conditions, while C. butyricum, the most commonly reported H2 producer, was more abundant in the controls. The energy balance of the LS-ultrasonication system was evaluated and future research directions were suggested.

A non-equilibrium control oriented model for the pressurizer dynamics

This paper deals with a new Control Oriented Model (COM) aimed at studying the dynamic behaviour of the pressurizer in Pressurized Water Reactors (PWRs). In literature, most of the pressurizer COMs treat the vapour and the water filling the system as a homogeneous mixture by adopting the thermodynamic equilibrium assumption. This hypothesis involves a reduced set of governing equations that is suitable for the study of the pressurizer dynamics in a simplified way since interphase and non-equilibrium phenomena (e.g., water drops and vapour bubbles generation) are neglected. To overcome this limitation, an innovative COM based on the non-equilibrium approach is developed. The new model is obtained from closed-rigid system mass, energy and volume balances and allows selecting a different thermodynamic state for each phase, according to the non-equilibrium framework. In addition, while equilibrium models take into account only the heat transfer from the electrical heating of PWR pressurizers, the new COM considers also the following processes occurring in the system volume: the water drops and vapour bubbles generation (inside the vapour and liquid phase, respectively), the condensation on sprayed drops, the heat exchange between vapour and water and thermal losses toward the external environment. The new COM is also characterized by a multiple control volume formulation to reach a good accuracy for several transients (also the complete emptying) that can be experimented by a pressurizer. The experimental data of “loss-of-load” transients in the Shippingport reactor are used to assess the new COM. A code to code comparison is carried out using RELAP5 as reference.

Психобиотические эффекты пробиотиков и пребиотиков

Aim of review. The review is devoted to the effects of probiotics and prebiotics on emotional, cognitive, systemic and central spheres of psychophysiological activity in animals and humans. Microbiome is a basis of the gut-brain axis. The bacterial colonization of the gut is initiated at the moment of delivery and represents incomplete copy of maternal microbiota. Intestinal microbiome is a factor of hypothalamic-pituitary-adrenal axis formation that is involved in regulation of immunomodulation, lipid metabolism, energy balance and electrophysiologic activity of enteric nervous system. Summary. Comparison of probiotic affects in animal and human experimental studies demonstrates their equivalence. Many experimental data indicative of relation of probiotic intake and patients’ mood are accumulated. The effect of probiotics on cortisol level was demonstrated. The proof of possible immunologic effects of probiotics at irritable bowel syndrome that is associated with gut-brain signal axis disorders and microbiome changes was received. Attempts to reveal intrinsic mechanisms of positive emotional shifts in humans are of a great interest. Ability of psychobiotics to influence the depth of emotions is confirmed. Conclusion. Psychobiotics are capable to provide positive impact on patients’ mood. Addition of behavioral criteria of concern, cognitive control and suppressed mood to the studies will broaden spectrum and palette of a self-assessment of study participants. At a systemic level suppression of cortisol and proinflammatory cytokines production by psychobiotics maintain the positive effect on the mood due to reduction of systemic inflammation severity.

Slow Pyrolysis Performance and Energy Balance of Corn Stover in Continuous Pyrolysis-Based Poly-Generation Systems

In order to analyze pyrolysis performance and energy balance of corn stover utilization in continuous pyrolysis, the continuous carbonization tests were carried out on a poly-generation unit of biochar, gas and liquid developed by our research team. Corn stover was naturally dried and crushed to length of 4-7mm, and the heating thermometers are 450, 550, 650℃, the physical and chemical properties, yield rate and influence of technological parameters on them were analyzed. On this basis, the system heat transfer calculation and energy balance analysis were done. Results show that the quality of corn stover char are affected tremendously by pyrolysis temperature and material residence time, the residence time generally should be not less than 30 min. The HHV of pyrolysis gases reach about 20 MJ/Nm3 at pyrolysis temperature of 550 and 650℃. In terms of energy balance, biochar at 47.88% accounts for most of the enthalpy of products, followed by pyrolysis gas (36.17%), and wood tar and light oil, accounting fo...

Sensitivity and requirement of improvements of four soybean crop simulation models for climate change studies in Southern Brazil.

Crop growth models have many uncertainties that affect the yield response to climate change. Based on that, the aim of this study was to evaluate the sensitivity of crop models to systematic changes in climate for simulating soybean attainable yield in Southern Brazil. Four crop models were used to simulate yields: AQUACROP, MONICA, DSSAT, and APSIM, as well as their ensemble. The simulations were performed considering changes of air temperature (0, + 1.5, + 3.0, + 4.5, and + 6.0°C), [CO2] (380, 480, 580, 680, and 780ppm), rainfall (- 30, - 15, 0, + 15, and + 30%), and solar radiation (- 15, 0, + 15), applied to daily values. The baseline climate was from 1961 to 2014, totalizing 53 crop seasons. The crop models simulated a reduction of attainable yield with temperature increase, reaching 2000kgha-1 for the ensemble at + 6°C, mainly due to shorter crop cycle. For rainfall, the yield had a higher rate of reduction when it was diminished than when rainfall was increased. The crop models increased yield variability when solar radiation was changed from - 15 to + 15%, whereas [CO2] rise resulted in yield gains, following an asymptotic response, with a mean increase of 31% from 380 to 680ppm. The models used require further attention to improvements in optimal and maximum cardinal temperature for development rate; runoff, water infiltration, deep drainage, and dynamic of root growth; photosynthesis parameters related to soil water availability; and energy balance of soil-plant system to define leaf temperature under elevated CO2.

Satellite Radiothermovision Analysis of the Evolution of a System of Interacting Typhoons

In this paper we develop further the satellite radiothermovision methods for analyzing the evolution of tropical cyclones. The complicated case of Goni and Atsani interacting typhoons is considered. It has been shown that, although their interaction does not explicitly influence the features of the typhoon trajectories, indications of the formation of complex advective fluxes in the lower troposphere can be revealed from both a qualitative analysis of miscellaneous satellite data and a quantitative estimation of latent heat advection. At the same time, in contrast to the previous works, we had to introduce the integration contours of a complex form (differing from a circular one) into the analysis, so that the energy balance of the typhoon system is correctly described. In a general way, defining such contours is a separate problem whose solution is probably related to the invocation of a large volume of additional satellite information. Due to the peculiarity of the considered case of Goni and Atsani twin typhoons, we demonstrated the effectiveness of a simplified approach that uses a composite contour formed by overlapping two circular ones. Generally, as in the cases previously considered, we found the interrelation between the intensification and dissipation of typhoons (tropical cyclones) and the modes of convergent and divergent advection of latent heat with amplitudes sufficient to support the total power of the system.

RESEARCH OF ENERGETIC BALANCE OF THE HYDRAULIC SYSTEM WITH FIXED DISPLACEMENT PUMP AND PRESSURE RELIEF VALVE

It was analyzed the basic schematics implementing energy level of industrial hydraulic systems. It was considered the structure and composition of the hardware system of fixed displacement pump and pressure relief valve with manual control. It was carried out a study of the energy balance of the hydraulic system of fixed displacement pump and pressure relief valve at 5 possible positions opening cross-section of adjustable throttle valve. For each of the provisions specified size and power consumption efficiency, as well as the value of energy loss of the hydraulic system. It is established distribution of energy losses between the actuator, pump, throttle valve and pressure relief valve under different operating conditions selected hydraulic system. The change in energy efficiency and the efficiency of the hydraulic system was determined under different operating conditions. Graphs change energy balance was built throughout the range of adjustment of the hydraulic system of fixed displacement pump and pressure relief valve.

Greenhouse gas and energy balance of Jatropha biofuel production systems of Burkina Faso

Jatropha curcas has been introduced as a low-cost energy crop in Burkina Faso for the production of straight vegetable oil (SVO) and biodiesel. It is cultivated in different plantation systems including smallholder inter-plantings with annual crops, large-scale monoculture, afforestation on marginal land, in traditional hedge systems along contour stone walls, and in living fences. We performed Life Cycle Assessment of these Jatropha systems using empirical data on yields and carbon stocks, and accounting for changes in agro-ecosystem provisioning and regulating services that occurred after the land conversion to Jatropha. The study found that all J. curcas production pathways substantially reduced greenhouse gas emission (68–89%) and saved energy (65–90%) compared to diesel fuel. Highest values are achievable under the assumption that by-products (husks, seed cake, glycerin) are used for energy generation. The decentralized production of SVO supplied by feedstocks from intercropping and hedgerow systems seems to be most promising option. However, very low land-use efficiency (6.5–9.5 GJ ha−1 production) characterized Jatropha intercropping and monoculture plantations, rendering the plant a competitor to food crops and increasing the risk of conversion of savanna land to Jatropha cultivation. Jatropha plantings on marginal lands largely failed. High labor requirements constrain integration of Jatropha plantation systems within small farmholdings. Currently, the traditional hedge systems show the lowest land-use replacement potential and labor needs while providing multiple ecosystem services, but alone cannot satisfy rural energy needs. In order to reach energy supply targets without claiming more land and compromising other ecosystem services, the J. curcas plantation systems in Burkina Faso need to be made more efficient through plant breeding and improved agronomic management.