PV and CHP Hybrid System/A hybrid architecture for photovoltaic system (PV) incorporating combined heat and power units

This literature review supported the following paper:

• Kunal K. Shah, Aishwarya S. Mundada, Joshua M. Pearce. Performance of U.S. hybrid distributed energy systems: Solar photovoltaic, battery and combined heat and power. Energy Conversion and Management 105, pp. 71–80 (2015). open access DOI: http://dx.doi.org/10.1016/j.enconman.2015.07.048
• The Potential for Grid Defection of Small and Medium Sized Enterprises Using Solar Photovoltaic, Battery and Generator Hybrid Systems

A HYBRID ARCHITECTURE FOR PHOTOVOLTAIC SYSTEM (PV) INCORPORATING COMBINED HEAT AND POWER (CHP) UNITS[edit | edit source]

HAJIAN GELAREHa1 AND AHADI MOHAMMAD SAEEDb aMaster of Science, Electronic Engineer, Razi University, Kermanshah, Iran bMaster of Science, Hydraulics Water and Wastewater, Research Center, Kermanshah, Iran

This paper mainly focus to presents a novel architecture to produce the electricity demand of a building and use the heat byproduct of this process for internal usage, simultaneously. In this paper, a novel architecture is proposed for connection of photovoltaic (PV) system and combined heat and power (CHP) to supply demand. The main advantage of proposed scheme is reducing of fossil fuel consumption and greenhouse gases. Also, the economic impact of our design on total cost of production is analyzed and discussed.

PV structure[edit | edit source]

1)The PV in the paper is installed at the top of the roof at certain tilt angle. 2)The DC output of the PV is then fed into DC isolator. 3)The output of DC isolator is then given to inverter unit to converter the DC into AC power. 4)The AC power is given to AC isolator from there it is used to satisfy the load demands. 5)Any excessive power bein generated is fed into grid as this paper present grid connected PV system.

CHP structure[edit | edit source]

1)The CHP consists of mainly-

FUEL storage tank
Engine
Heat Exchanger
Heat storage unit
Inverter

2)The CHP unit generates two output Electrical as well as Thermal. 3)The CHP thermal output is mainly used for space heating and water boiling.

Hybrid System[edit | edit source]

1)The two systems are combined together i.e. PV and CHP. 2)This hybrid system is able to fulfill thermal as well as electrical demands. 3)Fossil fuel required is reduced. 4)Efficiency is increased. 5)CO2 emission is reduced.

Analysis of hybrid energy systems for application in southern Ghana[edit | edit source]

Muyiwa S. Adaramolaa, , , Martin Agelin-Chaabb, Samuel S. Paulc

This paper focus on an economic analysis of the feasibility of utilizing a hybrid energy system consisting of solar, wind and diesel generators for application in remote areas of southern Ghana using levelized cost of electricity (LCOE) and net present cost of the system. Sensitivity analysis on the effect of changes in wind speed, solar global radiation and diesel price on the optimal energy was investigated and the impact of solar PV price on the LCOE for a selected hybrid energy system was also presented

INTRODUCTION[edit | edit source]

A convergence of factors such as global decline in fossil fuel reserves, damaging effects of global warming, and rising energy demand due to increasing population are forcing a shift to low-carbon sources of energy. As a tropical country Ghana has abundant solar energy resources. The problem with solar and wind energy sources is that they are unpredictable and can be unreliable. A stand-alone solar energy system cannot provide electricity around the clock throughout the year if there are cloudy days when there is no sunlight. Similarly a stand-alone wind energy system may not produce usable energy for considerable portion of time during the year due to relatively high cut-in wind speed. Thus, hybrid system which included both of this technologies will be a good option for satisfying energy needs. Feasibility, reliability and economic analyses conducted in a number of studies showed that hybrid power systems are more reliable and cheaper than single source energy systems. The objective of this article is to study an economic analysis of a hybrid energy system consisting of solar, wind and conventional diesel generators for application in rural areas of southern Ghana. It is believed that this information will broaden the scope of options available to policy makers and all stakeholders in the energy sector as the country seeks to make critical investments in energy.

LOAD AND ENERGY RESOURCES[edit | edit source]

1)The solar energy(monthly) and wind energy(hourly and monthly) resources at the selected site as well as the cost of diesel (to fuel the generator) and electrical loads(data for 10 years).

POWER PLANT COMPONENTS[edit | edit source]

1)The hybrid solar PV–wind–diesel generator energy system (also called PV–wind–Gen hybrid) consists of two parts: (1) power plant which is made up of a PV module, a wind turbine, a diesel generator, a battery and a power converter; and (2) a mini-grid transmission and distribution system. 2)The hybrid energy system is designed and analyzed using National Renewable Energy Laboratory software, Hybrid Optimization Model for Electric Renewable (HOMER). 3)For each component of the energy system, the HOMER software requires information about the cost (capital, replacement, operation and maintenance), number (or size) of units to be used, operating hours and lifetime, and other specific component properties. In addition, the economic information (such as applicable real interest rate at a desire location and the overall system fixed, operating and maintenance costs) is required.

OUTPUT POWER[edit | edit source]

1)The power at the output of PV module can be calculated. 2)The power at the output of Wind resource can be calculated. 3)The generator system is used to supplement the power production by the renewable energy conversion systems especially when the required electrical load is not fully provided by these systems. 4)The battery is used to meet the electrical load during the nonavailability of power from the energy generating systems. 5)A power converter maintains the flow of energy between the AC electrical load and DC components of the hybrid energy system.

SYSTEM SIMULATION[edit | edit source]

1)During the simulation process, HOMER ensures that the system's operating capacity is sufficient to provide for both the primary load and operating reserve. 2)In HOMER, three operating reserves are required: one relates to the variability of electrical load and the other two relate to variability of wind speed and solar radiation.

ECONOMICS[edit | edit source]

1)Based on all the cost data for each system component, the discount rate and the project economic lifetime, the optimized system configurations are ranked based on the minimum value of total net present cost. 2) The revenues from the system include income from selling power to the grid and any salvage value that occurs at the end of the project lifetime.

RESULTS[edit | edit source]

1)From the simulation results it can seen that the Electricity generated by the PV system and the Wind resource is around 50%of the total power demand. 2)On the other hand, the relative large contribution of renewable resource can reduce the dependence of the hybrid power system on diesel price, lower the operating and maintenance as well as fuel costs.

Large-scale integration of wind power into different energy systems[edit | edit source]

Henrik Lund,

The paper presents the ability of different energy systems and regulation strategies to integrate wind power. The ability is expressed by the following three factors: the degree of electricity excess production caused by fluctuations in wind and Combined Heat and Power (CHP) heat demands, the ability to utilize wind power to reduce CO2 emission in the system, and the ability to benefit from exchange of electricity on the market. Energy systems and regulation strategies are analysed in the range of a wind power input from 0 to 100% of the electricity demand. Based on the Danish energy system, in which 50% of the electricity demand is produced in CHP, a number of future energy systems with CO2 reduction potentials are analysed, i.e. systems with more CHP, systems using electricity for transportation (battery or hydrogen vehicles) and systems with fuel-cell technologies. For the present and such potential future energy systems different regulation strategies have been analysed, i.e. the inclusion of small CHP plants into the regulation task of electricity balancing and ancillary grid stability services and investments in electric heating, heat pumps and heat storage capacity. The results of the analyses make it possible to compare short-term and long-term potentials of different strategies of large-scale integration of wind power.Monthly data of electricity being generated by each unit in hybrid system is also presented.

ENERGY PLAN MODEL[edit | edit source]

1)PV MODEL 2)CHP UNIT 3)WIND INPUT FROM OFFSHORE AND ONSHORE 4)TRADITIONAL POWER PLANT

• Inputs required for technical analysis:-

1)Annual consumption of electricity, even required for transport. 2)Solar thermal and industrial CHP production input for district heating. 3)Capacity and operating efficiency of CHP, Heat pumps, Boilers, power stations.

• The model emphasizes the analysis of different regulation strategies:-

1)Regulation strategy I: meeting heat demand. 2)Regulation strategy II: meeting both heat and electricity demands.

Dynamic programming to a CHP-HES system[edit | edit source]

X.P. Chen Member, IEEE, Z.T. Li, W.Xiong,

M.H.Wang, X.F. Yuan Electrical Engineering School, Guizhou University

Guiyang City, P.R.China

e-mail: ee.xpchen@gzu.edu.cn This paper focus on to develop a optimal energy management algorithm for operating a targeted system that consists of a CHP with hybrid energy storage (CHP-HES). By applying a dynamic programming to the system, its energy efficiencies were improved dramatically with excellent dynamic performance during the test.

NOTES[edit | edit source]

1)CHP (combined heating and power) is widely considered as the key to solve the problems of enhancing energy efficiency and reducing carbon dioxide emissions. 2)stand-alone CHP application as decentralized energy technologies can reduce the energy loss mainly caused by the heat wasted during the production understood to reach up to 65% loss of the primary energy input. 3)It is believed that integration of an energy storage system into a CHP system will improve energy efficiency of the system 4)Household electricity consumption of the house is analysed. 5)In order to keep high efficiencies of the energy system, domestic electrical energy supply requires both high power and energy capability. 6)Hybrid energy storage system is the preferable option for enhancement of system dynamics, especially when batteries are coupled with super-capacitors.

RESULTS[edit | edit source]

CHP standalone CHP with battery integrated

• Electrical energy 33% 35%
• Efficiency 65% 50%

Energetic hybrid systems for residential use[edit | edit source]

Mustapha Hatti, Nachida Kasbadji Merzouk and Achour Mahrane Unité de Développement des Equipements Solaires, UDES / EPST-Centre de Développement des Energies Renouvelables 11 Route Nationale, B.P 386-42415, Bou Ismail, Tipaza, Algeria.

The main goal of this paper is to present combined technologies (wind, fuel cells and solar power) to achieve synergies in terms of cost and energetic efficiency compared to systems based on a single energy source and energy conversion technology. The consumptions can be mobility, space and water heating, cooling, cooking, illuminations, electronics. Finally the paper describes the models required to simulate the components and sub-systems of a Wind-Photovoltaic's-Fuel cells-Micro-turbine and Diesel power system for residential applications in highlands regions of Algeria.

INTRODUCTION[edit | edit source]

• Electricity demand is increasing year by year
• Hybrid renewable energy resource can provide higher quality and more reliable Power to the consumers then single energy resource.
• The CO2 emission by habitats is increasing year by year to satisfy the increasing energy demand.
• Expectation to reduce the CO2 emission and reduce the dependence of supply on fossil fuel.

ENERGY CONSERVATION TECHNOLOGIES[edit | edit source]

• Photovoltaic
• Batteries and superconductors
• Diesel Generators
• Wind generator
• CHP (FUEL CELL+MICRO-TURBINE)

ADVANTAGES[edit | edit source]

• As the fossil fuel consumption is reduced, the use of Hybrid system with renewable energy technologies, can help reduce cost of production of electricity.
• Diesel generators are mainly included to meet the peak load requirements when the power generated by the renewable sources couldn't meet the energy demands. A battery bank can be a good replacement for Generator( to make a complete renewable based hybrid system).
• Adding CHP unit can also be used to satisfy Thermal needs(hot water, space heating).
• Increases the economy of Wind and solar power and help increasing their penetration level.
• The CO2 emission reduces considerably.

Renewable energy strategies for sustainable development[edit | edit source]

Henrik Lund Department of Development and Planning, Aalborg University, Fibigerstraede 13, 9220 Aalborg, Denmark

This paper discusses the perspective of renewable energy (wind, solar, wave and biomass) in the making of strategies for a sustainable development. Such strategies typically involve three major technological changes: energy savings on the demand side, efficiency improvements in the energy production, and replacement of fossil fuels by various sources of renewable energy. Consequently, large-scale renewable energy implementation plans must include strategies for integrating renewable sources in coherent energy systems influenced by energy savings and efficiency measures.

• Potential of renewable energy sources is very high in Denmark. The estimated potential of all resources has been listed in paper.
• Energy-PLAN model is used for analysis of large scale integration of renewable energy.

AN ECONOMIC ANALYSIS OF PHOTOVOLTAICS VERSUS TRADITIONAL ENERGY SOURCES: WHERE ARE WE NOW AND WHERE MIGHT WE BE IN THE NEAR FUTURE?[edit | edit source]

Michael Woodhouse, Ted James, Robert Margolis, David Feldman, Tony Merkel, and Alan Goodrich National Renewable Energy Laboratory, Golden, Colorado, USA

This paper mainly examine whether solar will reach grid parity in the United States. In close consultation with U.S.-based residential PV installation firms, NREL has constructed a detailed analysis of PV system prices.

• Estimated residential PV system cost including cost of everything goes around 5.73$/W and best case it goes to 3.55$/W including grid interconnection.
• This estimated system cost can be used to determine LCOE.
• The operation and maintenance is required for just two main things-

1)10-year inverter replacement with labor price. 2)end of the year one check by installer.

• The effect of including federal investment tax credit for the PV system is shown in the paper.
• The PV LCOE is then compared with electricity prices.

The value of module efficiency in lowering the levelized cost of energy of photovoltaic systems[edit | edit source]

Xiaoting Wanga,∗, Lado Kurdgelashvili b, John Byrne b, Allen Barnett a a Department of Electrical and Computer Engineering, University of Delaware, Newark, DE, United St

One standard that is used to compare different energy generation technologies or systems is the levelized cost of energy (LCOE). The relatively high LCOE of photovoltaics (PV) is an obstacle to adopting it as a major electricity source for terrestrial applications. In a conventional PV system, the cost of the module contributes approximately half of the expense and the other costs are together summarized as balance of system (BOS). Across different PV systems with the same installation area, this part of BOS ($/W) is directly dependent on the module efficiency. Therefore, the LCOE is affected by the module efficiency even if the module price ($/W) remains the same.

INTRODUCTION[edit | edit source]

• Cost reduction for PV can be achieved through combination of market, tax and regulatory incentives (e.g., tax credits, rebates, solar energy mandates)

and research and development (R&D) support.

• This paper, increased module efficiency can reduce levelized (i.e., lifetime) energy production costs of PV systems.
• One measure to compare different PV technologies is levelized cost of energy (LCOE), a concept that was introduced at the beginning. The LCOE is calculated using the solar advisor model (SAM).

LCOE[edit | edit source]

• The levelized cost of energy (LCOE) is "the cost that, if assigned to every unit of energy produced (or saved) by the system over the analysis period, will equal the total life-cycle cost (TLCC) when discounted back to the base year".
• LOCE calculations requires two sets of information: (1) system cost items, payment method, financing and incentives; and (2) performance parameters and case study location.
• LCOE is calculated by running solar advisor model (SAM), a performance and economic model.

NOTES[edit | edit source]

• Currently, the efficiency of good conventional silicon modules lies in the range of 13–15%.
• The efficiency of the new module is incorporated in the LCOE equations by changing the denominator.
• Moreover the Numerator maximum cost is installation cost so, it is changed.
• A new LCOE equation for calculation is considered to include effect of efficiency change.
• The BOS is divided into three categories: electrical system, structural system, and business processes.

1)The electrical installation cost is also considered linearly proportional to the system power capacity. Therefore, all of the electrical system cost is power-related cost, or PRC. 2)The second part of the BOS, the structural system, includes site preparation, racking and relevant installations. Since these costs are linearly proportional to the total area of the modules, the structural system cost is area-related cost, or ARC. 3)The third part of the BOS, the business processes, including financing and contractual costs, permitting, interconnection etc., is usually constant so this cost is fixed cost, or FC.

• When module efficiency varies, the total PRC ($) changes linearly in proportion to the power capacity (W).
• The new equation of LCOE considering the PRC price shows that as module efficiency increases the LCOE cost of the system decreases.

Dispatch strategy and model for hybrid photovoltaic and trigeneration power systems[edit | edit source]

Amir Nosrat, Joshua M. Pearce,

This paper introduces a dispatch strategy for PV+CCHP hybrid system that accounts for electric, domestic hot water, space heating, and space cooling load categories. The dispatch strategy was simulated for a typical home in Vancouver and the results indicate an improvement in performance of over 50% available when a PV-CHP system also accounts for cooling. The dispatch strategy and simulation are to be used as a foundation for an optimization algorithm of such systems.

INTRODUCTION[edit | edit source]

The advent of small scale combined heat and power (CHP) systems has provided the opportunity for inhouse power backup of residential-scale photovoltaic (PV) arrays. These hybrid systems enjoy a symbiotic relationship between components, but have large thermal energy wastes when operated to provide 100% of the electric load. In a novel hybrid system is proposed here of PV-trigeneration. In order to reduce waste from excess heat, an absorption chiller has been proposed to utilize the CHP-produced thermal energy for cooling of PV-CHP system.

SYSTEM OVERVIEW[edit | edit source]

• The main units are

PV CCHP Battery

The output from battery is given to a inverter to convert DC-AC and then finally the output is given to electrical load. The output of CCHP is given electrical and thermal load. The output of absorption chiller is used for space cooling and output of heat exchanger is directly given for space heating and domestic water heating.

DISPATCH STRATERGY[edit | edit source]

• The dispatch strategy is intended to control the system such that the load requirements (electric and thermal [domestic hot water usage, space heating, and space cooling]) are met. The thermal load is further split into.
• In the proposed system the thermal output of a CHP unit tends to be larger than the electrical output, the dispatch strategy first prioritizes matching the electrical load and in the event that the thermal load is not met afterwards, is altered to match the thermal load.
• Excess electric power is first placed into the batteries, and in the case the batteries are at their maximum state of charge, the electricity is dumped either onto the grid or into the ground based on whether the system is a grid-connected or stand-alone.
• In the paper the dispatch strategy is simulated using MATLAB.
• Model validation was done using HOMER software.
• The results shows there is significant improvement in PV+CCHP as compared PV+CHP module.

Optimal sizing of renewable energy and CHP hybrid energy microgrid system[edit | edit source]

Yanhong Yang ; Grad. Univ. of Chinese Acad. of Sci., Beijing, China ; Wei Pei ; Zhiping Qi

The paper mainly focus on a new method for optimal sizing renewable energy generations and combined heat and power (CHP) units in a hybrid energy microgrid, considering system operation because of the stochastic varieties of renewable source and the heat and power requirements. A new microgrid system planning model was developed, which was based on hourly energy balance and can meet customer requirements with minimum system annual cost. To solve the planning model, the simulated annealing algorithm was used. The paper presents the development and implementation of the method, and demonstrates its application on the hybrid energy microgrid system of an office park in Beijing.

INTRODUCTION[edit | edit source]

• When designing a hybrid system the sizing of the elements and determining the most adequate operation strategy should be considered at the same time.
• HOMER uses relatively simple strategies based on the ones studied by Barley and it is able to obtain an optimal design of a hybrid system by selecting the most appropriate strategy.
• In this paper we have developed a planning model considering unit deployment and system operation to size the microgrid system components. Simulated Annealing (SA) optimization method has been used to achieve global optimum.

SYSTEM DESCRIPTION[edit | edit source]

• A typical hybrid energy microgrid system is shown in the paper, it is composed of PV array generation, wind turbine generation, microturbine/engine combined heat and power system, energy storage and boiler, it provides both power and heat to the customer.
• If one has the location information where the photovoltaic array will be installed, then the solar radiation and power output of photovoltaic can be simulated.
• The wind power computation model has two parts, simulate wind speed and compute wind turbine power output.
• Microturbine CHP can have a stable power output, but the heat to power ratio and fuel consumption of it are various at partial loading. One can get the heat to power ratio and fuel consumption of partial loading through curve fitting method.

CONCLUSIONS[edit | edit source]

• This paper presented an efficient method to optimal sizing hybrid energy microgrid system including renewable energy generation and CHP unit.
• The study case shows that the renewable energy generation and CHP unit can complement each other, and heat recovery plays a significant role in the optimization performed.

Modeling and Simulation of Photovoltaic module using MATLAB/Simulink[edit | edit source]

S. Sheik Mohammeda, aFaculty of Engineering, Dhofar University, PB. No. 2509, Salalah, Sultanate of Oman, PC-211. a Corresponding Author E-mail: sheik@du.edu.om

This paper presents modeling of Photovoltaic (PV) module using MATLAB/Simulink. The model is developed based on the mathematical model of the PV module. Two particular PV modules are selected for the analysis of developed model. The essential parameters required for modeling the system are taken from datasheets. I-V and P-V characteristics curves are obtained for the selected modules with the output power of 60W and 64W from simulation and compared with the curves provided by the datasheet. The results obtained from the simulation model are well matched with the datasheet information.

INTRODUCTION[edit | edit source]

• The main aim of this paper is to provide a reader with the fundamental knowledge on design and building the blocks of PV module based on the mathematical equations using MATLAB/Simulink.

OPERATION AND CHARACTERISTICS OF PV MODULE[edit | edit source]

• Usually, the cells operate in reverse direction so that the current drift is desirable.
• Solar-cell V-I and P-V characteristics varies with temperature and solar irradiation.
• Maximum Power Point is the operating point at which the power is maximum across the load.
• Efficiency of solar cell is the ratio between the maximum power and the incident light power.
• Fill Factor (FF) is essentially a measure of quality of the solar cell. It is calculated by comparing the maximum power to the theoretical power (Pt) that would be output at both the open circuit voltage and short circuit current together.
• Typical fill factors range from 0.5 to 0.82. The fill factor diminishes as the cell temperature is increased.

MODELING AND SIMULATION OF PV[edit | edit source]

• The Solarex MSX60/MSX64 PV modules are chosen for modeling.
• These modules consist of 36 polycrystalline silicon solar cells electrically configured as two series strings of 18 cells each.

CONCLUSION[edit | edit source]

• The I-V and P-V characteristics outputs are generated using the developed model for the selected modules and the obtained results are well matched with the datasheet information.

Energy, economic and environmental analysis on RET-hydrogen systems in residential buildings[edit | edit source]

M. Beccali, , S. Brunone, M. Cellura, V. Franzitta

The paper focus mainly on analyze energy, economic and environmental performances of a set of scenarios dealing with the production and the use of hydrogen as energy carriers in residential applications in combination with renewable energy (RE). Many energy systems have been considered according to several fuel-device combinations (electric grid, fuel cell, PV panels, wind turbines, boiler etc.). HOMER software was used to calculate energy balance of the system and its components.The net present cost and the cost of energy are the two main parameters used to compare economic performances of the systems with both actual and expected costs in the medium term. Sensitivity analysis for the same has been carried out.

INTRODUCTION[edit | edit source]

• This paper analyses the use of hydrogen technologies in residential buildings connected to an existing electric grid. The aim of the study is to investigate the economic and environmental impacts of the use of hydrogen fuel cells as a substitute for electricity provided by grid and heat from a gas boiler. The building is thought of as a self-sufficient system, and the electric grid represents only an emergency device that operates when the fuel cell is not running.

SYSTEM AND SIMULATION[edit | edit source]

• The house which is being used for the case is being analysed(Area of each room including the number of person staying in an house).
• The consumption of electricity by the house during and cold and hot day is noted in graphical form.
• Yearly, electricity demand is also noted in form of hours 1-(365*24).
• The thermal load profile of the house is also noted hourly in graphical form.
• We are interested in case 6 where we have fuel cell CHP, PV electrolyzer and grid connection when needed and simulation is done using HOMER software.
• In system no. 6, heating and cooling are provided by heat pumps. Electric energy demand includes energy for domestic devices and for heat pumps. It is entirely met by a PV installation and by a hydrogen fuel cell. The fuel cell runs when solar radiation is low or null.
• Surplus production of electricity from the PV can occur in correspondence with high solar radiation, and it is used for the operation of an electrolyzer to produce hydrogen.
• Electrolytic hydrogen is then used to supply the fuel cell.

ECONOMICS ANALYSIS[edit | edit source]

• The costs of the main components of the systems. Equipment performances and costs data have been assumed by market surveys and by literature.
• NPC is the present value of installation and operation costs of the system over its lifetime.
• COE is the average cost per kWh of useful electricity produced by the system.
• Equipment cost and technical parameters, cost of fuels (hydrogen and natural gas), electrical and thermal energy demand, pollutant emission factors, global solar radiation and wind speed annual time-profiles have been used as input for simulations.

SENSITIVITY ANALYSIS[edit | edit source]

• A sensitive analysis has been carried out in order to assess the influence of the variation of the COE carriers and devices.
• Factors that were considered for analysis were:-

!)Change in capital and fuel cost. !)Change the cost of hydrogen distributed by pipeline. !)Change the cost of natural cost distributed by pipeline.

Hybrid solar fuel cell combined heat and power systems for residential applications: Energy and exergy analyses[edit | edit source]

Mehdi Hosseini, , , Ibrahim Dincer, Marc A. Rosen

In this paper A residential solar PV–electrolyzer system is developed and coupled with a high temperature solid oxide fuel cell (SOFC) system (PV–FC) for supplying the electricity demand. It is possible for the PV system to generate electricity in excess of the demand during off-peak hours. The surplus electricity is used by the water electrolyzer for hydrogen production. The hydrogen produced is stored in a storage tank. The fuel cell is fed with the hydrogen generated by the electrolyzer. The PV–FC system is coupled with a heat recovery unit, which provides the residential area with thermal energy, to improve energy utilization. The heat recovery unit consists of a heat recovery steam generator and an absorption chiller utilizing the thermal energy of the SOFC flue gas for heating and cooling purposes. Determining system operational parameters is important for the design and implementation of the CHP system in a residential area. Therefore, the residential CHP system is assessed here based on energy and exergy. The hourly demand of the residential area is taken into consideration for component selection and sizing, and energy and exergy efficiencies of the developed system are presented.

SYSTEM DESCRIPTION[edit | edit source]

• The solar PV system is the main part of the electricity generation module. A PEM water electrolyzer is utilized for hydrogen production from surplus PV electricity. Hydrogen is stored during day when loads are below the peak and input to the SOFC to provide residential electricity at night.
• An atmospheric SOFC is used in the modeling, so the hydrogen temperature rises when its pressure decreases from the storage tank pressure (5 bar) to atmospheric pressure (1 bar). If preheating is still required, an external heat source is considered for this purpose, however, only the amount of the required heat is calculated in the analysis
• High temperature gases leaving the stack are directed to a heat recovery steam generator (HRSG), for steam generation. The HRSG provides steam for an absorption chiller.
• The PV and SOFC power output are converted in a DC/AC converter to meet the power requirements of the house.
• Solar radiation data hourly is noted.

RESULTS[edit | edit source]

• Efficiencies of the PV system has been noted.
• The power generated by the photovoltaic and the energy demand has been noted.
• Excessive power not fulfilled by PV is given by CHP unit.
• If the power generated by the PV module generally is summer is higher then the demand then it is used for electrolyzer operates to generate hydrogen.

Energy dispatching based on predictive controller of an off-grid wind turbine/photovoltaic/hydrogen/battery hybrid system[edit | edit source]

Juan P. Torreglosaa, c, , Pablo Garcíab, , Luis M. Fernándezb, , Francisco Juradoa, , This paper mainly focus on energy dispatching based on Model Predictive Control (MPC) for off-grid photovoltaic (PV)/wind turbine/hydrogen/battery hybrid systems. The renewable energy sources supply energy to the hybrid system and the battery and hydrogen system are used as energy storage devices. The modeling of the hybrid system was developed in MATLAB-Simulink, taking into account datasheets of commercially available components. To show the proper operation of the proposed energy dispatching, a simpler strategy based on state control was presented in order to compare and validate the results for long-term simulations of 25 years (expected lifetime of the system) with a sample time of one hour.

INTRODUCTION[edit | edit source]

• Depending on the objectives to meet by the energy dispatching there are two kinds of simulations that can be carried out: short term and long-term simulations.

1)Short-term simulations are focus on the dynamics of the sources which compose the system and take them into account to face the net power variations due to the changes in load power or disturbances in the renewable energy sources. 2)Long-term simulations are used when the main objective is to show the proper operation of the system during a considerable period of time (from months to the whole life of the system). they pay attention to other parameters such as operation costs, degradation of the sources, level of charge of the storage devices, etc.

SYSTEM UNDER STUDY[edit | edit source]

• In this HS, the main energy sources are the wind turbine and PV panels (renewable sources), whose operation is assisted by the battery and hydrogen system (composed by fuel cell, hydrogen tank and electrolyzer) working as backup and storage systems.
• In the hydrogen system, the fuel cell is supplied by the hydrogen provided by the tank, which is filled by the electrolyzer.
• The energy that flows among the energy sources is controlled by DC/DC converters which connect them to a common DC bus.
• In this HS, when the renewable energy is higher than the energy demanded by the load, this energy excess can be stored as electricity in the battery or as hydrogen in the tank (produced by the electrolyzer).
• On the other hand, when the renewable energy is lower than the demanded energy, this energy deficit can be supplied by the battery and/or fuel cell.
• The sizing of the HS was carried out using Simulink Design Optimization of MATLAB

SIMULATION RESULTS[edit | edit source]

• The control strategies presented in this work were simulated for 25 years (the estimated lifetime of the HS) with a sample time of one hour to evaluate and validate the performance of the proposed energy dispatching based on MPC.
• The sun irradiance, wind speed (hourly) and load power consumption profile (hourly for 4 different days of different seasons) used in the simulations.
• The efficiency for the hybrid system, the battery and the hydrogen system are calculated.
• Fuel cell efficiency is higher at low power demand.

Modelling an off-grid integrated renewable energy system for rural electrification in India using photovoltaics and anaerobic digestion[edit | edit source]

J.G. Castellanos, M. Walker, D. Poggio, M. Pourkashanian, W. Nimmo,

This paper focus on the design optimisation and techno-economic analysis of an off-grid Integrated Renewable Energy System (IRES) designed to meet the electrical demand of a rural village location in West Bengal e India with an overall electrical requirement equivalent to 22 MWh year�1. Micro-grid modelling software used was HOMER.

INTRODUCTION[edit | edit source]

• There is an increased interest in installing small scale renewable generation systems to electrify these communities.
• However, due to the intermittence in energy generation of many renewable systems depending on one single source, this option may be unreliable. To increase the reliability of the renewable energy system, the most suitable method is to develop Integrated Renewable Energy Systems (IRES) which rely on multiple generation technologies.
• Well managed integrated renewable energy systems, which combine a higher number of technologies, potentially produce cheaper energy than simple energy systems.

MATERIALS AND METHODS[edit | edit source]

• Due to abundance of bio-gas and Solar light the chosen energy conversion technologies were PV and anaerobic digestion (AD), with a Combine Heat and Power (CHP) generator fueled by biogas. Even storage unit was added to store excessive DC generated by the solar input during sunny days.
• The load demand of around 1000 residents in the village were noted hourly in graphical form.
• The demand is split into various categories and includes economic activity i.e. grinding spices, water pumping, the operation of a medical centre, adult and child education facilities, lighting and entertainment.
• Micro-grid modelling was performed using HOMER. This software allows simulation of the performance of an energy system with uncertain operational conditions, allowing robust design with reduced project capital risk.
• Here we will talk about the modelling and results just of the Gth scenario which include PV+STORAGE+CHP+DC=AC+AD.

PV[edit | edit source]

• Average radiation data of solar is noted whereas the graphical data representing monthly daily radiation data.A derating factor equivalent to 80% and

ground reflectance of 20% were assumed. The 20 years lifetime PV panels were considered not to have a tracking device, thus the angle at which the panels are mounted relative to the horizontal was set at 23degrees�.

STORAGE[edit | edit source]

• Vanadium redox battery were considered for storage for the DC generated from the PV.

CHP[edit | edit source]

• The fuel cell system consisted of three elements: fuel cell, electrolyser and hydrogen tank. The fuel cell operating lifetime was considered to be 40,000H.
• The expected operating lifetime of the CHP generators was 60,000 h and their operation schedule was assumed to be fixed and manually programmed.

ECONOMIC AND FINANCIAL VARIABLES[edit | edit source]

• Capital and O&M costs of the main components of the IRES are noted.

RESULTS[edit | edit source]

• The Net present cost of different scenarios were compared which depends on the capital as well as O&M cost and it was found the scenario G was the best fit.
• Similarly the LCOE of the different scenarios were compared and the one for the scenario G was minimum.

Economic and environmental based operation strategies of a hybrid photovoltaic–microgas turbine trigeneration system[edit | edit source]

Firdaus Basrawia, , , Takanobu Yamadab, , Shin'ya Obarac,

This paper mainly focus on the economic and environmental performance of a photovoltaic (PV) and microgas turbine trigeneration system (MGT-TGS) based hybrid energy system with various operation strategies.The hybrid system covers power, heating and cooling load of a selected building under a tropical region. A case of MGT-TGS without PV was also studied for comparison. Each system had an MGT with electrical output capacity of 30 kW or 65 kW as the core prime mover. Economic performance was analyzed using life cycle cost analysis and environmental performance was analyzed based on the actual emissions of MGT reported in literatures.

MATERIALS AND METHOD[edit | edit source]

• Ambient temperature conditions were noted.
• The area and dimensions of the rooms were noted. Moreover, the cooling, heating an power demand were also noted.Power demand increases during day hours whereas cooling demand increases during night hours.

HYBRID SYSTEM[edit | edit source]

• Power-match operation can be used in which PV can cover the power demand up to the maximum level during day time, and Micro-gas turbine in CHP will follow the rest of the power demand.
• Imbalance between the heat supply and demand can be controlled by the heat storage, and insufficient heat can be covered by the boiler.
• Heat-match is expected to have higher cost because of the use of battery.
• The problem with above mentioned stratergy is the MGT are designed to operate at full-load conditions.
• Under partial load operation, their power generation efficiency will decrease and their emissions level will also increase rapidly.
• Thus, another good operation strategy is by using smaller MGT to run at base load, and the PV and battery will cover the power demand at peak load. Insufficient and imbalance cooling and heating load can be covered by the heat storage and the boiler. Although this operation strategy is expected to have the lowest emissions level, it may also have high cost due to the use of battery.

ECONOMIC ANALYSIS[edit | edit source]

• All inflow or outflow of money throughout the life cycle will be calculated based on the present worth. Net Profit NP gained for 25 years of life cycle of the investment on the energy system can be calculated.
• This profit depends on PrPe is profit by not buying electricity from the grid [US$], Ceq is the equipment cost [US$], Cins is the installation cost of the equipment [US$], CO&M is the operation and maintenance cost of equipment [US$], Crep is the replacement cost for equipment that has life time less than 25 years [US$], Csal is the salvage and market value of equipment in the end of their life time and in the end of 25 years of life cycle [US$], and Cfuel is the fuel cost [US$].
• Present worth PWx of a uniform series of payment can be calculated and it depends on PWFAUP is Present Worth Factor for annual uniform payment [–] and AUPx is amount of annual uniform payment. In the case of operation and maintenance cost, AUP is the amount of operation and maintenance cost for a year.
• The present worth factor depends on the interest rate and the life time of project.
• Equipment including battery and MGT-CGS that have lifetime less than 25 years and therefore cost for their replacement are also needed.
• Fuel cost should also be considered.

RESULTS[edit | edit source]

• When the electricity price was highly subsidized, none of the hybrid system can give Net Profit throughout the 25-year life cycle time. Even the simplest MGT-TGS without PV cannot generate Net Profit. However, when the unsubsidized price of electricity was considered, all hybrid systems show positive Net Profit.
• Sensitivity analysis was carried out considering the changes of Net Profit when natural gas price increases.

Optimal Power Scheduling in a Virtual Power Plant[edit | edit source]

Davide Aloini, Emanuele Crisostomi, Marco Raugi and Rocco Rizzo

This paper focus on a novel approach where the Energy Management System of a Virtual Power Plant decides the optimal power scheduling not on the basis of some predefined policies, but upon the solution of an optimization problem. The scheduling decision is dynamic as it depends on variable factors, not fully predictable, such as renewable sources availability, electrical energy price, controllable and uncontrollable loads demand and possibility of storing or releasing stored energy. The optimal solution is computed according to a novel cost function that explicitly takes into account only direct costs.

ENERGY PRODUCTION COST FUNCTION[edit | edit source]

• Optimal management of a VPP requires both short-run and long-run decisions.
• The short-run is a time period in which some production factors are fixed. Fixed costs, such as those due to the existing plant instalLment and annual Operation and Maintenance (O&M) costs, do not have a significant impact on firm's short-run decisions, as only variable costs and revenues affect profits.
• On the contrary, in the long-run period all the production factors are considered as variable. Typical long-run decisions include investment decisions (e.g., plant upgrade), entering or leaving a specific industry, etc.
• a popular way to express cost functions is the so-called Levelised Costs Of Electricity (LCOE) form.
• LCOE can be calculated using Electrt is the amount of electricity produced in the year t, (1 + r)−t is the discount factor for year t (r is also called discount rate), and the terms at the numerator represent investment costs, O&M costs, fuel costs, carbon costs and decommissioning costs in the year t.

METHODOLOGY[edit | edit source]

• The optimization algorithm is explained through a case study, to improve the clarity of the presentation; the investigated scenario consists of (a) three distributed energy resources, i.e., a photovoltaic (PV) plant, a wind (W) farm and a Combined Heat and Power (CHP) unit; (b) two storage systems, i.e., a small pumped hydro storage and 10 low-speed flywheels; (c) controllable and uncontrollable loads; and (d) the grid, from which the EMS can buy/sell energy.
• PV: We consider the data of an Italian Solar PV characterized by a Net Capacity of 6MW, a capacity factor of 16%, variable O&M costs equal to 36.68e/MWh
• Wind plant: We consider the data of a French Onshore wind characterized by a Net Capacity of 45MW, a capacity factor of 27%, variable O&M costs equal to 14.00e/MWh.
• CHP: We consider the data of an American simple gas turbine CHP characterized by a Net Electrical Capacity of 40MW, a capacity factor of 85%, variable O&M costs equal to 0.73e/MWh and 54.41e/MWh for fuel and carbon costs.
• Small pumped hydro:In this case-study we assume a Net Capacity of 10MW, a capacity factor of 70% and variable O&M costs equal to 2.58e/MWh
• Low-speed flywheel:Here we consider variable costs equal to 2.78e/MWh, a 90% efficiency and a Net Capacity of 1650kW with a discharge cycle of 120 s.
• Renewable resources are always 100% exploited, because they are convenient as they do not require carbon/fuel costs.
• At some particular moments (i.e., night time), the EMS buys (or sells less) energy from (to) the grid as it is cheaper than using the CHP; CHP production is thus reduced during off-peak hours and is fully restored during on-peak hours, always according to its modulating capabilities.

DISCUSSIONS AND RESULTS[edit | edit source]

After solving the optimiZation problem, the EMS finds the optimal power flow values, and decides

• How much energy should be produced and by whom (e.g., by the CHP rather than by the PV plant);
• Whether surplus energy should be stored, or stored energy should be supplied to the grid/loads and by which storage system (i.e., either use the small pumped hydro or the flywheels);
• Whether energy should be bought or sold from the grid.

A PROPOSED HYBRID GEOTHERMAL - NATURAL GAS - BIOMASS ENERGY SYSTEM FOR CORNELL UNIVERSITY. TECHNICAL AND ECONOMIC ASSESSMENT OF RETROFITTING A LOW - TEMPERATURE GEOTHERMAL DISTRICT HEATING SYSTEM AND HEAT CASCADING SOLUTIONS.[edit | edit source]

Maciej Z. Lukawski1,2,* , Konstantinos Vilaetis1,2, Lizeta Gkogka1,2 , Koenraad F. Beckers1,2 , Brian J. Anderson3 , Jefferson W. Tester1,2 1Cornell Energy Institute, Cornell University, Ithaca, NY 14853, USA 2 School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY 14853, USA 3Department of Chemical Engineering, West Virginia University, Morgantown, WV 26506, USA

• Corresponding author: mzl8@cornell.edu

This paper focus on an in-depth technical and economic analysis of supplementing the existing natural gas-fired combined cycle heat and power (CHP) plant with an Enhanced Geothermal System (EGS) and a torrefied biomass boiler.Design of the district heating system and its operating parameters were optimized to obtain a minimum levelized costs of energy. An Organic Rankine Cycle (ORC) waste heat recovery unit was considered to utilize the excess thermal energy available in the summer from the EGS reservoir for generating electricity. A torrefied biomass boiler was used to supplement the heat output of EGS reservoir to meet peak winter heat demand. Proposed solutions were evaluated in terms of levelized cost of electricity (LCOE), fossil fuel consumption, and CO2 emissions.

ECONOMIC EVALUATION[edit | edit source]

• In this paper the discount rate is considered to be 6% and payback time is 20years.
• Capital investment costs:
• Operation and maintenance (O&M) costs:
• Natural gas price:
• Heat credits:
• Electric power generated:
• All the above mentioned factors are required to calculate the LCOE of the system.