RENEWABLE ENERGY SYSTEMS
HYBRID ENERGY SYSTEMS APPLICATIONS
Prof. Ibrahim El-mohr Prof. Ahmed Anas
Lec. 9 8-12-2014
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Compare the total cost ( Capital and running) for the following types of water heating:
Solar type
Electric type
Gas type
Assuming the following data:
Daily hot water usage = 150 liters, 6 hours/day
Hot water temperature = 65 Co
Cold water temperature = 20 Co
The capital cost of solar heater = L.E. 4000,
Bank interest rate = 10%
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Water Heating Energy System Design
Annual maintenance for solar system= L.E. 75 and 20 years life time.
Assuming 30 days/year without solar thermal, and using electric system
The capital cost of electric heater = L.E. 1500
Annual maintenance for electric system= L.E. 50
The Electricity cost (flat rate) = 0.25 to 0.50 L.E. /kWh
The capital cost of gas heater = L.E. 2000
The cost of gas bottle, 14 m3 = L.E. 20 to 30 L.E., and consumed in two weeks
Annual maintenance for gas system= L.E. 60
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Water Heating Energy System Design
Outline
Hybrid Energy Systems (HES) Application in Remote Area.
HES Application in Rural Areas (WWTP)
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Hybrid Energy Systems (HES) Application in Remote Area
The problem:-
Optimum Sizing of Hybrid Energy System for Electrification of Remote Area in Egypt.
Solution:
Optimum topology selection ( Generator, PV, Wind, Hybrid, etc..),
Percentage share of each source,
Best operation strategies
Optimum components sizing,
Target :
for minimum overall system cost.
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Hybrid Energy System (HES)
A hybrid energy system can be defined as: “a combination of different, but complementary energy supply systems at the same place.
It is commonly installed in remote areas isolated from the utility grid.
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Advantages of Hybrid Energy System
Reductions in size of diesel engine and battery storage system, which can save the fuel and reduce pollution.
Improves the load factors and help saving on maintenance and replacement costs.
The cost of electricity can be reduced by integrating diesel systems with renewable power generation.
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Advantages of Hybrid Energy System (Cont.)
Renewable hybrid energy systems can reduce the cost of high-availability renewable energy systems. This results from the system’s ability to take advantage of the complementary diurnal (night/day) and seasonal characteristics of available renewable resources at a given site.
On the other hand, high initial capital of the hybrid is a barrier to adopt the system thus the needs for long lasting, reliable and cost-effective system.
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Hybrid Energy System/ Applications (Remote Area)
Villages
Residential Buildings
Hospitals
Schools
Farmhouses
Hotels
Irrigation systems
Desalination Systems
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Hybrid Energy System Optimization
General formulation of HES optimization problem:
The problem is to develop a multi-objective model to design a HES with battery storage and diesel generators taking into consideration future system expansion.
The design objectives are cost and CO2 gas emission minimization.
The problem constraints are:
(1) reliability constraint which dictates that a certain percentage of the peak demand must be secured as a reserve,
(2) energy balance constraint.
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HES Optimization Modeling Tools
HOMER:
Hybrid Optimization Model for Electric Renewable
by NREL(National Renewable Energy Laboratory’s) of the U.S.
Department of Energy Office of Energy Efficiency and Renewable Energy by Midwest Research Institute
RETSCREEN:
developed by Natural Resources Canada's CEDRL with the contribution of 85 experts from industry, government and academia.
HYBRID2:
developed by NREL and the University of Massachusetts
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Comparison between Modeling Tools
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HES MODELLING WITH HOMER
Main features of HOMER:-
HOMER’s fundamental capability is simulating the long-term operation of a micropower system.
Its higher-level capabilities, optimization and sensitivity analysis, rely on this simulation capability.
The simulation process determines how a particular system configuration, a combination of system components of specific sizes, and an operating strategy that defines how those components work together, would behave in a given setting over a long period of time.
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Schematic diagrams of some micro-power system types that HOMER models
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HOMER Economics Analysis
HOMER uses the total net present cost (NPC) to represent the life-cycle cost of a system.
The total Net Present Cost of a system is the present value of all the costs that it incurs over its lifetime, minus the present value of all the revenue that it earns over its lifetime. Costs include capital costs, replacement costs, O&M costs, fuel costs, emissions penalties, and the costs of buying power from the grid.
Revenues include salvage value and grid sales revenue.
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The NPC is calculated according to the following equation:
Where: TAC is the total annualized cost (which is the sum of the annualized costs of each system component).
Where: N is the number of years and ‘i’ is the annual real interest rate (%).
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The capital recovery factor (CRF) is given by:
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System Under Study
Site Selection
Demand load and resources
Initial search space for
system components
Economic consideration,
System constraints and control
Net present cost calculations
Optimization technology,
system components
and sizing
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Site selection
Remote Village in East of Owienat area
22.35 °N and 28.42 °E
It is 340 km from the nearest Egyptian electricity grid line at Aswan City
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Electrical Load Demand
kW
Hours 0
200 400 600 800 1000 1200 1400
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 Load
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Load demand
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Renewable Energy Sources
Solar energy measured by kWh/m2/day Source: Egypt atlas
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Wind energy measured by m/s Source: Egypt atlas
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Source: NASA
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Energy Resources
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search space
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Economics consideration
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System Control
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Constraints
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System Components
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Simulation Results
Case I : Generator only
Case II: Generator and PV
Case III: Generator, PV and Wind turbine
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Case I : Generator only
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The 11 possible results:-
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Discussion for Case I:-
In case I we can have 11 possible solutions.
The optimum solution is to use two generators with 50%
load sharing.
The total NPC is $27,167,26.
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Case II: Generator and PV
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Discussion for case II :-
In this case, we have 2 possible solutions.
The optimum solution is to use the PV with 83% and the Diesel Generator with 17%.
The NPC is $ 16,260,053.
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Case III: Generator, PV and Wind turbine
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Discussion for case III :-
For this case, there are 6 possible solutions.
The optimum solution is to use PV with 79 %, DG with 14%
and WT with 7%.
The NPC $ 14,518,144.
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Results Discussion
These results are based on the available data, subject to the increase or decrease of the prices.
Diesel generator fuel Transportation cost was considered in the fuel price (USD/Littre).
Wind turbine with low cut-in speed was chosen to match the wind speed range in the selected site.
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Conclusion
In this thesis, the world’s energy problem was discussed, mentioning its main drivers (world’s population, economic growth and energy prices).
Hybrid energy system was presented explaining its applications, different configurations, advantages and disadvantages.
HOMER software was chosen as the simulation tools for its great advantages over other programs.
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Conclusion (cont.)
A case study ( remote village at East of Oienate ) was chosen and simulation carried out based on the available load data and renewable resources data.
The HOMER simulations results indicate that the use of hybrid energy source with the aid of available renewable resources (solar and wind) resulting in reduction of the NPC of the overall system from 27,167,26 (in case of diesel generators powered system) to 17,406,764 USD (in case of hybrid PV, wind, and diesel system)
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