Optimal Break-Even Distance for Design of Microgrids Omar Hafez and Kankar Bhattacharya Department of Electrical & Computer Engineering University of Waterloo, Waterloo, Ontario, Canada, N2L 3G1 Eng.omar.h@gmail.com 10/30/2012 1
Outline o Introduction o Research Motivation o Objectives o Case study o Results o Conclusions 10/30/2012 2
Introduction Microgrids with renewable energy resources are becoming attractive options to meet electricity demand in remote locations, because of: Long distance between the nearest grid and rural system High cost of transmission line expansion High oil prices Desire to reduce CO 2 emissions Improve power quality 10/30/2012 3
The Microgrid Microgrids are interconnection of DGs With dispatchable generators (gas turbines, fuel cells) Non-dispatchable generators (wind and solar PV) Integrated with electrical and thermal energy storage To meet customers local needs Operate as a single system and small-scale Provide both power and heat 10/30/2012 4
Motivation Cost of energy from conventional sources is typically lower than that from renewable energy sources However a supply-mix of renewables and diesel can reduce overall cost of energy in a microgrid There is a need to examine energy supply options in microgrids and determine the optimal supply mix So that maximum benefits can be obtained from the design To determine the optimal break-even distance for a microgrid for isolated versus grid-connected mode of operation 10/30/2012 5
Objectives Optimal design of microgrids considering various renewable energy technology options With realistic inputs on their physical, operating and economic characteristics Determine the break-even distance for connection of the microgrid with the main grid Compare that with the cost of an isolated microgrid 10/30/2012 6
Microgrid Using HOMER Hybrid Optimization Model for Electric Renewable 10/30/2012 7
Test Case: Microgrid Components - Wind turbines - Solar PV array - Battery bank - Micro-Hydro turbines - Diesel generator - Dump load - Boiler - AC/DC converter 10/30/2012 8
Renewable Energy Resources Solar radiation profile Wind speed profile 10/30/2012 9
Case Studies: Microgrid Configurations Case-1: Diesel Dependent Microgrid Case-2: Renewable Based Microgrid Wind, solar PV, battery, micro-hydro, converter Case-3: Diesel-Renewable Mixed Microgrid Diesel, wind, solar PV, battery, micro-hydro, converter Case-4: Solar only Microgrid Solar PV, battery, converter Case-5: Wind only Microgrid Wind, battery, converter 10/30/2012 10
Optimal Plan Configurations Case-1: Diesel Dependent Microgrid Case-2: Renewable Based Microgrid 10/30/2012 11
Optimal Plan Configurations contd. Case-3: Diesel-Renewable Mixed Microgrid Case-4: Solar only Microgrid 10/30/2012 12
Optimal Plan Configurations contd. Case-5: Wind only Microgrid 10/30/2012 13
Comparing cost components & breakeven distance Items Case-1 Case-2 Case-3 Case-4 Case-5 Net Present Cost, M$ Levelized cost of energy, $/kwh Operating Cost, M$/year 21.751 14.924 10.496 30.693 18.682 0.932 0.639 0.449 1.405 0.8 1.631 0.399 0.614 0.475 0.589 Break-even distance, km 918 579 359 1,363 766 10/30/2012 14
Comparing Production Production, MWh/yr Component Case-1 Case-2 Case-3 Case-4 Case-5 1,825 1,107.04 Diesel Generator 0 0 0 (100%) (46%) 633.5 3,800.8 Solar PV 0 0 0 (9%) (100%) 5,962.4 1,192.48 11,924.8 Wind 0 0 (89%) (49%) (100%) 115 115 Micro-Hydro 0 0 0 (2%) (5%) Boiler 182.5 0 0 14.1 0 Renewable Energy 100% 53.8% 99.6% 100% Contribution 0% Total 2,007.5 6,710.84 2,414.51 3,814.9 11,924.8 10/30/2012 15
Comparing consumption Consumption, MWh/yr Electrical Load Energy Served Thermal Load Energy Served Excess Energy to dump load 1,825 1,824.87 1,825 1,707.4 1,824.97 182.5 182.5 182.5 182.5 182.5 0 4,703.34 407.01 1,925 9,917.3 Unmet Energy 0 0.128 0 117.6 0.03 10/30/2012 16
Emission Comparison Emissions, ton/yr Pollutant Case-1 Case-2 Case-3 Case-4 Case-5 Carbon dioxide 6004.76 3.67 1078.4 4.47 3.43 Carbon monoxide 14.82 0 2.649 0 0 Unburned hydrocarbons 1.64 0 0.293 0 0 Particulate matter 1.12 0 0.2 0 0 Sulfur dioxide 12.06 0.008 2.17 0.009 0.007 Nitrogen oxides 132.23 0 23.64 0 0 10/30/2012 17
Effect of Distance from Grid: Optimal Break-even Distance Case-1: Diesel Dependent Microgrid Case-2: Renewable Based Microgrid 10/30/2012 18
Effect of Distance from Grid contd. Case-3: Diesel-Renewable Mixed Microgrid Case-4: Solar only Microgrid 10/30/2012 19
Effect of Distance from Grid contd. Case-5: Wind only Microgrid 10/30/2012 20
Concluding Remarks The diesel-renewable mixed microgrid (Case-3) has the lowest NPC which results in the shortest breakeven distance of 359 kms The break-even grid extension distance plays a significant role in microgrid design The microgrid located beyond its break-even distance local generation is the economical and optimal option HOMER is found to be an useful tool for microgrid planning and design 10/30/2012 21
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