B. S. E. E., M. S. Space Technology, LS IEEE 12.4 Wind Hybrid Systems Frank R. Leslie, B. S. E. E., M. S. Space Technology, LS IEEE 3/15/2010, Rev. 2.1 fleslie @fit.edu; (321) 674-7377 www.fit.edu/~fleslie

In Other News . . . Wind Turbines in Chicago Tribune 3/14/10 http://www.istockanalyst.com/article/viewiStockNews/articleid/3946002 (Source: Chicago Tribune) By Julie Wernau, Chicago Tribune “Mar. 14--Months have passed since anyone has waved hello to one another in Waterman or Shabbona in rural DeKalb County. Some people claim they've even stopped going to church to avoid having to talk to former friends. "It's gone. The country way of living is gone," declares Susan Flex, who lives in Waterman with her husband and their nine children. The animosity stems from the greenest of energy sources: a wind farm. “ Complaints of noise and light flicker 100315

12.4 Overview: Wind/Solar Hybrid Systems Erratic energy sources like wind and solar are not dispatchable, that is, available on command of utility dispatchers Sometimes or often, the wind blows when it is cloudy, or the sun shines when the wind is calm A system that combines various energy sources is called a “hybrid” system Diesel generators are often used for “reliable” power, and wind or solar are used to decrease the fuel costs Studies of a site can indicate the optimal combination of wind, solar, and diesel (or gasoline) to provide power at the lowest overall annual cost 050310

12.4 About This Presentation 12.4.1 Energy Mixture Availability 12.4.2 Hybrid Mixes 12.4.3 Economics of System Combination 12.4.4 Hybrid System Design 12.4.5 Balance of System (BOS) 12.4.6 Power Control 12.4.7 Power Availability 12.4.8 Hybrid System Examples 12.4 Conclusion 060306

12.4.1 Energy Source Mixture Availability Assessment of wind vs. solar for a specific site uses a small representative turbine or anemometer and a PV module The energy ratio plotted throughout a year indicates the relative energies available, which can then be compared with system cost ($/kWh) The actual energies available can then be compared with longer-term climate data to estimate annual variations Life-cycle costs of the two systems must be included to get a comprehensive determination of an optimal system design One of the systems might be omitted if the energy contribution is less than ~5% of the total Why bother if $/kWh is too high? 100315

12.4.1 Energy Source Cost Choices Hypothetical Cost Line $ 100% 0% http://dna-view.com/triangle.htm Wind $ 50% 50% $ 33.3%S, 33.3%W, 33.3% F Solar $ 0% 100% $ $ 50% 100% 0% 0%S, 100% F Fuel 100%W, 0% F Assess cost of various mixes of energy, enter total costs, sketch contours to seek lowest cost region 100315

12.4.2.1 Wind/Diesel Wind/diesel systems work well where sunlight is limited, as above the Arctic Circle or below the Antarctic Circle Wind turbines have worked well at the South Pole Station, but diesel generators are also hard at work there Gasoline engines also can be used, but may lack the life of a heavy diesel engine Diesel fuel costs $2.90; gasoline $2.77 as of 3/15/2010 www.renewableenergyaccess.com 100315

12.4.2.1 Wind/Diesel 3/15/2010 diesel prices 100315

12.4.2.1 Wind/Diesel 1970-2009 crude oil $ vs. production million barrels per day 100315

12.4.2.2 Solar/Diesel Hybrids Solar power has a much more stable short term output than wind power; the solar energy is less “volatile” than wind to use an economics term As the insolation rises in the morning, the diesel engine might be shut down until late afternoon or when clouds reduce solar power for a certain number of minutes The controller could run the diesel engine only when the battery voltage drops below a very low set point, such as 10.5 volts The diesel would be stopped when the battery voltage rose to approximately 13.9 volts A battery-charging procedure minimizes the number of engine starts and ensures full-load engine operation 100315

12.4.2.3 Diesel Engines A 9.2 kVA diesel package plant from Genasys Systems in a quieting package (top) Multiple large diesel sets (bottom) A small diesel might require 2.5 L/hr at idle and 7.5 L/hr at 14 kW changing somewhat linearly from idle to full load http://www.eere.energy.gov/windpoweringamerica/ 100315

12.4.2.4 Propane Engine Generator Liquefied petroleum gas (LPG) in the United States is primarily propane, but also contains propylene, butane, and butylene Gasoline-carbureted generators may be converted to propane; often done in pickup trucks in Western US The Onan (Cummins) generator shown below produces 5.5 kW and costs ~$2970 (~$540/kW) One gallon/hour of liquid propane will produce ~10kW http://www.merequipment.com/Frequently%20Asked%20Questions/Powergard_Elliott_faq.htm 100315 http://www.emnrd.state.nm.us/ecmd/html/propane.htm

12.4.2.5 Tripartite Systems A wind/solar/diesel system is only somewhat more complex than the wind/solar type The system balance between wind and solar is determined as in a conventional system, adjusting the costs of each to match the available energy If the sun rarely shines, the solar equipment would not be cost-effective If the wind rarely blows, the wind equipment would not be cost-effective Each of these sources offsets the need for diesel consumption, yet including some diesel capacity improves the availability and reliability of power 100315

12.4.2.6 Fuel Consumption The rate of diesel fuel consumption is critical to the analysis Diesel fuel costs ~20% more than gasoline Biodiesel is even more costly Fuel transportation raises the actual fuel cost and must be included in the total price The engine speed must be matched to the generator/alternator to optimize efficiency When the generator runs, it should do so at full load, charging batteries as necessary, then shutting down completely to save fuel 070226

12.4.3 Economics of Plant Combination The location is the prime driver of the cost-analysis When the remoteness and lack of roads makes fuel-hauling or helicopter transport too costly, the wind or solar components must be increased to ensure reliable power Mountain-top radio repeaters exemplify the inaccessible site, and access may be limited to hiking or horseback (pack trains) The handset radio has 5W to reach the repeater, the repeater receiver audio is patched to the 50W transmitter on another frequency, and the high power signal reaches other receivers farther away Matching of the load times to the energy times determines the need for storage capacity Scottish Moor http://www.windsund.com 070313

12.4.4 Hybrid Installation Design Some rules from Manwell, et al.: Without storage, the load limits what energy may be used or extracted Load matching for time of day limits output as well Diesel engines must be sized for highest load to carry the loads in normal operation The savings is never greater than the fuel savings 060308 Manwell, et al., 2002

12.4.5 Balance of Systems (BOS) The balance of system must include the necessary fuel tanks, piping, transportation support, etc. Local shops may be needed to perform engine overhaul, since the distance to civilization may be great BOS must include means of transporting fuel to the engine If a truck is normally used to travel to a location that has fuel, there might not be an extra trip or expense With dual truck tanks, one might be used just for hauling fuel for the generator The labor (driver) cost is increased slightly for getting fuel, but increased greatly if the trip would not have been otherwise made 080226

12.4.5.1 Balance of Systems (Wiring) An installation in China Please don’t do this! Wiring should be neat and well secured to prevent fires! 100315 http://www.nrel.gov/international/china/pdfs/vp_workshop_2002/wallace_undp.pdf

12.4.5.2 Balance of Systems (Diesel) Fueled systems will require tanks, lines, and possibly pumps In cold weather, diesel oil thickens, and insulation or heating of the lines may be required Hot water tubes can be run parallel to the fuel lines Small car engines may use 3 liters per 100 km (78 mpg) If at 78 mph, that would be 3 L/hr, or to avoid mixed units systems, approximately 3/4 gallon/hour A typical 500 gallon tank would hold ~500 hours of fuel, so replacement fuel must be obtained faster than that to keep the tank filled so the generator doesn’t stop 100315

12.4.5.3 Battery Storage Batteries provide an “inexpensive” form of storage They are required for wind and solar energy, but diesel (gasoline) generators could run to carry the load For reliability, some diesel service might expensively be kept online at all times to avoid starting delays Large battery systems require some maintenance checks but usually last for many years (7-20) A large Uninterruptible Power Supply (UPS) can carry the load for minutes to hours or longer depending upon the amount of battery ampere-hours that supports it Adding storage means that the energy available is “leveled” and unnecessary engine starts are avoided 050310

12.4.5.3.1 Battery Storage (Australia) http://www.solarshop.com.au This shipping container contains the controller and a very large battery 100315

12.4.6 Power Control System monitoring by computer allows programming of automated supervisory monitoring and determines actions to take in response The system functions in software might include Start an engine Control battery charging Control energy load dumping for wind turbine Change loads to match available power Engage engine clutch Report alarms to a distant operator 070226

12.4.6.1 Power Control for Backup Engine-Generator The engine-generator starting sequence automatically begins when the line voltage sags (drops) below perhaps 105 volts A transfer switch changes the load from the wind/solar inverter output to the engine-generator output The battery is connected to the starter motor and the engine is cranked to start under a solenoid-controlled choke fuel enrichment As the starter turns over the engine-generator, the speed is sufficient to provide voltage to the load Once the engine is running, the choke is opened to provide a normal fuel mixture The entire sequence is so fast that lights on the load side don’t noticeably flicker When inverter power returns for thirty seconds, the load is switched to the inverter (after a delay) and the engine is stopped 100315

12.4.6.2 Power Control for Continuous Hybrid System In a full hybrid system, the engine runs continuously and the wind/solar sources subsidize (add to) the available energy, saving fuel by shutting down the engine whenever possible The inverter is synchronously matched to the power frequency and voltage, providing more or less power as is available 100315

12.4.7 System Availability As long as the engine works and the diesel fuel lasts, system availability is high If the renewable sources are low, the fuel will be used faster (and require replenishment more often) If the engine fails and there is no storage (battery), the system will only have the varying renewable energy and might not function at all due to voltage variations Solar energy might carry the load until mid-afternoon, but the wind system would be too variable in many locations 100315

12.4.8 Example: Alaskan Hybrid Site Coast Guard Station in Alaska Wind and solar energy seem to be augmented by five large propane tanks near the base of the turbine If so, a propane-fueled generator would be used instead of diesel There is likely a really long fill hose on the supply boat that can connect to the tanks http://www.uaf.edu/energyin/webpage/pages/other_important_topics/hybrid.htm 090317

12.4.8.1 Example: San Clemente Island, CA US Navy turbine installation to reduce diesel fuel use by a navigation light NREL determined that cost of energy (COE) was $0.193/kWh vs. $0.45/kWh baseline with all diesel power 100315

12.4.8.2 PV Installation in Australia Diesel generator supplies backup power See www.solarshop.com.au for details 060217 http://www.solarshop.com.au/

12.4 Conclusion: Wind Hybrid Combinations of energy sources will provide more reliable power than any one source alone --- energy diversity Diesel, propane, or gasoline engine-generators produce power on demand, and can self-start when the power line voltage is dropping Natural gas can be piped to some areas When wind or solar energy is available, the fueled generator will shut down, saving its fuel cost Although overall costs are higher, the power is more reliable 070226

Olin Engineering Complex 4.7 kW Solar PV Roof Array Questions? 080116

References: Books Boyle, Godfrey. Renewable Energy, Second Edition. Oxford: Oxford University Press, 2004, ISBN 0-19-26178-4. (my preferred text) Brower, Michael. Cool Energy. Cambridge MA: The MIT Press, 1992. 0-262-02349-0, TJ807.9.U6B76, 333.79’4’0973. Duffie, John and William A. Beckman. Solar Engineering of Thermal Processes. NY: John Wiley & Sons, Inc., 920 pp., 1991 Gipe, Paul. Wind Energy for Home & Business. White River Junction, VT: Chelsea Green Pub. Co., 1993. 0-930031-64-4, TJ820.G57, 621.4’5 Patel, Mukund R. Wind and Solar Power Systems. Boca Raton: CRC Press, 1999, 351 pp. ISBN 0-8493-1605-7, TK1541.P38 1999, 621.31’2136 Sørensen, Bent. Renewable Energy, Second Edition. San Diego: Academic Press, 2000, 911 pp. ISBN 0-12-656152-4. Texter, 090227

References: Websites, etc. http://www.uaf.edu/energyin/webpage/pages/other_important_topics/hybrid.htm http://www.sandia.gov/wind/ http://gttserv.lth.rwth-aachen.de/~sp/tt/gtt-news/gttn_13.html triangle plotting of proportions http://www.nrel.gov/international/china/pdfs/vp_workshop_2002/wallace_undp.pdf RE systems http://alaska.bp.com/alaska/beyond_petroleum/limevillage/limevillage.htm Lime Village, Alaska by BP http://www.eere.energy.gov/windpoweringamerica/pdfs/workshops/2002_wind_diesel/san_clemente_california.pdf ____________________________________________________________________________ awea-windnet@yahoogroups.com. Wind Energy elist awea-wind-home@yahoogroups.com. Wind energy home powersite elist mailto:energyresources@egroups.com rredc.nrel.gov/wind/pubs/atlas/maps/chap2/2-01m.html PNNL wind energy map of CONUS windenergyexperimenter@yahoogroups.com. Elist for wind energy experimenters telosnet.com/wind/20th.html www.google.com/search?q=%22renewable+energy+course%22 solstice.crest.org/ dataweb.usbr.gov/html/powerplant_selection.html http://tonto.eia.doe.gov/oog/info/gdu/gasdiesel.asp http://www.pruftechnik.com/fileadmin/user_upload/COM/Condition_Monitoring/Products/Online_Systems/VIBROWEB_XP/Brochure/PRUFTECHNIK_WindBrochure2010_en.pdf 100315

Notes hybrid Sorenson p. 851 030315