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  • 1. International Journal of Advanced JOURNAL OF ADVANCED RESEARCH ISSN 0976 – INTERNATIONAL Research in Engineering and Technology (IJARET), IN 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 7, November – December (2013), © IAEME ENGINEERING AND TECHNOLOGY (IJARET) ISSN 0976 - 6480 (Print) ISSN 0976 - 6499 (Online) Volume 4, Issue 7, November - December 2013, pp. 101-108 © IAEME: www.iaeme.com/ijaret.asp Journal Impact Factor (2013): 5.8376 (Calculated by GISI) www.jifactor.com IJARET ©IAEME OFF-GRID HYBRID RENEWABLE ENERGY SYSTEM SIZING FOR HIGH ALTITUDE COLD DESERTS Neeraj Sharma, Jimmy Kansal*, Ashwagosha Ganju Snow & Avalanche Study Establishment (sase), Chandigarh ABSTRACT Renewable energy has become an important area of Research and Development for both environmental as well as economic reasons. This paper puts forward an approach to develop an economically feasible, self sufficient, wind diesel hybrid energy system for anoff-grid field location in Ladakh Cold deserts, Nubra Valley. The location under study is a remote place which has no source of grid power. The electricity demand is met with diesel generators that consume 1.42 Lakh Litres of fuel every year. Electricity generation by this method is very expensive due to ever increasing cost of diesel and transportation of fuel. In this research we look into the available renewable energy resources and conduct a pre-feasibility study of a hybrid power system at this location.The design of the system is sought to use wind energy in addition to the existing diesel generators to supply energy to the location. We present one-year power consumption data and wind energy resource and explore the potential of tapping the renewable resource available to bring down the diesel consumption at the site. From this data, the average daily, weekly and annual power requirements for the location under study are determined. Since the heating loads contribute a major part of the power requirements the monthly power requirements vary for the winter and summer months. The sizing of the hybrid power system for the location is also presented.Hybrid energy systems (using wind power only) were then researched and priced to determine feasibility in such harsh off-grid locations. The final system model proposed was simulated in HOMER. Successes and challenges of developing a completely self-sufficient, off-grid hybrid renewable energy system have been discussed.The pre-feasibility indicates that the location has significant wind and solar energy resource and using a wind-diesel hybrid system can reduce the diesel consumption by 23.5 % of its present annual consumption. Keywords: Renewable Energy, Fuel Costs, Weibull Distribution, Wind Power, Hybrid Energy System. 101
  • 2. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 7, November – December (2013), © IAEME INTRODUCTION The purpose of this project is to consider the feasibility of developing a hybrid renewable energy system that is capable of providing enough electrical power to sustain a field location in NubraValley. The site under study is SASE's field Observatory located in the Nubra Valley in the Ladakh region near the Saichen Glacier area. The total strength of the location is about 20-25 people. Access to the community is through air or by a metalled road only during the summer months. The observatory generates its electricity using diesel generators operated and maintained by persons staying in the location itself. It has three diesel generators with a total installedcapacity of 326kW that consume more than 1.42 lakhliters of fuel every year and produceabout 3,89,000 kWh of electricity. Electricity generation by this method is expensive due to ever-increasing cost of the fuel and transportation to this remote location. Transportof fuel in winter is also a major issue and pre stocking of fuel is required in the summer for running the gensets in winter season. The observatory location has renewable energy resources like wind and solar energy. But renewable energy resource assessmenthas not been done till date. Accurate renewable energy resource assessment involves onsite datacollection over a period of a year and primary site survey. In addition, the electrical load dataalso need to be recorded for a period of one year. In this research we have recorded sitedata, collected available information from all possible sources, visited the site and haveconducted a prefeasibility study of hybrid power generation at the site. The followingsections of this paper present detail of our research. EXISTING POWER SYSTEM OF THE FIELD OBSERVATORY Presently the electricity is generated in the observatory using three diesel generators. The higher rating generator is a 200kW capacity and the two lower rating generators are 66kW and 60kW. At one time typically only two generators of lower rating or one generator of higher rating are running. One of the major loads on the diesel plant is the motors and blowers of the central heating plant.Dieselgenerators require a major overhaul after 15000hrs of operation. Diesel generated electricityis mainly used for heating, lighting, water pumping and communication in the location. The electricity used for heating is for running of the heat plant motors and blowers. For the purpose of analysis we have considered two loads for the location. Primary Loadcaters for entertainment, lighting and communications demands of the location while the second load caters for the heating motors, blowers, water heating and submersible pumps of the location. The second part of the load varies for summer and winter months while the primary load is same for summer and winter months. Figure 1 shows plant power productiondata. Daily profile indicates that load varies from 3.4kW to 109.35kW for summers and 41.65kW to 109.35kW for winter’s everyday.Monthly profile indicates higher electrical load during winter months than summer months. Itis the heating plant and blowers operate for more time in winters than in summer months. Load profile also indicates that for a few hours in winters load may be as high as 140kW. Ever rising fuelcost is a major issue for such remote locations. Community survival depends upon low cost energy. 102
  • 3. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 7, November – December (2013), © IAEME Fig 1(a) : Daily Load Profile for Winter Day & Monthly Load Profile Fig 1(b) : Daily Load Profile for Summer Day AVAILABLE RENEWABLE ENERGY RESOURCES The field site under consideration has a met observatory in which the requisite parameters of wind speed, wind direction and temperature are recorded on daily basis. A semi automaticmeteorological instrument is also installed in the observatory which automatically records these values from different sensors and logs it into the datalogger memory. Table 1 below presents a summary of the collected data. 103
  • 4. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 7, November – December (2013), © IAEME Annual average wind speed at a height 10m = 10.12 m/s Highest wind speed in July and lowest is in January Maximum wind speed at a height of 10m= 13.22m/s Diesel generators are 200kW, 66kW and 60kW Annual average electrical load = 1000 kWhr/day Peak load 164kW Minimum load 3.4kW Annual average load is 41.7kW Diesel consumption in 2012 was 142560 litres Plant generation efficiency 2.76 kWhr/litre Total production in 2012 was 393361kWhr Electrical load is highest from October to April and lowest May to Sep Annual Average Solar Insolation = 4.15kWh/ m2/day Diesel price in 2012 about $1.0 per litre Table 1: Summary of Renewable Sources and Power Plant at Site Collected data at the field site under observation isshown in Figure 2,3 and 4. One year wind speed data is presented in figure 2. It shows windspeed is quite high at the field site under observation. Annual average wind speed is only 10.12m/s at a height of 10m from the ground level. Wind speedhistogram and best Weibull distribution fit is shown in figure 3. Wind resource is much higherthan our initial expectation. Solar insolation data is presented in figure 4. Clearness index ismoderate at the site. Average annual solar insolation is 4.15kWh/ m2/day. Fig 2: Daily Wind Speed Data of the Field Location for the Year 2012 104
  • 5. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 7, November – December (2013), © IAEME Fig 3: Histogram for Wind Speed data Fig4: Monthly Solar Insolation at Site PROPOSED HYBRID POWER SYSTEM FOR CARTWRIGHT The above section indicates that the useable renewable resources at SASE's field location are wind and solar. Therefore, a hybrid energy system for the sitecould consist of wind turbine/s, photovoltaics, batteries, power converter and diesel generators. A number of hybrid system sizing examples may be found in the literature [1,2,3,4]. These examples provide very good guidelines for the design of a hybrid power system. Each hybrid power system is unique and it should be designed for the site based on the available resources and load profile. A proposed hybrid energy system for SASE's field location is shown in figure 5. Sizing of a hybrid system can be done using Homer [5]. Other options are Hybrid2 and Retscreen [6,7]. We assumed that the load would remain the same in the near future. Different types of wind turbines were selected with batteries, diesel generators and 105
  • 6. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 7, November – December (2013), © IAEME converter were tried in Homer. In general wind turbine price per kW reduces with the wind turbines size. But there are installation issues of large wind turbine in remote locations. There would be no big cranes available in such remote area and bringing in a larger crane during the installation of wind turbines will cost a fortune. Therefore, we decided to include only up to 10 kW wind turbine during homer optimization. Fig5: Proposed Hybrid Energy System for SASE's Observatory Other inputs to the homer were already existing diesel generators, PV panels, batteries, and converter. We assumed that there will one 220V AC bus and one 12V DC bus as shown in Figure 5. Two 6V batteries will form one string. Prices of all parts of the proposed hybrid power system were obtained from manufacturers websites. The operating reserve of batteries was assumed to be 10% of the hourly load. Batteries will be recharged in cyclic mode and diesel generators will run as needed. Each homer simulation took about 1.5 hours to complete. Basically, homer calculated available energy and equated that to the load and selected a system configuration that can meet the site requirements. With a condition of a minimum 20% renewable fraction and diesel price of $1.0 per liter (2013price) homer suggested that we will need 10, Generic 10kW wind turbines. Figure 6 shows homer optimization results. Homer optimization results indicate that the hybrid systemcapable of producing lowest cost electricity should consist of 10, Generic 10kW wind turbines, oneof the existing 82.5KVA generator (250KVA and 75KVA generator will not be needed), 120 Trojan LP16 batteries,37.5kW rectifier and a50kW bidirectional converter to link ac and dc bus. Initial cost of such a system would beabout $89,000 including the generator cost and it will produce electricity at a cost of $0.16 per kWh. Such a systemwould result in a renewable energy fraction of 24% using only about 38,498liters of diesel. More homer optimization results are shown in figure 6. The expected electrical performance of the best system is shown in figure 7. In such ahybrid system the wind turbine energy contribution would be 27%, one 82.5KVA diesel generator willsupply 73%. The existing250KVA generator and existing 75KVA generators will not be required. Excess electricitywould be about 3.79%, whichcan be supplied for heating the places close to the existingdiesel plant. The cost of the energy would be $0.16 per kWh, which is lower than thepresent cost. Expected monthly electrical performance of the designed hybrid power system is also shown in figure 7. It shows that most of the electricity in winter months would comefrom wind turbines. 106
  • 7. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 7, November – December (2013), © IAEME Fig 6: Homer Optimisation Results Fig 7: Expected Electrical Performance of Proposed Hybrid Power System 107
  • 8. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 7, November – December (2013), © IAEME CONCLUSION The renewable wind energy resource at SASE's field Observatory is of prime importance since the wind energy can contribute significantly during the winter months. The wind energy and diesel power generation are estimated for a possible hybridpower generation. Diesel plant load data and renewable resources data of site wascollected during a site visit in 2013. Statistical analysis of the collected data was done and theone-year site renewable energy resource data and load data is presented in this paper. Thepublic domain software Homer was used to size a hybrid power system for SASE's field observatory. Hybridpower system sizing is done assuming no energy conservation efforts and no future increasein the electrical load. This research indicates that the available wind energyresource is high and wind energy can be exploited for providing cheaper and emission free power for the location. A hybrid systemconsisting of ten 10kW wind turbines, one existing 82.5KVA diesel generator, 120 lead acidbatteries, a 50 kW converter, 37.5kW rectifier and a new plant control system is proposed. This studyindicates that the proposed hybrid power system will reduce diesel consumption to about 76.5% of the present consumption. Cost of electricity generation fromsuch a system will be about $0.16 per kWh, which is less than the present cost of electricitygeneration i.e. $0.249 per kWh in the observatory. REFERENCES 1. Devine, M and Baring-Gould. I.E, Wind-Diesel Hybrid Options for Remote Villages inAlaska, Proceedings of the AWEA Annual Conference, Chicago, IL, March, 2004 2. McGowan, J.G., Wright S., Manwell J.F. and Abd-ul-Wahid U., Wind Power at Guantanamo Bay: A Hybrid Wind-Diesel System for the US Navy at Guantanamo Naval Base Using an Energy Savings Performance Contract, Proceedings of theAWEA Annual Conference, Chicago, IL, March, 2004 3. Cultura A, and Salameh Z., Design of a Distributed Wind/PV Hybrid System for Rural Electrification of an Island in the Philippines, Solar 2006, Denver Colorado July 2006. 4. Kaldellis J. K., Kondili E. and Filios A. Sizing a hybrid wind-diesel stand-alone system on the basis of minimum long-term electricity production cost, Applied Energy, Volume 83, Issue 12, December 2006, Pages 1384-1403 5. Avneet Hira, Vandana Kansal, TK Jindal, Jimmy Kansal and Ashwagosha Ganju, “Harnessing Wind Energy in Cryospheric Regions” International Journal of Electrical Engineering & Technology (IJEET), Volume 3, Issue 2, 2012, pp 313-319, ISSN Print: 0976-6545, ISSN Online: 0976-6553. 5. http://www.nrel.gov/homer/ 6. http://www.ceere.org/rerl/rerl_hybridpower.html 7. www.retscreen.net 8. S.Dileep Kumar Varma and Divya Dandu, “Modelling and Simulation of Hybrid Renewable Energy Sources Connected to Utility Grid”, International Journal of Electrical Engineering & Technology (IJEET), Volume 4, Issue 5, 2013, pp. 155 - 164, ISSN Print: 0976-6545, ISSN Online: 0976-6553. 9. Dr.S.M.Ali and Prof. K.K.Rout, “Application of Renewable Energy Sources for Effective Energy Management”, International Journal of Electrical Engineering & Technology (IJEET), Volume 1, Issue 1, 2010, pp. 18 - 31, ISSN Print : 0976-6545, ISSN Online: 0976-6553. 108