the role of small wind turbines in hybrid power systems for

This white paper was prepared as an account of work from Southwest Windpower Inc. Neither the Company nor its employees, sharehold-ers, board members or investors, makes any warranty, expresses or implies, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by Southwest Windpower Inc. The views and opinions of authors expressed herein do not necessarily state or reflect those of the Company.

© 2012 Southwest Windpower Inc. All Rights Reserved. Reproduction of this publication in any form without prior written permission is strictly forbidden and will be prosecuted to the full extent of US and International laws. The transfer of this publication in either paper or electronic form to unlicensed third parties is strictly forbidden. REV A 4-12

The Role of Small Wind Turbines in Hybrid Power Systems for Telecom Sites: Driving Cost Savings

WHITE PAPER

Solutions for off-grid and poor-grid sites

© 2012 Southwest Windpower Inc. 2

As of 2011, more than 5.6 billion mobile phone users worldwide account for about 90 percent of the world population1. With energy demand and prices on the rise, maintaining and expanding telecom services presents a challenge in many locations. In rural, remote or developing regions of the world without a stable utility connection, diesel dependence can be mitigated by on-site hybrid wind-solar energy systems. In order to enjoy cost-savings benefits associated with these systems, careful consideration of wind and solar resources is essential.

Introduction

Telecom sites in high-growth regions are often characterized by unstable or restricted electri-cal grids or are out of range of transmission lines. Power out-ages are frequent. The require-ment for continuous runtime makes total grid reliance impos-sible. This paper discusses the role of hybrid systems alongside conventional energy solutions, acting to reduce operating costs

SUMMARY

and open new market sectors in the telecom industry. The best hybrid systems combine wind, solar, diesel generators and bat-teries to reduce dependence on conventional generators. The cost and availability of conven-tional energy, site factors, cli-mate considerations, social and cultural environments, usage and objectives characterize this market for hybrid systems.


Energy Requirements

Factors affecting energy system design for telecom sites include grid availability, load, battery bank capacity and cost of com-ponents, fuel, operating expens-es and natural resources avail-able at the site. Power is the rate at which energy is transferred, used or transformed, typically measured in kilowatts (kW) or watts. Energy is the amount of power consumed over time, usually measured in amp-hours, watt-hours or kilowatt-hours (kWh). While maximum power requirements are helpful in characterizing momentary site loads, energy requirements should form the basis of system design. System autonomy is an-other factor. Autonomous oper-ation is the ability of a system to run on site-generated or stored energy, and is usually measured by the number of hours that system can operate without the input of outside sources such as an electric grid. Grid availability, stability and strain should be considered when determining how much autonomous opera-tion is desired. If natural re-sources allow, renewable energy solutions may be configured to support battery reliance to meet operational usage levels.

Factors Affecting Conventional Energy Sources

Electric grid availability and reliability: In high-growth rural and developing regions, the electric grid, if available at all, may prove unreliable.

Rising Fuel Costs: Crude oil prices have fluctuated since the early 2000s. Regional instability in oil producing areas continues to cause price uncertainties. At present the cost of diesel energy for telecom sites ranges from $1.25-$1.50 per kWh.

Fuel Transport: The ramifica-tions of transport include cost of capital, licensing, insurance, vehicle size, rate of delivery, value/supply chains, wages, and running costs (fuel, oil, O&M). The cost of diesel over time is also a factor when transport-ing it, which is affected by the international oil price, exchange rate and taxes.2

Fuel Theft: With rising prices comes an increase in diesel theft, which in some regions presents a significant challenge. Diesel theft from telecom sites in India amounts to 15 to 20 percent of diesel consumed.

Due primarily to theft, in the northern part of the country energy system prices have increased between 200 to 300 percent over budget projec-tions.3 Even in more developed nations, fuel theft has increased significantly.

An Alternative: Hybrid Renewable Solutions

Hybrid energy systems com-bine renewable energy sources (RES) such as wind and solar with a diesel generator and a battery bank for energy stor-age. Because they take advan-tage of on-site energy sources and reduce fuel consumption, these hybrid systems provide an attractive cost-mitigating solution. Coupled with diesel and energy storage, a hybrid system minimizes down time and provides occasional (sites with a stable grid) or constant autonomy (sites with a poor grid or no grid). The hybrid option also offers reduced sound and carbon emissions, which may provide added benefits in some areas.4


Renewable Energy Sources For Telecom

Because wind-solar hybrid ener-gy systems include inputs from solar, wind and diesel sources, they have tremendous potential to reduce operating costs over time. Combining the power of solar photovoltaic technology with that of small-scale wind turbines, a wind-solar hybrid energy system provides a viable and affordable solution.

Solar Photovoltaic (PV): The technology transforms UV rays from the sun into electricity in turn providing usable energy. Solar power is predictable from well-established data sources. Since solar panels tend to have

a shading effect, the array can reduce the heat or solar load on the lower edifice, which narrows the cost of cooling.

Factors to consider: Daily solar output is based on available daylight, which fluctuates day to night and season-to-season, with the obvious effect of reduced performance at night and in the winter. Due to these variations, solar is best thought of as a component of a more comprehensive system. Another factor to consider is the space PV arrays require. Low in energy density, PV arrays require signifi-cant real estate. Also, low-lying solar panels are vulnerable to theft, especially at remote locations.

Sample Wind-Solar Production

SOLAR POTENTIALWIND POTENTIALTOTAL PRODUCTION

MAR JUN SEPT DEC

KWH

/MO

NTH

200

0

400

600

800

1000

Figure 1 Complementary nature of wind and solar resourcesSource: Southwest Windpower

Wind Power: The small-scale wind industry has matured, and today’s products deliver energy more efficiently than in the past. Advanced wind systems are controlled by microproces-sors and are third-party tested and certified to standards such as the International Electro-technical Commission (IEC), Small Wind Certification Council (SWCC), Underwriters Labora-tories (UL) 1741, CE, CSA, MCS and others. Horizontal axis wind turbines (HAWT) have become the most favored type installed at mobile telecom sites due to dependable and efficient performance metrics. Systems range in size from 160 W to 10 kW or more.

The energy available from wind increases cubically with tower height, and these systems can often be integrated with new or existing towers for cost-effective installation. Additionally, tele-com sites on mountaintops, ridges or coastlines often pro-vide suitable wind resources. Coupled with solar panels, wind offers a compelling solu-tion. However, estimating wind performance is complex. Wind speed and quality vary greatly from site to site, even for sites within close proximity to one another.

Estimate for Mason City, IA, USA. Actual performance will vary with locaiton.


Factors to consider: When considering a wind system, a thorough analysis of wind dis-tribution and speed is required. Proper site evaluation is argu-ably the most important success factor, and there is no universal one-size-fits all solution. Site selection and even turbine positioning on a site directly affects performance. The ideal location for a wind system is at least 6 meters (20 feet) above any surrounding object within a 76 meter (250-foot) radius. The site area should be at least 0.2 hectares (0.5 acre). Generally

Figure 2 Site Placement Recommendations Source: Southwest Windpower

ing of solar data analysis and careful wind modeling and/or field analysis is paramount. As-sessing a potential project with quality data and site details will result in reasonable perfor-mance estimates. The granular-ity of the data source is key. For wind, field measurements for every location are not practical, so it is important to use quality data based on the most scientif-ic wind modeling technologies.

speaking, the taller the turbine is off the ground, the better the performance. It is best to place wind turbines away from sources of turbulence such as buildings or tall trees as these can disrupt the flow of wind and decrease energy production. See Figure 2.

Renewable Energy Source (RES) Evaluation

Analysis of potential renewable energy resources (RES) is crucial to the success of any system. Professional evaluation consist-

TOWER ATTACHED

GROUND MOUNTED

PREVAILING WIND

AVOID TURBULENCE FROM OBSTACLES

6m (20 ft) RECOMMENDED

Diesel GeneratorController

Telecom Loads

AC/DC

Optional for 3-Cycle Charging: Dump Load Controller

Wind Turbine

Wind-Solar-Diesel Telecom System

DC/DCMPPT

SIDE MOUNTED


Energy distribution: When evaluating potential use of wind turbines, the distribu-tion of energy over a range of wind speeds is a more use-ful metric than average wind speeds alone. In other words, how much energy is available in the range that produces useful energy, versus wind in very low or high ranges? The best way to understand the quality of avail-able winds is to examine Weibull distribution curves.5 See Figure 3. The Weibull distribution de-termines the frequency of winds that fall into ranges useful for the capture of wind energy.

Return On Investment

Wind-solar hybrid energy sys-tems offer the telecom industry fiscal benefits, with the reduc-tion of remote power asset costs associated with fuel and elec-tricity consumption. Southwest Windpower offers comprehen-sive performance modeling and financial analysis to partners in the telecom sector. Southwest Windpower will analyze renew-able energy potential, configure an optimum system, and esti-mate return on investment (ROI) for any site worldwide.

5 3010 15 20 25 400 350

5

10

15

20

TooHigh

TooLow

Range in which wind turbine converts

to energyFreq

uenc

y %

Wind Speed m/s

Sample Weibull Distribution

Figure 3 Weibull Distribution of Wind Energy Source: Southwest Windpower

This determination is based on best-in-class solar and wind data, plus site variables such as the cost of existing energy sources. In some areas, RES’ may be eligible for incentives such as tax credits, rebates, feed-in tariffs, and these factors may be included as part of the ROI calculations provided by South-west Windpower. The resulting report is used to further plan the installment of a wind-solar hybrid energy system.

In poor-grid and off-grid situa-tions, depending on the deliv-ered cost of diesel fuel (which can run up to $1.90 per liter) and other factors, ROI can be rapid (1 to 3 years) for hybrid wind-solar energy systems.


Figure 4 Recommended Stand-Alone (Off-Grid) System Configuration Source: Southwest Windpower

Diesel GeneratorController

Telecom Loads

AC/DC

Optional for 3-Cycle Charging: Dump Load Controller

Wind Turbine

Wind-Solar-Diesel Telecom System

DC/DCMPPT

CONCLUSION

Continued growth in the telecom market, coupled with increasing OPEX expenses associated with ener-gy availability makes a compelling case for wind-solar hybrid energy systems. Particularly in rural, remote or developing regions and in any locations without a stable electric grid, diesel has become the default power source. This costly dependence can be mitigated by an on-site renewable energy system. Hybrid systems combine wind, solar, conventional generators and batteries to deliver energy when it’s needed, whether for occasional or continuous autonomous operation. When evaluating energy options for tele-com, cost and availability of conventional energy, site factors, renewable energy resources, incentives, load and other factors should be analyzed. Professional resource analysis, configuration and ROI calcula-tions should be conducted as part of any inquiry into wind-solar hybrid energy systems for telecom. With proper site analysis and system design, hybrid wind-solar systems offer a viable cost-saving solution.


1 “World Population Clocks—POPClocks” http://www.census.gov/population/international/ Retrieved 15 March 2012 2 April 2010. Update: Trends in Transport Cost and Fuel Price. National Agricultural Marketing Council. Retrieved from http://www.namc.

co.za/dnn/LinkClick.aspx?fileticket=cy6hlCuPAuQ%3D&tabid=77&mid=551 PDF. 3 Gupta, Deepali. (2011, October 24). What is hurting telecom tower business. The Times of India. Retrieved from http://articles.timesofin-

dia.indiatimes.com/2011-10-24/infrastructure/30315880_1_standalone-tower-tower-companies-telecom-tower-business 4 Sopian, Kamaruzzaman, Othman, Mohd Yusof, Rahman, MohdAzhar Abd. Performance of a Photovoltaic Diesel Hybrid System in Ma-

laysia. ISESCO Science and Technology Vision, 1 (37- 39) [Retrieved] 15 March 2012 [from] http://www. Isesco.org.ma/ISESCO_Technol-ogy_Vision/NUM01/Kamaruzzaman%20Sopian/Kamaruzzaman%20Sopian.pdf

5 http://www.weibull.com/AccelTestWeb/weibull_distribution.htm [Retrieved] 3 April 2012


Southwest Windpower Inc.www.windenergy.com +1 (928) 779- 9463

1801 W. Route 66 Flagstaff, AZ 86001 USA

Southwest Windpower GmbH Mannesmannstr. 650996 Cologne Germany +49 (0) 221 16 53 94 50

SOUTHWEST WINDPOWER INC.

Southwest Windpower has been designing and distributing small wind turbines since 1987 and is recog-nized as the global leader in the design, manufacturing and distribution of small wind and wind-solar hy-brid systems. A pioneer in wind technology development, Southwest Windpower has built and shipped more than 170,000 wind turbines to over 120 countries worldwide with a sales representation in over 88 countries. Headquartered in Denver, Colo., the company manufactures in Flagstaff, Ariz. and has opera-tions in Cologne, Germany and a sales office in New Delhi, India. Southwest Windpower systems can be applied at industrial sites, commercial properties, micro-grids, telecom transmitters, offshore platforms, and pumping and desalination projects. Southwest Windpower is the manufacturer of the Skystream®, Whisper™, and AIR™ lines of wind energy systems.

Renewable energy systems for:

Telecom•Lighting•Water pumping•Industrial applications•Off-grid•Village electrification•Utility-connected•Government•Education•Residential•

Interlocken Advanced Technology Environment 101 Technology Drive Suite 325 Broomfield, CO 80021 USA

the role of small wind turbines in hybrid power systems for

Documents