Wind Energy Academic Programs at Texas Tech

Transcription

1 Wind Energy Academic Programs at Texas Tech Kishor Mehta, Ph.D., P.E. 1, Richard P. Walker, P.E. 2, and Andrew Swift, Ph.D.,P.E P.W. Horn Professor, Civil and Environmental Engineering, Texas Tech University, [email protected] 2. Research Associate/Instructor, Texas Tech University Wind Science and Engineering Research Center, [email protected] 3. Director, Texas Tech University, Wind Science and Engineering Research Center, [email protected] ABSTRACT: Wind energy as an industry is expanding at a phenomenal rate. There is a severe dearth of manpower that has a good basic understanding of wind energy for the industry. Texas Tech University, with its long term history of research and education in wind engineering, is developing curricula in wind energy at all levels of higher education. The curricula includes twoyear technical associate degree (this is being developed by a sister institution), a four-year bachelor degree program, a post-graduate Certificate program, and a Ph.D. research oriented degree in Wind Science and Engineering. This paper discusses interdisciplinary B.S. degree curriculum that is under development and an interdisciplinary Ph.D. degree that has been in place since The paper also discusses experiences of development of interdisciplinary degree that crosses the boundaries of departments and colleges. INTRODUCTION: There is a critical need for professionals in the wind industry that are specifically educated in the basics of wind energy and wind engineering. Currently, almost all new employees entering the wind energy industry have virtually no background in wind energy, while many wind-related businesses are growing so rapidly and have so much to do that little time can be devoted to training the incoming employees. The Department of energy s report, 20% Wind energy by 2030 [1] indicates that achieving the 20% goal will require 180,000 direct manufacturing, constructions, and operation personnel in the next two decades as shown in Figure 1. Meet the goal of 20% of electricity from wind energy will require a ready supply of professionals educated in the basics of wind energy. The need for professionals educated in the basics of wind energy will continue beyond the many decades to come, potentially forever. The wind energy industry is a complex industry. It requires workforce educated in a variety of subject matter. From an academic point of view it is a multidisciplinary industry that can include areas such as energy commerce, atmospheric science, electrical, construction and mechanical technology, natural resource management, environmental science and others. Our vision at Texas Tech University is to develop work force through education and training that can provide a steady stream of personnel for the wind energy industry. Our objectives are to establish curricula at all levels of higher education which can educate and train people to work in the wind energy industry including design and construction, maintenance, business, finance, supervision, management, policy making, environmental impact, as well research and development. 1

2 The paper presents an overview of a series of curricula to produce personnel for wind energy industry. In addition, it gives details of two curricula, a multidisciplinary bachelor s degree with wind energy emphasis and a Ph.D. degree in Wind Science and Engineering with research related to wind energy. Both degrees are multidisciplinary involving several related and existing disciplines. Uniqueness of these degrees are that they transcend traditional discipline oriented academic departments and colleges. Crossing multiple departments and colleges in the university with our curricula presents difficulties within a traditional university hierarchy, and these difficulties are also discussed in this paper. Wind Energy Curricula: Figure 1. Work Force Needs in Wind Energy Industry Over the Next Twenty years [1] VISION: To develop workforce through education and training that can provide personnel for the wind energy industry. OBJECTIVE: To establish curricula at all levels of higher education which can educate and train people to work in the wind energy industry including design and construction, maintenance, business, finance, supervision, management, policy making, environmental impact, as well as research. 2

3 APPROACH: It is proposed to develop model curricula for degree programs which can be used by other institutions. Four degree programs are suggested (two are in place) as well as a graduate certificate program. 1 Two-year program in Wind Energy Technology that trains personnel to operate and maintain wind turbines and wind power plants. Texas State Technical College in Sweetwater, Texas has this program in place. The program contains two-year Associate degrees or Certificate programs in safety, wind turbine maintenance, construction inspection and other subject areas. Texas Tech collaborates with this institution (located 120 miles from Lubbock) to provide quality control of the course contents as well as facilitating transparent transfer to four year degree program to Texas Tech or other state institution. 2 Bachelor of University Studies in Wind Energy curriculum will provide multidisciplinary scientific background for work in various facets of the wind energy industry. This curriculum will include general education, specialty courses in wind energy, and two focus areas related to wind energy. This curriculum is discussed in this paper. 3. Graduate Certificate in Wind Energy will include 15 hours of graduate-level coursework. There will be a technical track that is physical science based as well as a managerial track for non-technical professionals. Four graduate level courses are under development, two technically based and two managerial based, which will be offered on campus during 2009 and These courses are also formulated so that they can be offered through the College of Distance Education ( In addition to wind energy courses, the Certificate program includes courses on leadership/ethics, power electronics, wind energy meteorology, and other related courses. Successful completion of five courses (two in wind energy and three related elective courses) qualifies for a Certificate from the Graduate School at Texas Tech University. This program was approved by the Graduate Council and Academic Council in April Master of Science in Wind Science and Engineering (with optional emphasis in Wind Energy) will be a non-thesis degree and will include advanced coursework in wind science and engineering related to wind energy. Students with a bachelor s degree in engineering or physical sciences will be able to enter this program. This degree will be developed in the future. Currently, students with a master s degree in engineering, physical sciences, or mathematics are entering doctoral degree program in wind science and engineering. Any student with physical science or engineering undergraduate degree can take graduate level wind energy courses. 5. Ph.D. in Wind Science and Engineering degree includes dissertation research in a wind energy related area. This degree, approved by the Texas Higher Education Coordinating Board in 2007, is in place at Texas Tech University. It is discussed in this paper. 3

4 Bachelor Degree curriculum: Wind energy curriculum at the bachelor s degree level is designed to provide technical knowledge in wind energy along with general education for all college graduates as well as knowledge in other areas related to wind energy. The subject of wind energy is a complex multidisciplinary area which requires knowledge in other areas along with direct understanding of wind energy. With this thought in mind, a multidisciplinary bachelor s degree curriculum is established as shown in Figure 2. The curriculum is a 120 credit hour program. Of these, 50 credit hours are devoted to general education that is required for all bachelor s degrees in the university. This is a requirement for Southern Association of Colleges and Schools accreditation. It is necessary to include calculus and physics as part of the general education since wind energy is a technical subject. The next block of course work is in wind energy consisting of 18 credit hours. Not all of these coursesexist in the current university offerings, althoughthey are currently under development. More details of these courses are given subsequently in this paper. As shown in Figure 2, subject areas such as energy commerce, atmospheric sciences, natural resources management, etc. are part of this curriculum. These subject areas are in the colleges of engineering, arts and sciences, agriculture, and business administration and have existing courses in respective departments. It is required that each student s curriculum include two of these subject areas with six courses (or eighteen credit hours) in each one. By including the requirement of six courses the students will have prerequisite to take junior and senior level courses. This requirement of two subject areas is designed to let students choose the focused area that they are interested, but the desire is that these subject areas will be complementary to an education emphasizing wind energy. It is our goal to provide flexibility to students in the multidisciplinary area of wind energy. An additional requirement is the industrial internship for three months during a summer. Because the curriculum crosses the bounds of departments and even colleges, the degree is part of University Studies degree program.a typical four-year curriculum in University Studies with an emphasis in Wind Energy is shown in Table 1 (see page 6 for more information.) 4

5 Bachelor Degree Curriculum: CREDIT HOURS Core curriculum as required for B.S. degree by the university: 50 o Communication (9 hours) o Mathematics (6 hours; these will be Calculus I and II) o Natural Sciences (8 hours; Physics) o Applied Science (3 hours ) o Humanities (3 hours ) o Visual and Performing Arts (3 hours ) o Social Sciences (15 hours) o Multicultural Study (3 hours) o Foreign Language (by exam) **Listing of only the courses that have Texas Common Course Numbering System (TCCNS); this will assure transfer of courses from any other State College or University in Texas Wind Energy required courses: WE 1200: Introduction to Wind Energy (2 hours) 2. WE 2300: Social Impacts of Wind Energy (3 hours) 3. WE 3300: Wind Energy Science and Technology I (3 hours) 4. WE 3100: Wind Energy Lab (1 hour) 5. WE 3310: Wind Energy Science and Technology II (3 hours) 6. WE 4300: Power Distribution (3 hours) 7. WE 4310: Modeling and Design (3 hours) COIN (Cooperative Internship) 3300: Required Industry Internship (6 hours) 6 Choose six courses each from two of the following areas (A and B) 36 A. Energy Commerce (choice of existing 9 courses) B. Electrical-Electronics Technology (choice of 18 courses) C. Construction Technology (choice of 6 courses) D. Mechanical Technology (choice of 9 courses) E. Landscape Architecture (choice of 7 courses) F. Business Administration/International Business (choice of 12 courses) G. Atmospheric Sciences (choice of 11 courses) H. Natural Resources Management (choice of 10 courses) I. Study Abroad Program (with approval of advisor) Electives 10 Total Credit Hours 120 Figure 2: Bachelor s Degree Curriculum Focusing on Wind Energy A typical four year curriculum is shown in Table 1. 5

6 Table 1: A Typical Four-Year Curriculum in University Studies with Emphasis in Wind Energy YEAR ONE Fall MATH 1351 Mathematics 3 ENGL 1301 Communication 3 HIST 2300 Social Sciences 3 POLS 1301 Social Sciences 3 Any Humanities 3 15 Spring MATH 1352 Mathematics 3 PHYS 1408 Natural Sciences 4 ENGL 1302 Communication 3 WE 1200 Intro to Wind Energy 2 Focus A YEAR TWO Fall Any Communication 3 PHYS 2401 Natural Sciences 4 POLS 2302 Social Sciences 3 Focus A-2 3 Focus B Spring HIST 2301 Social Sciences 3 WE 2300 Social Impacts 3 Focus A-3 3 Focus B-2 3 Focus B

7 YEAR THREE Fall Any Social Sciences 3 WE 3300 Sci and Tech I 4 Focus A-4 3 Focus B-4 3 Elective 3 16 Spring Any Applied Science 3 Any Visual/Performing Arts 3 WE 3310 Sci and Tech II 3 Focus A-5 3 Elective 4 16 SUMMER YEAR #3 Co-op Internship 6 credit hours YEAR FOUR Fall WE 4300 Power Distribution 3 Focus A-6 3 Focus B-5 3 Elective 3 12 Spring Any Multicultural Studies 3 Focus B-6 3 WE 4310 Modelling 3 9 7

8 Focus A and B from different areas shown in degree curriculum in Figure 2 Details of wind energy courses are given below. The first two courses, WE 1200 and WE 2300, are open to any students with no prerequisite. The junior and senior level courses starting with 3000 series are technically based and require calculus and physics as prerequisite. As indicated in the descriptions of the courses, basics of boundary layer atmosphere, power distribution, safety criteria, electronic and construction technologies, social impact of wind energy as well legal aspects related to wind energy industry will be covered in the WE courses. The goal is to cover basics of wind energy in these courses and let students specialize in other aspects of wind energy by choosing two subject areas listed in Figure 2. Examples of curriculum related to subject such as construction technology, energy development etc that are based on jobs are shown in Table 2. WE 1200: Introduction to Wind Energy: This course is intended to give students a basic understanding of the wind industry and help them determine if this is a field they may want to work in upon graduation. This will be the introductory course for the university s planned undergraduate degree program in wind energy, and will provide the platform upon which students will expand their knowledge toward such a degree. Subject matter includes the basics of energy and electricity, meteorology and the causes of wind, the history of wind power, the basics of extracting energy from the wind, wind turbine architecture and technology, environmental issues of wind energy development, landowner issues and considerations, the electric transmission grid and power markets, finance and economics of wind development, and state and national energy policy. This course was offered in Spring Semester WE 2300: Social Impacts of Wind Energy: This course is the second course offered as part of the university s planned undergraduate degree in wind energy. The objective of this course is to give students an in-depth understanding of the impact that large-scale development of wind energy and other renewable energy sources, along with a gradual transition away from fossil fuels, can have on our environment, our economy, our health, our national security, and many aspects of our day-to-day lives. These impacts will be considered from a local, state, national, and international perspective. Topics will include government regulations, health and safety considerations, environmental issues of renewable and traditional generation technologies, and natural resources management. This course will be offered in Fall Semester WE 3300: Wind Energy Science and Technology: This course is intended to educate students about the basic aerodynamic, mechanical and electrical aspects of wind turbines and modern wind turbine architecture. The objective of the course will be to teach students to understand and be able to calculate (1) the energy in the wind, (2) that percentage which is then captured by the rotor and converted to mechanical energy, and (3) the conversion of mechanical power from the wind into electrical power. The course will also cover meteorology, wind farm electrical layout and interconnection to the electric transmission grid, and the efficiency and impact of wind energy relative to conventional energy sources. This course has prerequisite of calculus and physics.

9 WE 3100: Wind Energy Lab: This lab is intended as a means to reinforce the learning of topics covered in WE 3300 through hands-on applications including assembly of wind turbine models, wind measurements and instrumentations, data acquisition systems, computer simulation and modeling of turbine blade aerodynamics, the use of wind modeling software such as Windlographer, WAsP, or similar packages, and the design and optimization of wind farm electrical layouts. WE 3310: Wind Energy Science and Technology II: This course is intended to provide more in-depth and comprehensive education in the aerodynamic, mechanical and electrical aspects of wind turbines, and the architecture of modern wind turbine and wind energy projects. Students will learn about and be required to demonstrate knowledge of subjects including (1) the lifecycle cost of energy from wind projects, (2) legal and environmental issues/challenges pertaining to wind energy, (3) standards and certifications of the wind industry, and (4) project development and construction. WE 4300: Power Distribution: This course is intended to educate students on the integration of modern wind turbine technology and other renewable energy sources with the electric grid. Topics covered will include three-phase power, the electrical characteristics of differing wind turbine technologies and their impact on the electric transmission system, power electronics in wind turbines, the interconnection of wind projects at both transmission and distribution voltages, components of the electric grid, the challenges of integrating large amounts of wind generation into the electric grid and the associated costs to the operator of the electric grid, electric utility regulation and tariffs, identification of the various electric reliability councils (ISO s or RTO s) and their rules and protocols relevant to wind energy, and electricity markets / power marketing. WE 4310: Wind Energy Modeling and Design: This course is intended as a capstone course incorporating the use of knowledge gained from each of the previous courses. Students will be assigned a geographic area in which they will be asked to go through the steps necessary to develop and design a wind energy project including field reconnaissance, mapping, use of GIS databases, site selection, landowner identification, fatal flaw environmental review, undertaking steps that would be necessary for permitting, identification of transmission interconnection options, site layout, securing available geotechnical data to aid in estimating foundation costs, electric collection system design, use of wind modeling software to estimate annual energy production, and development of a pro-forma financial analysis. COIN 3300: Industry Internship: The summer-long internship program will provide students with real-world experience in the wind energy industry and help them better understand and be able to apply those topics being covered in the wind energy courses. An internship also provides the student a better understanding of the industry which will allow him to direct his/her future studies in those areas he or she is most interested in pursuing as a career path, and it provides employers an opportunity to identify high-quality candidates for continued employment following the student s completion of his or her education.

10 Table 2: Examples of Combinations of Blocks that may be Appropriate for Certain Jobs in the Wind Industry Wind Development: Environmental/Siting/Permitting Specialist: 1. Wind Energy 1. Wind Energy 2. Natural Resources Management 2. Natural Resources Management 3. Energy Commerce 3. Geosciences / Atmospheric Studies Construction Management: Financial Analysis / Business Management: 1. Wind Energy 1. Wind Energy 2. Construction Technology 2. Energy Commerce 3. Energy Commerce 3. Minor in Business Admin. Wind Resource Analyst: 1. Wind Energy 2. Geosciences / Atmospheric Studies 3. Energy Commerce Doctoral Degree: The past NSF-IGERT program, Multidisciplinary Program in Wind Science and Engineering, was funded for the duration of five years (Jan Dec. 2007). The program has achieved an outstanding success in contributing to the multidisciplinary Ph.D. degree in Wind Science and Engineering. The degree curriculum has been scrutinized by committees in the Colleges of Engineering and Arts and Sciences, in the School of Architecture, and in the Graduate School. The Board of Regents and the Texas Higher Education Coordinating Board (THECB) have approved this curriculum. This multidisciplinary doctoral degree program in wind science and engineering is unique in the United States. It permits in-depth study and research in various areas related to wind such as wind energy, wind engineering, boundary layer meteorology, economics/risk management related to wind disaster, or emergency management Our goal is to provide students with the broad education demanded by the complexity of hazards and the human habitat as well as addressing problems with the implementation of wind energy systems. Students are required to take core courses in atmospheric science, wind engineering, economics/risk management, statistics, and leadership/professional ethics. In order to assure the viability of graduates entering the job market, at least six graduate-level courses in one area of major (e.g., civil or mechanical engineering, atmospheric sciences, economics, statistics, or other physical science field), or a Masters degree in a discipline is required. This

11 core knowledge is enhanced by gaining innovative experimental knowledge from laboratory and field experiment courses and through participation in an internship. Studies in ethics provide a vital link between research and implementation. Finally, students apply these integrated skills to research focus areas of the wind program that include wind loads on wind turbines, wind damage documentation, and economics of wind energy production, damage mitigation and other research areas. We believe that this process produces well-rounded graduates who are prepared for deciding public policies, broader research, professional practice, or educating the next generation. Curriculum and Polices: The doctoral curriculum includes required core courses, optional coursework tailored to each student, transfer credit from M.S. degree, external internship, and dissertation. Required core courses are: Atmospheric science of boundary layer Economics and risk management Wind engineering Statistics (two) Leadership/professional ethics In addition to the required courses, coursework of optional courses is tailored to the need of each candidate. Some of the optional courses available are: Atmospheric field experiments Wind storm hazards Meteorology for wind energy Wind engineering laboratory Wind power systems (two) Windstorm damage analysis Systems theory Managerial economics Stochastic processes Numerical analysis Public policy theory and process The goal of coursework is to provide a broad background that permits the student to pursue dissertation research. Students are required to participate in an external internship at an academic institution, government agency or laboratory, or industry. This internship has helped students understand practical aspects of research. Close to twenty-five institutions, agencies, and companies have shown interest in hosting an intern from the program. These internship experiences have assisted candidates in their pursuit of dissertation research and have provided a network for future collaboration. Past internship locations include the following: NOAA Hurricane Center in Miami, Duke Energy, Oklahoma Climatological Survey Center for Spatial Analysis, Wisconsin Emergency Management, USDA, Louisiana State University Hurricane Center, University of Western Ontario s Boundary Layer Wind Tunnel, National Center for Atmospheric Research,

12 ABS Consulting, State farm Insurance and Babcock and Brown Wind Energy. Current students on internships this year are working with Tokyo Polytechnic Institute, Iowa State University, and ABS Consulting. Students are given many opportunities to present their internship and dissertation research. Students are required to give a seminar highlighting their internship experience once they have returned to Texas Tech. In addition, students have been able to share their research and internship experiences by participating in national and regional conferences, including the following: Workshop for Uniform Windstorm Damage Documentation Methodology, ASME Wind Power Symposium, Graduate School Fair at University of Puerto Rico at Mayaguez, American Wind Energy Association Wind Power Finance and Investment Workshop and annual conference, American Meteorological Society Severe Local Storms Conference, the ESRI Homeland Security and GIS Conference, and American Association for Wind Engineering Workshop and Americas Conference. Students also are also required to participate in weekly Brown Bag lunch seminars, where students, faculty, and visiting scholars are invited to present their research. A Masters degree is not required to pursue this doctoral degree, though it is preferred. Students without a Masters degree are required to take six courses in a traditional discipline, (e.g. atmospheric sciences, civil or mechanical engineering, mathematics, economics, etc.) These courses in a traditional discipline provide a focus to make students viable for the job market. Students are admitted to doctoral candidacy to pursue independent research by the graduate school upon completion of qualifying examination. Doctoral dissertation is guided by the Chair or co-chairs of the student s advisory committees. Faculty members from at least two departments are required to be represented on the doctoral committee of each student. Multidisciplinary research for each dissertation is part of the requirement. The program has produced ten graduates with Ph.D. degrees in Wind Science and Engineering as of May Currently, sixteen students are pursuing doctoral degrees; of these, four of them are doing research in the field of wind energy while some of them have not yet decided their field of research. Dissertation Research Dissertation research topics have a wide variety, though they are all related to wind. The ten graduates completed dissertations of following titles: Remote-sensing applications to windstorm damage assessment Probabilistic damage and loss modeling for metal roof using artificial neural network Risk Assessment Model for Wind-Induced Fatigue Failure of Cantilever Traffic Signal Structures Wind Power Systems in the Stable Nocturnal Boundary Layer Design and Control of an Integrated Wind-Water Desalination System for an Inland Municipality Modeling of Low-Level Jets Over the Great Plains: Implications for Wind Energy Wind Directionality: A Reliability-Based Approach An Analysis of Hazard Mitigation Planning Policy in Local and Regional Government

13 Economic Analysis of the Tornado Impact upon Two Communities The Effect of Geographic Features on the Wind Field in Landfalling Hurricanes These titles show that research is pursued in virtually all aspects of wind problems. As our wind energy faculty strengthens, more research in wind energy is likely to take place. Life After Graduation: The graduates from this program have been in high demand from the companies. They have been employed in a combination of professional market including consulting companies, academic institution, and governmental agencies. Table 3 shows employment locations and titles of the graduates. None of the individuals have changed their employment. Table 3: Place of Employment of Graduates Name Graduation Date Job Title/Position Place of Employment James Arn Womble 2005 Instructor, Wind Engineering Consultant Texas Tech University and independent consultant Dabral Apoorv 2007 Civil Engineer/metal Eqecat, San Diego, CA frame structures Hector Cruzado 2007 Assistant professor, Civil Engineering Polytechnic University of Puerto Rico (PUPR) Kevin Walter 2007 Wind Energy, Chief of Meteorology Trade Wind Energy, Overland Park, KS Brandon Storm 2008 Wind Energy Analyst EAPC, Grand Forks, ND Rolando Vega 2008 Group Lead Engineer in the Extreme Loads and Structural Risk Division ABS Consulting, San Antonio, TX Maribel Martinez 2009 Assistant Emergency Management Coordinator Andrea Gamret- Jackman Rebecca Paulsen- Edwards Observations from our Experiences: Office of Emergency Management for Amarillo/Potter/Randall Counties, Texas 2009 Senior Consultant FEMA and IBM, Fairfax, VA 2009 Available N/A The curriculum development of the Ph.D. degree program started in 2003 with the assistance of the NSF IGERT grant. It took several years to formulate the program where it can be proposed for a degree program and can withstand the scrutiny of various academic committees in several colleges. The Texas Coordinating Board approved the degree program in

14 July The program has had success in recruiting students who are passionate about wind. They have worked as a group and find the degree program suitable to their need. Being a new multidisciplinary program, it has had growing problems. Some of the difficulties encountered along the way are indicated here for potential use by others who may be envisioning establishing a new doctoral degree program. Faculty members participating in the Ph.D. degree program feel the strain of overload. Active faculty members have their normal load of graduate students and course teaching in their home departments. Adding Ph.D. students from WISE degree program often is a burden to some faculty members. The experiences of the initial years of curriculum development suggested that some basic courses need to be developed to bring students with different backgrounds to at some basic level of understanding of disciplines. Resources for course development are not available. This is an example of overload on faculty members. There have been some difficulties in connecting students with faculty for direction of dissertation research. Students are drawn to faculty who teach the basic courses, which are limited in number. NSF IGERT funding provided resources for student fellowship stipends, tuition and fees, and student travel to conferences. With the end of NSF funding, it is difficult to fund students while they are pursuing Ph.D. degree. Mechanisms need to be developed to fund students on a long-term basis. Notwithstanding the above observations, the Ph.D. degree program will pay high dividends for the university, the State, and the country. CONCLUDING REMARKS: Wind is a natural environment that will be present forever. To tap the beneficial effects of producing energy from wind, it is necessary to develop academic programs that will produce workforce for industry, government agencies, research laboratories, and academic institutions. Recognizing that wind energy is a complex endeavor, interdisciplinary academic programs are necessary. Texas Tech University is making a commitment to develop such programs. The Ph.D. degree in Wind Science and Engineering is in place and is thriving. A Bachelor of Science degree with the focus on Wind Energy is being developed. It will take a few years for the program to mature and be established on a permanent basis. ACKNOWLEDGEMENTS: Academic degree programs are developed with the assistance from many faculty and departments. The administration of Texas Tech University has helped along the way in encouraging and providing resources when needed. The doctoral degree program was scrutinized by several internal academic committees as well as by external advisors; their comments and contributions are appreciated. The National Science Foundation Grant and the Texas

15 Workforce Commission grant provided financial resources to attract students for the program and faculty to develop the programs; their contribution is acknowledged. Manuscript of this paper was assembled by Ms. Elizabeth Inskip-Paulk and Ms. Kelsey Seger; their assistance is appreciated by the authors. Reference: [1] DOE (2008): 20% Wind Energy by 2030, Increasing Wind energy s Contribution to U.S. Electricity Supply, DOE/GO , July 2008; available at Internet; accessed May