USING A MODIFIED GRAIN SILO TO POWER A VERTICAL AXIS WIND TURBINE

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: SMALL BUSINESS GRANT
• Reporting Frequency: Annual
• Accession No.: 0228723
• Grant No.: 2012-33610-19478
• Cumulative Award Amt.: $100,000.00
• Proposal No.: 2012-00308
• Project Start Date: May 15, 2012
• Project End Date: Jan 14, 2014
• Grant Year: 2012
• Program Code: [8.6]- Rural & Community Development

Recipient Organization
Agri Wind Turbines, LLC
9 Stonebridge Cir Apt 925
Little Rock,AR 72223

Performing Department
(N/A)

Non Technical Summary
Global electricity from wind power will reach 12 percent by 2050, requiring 3.2 trillion dollars to be invested over the next 40 years. In 2009, wind power additions in the United States were valued at 21 billion dollars, reaching nearly 10GW of new capacity. Despite the financial crisis in 2009 and the significant reductions in wholesale electricity prices that began in mid 2008, cumulative wind power capacity grew by 39 percent during this time period. For the 5th consecutive year, wind power was the second-largest new resource added to the electric grid. States' renewable portfolio standard (RPS) policies will require 73 GW of new renewable capacity by 2025, 6 percent of the total US retail electricity sales for that year and 30 percent of the projected load growth between 2000 and 2025. There are several advantages to using a ducted nacelle for a vertical axis wind turbine. The ducted nacelle may increase the wind speed from compressed laminar airflow into the turbine, producing more power and increasing the economic feasibility of deploying the turbine to previously undesirable wind map locations. Most of the 2 million farming and ranching locations across the country have connections to the grid by distribution lines. This established infrastructure will facilitate sustainable renewable energy development while mitigating climate change and increasing reliance in the national grid. Variations in size can support a large array of potential nameplate capacity and easily be fitted with a tower to reach premium wind speed conditions. Depending on landowner consumption and the wind turbine's nameplate capacity, small to mid-size farms could potentially erase their electric bill while profiting from the sale of excess generation.

Animal Health Component

70%

Research Effort Categories

Basic

(N/A)

Applied

70%

Developmental

30%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
401	5330	2020	100%

Knowledge Area
401 - Structures, Facilities, and General Purpose Farm Supplies;

Subject Of Investigation
5330 - Farm structures and related facilities;

Field Of Science
2020 - Engineering;

Keywords

ducted nacelle

vertical axis wind turbine

tubercles

grain silos

Goals / Objectives
The purpose of this research is to develop an alternative wind energy solution that is less expensive than conventional wind turbines. Significant advancements in the study of aerodynamics have been made in recent years and can now be applied to wind energy. The overall objective of this proposed Phase I effort is to utilize this body of work and develop an affordable wind energy solution that can be easily adopted by small and mid-size farms using existing resources and infrastructure. While there have been significant advancements in the wind turbine industry, steps are still needed in order to capitalize on difficult wind speed resources and increase economic feasibility. The focus of this research is to prove the feasibility of using state-of-the-art aerodynamics to power a vertical axis wind turbine. Specific objectives will answer the following questions. What is the optimum design for the ducted nozzles to maximize wind speed What is the optimum design for the exhaust to maximize wind speed Does the computer simulation reflect actual results collected in the field Task 1 - Develop the Computer Model for the Nozzles and Exhaust start May 1. Task 2 - Run Simulations on Nozzles, Exhaust, and Nacelle will begin immediately following the completion of Task 1, approximately July 15. Task 3 - Fabricate Nacelle Prototype will start after the finalized computer model has been tested. It is estimated that the fabrication of the prototype will begin on September 15. Task 4 - Collect Field Data and Finalize Report is expected to start June 15. Upon completion of the feasibility research, Agri Wind Turbines will have developed an interactive computer model capable of simulating real-world wind speed data from various input conditions. The convergence of the results from both the CFD simulations and wind speed field data will be proof-positive verification of an optimum wind turbine design. The results of this simulation will reflect actual empirical wind speed data collected from the ducted nacelle prototype. The Phase I effort will result in the modeling, development, and prototyping of key design components of the turbine and serve as the intellectual foundation for Agri Wind Turbines while reducing the risk of a full-scale wind turbine prototype developed in Phase II.

Project Methods
The nozzles and exhaust are the most critical inputs to the wind turbine design. Their configurations and design will ultimately control the amount of wind power developed. The shape of the nozzles, their size, and their points of attachment on the nacelle will affect the velocity of airflow into the wind turbine. There are several variables affecting the nacelle design that will determine the maximum power output. The swept area of a vertical axis wind turbine is a function of diameter and height. Wind speed is the most important variable to consider when calculating the amount of potential power. In order to optimize the nacelle design, Dr. Pidugu and Mr. Brown will determine the best geometrical placement of the nozzles and exhaust. In order to determine this geometrical placement, a working computer model will be developed using SolidWorks. Then a computational fluid dynamics program will analyze airflow through the system. The model will produce empirical data from which interpolation will reveal the optimum design. The computer models will allow multiple permutations of variables. This empirical data will then be used to determine relationships to form equations that will optimize the design of various wind turbines depending on silo diameter and height, as well as wind speed. Once the computer model for the wind turbine features have been developed, the computational fluid dynamics analysis will be ran through multiple iterations on each individual feature. The reports generated from the simulations will provide the data necessary to conduct a sensitivity analysis. Once the controlling element is determined, the other elements will be designed around the controlling feature. Once the plans for the nozzles and exhaust have been finalized, finite element analysis will be used to analyze the loading stresses on the nacelle and is necessary to determine the structural load capacity of the wind turbine. With the stress concentrations understood, a safe prototype will be fabricated for field data collection.

Progress 05/15/12 to 01/14/13

Outputs
OUTPUTS: The purpose of this research project was to develop an alternative wind energy solution that is less expensive than conventional wind turbines. Significant advancements in the study of aerodynamics have been made in recent years and can now be applied to the wind turbine industry. The overall objective of this proposed Phase I effort was to utilize this body of work and develop an affordable wind turbine that can be easily adopted by small and mid-size farms using existing resources and infrastructure. The following four tasks were completed to answer these questions. Task 1 - Develop the Computer Model for the Nozzles and Exhaust A 3D model was developed to optimize the wind speed increase. After running multiple simulations for different shapes, the vane proved to be the most promising and increased the wind speed from 5 mph to 7.044 mph, a 41% gain. To ensure safety and aid in prototype development, finite element analysis was applied to the structure. Task 2 - Run Simulations on Nozzles, Exhaust, and Nacelle One concern of the design was the variability in wind direction. To address this concern, AWT modeled a simple nacelle design that could rotate into the prevailing wind direction and maximize velocity to the turbine blades. The vane angles are optimized from task 1. With a 5 mph ambient wind speed, the wind velocity is increased to 9.85 mph, a 97% gain. The consistent gain in wind speed without regard to ambient wind velocity will significantly reduce the time for future R&D efforts. This rapid scalability is an important competitive advantage over conventional wind machines and will decrease R&D cost and risk. Task 3 - Fabricate Nacelle Prototype A rough draft prototype was built in an effort to prove empirical data matched computer simulations. Although the prototype was not an exact match of the computer simulation, an increase of 65% in wind speed will produce a calculated increase of power by 449%. Task 4 - Collect Field Data and Finalize Report Wind speed data was collected during the project using a weather station. Intervals of five minute averages provided more accurate readings than a yearly average and revealed when and how much potential wind speeds could produce. At present, the research findings are not being disseminated until a provisional patent is secured. PARTICIPANTS: Agri Wind Turbines would like to show our appreciation for the guidance and continued support of the U.S. Department of Agriculture, the Small Business Administration, Arkansas Science and Technology Authority, the Arkansas Small Business and Technology Development Center, EnableVentures, Inc., The Riggins Group, and ESA Corporation. Specifically, we would like to thank Sharon Ballard, CEO of EnableVentures, for providing experienced guidance through the SBIR program and introductions to key business development contacts; John Riggins of the Riggins Group, whose engineering background with Entergy proved as valuable as his marketing expertise; Martin Martinez of ESA Corporation for his professional engineering experience as a subcontractor and a veteran SBIR grantee; and Rebecca Norman, an innovation consultant and technical writer for the Arkansas Small Business and Technology Development Center. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
While developing the computer model during task 1, multiple simulations produced empirical data that revealed the increase in wind speed was consistant regardless of the ambient wind speed. It is very useful to understand that, regardless of the input wind velocity, the percentage gain was consistent for each individually sized ducted wind turbines. For example, a wind turbine of one size has a gain of 84%. For a wind turbine of another size, a gain of 97% was the result no matter the ambient wind speed. The consistent gain in wind speed without regard to ambient wind velocity will significantly reduce the time for future R&D efforts. Also, understanding the difference in gain between the different size turbines will help Agri Wind Turbines determine what size wind turbine should be used for a given location on a wind speed map.

Publications

• No publications reported this period