Non Technical Summary
Wind turbines have reshaped rural America by boosting incomes, creating jobs, and harnessing local energy sources. However, conventional tower-mounted wind turbines have three main problems that limit their potential: (1) only about 12 percent of communities have strong enough ground winds to make projects economical; (2) installations are too expensive, requiring a crane and concrete foundation; (3) many communities oppose wind, citing noise or avian impact. This project will develop a breakthrough Airborne Wind Turbine (AWT) to expand the potential low cost wind energy in rural communities. The AWT uses a helium-filled inflatable shell to lift a lightweight turbine 50 to 200 stories high, where winds are up to five times stronger than those reached by a tower. A conductive tether holds the AWT steady and sends power to the ground. The lifting technology is adapted from aerostats: tethered blimps that have been used for decades to reliably lift telecom and surveillance equipment into the air for months at a time. The AWT can expand low cost wind power to hundreds or thousands of new rural communities by tapping stronger high altitude winds, reducing installation time, and lowering community impact. The key research objective of this project is to develop and test a fully-functional AWT prototype that demonstrates its potential for commercial deployment. There are three main technical objectives: (i) design and fabricate a rotor and drive train that integrate composite materials and compact design to significantly lower weight relative to leading tower-mounted turbines, (ii) demonstrate extended, autonomous operations of the AWT prototype in real-world environmental conditions, and (iii) demonstrate a communications and controls systems that allows for remote monitoring and control of the AWT prototype. Following on the Phase I feasibility analysis, Phase II will include a requirements definition, the design and fabrication of a custom lightweight turbine, development of the controls and communications infrastructure for remote operation of the AWT, assembly of a sub-scale inflatable shell, and extended duration autonomous testing in real world conditions. Altaeros anticipates that this technology will demonstrate reliable, high capacity power production beyond the current technology of tower-mounted turbines. The main commercial opportunity is to develop a mid-sized AWT that can expand economical wind power to regions with weak ground-level winds. In addition, the AWT can displace expensive diesel fuel used in off-grid generators used at a variety of sites including remote industrial, island and arctic communities, emergency power, and military bases. In the long term, the AWT will be scaled up to provide a solution to harnesses vast offshore wind resources located over deep water. This research supports USDA goals by enhancing rural prosperity by lowering consumer energy rates, increasing electric system reliability, mitigating climate change, decreasing regional pollution and water shortages, and providing new direct turbine lease payments to rural landowners.
Animal Health Component
Research Effort Categories
Goals / Objectives
This USDA Phase II SBIR project will result in significant development of the Altaeros Energies airborne wind turbine (AWT). While the technical feasibility of the AWT concept has been established during Phase I, additional research is needed to further improve the reliability and economic viability of the AWT to the point where it can be successfully commercialized. The overall objective of the Phase II work is to bring the technology readiness of the major sub-systems of the AWT forward to where they can be integrated, at the culmination of Phase II, into a complete demonstration prototype representative of a commercial product. There are three main technical objectives and outputs for Phase II: 1) Achieve a significant reduction in the weight of the wind turbine components, including composite rotor and nacelle frame, compared with leading tower-mounted wind turbines of equivalent power. The project will lead to the fabrication and testing of a prototype wind turbine for the AWT that demonstrates the ultra-lightweight design. 2) Demonstrate extended, remote operation of the inflatable shell lifting platform in real world conditions. A remote communications and cnotrol system will be developed to autonomously control a prototype inflatable shell lifting platform, in order to demonstrate the key autonomous functionality of the AWT. 3) Integrate the major sub-systems into a complete AWT demonstration prototype that achieves the key features of power production and autonomous operations. The project will culminate in the assembly and subsequent testing of a fully functional demonstration AWT.
The Phase II project is divided into eight sequential sub-phases, which will occur over a period of 104 weeks. The project will begin with a detailed study of product requirements in sub-phase 1, based on review of rural customer's needs and considering environmental and avian impact of the AWT. The product requirements will flow through to the parallel development of each of the major sub-systems in the remaining sub-phases. The design team, which includes the University of Maine's Advanced Structures and Composites Center, will utilize several strategies to reduce the weight of the rotor and drive train components, including a) reducing component count (through elimination of the gearbox, yaw system,etc.), b) utilizing a compact load path to minimize structural material volume, c) reducing the torque and load in the drive train and d) utilizing high strength- and stiffness-to-weight composite materials. A finite element model of the structure will be built and analyzed to refine the design before the prototype system is fabricated. Once fabricated, the turbine will be assembled and tested in a controlled environment, in order to measure the torque-speed curve, before it is integrated into the inflatable helium shell lifting platform. A remote communications and control architecture will be designed and evaluated in a simulated environment, including hardware-in-the-loop testing. This will allow the development of a reliable system for autonomously and remotely operating the AWT to occur in parallel with the development of the physical plant. The control and communication hardware will be integrated into the prototype inflatable shell once it is fabricated by leading softgoods design company, ILC Dover. The inflatable shell lifting platform will be tested in real world conditions at the Loring Commerce Center in Limestone, ME, in order to evaluate it's performance. The dynamic motion of the shell during flight will be measured to evaluate flight characteristics. Allowable test conditions will be progressively increased to include ever more challenging environments. Once the autonomous functionality of the lifting platform is demonstrated, the turbine will be integrated and the system will be readied for fully functional tests. Determination of the success of the project will be based on whether the specific, quantitative technical objectives are successfully met.