Source: EWINDSOLUTIONS LLC submitted to NRP
CONTINUED DEVELOPMENT OF AIRBORNE WIND ENERGY SYSTEM GROUND STATION
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
SMALL BUSINESS GRANT
Reporting Frequency
Annual
Accession No.
1016578
Grant No.
2018-33610-28622
Cumulative Award Amt.
$600,000.00
Proposal No.
2018-03218
Multistate No.
(N/A)
Project Start Date
Sep 1, 2018
Project End Date
Dec 31, 2020
Grant Year
2018
Program Code
[8.12]- Small and Mid-Size Farms
Recipient Organization
EWINDSOLUTIONS LLC
30678 SW ORCHARD DR
WILSONVILLE,OR 97070
Performing Department
(N/A)
Non Technical Summary
Airborne Wind Energy (AWE) is still a relatively new field but is growing quickly. There are approximately 13 other AWE companies worldwide that appear to have the technical competence and realistic understanding of business such that we view them as realistic competitors. As we have detailed above, eWind differentiates itself from them by focusing on following current FAA (or European) flight rules, staying small and competing against the traditional small wind market with a better value proposition and being able to go straight to selling systems to farmers without bureaucratic waivers.There is increasing business focus on the field, there is increasing university funding to study basic problems common to most AWE systems. TU Delft, a university in the Netherlands, is a leader in this field and has even started a fledgling academic department focused on it. This has produced numerous papers and theses dedicated to various problems of AWE (e.g. Ahrens et al. (2014); Fagiano (2009); Haug (2012)). In addition, there have been publications about simplified control systems and prototyping lessons and guidelines (e.g. Fagiano (2012); Fagiano et al. (2013); Fagiano and Marks (2014); Fagiano et al. (2014); Zgraggen et al. (2014)). Unfortunately, much of this work has centered on soft kites with multiple tethers that allow control systems for the airborne device to be placed on the ground.While we agree that this greatly simplifies the control system problem, the cost in drag (and, thus, electricity production) of additional tethers makes the business and financial case for these systems tenuous at best. AWE represents a significant increase in mechanical and control complexity and, thus, must also come with an even greater increase in energy production and value to make financial sense to farmers. Additionally, soft kites (imagine a kite-boarder or para-sail) are very likely to be harder and costlier to maintain in the field for years at a time. In short, rigid frame crafts (such as ours) are more efficient, rugged and easier to launch and land. Conversely, they are less studied, harder to control on a single tether, and less stable, requiring a more robust control system to manage them.The other major category of AWE is called "sky-gen". In this case, the generator is placed on the flying craft itself (as opposed to on the ground) and the electricity is transferred down the tether. There are numerous benefits and disadvantages of both sky-gen and ground-gen. There is a legitimate business case to be made for each one within certain operational regimes. However, while sky-gen is likely better at higher altitudes (i.e. greater than 1000m), ground-gen is better at the altitudes currently allowed by regulations (i.e. below 150m). Companies such as Makani are pursuing sky-gen systems, but because of this height/efficiency tradeoff, they are building utility scale systems that require individual waivers from the FAA to even test. This is not an appropriate model for farmers.As previously detailed in Section 3, we have based our design around the needs of small farmers. We maximize the financial return to farmers while following all current regulations and permitting, allowing the customer to reap the benefit as easily as possible. This focus leads us to the rigid frame flying craft, a ground-gen system and automating the system to minimize farmer involvement. This approach places a greater burden on the research and development side by increasing the design complexity of TED, its controls and the flight software.Previous work on our system has focused on TED, its aerodynamic design and physical control surfaces. This work has already led to a utility patent 9,643,721 titled "Wind Energy Conversion System, Device and Methods" that was issue 05/2017 it covers a flying system with multiple lifting surfaces and side rudders to maximize lift in a given wingspan and improve maneuverability, as well as it's flight path. As noted earlier, we will submit another disclosure for stability control features that enable a rigid frame kite to have soft kite like stability which minimizes the need for onboard power consumption to otherwise achieve that stability.Previous work (published) on ground stations is relatively minimal. Fagiano et al. (2014) is one of the few who details the decisions and trade-offs in tether control systems. However, as previously mentioned, they operate a soft kite, a very different scenario from our system. We will still consider the sensor systems they detail (modified to our needs) as viable solutions for part of the ground station.
Animal Health Component
30%
Research Effort Categories
Basic
10%
Applied
30%
Developmental
60%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
13174102020100%
Knowledge Area
131 - Alternative Uses of Land;

Subject Of Investigation
7410 - General technology;

Field Of Science
2020 - Engineering;
Goals / Objectives
Group I:Determine the optimal power generation configuration (generator, gearbox, inverter, reel in motor, battery, etc.) of mainly off the shelf components placed directly after the tether drum to:Supply 5 kilowatts of electrical output power (common size generator)120 or 230 VAC (using the appropriate transformer outlet) at 60 Hz single phaseProvide 2 hours of battery backup capabilityOutput power should meet utility power quality requirementsThis is approximately the power required to run a 5 HP Deep Well Submersible Pump or similar sized Irrigation Pump that might be used on a farm.Note: without a utility grid tie, providing the system nameplate capacity (11.6kW or 100% of the electricity used on average) would greatly exceed the farm's instantaneous electricity demand on a regular basis, forcing the need for a larger dump load or battery backup system (more likely at night when the electricity demand is lower, but winds are higher).Group II:Design, build and test a functional 5kW airborne wind energy ground station system, complete with the following key sub-system components (this is building upon and a substantial expansion and scaling up of the phase I ground station activity):Wind tracking system such that the ground station can pivot as requiredGround station frame assemblyTether drum and tether cross spooling controlMeasurement sensors for wind speed, tether reel speed, environmental, tether angleA separate reel in motor if required.Ground station soil anchoring systemA weatherized ground station enclosure with service accessEnclosures and access panels for the main electrical power generation equipmentExterior electrical connection, customer interface, status lights and emergency shut offSpace for a small battery backup systemGroup III:Design, build and test a system performance monitoring system for ongoing tracking of key system performance metrics (phase I focused on measurements of tether tension and tracking, while Phase II will focus on the entire ground station system) such as:Wind speed/direction and tether release speedMechanical and electrical power generatedOccurrence of soft and hard faultsTo increase test hours on non-windy days, design and build a 5hp tether tension simulatorGroup IV:Compliance with current Federal Aviation Administration regulations regarding the need for flag and lighting requirements and potential changes being considered as they apply to AWES (This is an expansion of PI activity and more direct engagement with the FAA).Specially the following regulations:FAA title 14 (Aeronautics and Space) → Chapter I → Subchapter E → Part 77 (safe, efficient use, and preservation of the navigable airspace)FAA title 14 (Aeronautics and Space) → Chapter I → Subchapter F → Part 101 (moored balloons, kites, amateur rockets, unmanned free balloons, and certain model aircraft)FAA Advisory Circular 70/7460-1 Obstruction Marking and Lighting Finally, we must address the time duration of TED flight which also impacts test time on the ground station energy generation system while also collecting reliability data. This is challenging given our dependency on local weather conditions. Thus, we have decided to place flight time duration as a "stretch goal" for this grant to get at least 20 hours of cumulative outdoor test time utilizing TED and the ground station. Concurrently, we would track the total power generation time at a system level and any failures that occurred in order to begin building a runtime and reliability growth curve as well as a corrective action plan where needed.
Project Methods
Further develop and implement the aerodynamic analysis of the tether. Expand on the success of the Phase I project in the areas of tether management system. This includes, sensors, tether guides, and temporary tension control mechanisms. Utilize the testing apparatus that was developed and built in the Phase I project for further testing and development of the ground system. Further development and implementation of the software control system and tether management system.

Progress 09/01/18 to 12/31/20

Outputs
Target Audience:Our target audience is small to mid size US farmers in rural areas. These individuals are involved in agricultural production and seek a need to provide off-grid energy production systems as well as supplement their income by becoming energy independent or selling produced energy back to the utility company. Over the past 6 years, we have visited farms throughout the state of Oregon and have participated in agricultural trade shows, forums, etc, explaining the technology and getting valuable feedback from the farmers and learning what their needs are. Changes/Problems:Goal 1: supply 5 kilowatts of electrical power - as noted earlier, mechanical power (BHP) was measured. Shown in figure 7 are two representative power generation cycles results from our figure 8 flight pattern away from the ground station. The first trace is power generated flying in the upstroke of the figure 8 pattern, then power drops to near zero in the turns, then the second trace is power generated when flying down in the figure eight crosswind flight path (obviously at a higher speed and power generated then in the up stroke). The third and fourth traces are just another figure eight cycle. You can see rounding up, that 3 kilowatts of peak power was actually achieved (figure 7) in an average wind speed of 25.8 MPH (figure 8) at 4212 seconds into the flight test. However, as noted in Miles Loyd's highly cited technical paper in the airborne wind energy industry "Crosswind Kite Power", there is an ideal velocity ratio (VL/VW) where the power generated is maximized. Power maximization occurs when the tether release speed (VL project on the wind plane) divided by the wind speed (VW) is approximately 1/3rd as noted by Point 1 on the FC curve in Figure 9. The FC curve indicated power in a crosswind flight pattern which eWind utilizes. FD indicates a drag mode flight pattern, like what Google Makani (now out of business) used and FS is a simple but highly inefficient, straight downwind flight path using an old-style diamond shaped kite. At the time when maximum power was produced at 4212 seconds into our test flight, the tether speed was 23.9 MPH with a tether angle of approximately 45 degrees relative to the horizontal wind plane. Hence our test velocity ratio was 23.9 MPH *Cosine (45 degrees)/25.8 MPH = 0.65 which is noted as Point #2. So, the results indicate that the speed at which we controlled the tether was too high and as a result, power levels were not optimized. Hypothetically, given the test site wind conditions, if we had optimally controlled the tether release speeds, based on the relative difference in normalized power output levels between Points 1 and 2, which could have achieved a power level of 5,200 watts. To achieve this level of power, in the future, we clearly need to improve our servo control system and develop a system to measure wind speed at altitude (wind speed increases with height off the ground) to obtain the ideal VL/VW at the flight height. What opportunities for training and professional development has the project provided?Business planning through the LARTA program How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Group I - Results and Deviations to Original Work Plan Results: Goal 2: Output 120 or 230 VAC at 60Hz - we clearly did not achieve this goal as previously mentioned. Goal 3: Provide 2 hours of battery backup capability - we utilized one standard lead acid car battery which has approximately 0.6 kWh capacity to control the tether drum speed. A better choice would have been a deep cycle battery for longer life. Unfortunately, in the initial specification, we failed to note the expected power usage requirement (ie the kilowatt-hours required). Goal 4: Deliver utility power quality requirements - we clearly did not achieve this goal as previously mentioned. Group II - Results and Deviations to Original Work Plan Goal 1: Wind tracking system such that the ground station can adjust its orientation as required - this goal was achieved. The table bearing noted in figure 5 allowed the tether arm to rotate a full 360 degrees to align with the wind. Goal 2: Ground station frame assembly - two assemblies were designed and built, so this goal was achieved Goal 3: Tether drum and tether cross spooling control - two tether drums and cross spool assemblies were designed and built. The cross-spool assemblies required additional electronics and software to synchronize its motion with the tether drum and that was completed. This goal was achieved. Goal 4: Measurement sensors for wind speed, tether reel speed, environmental, tether angle - all these goals were achieved. Data from these sensors are saved to a SD drive approximately every second during testing and reviewed afterwards. One might expect that the tether angle could be measured directly off the tether arm, but the bow in the tether connection between the ground station and TED is significant, rending that method useless. Instead, we developed software and used the NAVIO2 controller in TED to log the GPS location of the ground station and then dynamically stream TED's pitch, roll, yaw, X, Y and Z positions readings during flight. Goal 5: A separate reel in motor if required - it was not needed Goal 6: Ground station soil anchoring system - was designed, built, and used only a few times. Goal 7: A weatherized ground station enclosure with service access - this was not completed as noted earlier. Goal 8: Enclosures and access panels for the main electrical power generation equipment - this was not completed as noted earlier. Goal 9: Exterior electrical connection, customer interface, status lights and emergency shut off - an exterior electrical connection and a convenient customer interface was not completed. We utilized a laptop to communicate back and forth with TED. Status lights were added to the Arduino controller. System status information was continuously fed from the controller to a second monitoring laptop via the serial interface. A big red EPO switch was added and can be seen in figure 4. Goal 10: Space for a small battery backup system - one standard car lead acid battery was utilized. Group III - Results and Deviations to original Work Plan Goal 1: Wind speed/direction and tether release speed - achieved - all these parameters are measured and recorded on an SD card. Goal 2: Mechanical and electrical power generated - partially achieved - mechanical power was measured and recorded on an SD card. Electrical power generation was not implemented as noted earlier. Goal 3: Occurrence of soft and hard faults - mostly achieved - unanticipated events are logged on the SD card and posted to the monitoring laptop when they happen. Goal 4: Tether tension simulator - partially completed - built, software developed and tested as part of the Phase I portion of this grant but not used as much as we would have preferred. Field testing always led to needed repairs and constant software and hardware upgrades to TED (not the subject of this Phase II project - but required to test the ground station) and the ground station. Group IV - Results and Deviations to Original Work Plan Goal 1: Federal Aviation Administration update eWindSolutions had a discussion with FAA representatives on March 8, 2018 regarding proposed Airborne Wind Energy lighting and marking requirements and that was documented in the initial proposal. However, since then Makani, an airborne wind energy company that was owned by Google which had sufficient resources to work directly with the FAA on a regular basis at their Makani's test facilities in California and Hawaii. Below are Makani and FAA notes: (Part of the Makani Archives - The Energy Kite - Part III) Google purchased Makani in 2013 Makani started working directly with the FAA in 2014 The last communication between Makani and the FAA was a DNH that was issued Dec/2019 and valid for 18 months at the Hawaii location. A DNH is a "Determination of No Hazard to Air Navigation" The final test requirements: NOTAM issued during operation (notice to local airmen) No TFR required 354 Makani Technologies LLC (temporary flight restriction) Marking: Wing: conspicuous colors Base station: white Tether: alternating 150 foot bands of white and aviation orange (Makani had a huge tether - ours is 3mm) Lighting: Kite: four enhanced hemispherical ACL strobes Base station: L-865 Tether: none Nighttime operation permitted We include here, the final and most up-to-date DNH issued, in the hopes that they may be useful for other developers seeking to navigate the waters (or "winds") of FAA regulation of Airborne Wind Energy. eWind team: this information is still pretty much inline with the last conversation we had with the FAA in 2018. The only difference is tether marking, which the FAA suggested would possibly not be required due to our small off-the-shelve 3mm diameter tether. Also the FAA previously noted to us and Makani, there was a "The preferred pattern was a double-flash at a rate of 40 times per minute, synchronized with the wing tip, tail, and ground station tower lights" that is not noted above. Either way, the above proposal is currently not an official FAA requirement. So, we will continue to stay in communication with the FAA until final AWES regulations are developed. Goal 2: A "stretch goal" for this grant to get at least 20 hours of cumulative outdoor test time utilizing TED and the ground station - achieved - not rigorously recorded but would estimate we had 20+ hours of actual flight time. There is no question, that additional field test time would have been highly desired but was limited by the number of days windy enough to test and the drive time to get to our test sites. Our two key test sites were the Pacific Coast (Gearhart to Astoria Oregon is many miles of sandy beachline that has open vehicle/trailer access) and Pendleton, Oregon (where we had access to 7,000 acres of farmland via the local Chief of the Fire Department). The Pacific Coast is 1.5 hours away and Pendleton is 3.5 hours away. You would think being near the Columbia River Gorge, which is full of traditional wind turbines, we would find other sites, but after many hours calling and looking, unfortunately not. For our prototype, we need a wide open and accessible area that was free of trees, people, animals (snakes), power lines, large rocks and was relatively flat. Each team member had multiple wind apps which we would compare on an almost daily basis. About 25% of the time, when we decided to test, the winds were not high enough to test by the time we got there. Given our extensive product design background, when we did test, we spent roughly the first 45 minutes "not pushing TED to extremes" to get good video (potential investors love) and typical performance data, then pushed the system and eventually almost always, till something failed (standard find and fix the weak links approach). Even with 20+ hours test time, in my opinion, we still were not to a point to start building a reliability growth curve.

Publications


    Progress 09/01/18 to 08/31/19

    Outputs
    Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals?Stay the course as described above. Continue developing the back end of the system thru a partnership with Burnshire Electric (also a USDA Phase II funded company). We are directly working with the FAA in forming policies for AWE development and will continue our dialogue regarding outcomes in field testing. We will continue working with our LARTA advisor, Peter Hong and will submit our final CSR in November 2019.

    Impacts
    What was accomplished under these goals? 1. The first objective was selecting a generator technology given the three primary architecture choices of: DC, induction, or synchronous generators. We will control the rotation (in both directions) electronically by varying the back-EMF within the motor. 2. We chose to output power as 230VAC. The end product will output smoothed 230VAC power to be used directly by farm equipment or passed through a net-meter to the grid. 3. We made a slight pivot regarding the 2-hour battery backup capability outlined above. In depth analysis determined that in the event of a "system power disconnect error", the quickest and safest response is to immediately dock/secure the TED and halt energy production. Summary: 100% complete - finalized decision to use AC induction motor/generator 100% complete - finalized decision to use 230VAC output to grid and/or equipment 100% complete - revised battery backup requirement to 20min 100% complete - selected equipment will meet power quality requirements Progress and deviations to original plan of group II Frame Design - 70% complete - the frame is constructed from 80/20 T-slotted Aluminum Extrusions, Figure 3. This material system is highly modular, easily modifiable, and includes a variety of components to enable weatherization, cable management, and linear motion. Tether drum and cross spooling - 80% complete - The tether storage drum is currently of wooden construction, is mounted to the drive shaft by use of flanged clamps, and mounted to the frame with pillow block bearings. With the second half of the funding we plan to replace the drum with a more robust custom built all-aluminum one. System Sensors for: wind speed, drum rotation, environmental, tether angle - 50% complete Secondary motor - 100% complete - Because of the architecture of the generator selected, a secondary reel-in motor is not required. The generator will control all functions for tether deployment, rotational braking, and retracting tether during power cycle reset or docking. Ground anchoring - 70% complete - One of the main selling points for our system is that it is highly portable. Therefore, we needed to find a method of temporarily securing the station to the ground that is effective, reliable, and removable without disrupting the ground. Earth screws are our solution. They are simple to install (via handheld impact wrench or T-handle), effective at anchoring the station for as long as needed (will not creep loose), and easily removed with minimal equipment and damage to the site. Weatherized enclosure - 50% complete - Because the system will be outdoors throughout its operational lifespan, appropriate weatherization must be implemented to protect the equipment, customers, and technicians. We are striving to achieve protection rating of NEMA 3 which is defined as: Enclosures for power generation and smoothing equipment - 20% complete - the equipment is contained within a NEMA-3R enclosure mounted on the station frame, shown in Figure 4. This enclosure will house the inverters, metering equipment, motor controllers, and display interfaces provided to us by Burnshire Hydroelectric. Electrical connection, customer interface, status lights, and emergency shut-off - 10% complete - will be developed during the second half of the grant once control systems are developed and we have determined the appropriate configuration of these features. Space for Battery Backup System - 50% complete - A small battery backup system is necessary to retract and store the aerial device in the event of a power loss error. Summmary Wind Tracking - 70% complete - need to order and install components Frame Design - 70% complete - will make adjustments as needed Tether Drum and Cross Spooling - 80% complete - order and install components System Sensors - 20% complete - install and program sensors Secondary Motor - 100% complete - deemed unnecessary Ground Anchoring - 70% complete - selected, need to order Weatherized Enclosure - 50% complete - design complete, need to order and install Power Generation and Smoothing Equipment Enclosures - 20% complete - contracted design and construction, awaiting delivery of equipment GUI and Safety Lighting - 10% complete - system control software development required to determine and incorporate GUI features Battery Backup - 50% complete - battery backup design complete, need ordering and installatio 65% Total Completion Progress and deviations to original work plan of group III 1. Wind speed/direction and tether release speed - currently only tracking wind speed and tether release speed; update/incorporate wind direction and real-time tracking of TED positioning relative to the ground station. 2. Mechanical and electrical power generated - currently calculating power generation potential using mechanical torque sensor; update/incorpoirate generator's actual power generation and power smoothing equipment efficiency/optimization 3. Occurence of soft and hard faults - currently not tracking error/faults in software; update/incorpoaret tracking while testing in the field and in the lab. 4. Tether tension simulator - currently have hardware and software sized to function with the Phase I ground station; need to upgrade the hardware function with the 5kW station and upgrade software to be more robust and incorporate larger variety of wind conditions (eventually using data collected during field tests for more realistic "practice") Summary: 30% complete - update existing software and incorporate more functions 30% complete - update existing and add all power generation tracking functions 0% complete - develop/implement error/fault tracking software 20% complete - update hardware (more robust); update software (more robust) to record and practice with real-world wind profiles. 20% Total Completion 6. Progress and Deviations to Original Work Plan of Group IV eWindSolutions had a discussion with FAA representatives on March 8, 2018, just a week after the submission of this Phase II project proposal. The FAA is considering and examining regulation changes regarding the operation of airborne wind energy devices in navigable airspace. In summary, the proposed regulation changes (to remove flags and lighting requirements on the tether) removes a key system performance restriction and, as a result, has a positive impact on the commercialization of airborne wind energy technology. 7. Update on Phase II Commercialization Objectives Larta principal advisor Peter Hong and USDA ACT leader David Schaefer have been working together on eWind's commercialization strategy and have completed several tasks outlined in the Larta Commercialization Objectives/Prioritization Schedule. Additional funding has been a main goal for eWind and we have recently been awarded a $100k grant from the State Of Oregon to assist in completing the following objectives outlined in our CP: additional IP patent submissions for the ground station, strategic business planning & partnerships (we are collaborating with Balsa Group and Elevator), market entry strategy development, and improving our business model to attract high-level investors both in the US and abroad. We are in the final stage of hopefully closing a round of Revenue Based Financing with the Canadian Investment Group, David Haig & Associates, CA. This funding will allow us to hire personnel for key positions which will accelerate our timeline for BETA testing and finally commercializing the technology. As discussed above and per our CP objectives, we are continuing our involvement with the FAA as they develop rules and regulations for the AWES industry. 8. Midterm Summary: During this first half of the project, we have made the driving architecture decisions, completed the design work, and have made headway on construction of the physical components of the ground station.

    Publications