1. VERTICAL AXIS WIND TURBINE (VAWT) FOR MICRO-ENERGY GENERATION: SPINNING STUDENTS’ MINDS Summary Lecture Authors: Betina Baère Campos Neves, MSc [1] & Pedro Barbosa Guedes, MSc [2] [1] Professor Department of Electrical Engineering Institute of Engineering of Porto – Polytechnic Institute of Porto (ISEP - IPP); Portugal [2] Professor Department of Mathematics Institute of Engineering of Porto – Polytechnic Institute of Porto (ISEP - IPP); Portugal

2. OBJECTIVES Proposition of a hands-on, team-based project addressed at first-year students that: Will encourage student learning through participation Increase student retention through satisfaction Improve student confidence through achievement Having meaningful basic context. This means that those possessing the correspondent knowledge will have a positive impact on society & environment while acting as engineering agents DIY VAWT 52 W, 12.5 mph

3. OBJECTIVES To focus on energy generation where it is most needed, using different approaches and locations, respecting the environment and contributing significantly to the well-being of society. Microgeneration technologies, especially the ones based on renewables, have the potential to reduce built environment related CO 2 emissions coupled with reductions in consumers’ electricity costs. Kazekamome Remote Hybrid Street Lamp by Hybridyne Power Systems, Canada In a best case scenario Small (<100 kW) and Micro (<10 kW) Wind electricity generation in a built environment could be equivalent to about 4% of the domestic electrical demand (UK estimates for year 2000 consumption reference numbers and actual wind resource category).

4. OBJECTIVES Small VAWTs – A GOOD POSSIBILITY Urban renewable generation – THE NEXT BEST THING Engineering spirit – THE KEY TO THE PROBLEM Fun but requiring knowledge – CHALLENGES BRING OUT THE BEST IN EVERYONE “Doing is learning” – LEARNING BY DOING SPARKLES CREATIVITY AND YOU FEEL GOOD ABOUT IT

5. FIRST STEPS Equations and laws are extremely helpful! They mean less trial and error and better results! Existing types of VAWTs How do they work… - from an amateur point of view - from an engineer’s point of view Low-cost Savonius turbine by EMAT Ltd, England

6. FIRST STEPS But still…there is always trial and error. VAWTs built: Savonius - covered - uncovered Giromill - 3, 4 and 6 blades using quarter- cylinder shaped blades - 3 and 6 airfoil shaped blades

7. FIRST STEPS THE ONES THAT WORKED Savonius works just fine and has better performance if covered. Is self-starting, even at very low speeds. Tall models tend to require a stabilization point on top, otherwise they will oscillate far too much. These models can be good prime movers for high torque pm stepper motors if made taller/bigger… Our Savonius model, with top and bottom covers, spinning for testing purposes!

8. FIRST STEPS Giromill VAWTs Airfoil shaped blades work just fine. Other types tried in the process did not. It is advisable to build these VAWTs with an uneven number of blades. They may sometimes need a push to start if done in a bigger scale Rotation is faster than for Savonius but torque is much smaller A simple way of doing an airfoil shaped blade is by folding a piece of PETG or polycarbonate, aligning and holding it, using a small adjustable workbench structure and, finally, riveting it underneath the workbench! Loosening the support system we have a nice symmetrical airfoil blade!

9. FIRST STEPS Since Giromill models were hard to self-start an hybrid model was tried out, adding something new… It simply got a small Savonius structure right in the middle… and things did improve!

10. THE ENGINEERING EXPERIENCE Building a Savonius turbine Testing layout changes on the turbine Extracting data from tests Generating electricity with a motor working as generator Estimating parameters What measurements are still missing in order to get more relevant data out of this experience - parameters that were left out for lack of data ? C p, C t, … Details of our Savonius model

11. WHAT CAN BE LEARNED FROM THIS EXPERIENCE BUILDING: not easy nor immediate but rewarding. Learned quite some new vocabulary and now I know how bearings and couplings work. I’ll be able to choose them on my own if I need to. Aligning the structure: not easy but extremely important to have a smooth and light rotation. 3 bearings (in 2 levels), to minimize contact and friction, solved the puzzle. Other solutions didn’t work as good. IGUS plastic plain bearing. Not as good as 3 bearings… The reflector for speed measurements with an optical digital tachometer 3 bearings: 2 fixed and one adjustable, by rotating the metal bar holding it, against the axis. A small screw holds it in place.

12. WHAT CAN BE LEARNED FROM THIS EXPERIENCE “Creative engineered solution”: A small screw (not very visible…) prevents the garden hose from rotating inside the shaft. A small hole in the hose, along with markings helps inserting, aligning with shaft hole and fastening with screw. HOW ABOUT ATTACHING THE MOTOR/ GENERATOR TO THE SHAFT WITHOUT UNBALANCING THE TURBINE? FLEXIBLE COUPLING! Standard (expensive) solution for flexible precision couplings

13. WHAT CAN BE LEARNED FROM THIS EXPERIENCE MEASURING Equipments: Multimeter, Oscilloscope, Tachometer, Anemometer… now I know how to use them, what they are for and have an idea on how they work (I’ll need some more knowledge to explore them) Units: Some old ones…some new ones… Engineers speak a “standard” language! That’s very useful! [1] [2] [3] [4] [1]: Digital oscilloscope, 2 channels; [2]: Digital multimeter; [3]: Digital optical tachometer [4]: Digital hand-held anemometer [1]

14. WHAT CAN BE LEARNED FROM THIS EXPERIENCE Maybe not easy while you don’t grasp it… Easy once you start leaning about it. Addictive once you see your first generator working! It can only become better from this point onwards! ELECTROMECHANICAL ENERGY CONVERSION [1][2][3] [1][3] Details on the two LED’s that served as electrical (very visible!) charge. The PM motor [2] working as generator has 6 wires. Each group of 3 represents one winding, Example: yellow / green – 1 “full” winding; The orange wire is the “middle point”. We used 1 “full” winding per LED. The other winding: black / brown; red = middle

15. WHAT CAN BE LEARNED FROM THIS EXPERIENCE THE GENERATOR WE USED A PM MOTOR AS GENERATOR… With another schedule and more knowledge it would be possible to build a generator for the turbine. In a real-world application, as far as small and medium size wind turbines are concerned, it is usual to have a direct drive pm generator built exclusively for that turbine. [1] [2] [3] [1] Coil arrangement for a DIY PM axial flux generator for wind turbines [2] STAMFORD radial flux PM generator – Wuxi Huaxiang, Ltd. China [3] PM direct drive axial flux generator assembly by PacWind

16. WHAT CAN BE LEARNED FROM THIS EXPERIENCE NOTIONS AND FORMULÆ What is wind Drag and lift – what makes turbines go round How to evaluate a turbine Cp Ct TSR or λ Basic electromagnetics in action

17. WHAT CAN BE LEARNED FROM THIS EXPERIENCE From the obtained data it is possible to estimate the turbine’s Tip-Speed Ratio Graphics summarize some of the observations and data collected

18. WHAT CAN BE LEARNED FROM THIS EXPERIENCE LOOKING CAREFULLY AT VISUAL DATA There is more to it than the eye can meet… In the next months, years, it will all be unveiled …

19. CONCLUSIONS WE NEED ENERGY! WE NEED IT MORE AND MORE! WE LIVE, CONCENTRATED, IN TOWNS AND CITIES! IT IS BEST TO GENERATE ENERGY RIGHT WHERE IT IS CONSUMED… WITHOUT BURDENING EVEN MORE OUR ENVIRONMENT. SO MUCH NATURAL RENEWABLE POTENTIAL UNTAMENED AROUND US. ENGINEERS PROVIDE SOLUTIONS WHERE THEY ARE MISSING, WHERE THEY ARE NEEDED. Clean Technology Tower, soon in Chicago!

20. CONCLUSIONS This ends the 15 day first experience with engineering. This lecture only shows a fraction of all the learning and experimental processes behind the project. The great adventure of engineering has already started. May you all fully enjoy it! Thank you!