The SED3 Project – Designing and Building a Micro Wind Turbine

Sustainable Energy Design 3 (SED3) was one of the newer but compulsory courses on my degree last year and as I am currently beginning my new dissertation project this in the one year anniversary on possibly the most amazing group project I will ever have worked on, I thought I would actually get around to writing up about it. I would apologise for the delay but basically I can’t really write up loads of things about coursework like that immediately because then the plagiarism checker will flag up my work as copied from my blog in the public domain and things like that so I have had to leave it for a little while for logistics sake…

I am slowly publishing things in the slightly more formal context of a Research Gate project which you can check out for our group report submitted and a few other things I’m adding to that.

ResearchGate Project here: https://www.researchgate.net/project/Designing-and-Manufacturing-a-Micro-Wind-Turbine

The Background

The course has only been running a few years, improving each time but the premise is simply a group engineering project run by the Mechanical Engineering group (via the legendary guest lecturer Uwe Stein) to demonstrate all the various skills that good engineers should have. Each year so far Uwe has varied the format of how the groups are formed and what the challenges are for the groups to complete, although it is worth noting that these changes have been partially in response the simple feedback that no one has ever finished building anything working. My experience on this course makes me inclined to lie that problem with the University’s system, particularly for ordering in components, for taking too long to process, and thus only really solved by enabling the ordering of components in the semester beforehand. But hey, that’s maybe just me.

The Challenge

The 2016 challenge was:

Design and build a small wind turbine of about 100W to charge a lead acid battery such as may be used for caravans and camping applications.

Additional requirements included product portability, the production of a working generator, calculation analysis, and the ability to operate in light winds (<12m/s) as well as high winds (≈20m/s). Lastly, each group had a £100 budget. In the end, a full written report was required along with the finished prototype.

The Team

• Me (Electrical and Mechanical Engineering, The University of Edinburgh, UK)
• Jennifer Jones (Mechanical Engineering, Michigan State University, US)
• Omar Longou (Mechanical Engineering, Iowa State University, US)
• Ellen Handberg (Environmental Engineering, Lund University, Sweden)
• Natasha Neeve (Chemical Engineering, University of Auckland, New Zealand)
• Sam Cunningham (Mechanical Engineering, The University of Edinburgh, UK)

Anyway, this year I was placed in a group with some amazing people, none of us ever having met before starting this course together. We were placed together as a group of oddities – I had just joining my new year group after my interruption of studies, Jennifer was doing her final exchange of her degree in the final semester of her degree (she was graduating that summer!!), Omar was on exchange for Mechanical Engineering, Natasha was on exchange for Chemical Engineering, and Sam just apparently missed something for the normal MechEng students the semester beforehand…

Research and Development

A lot of work was done, some parts a little more complicated to explain than others, and so I have broken up descriptions of the research and development that I was directly involved in across several sub-sections. It is worth noting that some of this is simply a direct copy of what is written in the report, some writing not. I am hoping that by sectioning out certain individual parts of the project, I’m providing the information in a more useful format for some who may wish to use it (any amateur generator builders out there) and also giving a focus/skew on my personal contributions, I’m not showing all the whole project from the whole group as the report does.

1. Initial Research and Planning
2. The Generator Theory
3. The Generator Manufacturing
4. The Rectifier
5. The Control System
6. The Battery Management System
7. The State of Charge Measurement
8. The Voltage Regulator
9. The Complete Circuit
10. And The Rest Of It…

Final Design

The Theoretical Design

Omar produced some fantastic CAD models of the final completed design, as you can see in the images below. He also produced the corresponding technical drawings of all the components, which I haven’t reproduced here but can be found in the report itself.

Similarly, I produced a table outlining the final specifications of the generator design but I have included that earlier under Research and Development as it made more sense to keep it with the development of the generator so the nomenclature could be understood.

The Prototype

I couldn’t actually find any of the photographs that were taken of the finished thing at the time of writing this, but here is a picture of the mostly completed prototype:

Did it work? Unfortunately we were unable to test it in the time given, but we believed it was unlikely predominantly due to the significantly lower quality of the bearings than expected (you could feel how much more power was required to turn those blades than the theory by just trying to turn it by hand), and the much less than ideal quality of the coils in the generator stator (if we’d had more practice but alas there was no time or budget for that).

The Project Management

Firstly regarding costs, we were slightly over budget in the end, costing £111.29 in total as opposed to the £100 goal. Meeting this budget did also involve a lot of costs absorbed by the University and through one-off and certainly not scalable scavenging in order to keep the costs down. So if you are looking to recreate this project, please examine the budget more carefully as you will probably need to add a lot of costs that we avoided.

Time management was a more difficult aspect to assess because of huge delays incurred by the University when ordering components (if we wanted the costs covered by the University within that £100 allowance we really needed to order it formally through them). There were various things creating these delays but regardless, most of the components and resources arrived ridiculously late, just before semester finished.

Personally, I was ridiculously proud of our team because we were significantly ahead of all the other groups at the date of the deadlines originally set in place for the course.

However, to try and compensate for the problems they’d made, the University “kindly” allowed us to continue manufacturing over the Easter holidays. Except of course, most of our team being exchange students who had been making plans for their trips and travelling far in advance to keep costs down, were busy and fully booked over the time that is officially a break after all deadlines have officially finished. So we couldn’t use any of that extra time offered, but I believe most of the other groups (who mostly desperately needed it) used it. I’m not bitter about it but I am sad that it devalued the huge extra work we had all gone to try and meet the original deadlines, embarrassed to be part of the institution that was making my teammates feel unfairly guilty, and exhausted to be adding it to the long list of poor student experience at the School of Engineering here.

The Grades?

My personal overall grade for the project was 67% (a high 2:1 level to translate from Edinburgh’s grading system) which I admit was lower than I was expecting for our group in the midst of our excitement.

I would have loved more feedback breaking down where we lost the marks but hahaha, the Mechanical Engineering group at the University of Edinburgh have consistently failed to do anything like that over my time here, but in this case I think it can definitely be forgiven because Uwe did such an incredible amount for the course anyway.

Personally, I think we were tripped up slightly by the Easter holidays scenario as I believe most, if not all, other groups achieved a lot over that time and grades being relative within the class, I think we effectively lost most of our advantages over that time. We did fail to get the final thing working in the end which I think prevents us from being allowed a 70% or higher anyway (that’s a 1st class grade if you were wondering).

In the interview I was asked if I had looked into how many caravan and camping systems would allow a battery to be run below its float voltage, which I realised with mildly sleepy horror I had never actually done. I had committed that major designer’s sin and not paid enough attention to the users and so perhaps my final electronics design was fundamentally flawed. I don’t know, I haven’t really investigated it any further to give a real answer, sorry.

The Important Lessons I Learned

In no particular order:

• Machine learning is being used everywhere
• Wind turbines are going to become surprisingly unsustainable in the near future because of those rare earth magnets they all need for the generators.
• Generators are difficult to build by hand, and the high level of precision required and use of epoxy resin means they are difficult, if not near impossible to repair, reuse or recycle, at least using the current designs.
• Diversity really does induce creativity and increase motivation.
• In Lundt University in Sweden the students have overalls that they cover in badges that they earn throughout their university life. Whaaaat.
• There is a scale of handling electricity that is awkwardly too small for electrical power labs, and too big for electronics labs.
• University group projects don’t always have to be completely terrible nightmares. Deadlines can be reached. Groups can actually become better friends than they were before. Artisan cheesecakes are way better than all-nighters.
• You need to really scrape the ends off of copper wiring to remove the coating and make that electricity work.
• Some embedded processing design experience with C and a Photon Particle Core processor.
• Engineering is the best and the worst sometimes.