Renata Hegyi: Energy Systems Engineering, Dartmouth College – Hungary

“I’ve had an incredible month with WindAid. I could not have imagined a better way to learn about wind turbines, manufacturing, construction, Peru and energy engineering. The WindAid team is passionate, dedicated, smart, caring, and so fun. Working with volunteers from all over the world made the experience even more special. I learned first hand what goes into building a wind turbine from scratch and watched how it impacted the lives of a Peruvian community for the better. I also received a great introduction to Peruvian culture, practiced my Spanish a lot, and traveled a bit on the weekends with the other volunteers. I left Peru with a stronger sense of direction, inspiration, and life long memories. Regresaré pronto! Gracias por todo, WindAid. ”

Redesigning the wind turbine tower assembly

Posted by Bryce Alsten on June 2016

University of Florida and WindAid volunteer

Research and design; it’s the meat and potatoes of any engineering project. It is also an ongoing process, because no matter how good you think your product or system is, there’s always room for improvement.

The collective understanding that our wind turbine systems need continuous development is what makes working at WindAid a truly immersive learning experience. Volunteers from all over the world with a myriad of skills and experiences come together to learn from each other and contribute their own unique knowledge towards the ultimate goal of improving the way we empower developing communities by providing them with electricity.

There are many factors and constraints that go into the successful design of small wind turbines, but above all others, the most important factor is safety. Currently, one of our main focuses is on ensuring safety over the lifespan of our 500W WindAid 1.7 model turbine by analyzing and improving the structural integrity of the tower assembly.
During our most recent installation in one of our communities, Playa Blanca (on the northern desert coast, where there is little rain, strong sun and very sandy soil), we took note of some concerning levels of degradation in the towers and foundations of some previously installed turbines. The most concerning signs were structural cracks in the concrete foundations (pictured below).

Base crack

 

There are two types of cracks in concrete: structural cracks and non-structural cracks. Non-structural cracks are normal and to be expected. They are unavoidable and are often caused by variations in moisture and temperature. A common adage is that there are two guarantees with concrete: one, it will get hard and two, it will crack. Structural cracks on the other hand, are larger (generally wider than 1/8”, or the thickness of a credit card) and must be addressed before they become larger and propagate, leading to eventual structural failure. Structural cracks can be caused by many factors including improper mixing and pouring of concrete, as well as excessive forces acting on the concrete.

It is our opinion that these structural cracks are being caused by a combination of the two previously mentioned factors. Because of the concern over the long-term structural integrity and safety of the turbines that these cracks raise, we have begun the process of completely redesigning the way be build and install the towers. Wind turbines experience a variety of different forces (pictured below), and in general the stresses caused by these forces build up throughout the turbine’s tower, especially at the base of the tower where it is connected to the foundation.

Base Options

Our current tower design is simple – like the example depicted above minus the tension cables (guy wires). The tower shaft is a circular post that is approximately 8m long and 13cm in diameter made of eucalyptus wood. We use eucalyptus because it is low cost, relatively strong, and readily available in Playa Blanca. The actual turbine assembly is bolted onto the top of this post. We then place the bottom of the tower into a hole that is approximately 1.5m deep and 0.75m in diameter and backfill the hole with concrete.

Based on the evident structural cracking in the foundations, it is clear that we must design a new tower structure that provides more support than our current design does. There are three common types of tower structures used to support wind turbines: lattice, monopole, and guyed mast (all pictured below). Our current design is a monopole. After extensive research, we have decided that the best option to properly support our turbines is to use a guyed mast structure, the most commonly used type of support structure in smaller scale turbines.

bases

 

 

However, using guy wires in our redesign brings a new problem – a significant increase in the footprint area of the tower. This is a problem is because in Playa Blanca, the tower foundations for all the existing turbines are located within 0.5m from the walls of the owners’ houses. This means that a traditional guyed mast tower setup would require anchoring one or more of the guy wires inside of the owner’s houses, which is simply not a realistic option. This issue has forced us to get creative. We want to use guy wires but we don’t want to increase the size of the tower’s footprint.

Our preferred solution is to add horizontal crossbeams towards the top of the tower that allow us to redirect the guy wires back towards the tower’s base while still maintaining proper tension. Think of the new tower design as a lower case letter t. The guy wires are attached at the top of the t, then at the ends of the cross of the t, and then again at the bottom. The only difference between our theoretical design and this simplified letter t example is that there will be three guy wires spaced 120 degrees apart so there will also be three beams supporting them as opposed the two that you would visualize on the t –shape.

Decisions now must be made on several factors including but not limited to: how high up the guy wires should be installed, how long the cross beams should be, and how much pretension should be installed in the guy wires. We will be able to answer these questions when we finish analyzing the forces and moments experienced by our turbines in Playa Blanca. When we are confident with the accuracy of our numbers, we can begin optimizing the equations and running finite element analysis (FEA) on the new structure design in programs like SolidWorks so that we can be confident that our design will remain structurally safe and sound for the entire lifespan of the turbine.

If you have any comments or suggestions on this article, we would be interested to hear from you at [email protected]

 

Electrifying Playa Blanca and exploring Peruvian desserts…

Posted on June 9, 2016 by Katherine Guo

It’s been about a week and a half since I arrived in Trujillo, Peru. From sanding blades at the workshop to having celebratory barbecues at the house, I have not had much time to reflect on our project, its impact, and my time in Peru, in general. Unfortunately, I am currently sick with a cold and could not make it to the workshop today, but this opened up some quiet space to finally think.

Sustainability is Key

I, along with two other Duke students Danielle and Aashna, are working with WindAid Institute to help electrify Playa Blanca, a rural community where most residents do not have access to electricity. Although efforts have been made by the government to install solar panels in the homes in Playa Blanca, the solar panels have been proven to be unreliable, as many of them have broken down and can no longer generate electricity. Therefore, with the support of the community, WindAid has stepped in and offered to provide wind turbines for any household that wants one. WindAid has already electrified 15 houses with wind turbines, and over the next few months, we will construct the components (blades, rotors, stators, etc.) and install two more wind turbines for two families.
When learning about what WindAid does, my first thought was: Since Playa Blanca is quite far from Trujillo (where WindAid’s workshop is), so what happens if the turbines break? How would they be maintained?

After talking to Jessica, our point of contact at and co-founder of WindAid Institute, she explained that a project was underway to create a workshop in Playa Blanca, as a centre for wind turbine maintenance, as well as a space for providing educational sessions to the community about the wind turbines. The community members are ever so passionate about being environmentally friendly and preserving their home, making them excited to learn about renewable energy and the nooks and crannies of the wind turbine. Hopefully, with a more permanent space for WindAid in Playa Blanca, community members would be able to gain enough knowledge about the wind turbines to eventually be able to maintain the turbines on their own.

Side Note: WindAid is currently seeking funds for the construction for this Community Wind Workshop, check out the campaign here

For me, sustainability is arguably the most important component to any service project. I want to ensure that the impact we are making will last longer than when WindAid completes their project in Playa Blanca. The development of the test center drew me the most to our project, and is going to be my main focus during my time with WindAid.

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Reading to attentive kids at Playa Blanca!

Workshoppin’

During the weekdays since I’ve arrived in Trujillo, we go to the workshop to make the different components of the wind turbine. What I’ve enjoyed most is that the people at WindAid really wants us to learn. For example, welding is a technique that serves to bind pieces of metals together. It involves lots of sparks, and I have to admit, I was pretty terrified of it in the beginning (and still may be a little bit). After a long day working with sparks and trying to weld, I was ready to call it a day, but Ross, one of the founders of WindAid, made sure that I would not leave that afternoon without welding the two pieces of metal together. Ross gave me a demonstration and some tips on how to get the flame going. Thereafter, I was successfully able to make the welds. I am very grateful that instead of asking someone who was already adept at welding to combine the two metals, Ross was determined to assure that I was able to weld and comfortable with it.

Aside from welding, I have been making the blades of the wind turbine smooth by sanding and adding filler, constructing the tail, and making coils for the stator. As all the different parts of the turbine reach their final stages, it’s exciting to finally start to the wind turbine come together!

This Saturday, we are going to Playa Blanca to actually install two wind turbines, one for a family and the other one to be used at the test center. During the time in Playa Blanca, I will be able to work on the sustainability aspect of the project, by creating lesson plans for the community, building paper airplanes or boats with kids in schools, and talking to community members to understand their thoughts and feelings about the wind turbines. Interacting with the community is what I am most looking forward to doing in Playa Blanca!

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Assembling the stator onto its structure in the workshop

 

Work Aside

Peru is also really fun! To start, the people here are really nice- although I don’t know much Spanish, Peruvians still try making conversation with me and are always smiling at me even when we cannot understand each other. From the past week, I have picked up some Spanish that helps me get by, including how to catch a taxi and the numbers to buy things at the bodega (small neighborhood store). Hopefully, by the end of this trip I am able to actually have conversations in Spanish so I can learn more about Peruvian life and culture.

In Trujillo, there is a beautiful beach town called Huanchaco, where we went the past two weekends to eat ceviche (citrus infused fish) or to just admire the surfers in the ocean.

Finally, I have been eating so much dessert here! From palmier cookies to three milk cakes, all the options are so delicious and cheap. Luckily, one of the WindAid workers loves desserts as much as I do (maybe even more) so he can be my guide to all desserts Peruvian.
That’s all for now. Stay tuned for blog posts from Danielle and Aashna as well as more updates from me after we get back from Playa Blanca!

Hasta la vista,
Katherine

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Visiting the giant rock wall in Buenos Aires, Trujillo

Katie Fry: Conservation, University College Birmingham, Derby, UK 

“I thoroughly enjoyed every moment with WindAid Institute. The team were so welcoming and I have never laughed so much in a month! The workshop was fun, interesting and easy to understand, even with no engineering background. The installation was heartwarming, it’s amazing to know you physically made electricity for a house or community when they had nothing!

I learned about renewable energy, engineering, climate change and different cultures. I would recommend it to anyone- from any background. I loved it and I would do it all over again in an instant!

Oh… but learn Spanish! Purely to avoid getting picked on by gringos…”

Eamonn Fetherston: Virginia – USA, Music Journalist

“Spending a month working with a team of like-minded individuals who are committed to building a sustainable future and bringing renewable energy to disadvantaged communities was an experience I am certain never to forget. Unlike many of WindAid’s volunteers, I do not have a background in science or engineering. Because of this, I suspected that I might have trouble participating in some aspects of the project. My assumptions couldn’t have been more wrong, as the WindAid team immediately made it clear that they would teach me everything I needed to know along the way, and that volunteers with non-science backgrounds are often capable of bringing a fresh perspective to the build and installation processes.

Installing a turbine at Playa Blanca, the fishing village in which WindAid had installed several turbines already, was an incredibly rewarding experience. After witnessing what day-to-day life looks like for a community in which many members lack regular access to electricity, I came to understand more clearly than ever before the crucial role renewable energy will play not only in ensuring that our future is a sustainable one, but in providing aid to impoverished communities around the world.”