Portable Energy Generator for off-Grid Villages

[moatis1]

I am a 3rd year integrated Engineering Student. For our 3rd year project we decided to make a portable generator to power laptops that were previously donated to an isolated off grid village in Nepal (for educational purposes). The laptops are currently sitting in rice bags and not being used because there is no way to charge them.

We are making the product mainly for charity that donated the laptops, but the university project course has an entrepreneurial aspect to it, so we have to think of ways of making this product "marketable" or scale-able, so that it can be applicable for other charities. (not exclusively tailored for this specific situation, but useful in general). So during the design and brainstorming phase, we are reaching out to other charities, subject matter experts, potential customers, and any possible relevant stakeholder to ask for their input. Any input would be greatly appreciated.

The device we are making must be portable, and relatively simple and easy to fix and use (so users can fix it themselves in case of damage). The villagers themselves also may not sacrifice a huge portion of their busy survival life to spend on setting up power, as they are yet to "see" the full benefits of education and are trapped in a poverty subsistence life. So any solution has to fit into the lifestyle of subsistence farmers who spend the whole day ploughing land with ox and other beasts, cutting and collecting firewood, collecting water from a river which is 3 km away...etc.

At night the villagers are usually around a camp fire inside their homes. The area gets around 6-8 hours of direct sunlight from sep-may, and the monsoon season is Jun-Aug. The water does freeze during winter, as the location is in the himalayas. During the Monsoon season, the children do not attend school, or do much of anything actually, except stay at home, so ideally, we want them to be using the laptops during this time. However the main goal for now is to have them be able to use the laptops during school time for at least an hour/day. The laptops are divided between two villages that are a day's hike away. There are no roads anywhere and walking distances are large. (so installing large hydro system will be expensive and hard)

As a minimum, the total amount of energy generated must be enough to power 20 laptops for 90 min 5 days a week. we are aiming at 1.5kWh of power. Ideally we want the villagers to be able to charge their laptops everyday 365 days a year so we will likely have to store power. Whether the power is generated by one device and used directly or by several devices collecting and storing small amounts of energy is still to be determined. (would love some input on this) The prototype must not cost more than $500. (university funding available to us)

The forms of energy we can use range from microhydro, mechanical energy (of animals, or somehow harnessing the energy of walking from humans), solar ,or wind (both harder to fix). Other less orthodox ideas are using the fire pits that are created nightly, or the rain during monsoon season. There is no geothermal, and gas or diesel are not available (we also prefer sustainability). Also it will probably cost too much for us as students to travel to Nepal and set up a hydro generator if it involves having to change the landscape, install pipes...etc.Any suggestions, comments, or ideas would be greatly appreciated.

1. What are some of the ways people in remote communities produce electricity? Any innovate or unorthodox solutions you know of?
2. How do you think we can tailor this device to solve the specific needs of the community mentioned and also be useful to other charities or even to camping enthusiasts?
3. Do you use any similar devices ? What bothers you about them?
4. What are some of the challenges of producing power in an off grid community that you can think of?
5. What improvements would you like to see in your current power generators?

 

[anorlunda]

I have two laptops. One draws 70 watts, the other one draws 10 watts. As a first step, translate that silly energy requirement to required watts and watt hours.

Solar panels with no moving parts are much easier to own and maintain than anything with moving parts. Does the energy need to be stored until night, or can it be consumed during the 5 hours of peak solar productions?

Hydro can be an excellent source, but they are typically custom designed to match the flow rate and vertical height of the waster source. It would be very difficult to design a micro hydro soulution without knowing that data.

Is it required to function rain or shine, 365 days per year? Villagers might not make fires very day. Water can freeze. Does it require a backup if the primary power generator needs repair?

Keeping 20 laptops repaired sounds much harder than repairing the power generator. 20 smart phones sounds more realistic than 20 laptops.

You said portable in the title. Why?

Best advice. Push hard to clarify the requirements and constraints before attempting any design. The quickest path to failure is designing something without a clear idea of what the design is required to do. The requirements you stated are very inadequate.

 

[jim hardy]

The villagers themselves also may not sacrifice a huge portion of their busy survival life to spend on setting up power, as they are yet to "see" the full benefits of education and are trapped in a poverty subsistence life.

I don't know if i'd wish Microsoft on those people... ever seen a movie "The Gods Must be Crazy " ?

 

[moatis1]

I have two laptops. One draws 70 watts, the other one draws 10 watts. As a first step, translate that silly energy requirement to required watts and watt hours.

Solar panels with no moving parts are much easier to own and maintain than anything with moving parts. Does the energy need to be stored until night, or can it be consumed during the 5 hours of peak solar productions?

Hydro can be an excellent source, but they are typically custom designed to match the flow rate and vertical height of the waster source. It would be very difficult to design a micro hydro soulution without knowing that data.

Is it required to function rain or shine, 365 days per year? Villagers might not make fires very day. Water can freeze. Does it require a backup if the primary power generator needs repair?

Keeping 20 laptops repaired sounds much harder than repairing the power generator. 20 smart phones sounds more realistic than 20 laptops.

You said portable in the title. Why?

Best advice. Push hard to clarify the requirements and constraints before attempting any design. The quickest path to failure is designing something without a clear idea of what the design is required to do. The requirements you stated are very inadequate.

I believe the laptops are 30W. they will be used for 1 hour/day and there are 20 of them so 30*1*20/1000 = 0.6kWh? not sure, but in the requirements we chose we are aiming at 1.5kWh of power.

The area gets around 6-8 hours of direct sunlight from sep-may, and the monsoon season is Jun-Aug. During the Monsoon season, the children do not attend school, or do much of anything actually, except stay at home, so ideally, we want them to be using the laptops during this time. However the main goal for now is to have them be able to use the laptops during school time for at least an hour. The laptops are divided between two villages that are a day's hike away. There are no roads anywhere and walking distances are large...so it should be relatively portable.

The laptops were already donated by "Zen's Outdoor Youth Leadership Camp" (http://www.olcy.ca/index.html) and are currently sitting in rice bags and not being used because there is no way to charge them. We are making the product mainly for this organisation but as part of our university course, we have to think of ways of making this product "marketable" or scale-able, so that it can be applicable for other charities. (not only tailored for this specific situation) This is why the requirements are a bit unclear still... Thats why we are looking for suggestions and ideas.

Ideally we should be able to store power as well because solar panels won't work during monsoon season, and may not be enough on cloudy days.
The water does freeze during winter, as the location is in the himalayas. These villagers do make a fire everyday in their homes to cook, and stay warm. thinking about backup generators is a bit beyond the scope of what we are doing at least during this design phase, but ideally we want the villagers to be able to charge their laptops everyday 365 days a year.

 

[Tom.G]

Ideally we should be able to store power as well because solar panels won't work during monsoon season, and may not be enough on cloudy days.
The water does freeze during winter, as the location is in the himalayas. These villagers do make a fire everyday in their homes to cook, and stay warm. thinking about backup generators is a bit beyond the scope of what we are doing at least during this design phase, but ideally we want the villagers to be able to charge their laptops everyday 365 days a year.

To meet the stated requirements, it sounds like two options so far:
1) Thermopiles in the fires. Drawback: likely expensive; most are for stove-top, not open fires
2) Human power, i.e. pedalpower (bicycle frame or treadles driving a generator) Drawback: only moderately portable; more daily exercise for subsistence population

A quick search using https://www.google.com/search?q=thermopile+30W++generator+-sensor&oq=thermopile+30W++generator+-sensor
turns up several Thermopiles for wood stoves, some water cooled, some fan cooled. Also check the Related links at the bottom of the search page.

Sounds like an interesting project. Please keep us posted.

 

[Borek]

Solar and wind sound the easiest.

 

[Nidum]

Look up clockwork radios .

 

[Borek]

Look up clockwork radios .

Won't work with the power requirements given. In the past, when similar question arose (charging cell phones in the rural areas without power) I thought about raising something heavy and use it to run a dynamo. Did some simple estimates and it turns out even with 100% conversion that's completely unrealistic. Energy required to charge a cell phone (assuming 2.2 Ah, 3.3 V) is equivalent to 1306 kg (well over the metric ton!) raised up by 2 meters (2.2 A * 3600 s * 3.3 V = 1306 kg * 10 m/s² * 2 m). And we are talking about laptops that use much more energy than cell phones.

 

[anorlunda]

It is a frequent problem here on PF that someone asks for suggestions. We use our skill to provide suggestions, but the poster then says "No that won't work because of this additional requirement that I forgot to tell you about." It sounds like that is happening here. You are only revealing requirements that you think we need to hear. That wastes our time and effort, and it is not a nice way to treat people that you are asking for free help.

The laptops were already donated by "Zen's Outdoor Youth Leadership Camp" (http://www.olcy.ca/index.html) and are currently sitting in rice bags and not being used because there is no way to charge them. We are making the product mainly for this organisation but as part of our university course, we have to think of ways of making this product "marketable" or scale-able, so that it can be applicable for other charities. (not only tailored for this specific situation) This is why the requirements are a bit unclear still... Thats why we are looking for suggestions and ideas.

Then don't ask for technical suggestions and ideas, ask for help to develop the real requirements. Based on that paragraph it sounds like the real goal is not to benefit the people of Nepal. but to develop a marketable product. You need to start at the ground level. What benefits those children, hardware, educational software, internet? Bear in mind that even in rich countries, computers in classrooms have a very poor record of providing actual benefits. On the other hand, the KISS approach of giving villagers connectivity, even via dumb phones, allows them to use their own ingenuity to provide major benefits. It has been very successful in Asia. So one of your first questions should be "Why just the classroom" Why not benefit all villagers? What do the villagers say they need most?"

Only after those "human" requirements are defined in detail, should you begin to look at electrical technical approaches. Part of what the university might be trying to teach you is the need to nail down requirements before commencing design.

 

[russ_watters]

...we are aiming at 1.5kWh of power.

Please, please(!) learn the difference between energy and power and try that again.

 

[jim hardy]

For a prototype something like this would get you going inexpensively..
https://www.harborfreight.com/100-watt-solar-panel-kit-63585.html
So that you don't have to complicate the villagers' lives with lead-acid batteries and inverters, that is instead of making 120 VAC just charge the laptop batteries, add one more panel and you'll have about 18 volts which is what i find most laptops want at their power receptacle
BUT
The HP laptop i got into requires more than just power at its receptacle. There's a third wire for communication between the laptop and the power supply. I know nothing of that communication protocol . You'd have to learn yours and replicate it to keep the laptop happy.
But i did run across a Dell laptop that gave me a message to effect "Detected a non-Dell power supply and I refuse to cooperate with it, so please connect a DELL supply instead." . That made me so mad i blackballed the brand and won't ever again buy anything from them.
Anyhow, where i was heading is you'd have to see if your laptops will accept charge straight from a solar panel.

I looked up the topographic map of Nepal . Looks like most of the country is mountainous where microhydro should be perfect. Beauty of it is it runs at night and when becalmed, and could power LED lights too.

The kids would LOVE one of these and it'd burn waste .
...

 

[moatis1]

It is a frequent problem here on PF that someone asks for suggestions. We use our skill to provide suggestions, but the poster then says "No that won't work because of this additional requirement that I forgot to tell you about." It sounds like that is happening here. You are only revealing requirements that you think we need to hear. That wastes our time and effort, and it is not a nice way to treat people that you are asking for free help.
Then don't ask for technical suggestions and ideas, ask for help to develop the real requirements. Based on that paragraph it sounds like the real goal is not to benefit the people of Nepal. but to develop a marketable product. You need to start at the ground level. What benefits those children, hardware, educational software, internet? Bear in mind that even in rich countries, computers in classrooms have a very poor record of providing actual benefits. On the other hand, the KISS approach of giving villagers connectivity, even via dumb phones, allows them to use their own ingenuity to provide major benefits. It has been very successful in Asia. So one of your first questions should be "Why just the classroom" Why not benefit all villagers? What do the villagers say they need most?"

Only after those "human" requirements are defined in detail, should you begin to look at electrical technical approaches. Part of what the university might be trying to teach you is the need to nail down requirements before commencing design.

Hmm... I see your point there. Sorry for not being clear in the beginning and thank you very much for your suggestions. You are absolutely right the university wants us to nail down our requirements and specifications before we start. In fact, we have a report due soon on that.

The university course has nothing to do with charity. It is a year long design project with an entrepreneurial aspect to it. One of our team mates knew someone in the charity (olcy.ca) company who went to nepal and donated laptops to this school. So he came up with the idea of making a project that can help power these laptops. However, yes the point of the project course is to make something new (that can be marketed or turned into a business) or to improve an already existing product (then market it and turn it into a business). If I wanted to help this village I would just go there and install a microhydro system or some basic solar panels, I also would have probably given them ipads instead of laptops as you mentioned...I feel like microhydro is the most robust and most tried solution to these kinds of situations...but we can't do that and fulfill the requirements of the course...we have to make something slightly innovative or new

My "real goal" is to pass this course by fulfilling the requirements and at the same time help charities bring power to off grid communities...

 

[anorlunda]

Thanks for being candid.

I see your point there. Sorry for not being clear in the beginning and thank you very much for your suggestions. You are absolutely right the university wants us to nail down our requirements and specifications before we start. In fact, we have a report due soon on that.

That's the opening you need. You could point out that tablets rather than laptops cut the power needs by half or more. That savings might make it possible to make one permanent system for each village rather than one portable one. With a permanent system instead of portable, micro hydro becomes a contender. (Unless the water source freezes hard in winter.) There are lots of simple yet effective DIY hydro projects on youtube.

It may help to have a conversation with the instructor first. How will the teams be judged? How open are they to ideas? If they're fixed on laptops and a business plan there may be an unethical conflict of interest hidden motive. If that's the case, forget rationality and just brown nose.

 

[Rive]

we will likely have to store power.

You wanna' charge devices which already has batteries.

Guess it's about the lack of 'integrated Engineering' at the start of the project, but would have been better to pick devices with adequate battery-time and omit (system level) external storage entirely.
Tablets were mentioned already.

Also, for tablets 'power banks' are a relative cheap commodities and most of them also has multiple use (pocket light). Comes handy in that environment.For already existing laptops... Well, for the cost of making this working with laptops I would make it work with tablets (with the price of tablets included).
Matter of the amount of solar panels/inverters available.

 

[JRMichler]

Like Rive said, use the battery in the device as the energy storage.

Here's another solution. Additional description is at http://www.antiqueradio.com/traeger_pedal_07-99.html.

 

[moatis1]

Update:

First off, I just want to say thank you all for your contribution to our project, you've all been a huge help to us in generating ideas. Attached are some of the reports we handed in so far, if you guys are interested to read. (the interview report may contain some of your inputs)
The project is moving along fine. We have ruled out using Mechanical Energy (animals, human powered), Solar, Hydro, and hydro-cell (PEM).
We are now deciding between using biomass in the form of wood, or using wind energy. (there will be a report explaining why we ruled out those things in the future)

Our second round of interview reports are due on Sunday, meaning we need your help again!

The villages that we are trying to help, unfortunately do not have enough manure, wood, or food to spare for efficient biomass energy generation. However, they do have just enough wood to maintain a fire in each household (60 households total) all day round to use for heating cooking and making tea. (they can't spare more wood to feed a burner).
There are two "designs" (not full designs, more like ideas) that are competing right now:
The first model is where we use the fire that each villager makes (in each house) to generate and store a small amount of electricity. The device we imagined (picture drawing) is a quarter sphere "chimney-stove" made of copper or some other material with high thermal conductivity. The whole outside of the "chimney-stove" will be covered with thermoelectric generators (TEG modules) to capture the waste heat. The top of the "chimney-stove" which is the hottest part (because the fire will be touching this part) will have the hot side of a b-type sterling engine. The cool side of the engine will be outside at the top, and will be cooled with a water pack or heat sink, and by the air (15 degrees C). The sterling engine turns a disk which turns a motor (or some similar arrangement to run a motor). The motor and the TEG are connected to a regulator which is connected to a battery or an appliance (depending on output power). I am currently in the process of figuring out the potential power output of this design, and would appreciate any input on how to do this (I am trying to fin the Temperature at the hot side of the sterling engine and on the outside surface of the device given a 1000 degree C fire producing 10KW heat). Also attached is a picture of a rudimentary CAD drawing of the design (the cone is the fire and the cylinder is the sterling engine, the motor and thermoelectric generators are not shown)

The second design is some kind of a Vertical Axis wind turbine. We don't have our own design for this yet but, this turbine configuration was chosen because it can better handle rough winds and doesn't need to face the wind direction. Also the gear box and motor are located at the base, which minimizes materials and maintenance. using wind speed of 10mph and a low end efficiency of 25% with this formula:

(link)
Where:
P = Power output, kilowatts
Cp = Maximum power coefficient, ranging from 0.25 to 0.45, dimension less (theoretical maximum = 0.59)
ρ = Air density, lb/ft3
A = Rotor swept area, ft2 or π D2/4 (D is the rotor diameter in ft, π = 3.1416)
V = Wind speed, mph
k = 0.000133 A constant to yield power in kilowatts. (Multiplying the above kilowatt answer by 1.340 converts it to horse- power [i.e., 1 kW = 1.340 horsepower]).

We get a power estimate of 0.01265*A (KW). so (12.65 * A) W where A is the rotor swept area in ft2.

On Tuesday (Nov. 14th) we will discuss and then decide on which road we will take as a team, using our research, and the feedback from subject matter experts (professors), potential customers (NGOs, and outdoor enthusiasts), and online forums (you guys!).
Keeping the specifications in mind (in the project proposal pdf):

• produce 1.2kWh of power (main specification)
• Have marketable potential (this one is not in the pdf because the pdf is for the technical course, this requirement is for the business, and engineering entrepreneurship course. Both courses are related by the same project and team) (main specification)
• fully recharge simple electronic devices in under 12hr
• water proof (main specification), durable, under 30kg, and easy to maintain
• 30% locally sourced

Here is how I personally see it:
Fireplace "Chimney-Stove" Design:
Disadvantages:

• Immediate drawback is that each household has to have one of these, which may mean that this option will be more expensive.
• 1 device only may not produce enough power to charge all the laptop and several of these devices charging several batteries will suffer from more inefficiency. However, the details of this remain unknown because I haven't yet calculated the potential power output possible. (would love some help with that)
• May be very heavy depending on the size and the material.
• The sterling engine may easily break down, and I was told that it is hard to re-calibrate such a device (never built one so I don't know, anyone have any experience with this?)

Advantages:

• If the device produces enough power, each household will have autonomy, and won't need to draw power from a centralized generator that depends on the wind, meaning each house can even light a light bulb and not rely on fire light to study. (the wind turbine will most likely only be able to power the laptops and the phones, if we aim to keep the device small and portable <30kg)
• This is a power generation, heating, cooking, and fireplace device. It improves protection and security from fire hazards by keeping the fire contained and not open, it helps direct the heat of the fire to one side of the room (like a fireplace or chimney), it can be used as an oven or wood stove, and it simultaneously generates power while in use. I would imagine the efficiency will be very high.
• The device is minimally invasive in the sense that, villagers do not have to spend too much energy setting it up, and don't have to significantly change their lifestyles to run it. All the villagers have to do is to continue to make a fire and cook and heat with it.
• This device has allot more market potential than a wind generator, especially for camping enthusiasts. (depending on how big and heavy it will be) This is because of it's many functions.

Vertical Axis Wind Turbine

• Only one big device to power the entire village.
• Can meet power goals more easily.
• May be too heavy.
• will work continuously in any wind direction, so constant power generation.
• Other than the setting up cost, time and the maintenance cost and time, this will not intrude on the lives of villagers.
• Depending on the scale, this may make enough power to power not only laptops and phones but also lights in each household. (the trade off is size and weight of the device)

I'm a little biased here because I came up with the "Chimney-stove" design so please try to think of your own pros and cons.

Anyways, I would love to hear any suggestions comments or advice regarding our project and the next steps we should be taking now.

 

[anorlunda]

1.2 kW sounds excessive. If it runs 6 hours per day, that's 7.2 kWh per day.

Can you show calculations? How much energy per day to charge a phone, a laptop (really should be a tablet), plus a LED light for 4 hours, assuming 12 VDC for everything, no AC.

I'm skeptical because based on my own experience, 0.12 kWh per day is enough for a household. So 1.2 kW sounds 60 times too big to me.

Edit: Also, some back of envelope calculations for the flue gas generation idea. You'll have a propeller in the flue to capture energy. The pressure drop across the prop times the mass flow rate is the simplest estimate of the energy available. What numbers do you have for the two,parameters?

 

[JRMichler]

Have you considered a low cost off the shelf wind turbine of about 400 watts? You would need several of them with MPPT controllers, but they are readily available from multiple sources. An example: https://www.northerntool.com/shop/tools/product_200481463_200481463.

An excellent book on Stirling engines is Air Engines, by Finkelstein and Organ, ASME Press 2001. They discuss in detail a low cost engine of about the size that you are looking for. And why air is not a good working fluid (oil gets past the piston into the hot side, then explodes). Other good books are Stirling Engines, by G.. Walker, Clarendon Press, 1980. Also Stirling Engine Design and Feasibility for Automotive Use, M.J. Collie, Noyes Data Corporation, 1979.

You might also google Rocket Stoves for small, efficient biomass burners that would be a good basis for a combined cooking / power system.

 

[moatis1]

1.2 kW sounds excessive. If it runs 6 hours per day, that's 7.2 kWh per day.

Can you show calculations? How much energy per day to charge a phone, a laptop (really should be a tablet), plus a LED light for 4 hours, assuming 12 VDC for everything, no AC.

I'm skeptical because based on my own experience, 0.12 kWh per day is enough for a household. So 1.2 kW sounds 60 times too big to me.

Edit: Also, some back of envelope calculations for the flue gas generation idea. You'll have a propeller in the flue to capture energy. The pressure drop across the prop times the mass flow rate is the simplest estimate of the energy available. What numbers do you have for the two,parameters?

Okay so 20, 60W laptops have to be fully charged every night. (this is the primary function) the laptops generally take one hour to charge at 60W so 20*60*1=1.2KWh. If you want to charge them in 6 hours, then you need 1.2KWh/6 = 0.2KW of power. I'm not an electricity guy but I believe that's correct right ?

Referring to the attached pdf, (reattached here for convenience)
In the document, we define the primary specification in table 1 as "Provide at least 1.2kWh of power" not as 1.2kW (I guess that should say 1.2kWh of energy because the amount of hours we want to charge the laptops in is not specified).

But then in the actual text it says "The primary function of the generator is to provide electricity. We developed the power specification by taking the average power consumption of a laptop, estimated to be 60W, and multiplying that by 20 laptops [6]. The result is an average power consumption of 1.2kW". This implies that the laptops must be charged simultaneously in 1 hour, which is not necessarily what we need. We need to provide enough daily electrical energy to charge 20 laptops so we need 1.2kWh but an undefined amount of kW. The more KW the better obviously.

I'm surprised no one noticed that XD
The grades for this haven't come out yet, but it's not looking good...
Thanks for pointing that out. If we say that the minimum time to charge should be 12hr (while the children sleep) then 1.2kWh/12 = 0.1kW of power minimum.

***I suck at power stuff, so if it's blatantly obvious that I'm misunderstanding some concepts, please point it out to me.

 

[moatis1]

Have you considered a low cost off the shelf wind turbine of about 400 watts? You would need several of them with MPPT controllers, but they are readily available from multiple sources. An example: https://www.northerntool.com/shop/tools/product_200481463_200481463.

An excellent book on Stirling engines is Air Engines, by Finkelstein and Organ, ASME Press 2001. They discuss in detail a low cost engine of about the size that you are looking for. And why air is not a good working fluid (oil gets past the piston into the hot side, then explodes). Other good books are Stirling Engines, by G.. Walker, Clarendon Press, 1980. Also Stirling Engine Design and Feasibility for Automotive Use, M.J. Collie, Noyes Data Corporation, 1979.

You might also google Rocket Stoves for small, efficient biomass burners that would be a good basis for a combined cooking / power system.

Thanks the books are awesome!
If only we could just buy something off the shelf and hand it in my friend!
unfortunately, we must design and make our own turbines(and "innovate" a little)...
But thanks for the suggestion, perhaps we can learn something from the design of the turbine in the link you posted.

The main issue right now though is deciding between biomass or wind. What do you think we should go for ?

 

[anorlunda]

I believe that's correct right ?

My mistake. I thought from your post #16 that you were switching to a per household flue gas system and that the 1.2 kW was for one house, not the whole village.

 

[JRMichler]

The main issue right now though is deciding between biomass or wind. What do you think we should go for ?

Development time and cost will be far lower with wind. If your blades are less than optimal, it will still work. And you can always retrofit better blades. Generators, bearings, MPPT controllers, and other materials are all readily available.

TEG is expensive and low efficiency. Stirling is expensive and will have long development time. Considerable development time will be spent getting it to last without wearing out, and keeping oil out of the hot side. It will still need a generator with MPPT controller.

 

[anorlunda]

Don't forget energy allowances for an Internet connection. Putting laptops in a school with no Internet and no educational software is pretty pointless. Including educational software is very difficult. Are your professors and the charity donating the laptops familiar with the One Laptop Per Child project? They failed despite an annual development budget of $12 million? Read the criticism section of that wiki article and compare it with the requirements you have been given. The "US mind set" criticism of OLPC sounds very apropos here.

https://en.wikipedia.org/wiki/One_Laptop_per_Child

Some tablets can use cell phone signals to get Internet connections. If the village has phones, it has cell signals, but laptops typically don't have that. So WIFI connecting to a cable or satellite modem must be included (plus maybe the satellite dish). Tablets also use much less electric power than laptops.

I realize that you are just a student struggling with seemingly stupid requirements imposed by your professors. Have you tried talking sense with them as suggested earlier in this thread? Perhaps you could print out the history of posts in this thread and show it to them.

 

[moatis1]

Don't forget energy allowances for an Internet connection. Putting laptops in a school with no Internet and no educational software is pretty pointless. Including educational software is very difficult. Are your professors and the charity donating the laptops familiar with the One Laptop Per Child project? They failed despite an annual development budget of $12 million? Read the criticism section of that wiki article and compare it with the requirements you have been given. The "US mind set" criticism of OLPC sounds very apropos here.

https://en.wikipedia.org/wiki/One_Laptop_per_Child

Some tablets can use cell phone signals to get Internet connections. If the village has phones, it has cell signals, but laptops typically don't have that. So WIFI connecting to a cable or satellite modem must be included (plus maybe the satellite dish). Tablets also use much less electric power than laptops.

I realize that you are just a student struggling with seemingly stupid requirements imposed by your professors. Have you tried talking sense with them as suggested earlier in this thread? Perhaps you could print out the history of posts in this thread and show it to them.

The charity gave 20 laptops that have a database of knowledge, like an encyclopedia kinda of thing, and an educational software already installed. The whole point was so that they never have to use or need internet. Then the earthquake came along and knocked the power out. And it's been out ever since, so the laptops are sitting there not being used. The charity did not anticipate a complete power failure, and then a subsequent inability of complacency of the Nepalese government to restore power, and that's when we got in touch with them. We're basically trying to help them salvage their project in a way. Neither us nor the professors have any control over what the charity decides to do. The only connections is that one of our teamates knows someone in the charity and that's how we decided to help.

The professors have nothing to do with the charity. The professors are just teaching a design course to engineering students. Our specific team in this course decided to contact the charity and tailor our class project to their needs. The class requirements and projects have nothing to do with any charity or outside organization. Our team personally went out of their way to contact this charity and ask them what they need, so that we do our class project and pass the course, and at the same time maybe help out a charity...

So I don't know what to say to the professors, I can't really ask them to bend the course requirements for one specific team just because we are helping charity. Other teams in the class are doing other projects, like a soldering pen that injects solder and heats at the same time (like an ink pen but with solder instead of ink). Some other team is doing a roof gardening automation project...etc. The requirements of the course are the same for all the teams regardless of what the project is.

Development time and cost will be far lower with wind. If your blades are less than optimal, it will still work. And you can always retrofit better blades. Generators, bearings, MPPT controllers, and other materials are all readily available.

TEG is expensive and low efficiency. Stirling is expensive and will have long development time. Considerable development time will be spent getting it to last without wearing out, and keeping oil out of the hot side. It will still need a generator with MPPT controller.

That's really helpful thank you!
We will most likely go with wind because of your input and the input of several of our professors, NGOs and camping enthusiasts. The final verdict will take place on Tuesday, but so far it's not looking good for the design I drew :(

 

[jim hardy]

What is prevailing wind direction and speed there ?

Search on phrase " DIY wind turbine blades pvc pipe" , no quotes. There are literally thousands of sites
here's just one that seems practical
http://www.mdpub.com/Wind_Turbine/