It is interesting that people in the US who want off grid power are exploring some of the same technologies that would be useful in Africa. A cost effective way to store energy for night / no-wind for a full house is probably going to be a big hit.
They mention de-forestation in the article. I do worry that if our next "green" energy source isn't cheaper than oil/coal then the third world will ignore the cleaner alternative.
I can't find the reference off hand, but I once heard that it takes 7 years of operation for a solar panel to generate the same amount of energy to build a panel, .. and the energy that it takes to build one comes from ... guess what .. coal and gas.
There are cases where a relatively maintenance free power source which can be installed a point of use is worth a lot more than you'd think -- it's basically like a primary battery cell -- a way to transport energy. It doesn't matter if it's less than unity efficient in recovering the power used to make it, if distribution and storage costs for that power would otherwise be really high.
On cellphone towers in the middle of nowhere with no wirelines linking them, a solar panel makes a lot of sense, even if it never recovers as much power as it cost to build. Or on a satellite. Or, apparently, on a shack in rural Africa.
I agree Africa probably could do better with natural gas, oil, hydro, or coal central plants for now, vs. big solar plants, but a combination of cheap big grid power sources and decentralized renewables seems like the best solution. Building out a grid in rural areas isn't really cost effective.
Is that necessarily an ironclad reason not to use them? Can you not think of the panel as an investment of energy that is slowly returned over the course of 7 years? Like a battery, but with much greater charge density and a longer viable lifespan.
I mean, it's not like they can freely use coal and gasoline in their huts. It is also more efficient to burn the coal & gas in a plant.
I recently bought a small dual solar/dynamo powered flashlight. 30 minutes of solar power can power the light for 10 minutes, but 1 minute of turning the crank can power the light for 30 minutes.
If the sun is out for say, 12 hours a day, that means it can power my light for 240 minutes. But turning my crank for 10 minutes would power the light for 300 minutes.
Is solar really efficient at all, because wouldn't getting a hand-turned generator get more electricity than waiting for the sun?
Solar power is a function of area. If you are comparing a small cell, say one that fits on a flashlight, to a small generator that fits in the same flashlight, then there will not be much solar power available.
If you are expand your solar cell to a square meter then you will make more power than an "in shape" cyclist can sustain for an hour (200 watts).
Rules of thumb:
• 1 square meter in full noontime sun gets about 1000 watts of sunlight.
• Solar panels are about 20% efficient, so 200 watts per square meter at noon.
• Total sun delivered during the day is equivalent to 4 noon hours in the summer, 2 noon hours in the winter.
1. If your solar panel were 30 times bigger than it is, 1 minute of solar power would power the light for 10 minutes too.
2. Even a small solar panel can power your water pump/weather station/radio repeater when you're ten miles away and don't have the time to spend all day walking ther to spend a minute turning its crank.
3. Solar panels break down less than hand-turned generators. They don't have bearings or windings or gears. If you keep replacing the batteries, your flashlight will ber a usable solar-powered flashlight much longer than it is a usable dynamo-powered flashlight. (The "shake light" design, with a magnet sliding back and forth in a tube through a coil, might be an exception there.)
4. Solar panels keep working even without being fed more rice. Human labor does not produce energy, regardless of what you may have heard in The Matrix; it merely converts it quite inefficiently from chemical energy into mechanical energy.
5. An athlete working his hardest might consume 10 000 calories per day in food, but can only convert some 2000 of those calories into work. If your Lance-Armstrong-level athlete is turning a crank 12 hours a day and eating 10 000 calories, he's producing 200 watts during that time, 100 watts averaged over the 24 hours. Three square meters of solar panel can do the same. Six square meters can do twice as much. And the solar panels won't drop dead of exhaustion after a month.
(Supposedly Lance averaged 5200 kcal/day during the Tour de France with a peak power output of 1000W: http://www.wired.com/wired/archive/12.07/armstrong.html --- but presumably ate more on uphill days than on level days.)
> 3. Solar panels break down less than hand-turned generators.
I live in an African country and solar panels have one huge disadvantage. Solar panels are often used now to power boreholes (usually fully submersible pumps which have become fairly cheap and easy to install, compared to so called "mono-pumps" of the old days) and pumps near rivers that are far from grid electricity. It is also used to power electric "energizers" for electric fences.
The problem is that solar panels keep getting stolen. It is something that is fairly valuable that should be outside. I can just imagine the amount of theft that will go on when people have solar panels on the roofs of their homes/shacks.
Also, the article failed to mention the real problem with using candles and fire for lighting - frequent fires.
That's very interesting! What country are you in? What kind of pumps do people use now?
I imagine that for applications in town, the theft problem will be less. If you have ten or twenty houses clustered together, you can probably leave one rifle home with one of the women in case someone tries to steal the solar panels. I mean, that's the same problem as someone trying to steal a motor scooter or whatever, right?
> That's very interesting! What country are you in?
I lived in rural South Africa (not anymore though).
> I mean, that's the same problem as someone trying to steal a motor scooter or whatever, right?
What is funny for me is that motorcycles aren't as popular in the African countries that I have been (e.g. China or India). But yeah, things that is not inside the home is easily stolen. Things like car batteries or solar panels are extremely popular items to steal.
> What kind of pumps do people use now?
In the old days they used mono-pumps (where the motor was above ground and connected with rods).
Nowadays the pump is in one sealed unit that is connected with plastic piping and electricity. Two people can install a pump in less than half a day and everything is light. The price of pumps also dropped.
Cranks have moving parts, and thus are more likely to break and need service. Additionally, those little combo flashlights (I have one too, I love them) have a very small solar panel. Notice the solar panel in the photo is at least as large as an 8.5x11 sheet of paper- I'm sure it produces much more current.
Very off topic, but I have been very interested in Peltier units and Seebeck engines for the last month or so; winter is indeed here. It would be interesting to see these used in a wider scale, or if it is even possible. Here are some links that describe them in more detail:
Using both heat and cold you can create a small amount of electricity from these units. I have seen something like this used in a camp. They would place one end of a metal rod into a fire and the other in a bucket of water. Then they could create enough electricity, using some type of thermoelectric circuit, to 'trickle charge' a cell phone or GPS.
If Lenin had said "the internet will cause great cultural and geopolitical change" would you scoff and ignore him because you think of him as a bad person? Of course not.
The same applies to Trotsky, if you read that wiki page you will see Trotsky's idea is actually pretty damn good.
He is obviously expressing surprise at who it was. Just because the person may have not been a role model or the brightest person in general, however, does not mean all of their ideas must be thrown out. If you disregarded the ideas of anyone who believed or did something you disagreed with, you´d only have yourself to look at.
How would one go about implementing this in poor suburban areas, like around third-world-countries' metropoli?
I live in Buenos Aires, where there a lot of poor "villas" scattered all over the city and at the outskirts, and this seems like something that would be great to implement here. Specially during the summer when the exesive power consumption generates blackouts at least once a week.
I haven't been to the villas, and I don't know anybody who lives there. However, what I hear is that the people there already have grid power, which they don't pay for, and they are very often targets of theft. I have to imagine that hauling in an expensive solar panel in order to conserve energy paid for by the electric company would be a very difficult sell there. I don't think many of the shacks there have air conditioning, and the air conditioners are the culprit there.
If the objective is to keep your TV and radio on during the blackouts, I think a car battery is probably a better choice than a solar panel.
Somewhat tangential of a question, but does anyone have recommendations for buying cheap solar panels in the states? Like, suppose I wanted a solar panel to put in my apartment window so I could charge my phone. What would it take to get something like that?
SparkFun sells some solar panels, http://www.sparkfun.com/categories/116 You might need to attach them to some kind of 5v regulator though because a panels output is going to vary with the intensity of the light it's exposed to.
Solar panels are photodiodes. Their junction voltage is determined by the properties of the material, not by the light intensity, although of course at sufficiently low light intensity they will cease to be reverse-biased. More sunlight will just produce more current, not more voltage.
All I know is that I hooked a small panel up to my multimeter and if I put it in direct sun light it produced 5 volts and under indoor lighting conditions the voltage was around 3 volts. So I don't really know how they work but I know how to measure the voltage coming out of them.
You may be aware that direct sunlight is thousands of times more intense than indoor lighting conditions. Probably if you'd hooked up a resistive load to it while indoors, the measured voltage would have dropped to a fraction of a volt; and if you'd used an oscilloscope instead of a multimeter to measure the voltage, you would very likely have measured 5 volts.
2 years ago I spent a summer in Kenya establishing reforestation projects with local schools and many families already owned a car battery and a cheap solar panel as well as one cell phone per person. This is not a new development.
It is very pleasing to hear that a small family far off the grid can afford an $80 solar panel. It means they have at least some means, and makes the future look a bit brighter.
A full grown cow in the west can sell for $500 to $2000 depending on weight and breed. The main input for a cow is pasture, which is plentiful in rural Kenya. More importantly $80 for a solar panel is a lot cheaper, over time, than the ride into town and back. Since this all makes practical economic sense, it didn't require an aid agency to come their and tell them to do it all.
Given that they survive, many people in third world countries have enough resources to survive and occasionally a few left over.
They are often portrayed as "poor as beyond poor" because many economies are much less money-based than in the West.
Not to say that they're wealthy but if you combine food being less expensive with a lot of subsistence agriculture, a person can have a very low income without being utterly miserable. IE, "Surviving on pennies a day" is a lot easier in Kenya than San Francisco.
They mention de-forestation in the article. I do worry that if our next "green" energy source isn't cheaper than oil/coal then the third world will ignore the cleaner alternative.