There is a lot of discussion about alternative power generation with respect to wide-scale distribution, but I have a slightly different question.
Friends and I, in moments of drunkeness or extreme lucidity often chat about the prospect of purchasing an island and setting up a commune of sorts (actually a constitutional monarchy but the details are relatively unimportant there). Let it be said that there would be approximately six of us.
Food would mainly be from fishing and whatever farming we could manage. It would seem that we could probably sustain enough farming to feed the six of us and get the vitamins we require which fish wouldn’t provide. No scurvy for us!
But power consumption is a concern. Granted, our power consumption would have to be much more moderate than the average American family, but heating/colling wouldn’t be a large concern because of a tropical climate. Thus, entertainment would be the only requirment of power consumption, and food, too (since firewood wouldn’t be plentiful enough on an island for six people).
So we have a few options for power generation. Obviously they would all rely, primarily, on battery storage. But is it plausible that the reduced power consumption of six people could be covered by solar power? Could we set up some sort of tidal generator easily enough? I had also considered using bikes hooked up to alternators for some small moderate personal consumption (like lighting to read books, for example).
In my mind it seems plausible, but I think that is not enough for reality. Any dopers care to comment on it?
The standard setup in this case would be a diesel generator. I’m not sure if you are actually aiming for self-sufficiency, in which case fuel would be a problem. You could theoretically grow some oil-crops; making diesel fuel is a very low-tech process.
You could not easily set up a tidal generator, or even a wave-power generator, which is more likely what you meant. The area of solar panels you would need to match this would be huge.
You could however buy a small wind-turbine that would deliver, say, 15 kW, which would be more than enough for your needs, but would only be available when the wind blew. Another possible choice is a small water-turbine if there’s a swift-flowing stream nearby.
You can produce some hundreds of watts by cycling, but only for a few minutes, and I doubt if it’s worth it. Reading and pedalling don’t really go well together.
People who sail and/or live aboard boats have been dealing with this problem for a long time and there is no easy solution. On an island you do not have the space problems you have on a boat so wind generators are a feasible solution but get some cash ready as these systems are not cheap.
I grew up on a farm in the middle of Nowhere, Illinois. Out next to all the conservative farmers and their traditional values, just beyond the Rebuplican center of the universe and the land where racism isn’t an issue because we have only one race lies Stelle, Illinois.
Stelle is a commune of sorts, set up under mysterious circumstances years ago. Rumors in my high school were plentiful and actual knowledge minimal. All we knew was that when kids from Stelle transferred in to OUR high school from their Stelle-run Montessori school they were YEARS beyond us educationally, if a bit behind socially.
In any case, the answer to your question “can solar power cover the consumption of six people” is YES. The people at Stelle have their own power company, own telephone company, and own internet service provider. I’m not certain how many people live there anymore, but there are around 40 homes on the site. I don’t have any information on power outtages or failures of their systems, but I did find this:
Solar would be entirely feasible. If you know exactly what you will be using the power for you can get a system custom engineered for your needs. Battery back up is a must, and the stationary bike generators are a good idea if you are hit with a couple of weeks of cloudy days. There is a bit of maintenance you would need to keep up with, but it would be a lot less than with a wind-turbine or tidal generating system.
The bike generators connected to batteries that power entertainment devices such as TV’s is a great idea for everyone IMHO, to make sure that couch potatoes get a decent workout every now and then. Pedal for a half hour, and then watch TV for 2. People would either exercise more or watch less TV, both of which is good for body and mind respectively. The bike deals would be sort of expensive, but if someone is springing for an island you might as well have them spring for the bikes as well.
I agree that wind power is the most likely reliable source of power but there is another option that may work.
If you put your island in the tropics, near a deep water canyon, you can use a heat pump to generate power. The surface water is much warmer than the water is the canyon, so you would take heat from the surface through a heat pump and use the cold water in canyon as your condenser. The heat you take from the water could be used both directly for cooking and also used to power a generator to keep the batteries going. Your heat pump would run from the batteries. This solution is not as elegant as windmills but does not require the wind be blowing so would be more reliable. It would also have to be very efficient so that it converts more power than it consumes.
I think this process is actually in use in the mid-east somewhere. I saw it on TV so it must be true.
Please tell me what planet you live in as I would like to move there ASAP.
>> you can use a heat pump to generate power
I don’t think so.
>> The bike generators connected to batteries that power entertainment devices such as TV’s is a great idea for everyone IMHO
Engineer Don, I don’t think so either. Let’s see… A strong person in good shape can generate maybe 200 watts which multiplied by 0.5 H is 100 wh. Losses in the batteries and other inefficiencies would be at least 20 - 25% leaving you with 75 to 80 wh if you are lucky. A TV would probably consume at least 250w so you’d be lucky to get 20 minutes of TV viewing. I do not think I’d pedal hard 30 minutes to watch 20 minutes of Survivor. You might want to do the numbers to see how much you have to pedal to keep the beer cold or to run a microwave and you’ll see that pedaling is not really much of an option escept to power the emergency radio and call for help to get you out of there.
Geothermal is a good option depending on hte geology - take watetr and pump it deep into the ground and it comes back as steam (you can figure the rest out yourself)
Solar, wind power will require a backup method
Slave labor riding bikes will not generate enough power IMHO.
SOmeone also mentioned using diffrences in sea temp.
biomass fuels could be enough if ou hav enough land and very little people.
Sailor - 80 Wh would be an hour work out or so from practical experiments I have seen, at least with the home-made bike generators. Where we differ is in our estimates of TV usage. I don’t think you could use the bike generator for much else, certainly not a refrigerator. While it is true that a typcial good sized TV will use a good 200-250 Watts, a flatscreen pulls considerably less. A modestly sized flatscreen could be kept in the 50 to 100 Watt range, which would allow a group to watch a reasonable amount of TV. Cutting the usage in half with good conservation is generally a lot more cost effective than doubling the electrical supply. Since money is no object, I was assuming that they could get a good quality flatscreen that is highly efficient, and that they would size it to allow them longer run time rather than larger sizing. Give everyone binoculars and it’s just like a big screen!
The same goes for lighting and especially refrigeration. A friend of mine designed a in-ground refrigeration system for the use of the Peace Corps in Africa that was solar powered. Solar cells haven’t changed a whole lot, but insulation has, and the key was reducing the heat load by using a but load of refrigeration and the equivalent of an air-lock.
Solar power in remote areas tends to be cost effective if it allows one to avoid building a lot of transmission lines and a large transformer. It is not as reliable as a couple of nice diesel generators, but for six people who wouldn’t imediately die without power it would be reasonable, especially if money wasn’t particularly important for some reason. There are (at last count that I know about) at least 18 homes in California that are entirely off-grid, and they use solar power for their basic electrical needs. At least one of them uses excess power to create hydrogen gas for cooking. Most of the houses make the best use of passive solar design, and have smaller European style 'fridges. It is expensive compared to just buying your power from the local utility, but they do it to prove it can be done.
Most of this is pie in the sky unless you are Bill Gates.
Unless you plan to live on your little island the rest of your life, you need to concentrate more on capital cost than on recurrent costs.
Everyone with a bright idea should specify the capital cost per kilowatt produced within the range of power that you expect to need. If you need to power a frig 24/7, and a TV, stereo, and some lights at night, I think you will find that the diesel is going to be the the cheapest by far.
Why not do what real island dwellers do. Use kerosene for lighting and refrigeration and dry cells for your boom box.
Hmm… getting some mixed messages here. The idea that I could make diesel fuel seems a little out there (even in a fantasy where I run my own constitutional monarchy on an island) but I’ve never looked into it either so I am not intensely skeptical.
Thanks for the interesting responses so far, even if I am getting some mixed signals.
sailor, we have six people that would, presumably, use the TV together (not for watching TV but for playing video games). This would increase available power for the same usage time. Granted, we can’t play 24/7 but I’d be willing to let that ride.
RE: refrigeration. Not a big deal, though I hadn’t really thought about it. I figured that having a food source like the ocean and some simple farming might stave off the need for refrigeration explicitly. Not gonna want ice cream sandwiches here, the idea is self-sufficiency after inital investment.
What you need is a Gorlov turbine. Just make sure you’ve go a long shore current on your island.
Another test installation is now in operation in a remote area of the Amazon River in Brazil. There, local residents, who are far from the nearest power lines, use the turbines to recharge dozens of car batteries to run their television sets.
Don’t write off diesel generators so quickly. Diesel motors can run off of almost anything flammable and liquid… There was a story going around a while ago about some folks who drove across country fueled by used fry oil from restaurants. Grow some rapeseed on your island, and process it into oil.
Several advantages to this method: First off, it’s simple. If anything happens to your crops (drought, or whatever), you’re screwed anyways, food-wise, and the diesel motor/generator itself is cheap and compact enough that you could easily have a half-dozen backups in case of breakdown. It’s also a lot easier to stockpile energy: Batteries aren’t too efficient, and can slowly discharge over the long term. Oil, however, you can put into any sort of container at all, and it lasts a very long time indeed.
I don’t claim to be up on my thermo dynamics but I’m not sure this idea violates any laws of anything.
Oh ya, and the US military agrees with me. And if they can’t be trusted to tell the truth, who can? Just like the TV.
Follow this link: http://web.usna.navy.mil/~m010312/
[[sailor, we have six people that would, presumably, use the TV together (not for watching TV but for playing video games). This would increase available power for the same usage time. Granted, we can’t play 24/7 but I’d be willing to let that ride.
RE: refrigeration. Not a big deal, though I hadn’t really thought about it.]] erislover
Wait a minute. You’ve thought about video games but not refrigeration? I don’t get this.
And what happens when you get a toothache? Or is this a highjack?
A wind generator feeding some batteries or a hydroelectric generator if you’ve got a running stream on the island would both suffice, and would not be horribly expensive. One of my first projects in college was to properly size a small stream powered generator so that it would provide enough electricity for a cabin. We designed it all out of catalog parts, although since we didn’t spend any money, it was never built of course. We also had to calculate how much of the stream we had to dam up to make an adequate resevoir. If a first year engineering student can do it, so can you.
An internal combustion engine could also be used, I suppose, but I don’t know if I’d recommend it simply because of the fuel requirements. I suppose with some plants and some yeast you could make alcohol. Water or air makes a much simpler power source, IMHO.
You better re-think your food situation. There was a television show on the other night about the Aluetian Islands, and one of the facts they mentioned was that fish alone is not enough. The Alutes managed to survive by supplimenting their diet with sea lions or seals or whatever it is that lives up their way. This might not be a problem if your Island has a lot of fruits and veggies on it.
As for the toothache, of course the answer to this is that you chip out the offending tooth with an ice skate. And don’t forget to bring along a volleyball for company, preferably one made by Wilson.
low-tech degumming of vegetable oil to make diesel:
get a big barrel, mix the oil with methanol and sodium hydroxide, wait, and separate the fuel (on top) from the glycerine (on the bottom).
Choose your oil crop according to your climate.
A couple of people have suggested geothermal power. A plant like this would take years in planning and construction, would cost tens of millions of dollars, and would require manned operation. It’s one thing to get heat out of the ground. It’s quite another to get steam and run a turbine.
First, I would tend towards the diesel idea. Diesel is damn cheap. However, the suggestions that you grow rapeseed or process some other vegetable matter for fuel is not practical for six people. Obtaining that oil from the plant is carried out using large quantities of nasty chemicals in complex extractions. Additionally, you’d have to grow immense quantities of vegetable matter just to get a very small amount of fuel- you’re not likely to have any time to enjoy those video games, because you’re busy growing the fuel.
If you really want to get sophisticated, operate solar panels to crack water into oxygen and hydrogen, which you then store in tanks and pipe to generators.
However, I would suggest something else entirely: a low-tech steam turbine. Feed the boiler with driftwood, garbage, biomass, spare friends, whatever you’d like, and generate you up some pow’r. Certain fish, when dried, can be burned, for light or steam power.
