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The best method for solar energy generation

 
                              
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http://www.youtube.com/watch?v=1dTt2s6YwJ8
This is the most efficient, most accessible form of renewable energy generation.
Anyone could build a parabolic mirror out of 2x4s, plywood, and thick mylar. Then, once you determine your focal point, you mount a Stirling engine into the focal point. The Stirling engine would have to be produced by an experienced metal machinist(I hear they are desperate for work these days!)
Also, since these engines generate power by having negative thermal entropy, you can actually increase the output of the engine by cooling the bottom half of the engine with water, then running that warm/hot water to your insulated hot water tank.

The main issue with this method is that on a heavily overcast day, the focal point of the mirror is mostly lost, and therefore nearly all energy generation is lost. Standard PV cells can still generate 30%(?) of their capacity during cloudy conditions.
 
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PeakEverything wrote:
This is the most efficient, most accessible form of renewable energy generation.



I always love titles that have 'free energy' in them... somethings will never change for 100's of years.  It ain't free!  a 30ft dish?  I'd like to see a hobbyist build that.  much less the stirling engine...

All kidding aside.  Solar lo-temp thermal - as in hot water heating is upwards of 60-80% efficient and makes lotsa hot water even on a very cloudy day.  Even the big boys hi-temp thermal farms only have a 34% efficiency - the HIGHEST of any renewable energy source.
 
                              
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winsol3 wrote:All kidding aside.  Solar lo-temp thermal - as in hot water heating is upwards of 60-80% efficient and makes lotsa hot water even on a very cloudy day.


Yes, but how would you turn that thermal energy into electricity?

Maybe I should have clarified that this is for electricity as an alternative to PV panels.

It ain't free!  a 30ft dish?  I'd like to see a hobbyist build that.  much less the stirling engine... tongue



The dish could be made out of wood. And 100 sq feet of reflective mylar is ~$50. The stirling engine would have to be made by an experienced machinist with access to a tool & die shop. Yes, you couldn't build the engine yourself, but someone else could for $500-1,500.
 
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there's a reason you don't see these in every backyard...

it's not as easy to build as it sounds...

I challenge any backyard setup to match the efficiency and cost of PV panels.
 
Fred Winsol
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I think the term 'appropriate' energy is errr... appropriate here.  I'd rather focus on what I want... like hot water, or lights and get it as directly as I can.  on a cold day I'd use biomass or solar for hot water.  in the dark I'd use LED's powered by a small PV panel charging a small battery all day....

that's just me.  I'll leave all the complicated stuff to the 'big boys' , i like it simple and direct.

Converting thermal to electricity via a stirling engine is great if you're advanced hobbyist and that's your passion.

Beating 15-18% PV efficiency ain't that hard.  try biomass gasifiers.
 
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I totally agree that a wood gas generator would be superior to this contraption. By capturing heat from the exhaust and the radiator you could also have hot water. Electricity and hot water from one system. If you must concentrate sunlight get an old satellite dish and coat it with mylar or some other reflective material.     
 
                        
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well -  making a wood gas generator isn't exactly  a job for a klutz either   You can buy sterling motors   but what capacity they would have is the question..  I am a fan of the theory of Sterling motors but was thinking about hooking one up to a wood heater at least for the winter time. I like things simpler and easier to get along with.

What I want to know is how to make the sterling motor run silently or almost silently. Most of the ones I have seen on You Tube clank like the ghost from Christmas past with the jitters and I can't imagine being too happy about living with that noise all the time.
 
Abe Connally
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Beating 15-18% PV efficiency ain't that hard.  try biomass gasifiers.


I don't think you are going to beat that efficiency at the same cost.  You have to grow a decent biomass without much added cost or water, harvest it, process it, gasify it, and then you have the electricity.

I've done the math several times for my property, but I can't get it to be cheaper or easier than PV.  If you had crops that self harvested, maybe.

On the plus side, biomass stores very easily, much better than batteries.  I've got hay that is over a year old, and it is still fine.

But generating enough biomass year after year would be difficult.

For my area, we get about .6 kWh/ft2/day average. Think about it this way, a 10 ft square (100ft2) piece of land could collect about 60kWh per day.  It could generate about 9 kWh per day with PV (60 X .15).  

To get that electricity with biomass, you're looking at 30% efficient at best (gasifier to ICE). So, you'd need at least 30 kW of heat from biomass, which would require at least 20 lbs of biomass (5100 btu/lb of biomass) a day from that 100 ft2. That's 7,300 lbs (3.3 tons) of biomass from 100ft2 every year. We're not even including energy required to harvest and process that biomass.

I know my land couldn't support those kind of production rates, we're lucky to get 5 tons per acre of irrigated pasture, but maybe yours can.
 
Fred Winsol
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I guess we're still 10-20 years from getting to what the europeans are doing on a regular basis.

there is hope ... check out    http://gekgasifier.com/

(burning man attitude w. PhDs doing DIY gasifiers ... the locations of where they have shipped their units to, says a lot. )
 
Abe Connally
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Yeah, the GEK is awesome.  Look in there info about gasoline to biomass equivalents.

1 gallon of gasoline equals 20 lbs of biomass equals 10kWk of electricity.
 
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I love the concept and efficiency of sterlings, and I hope to some day build a GEK gasifier, but I keep coming back to KISS (Keep It Simple Stupid).  You have to consider reliability, maintenance, complexity and the number of failure points, and cost effectiveness.  I've built all kinds of things in my lab (solar, wind, biogas, biodiesel, etc.), but what powers my house -- and a whole bunch of client's homes -- are regular PV panels.

Unless you live in a Northern rainforest or in a very reliable higher wind area, PV is the simplest, most reliable, and cheapest power source for your money.  AND you can get it (with charge controller) for about $2 to $3 per Watt (less than HALF the cost of a few years ago).  This doesn't include an inverter or batteries, but all of the other systems would require that too (unless your systems are entirely DC and only used when they're running).  You don't have to set up an elaborate and precise solar tracking system, constantly feed it oil/wood/biomass, and there is ZERO maintenance (unless you have a lot of large birds perching above the panels 

Save your time, money, and muscle for food production and simpler living.  I'd be more than happy to design and sell system to 'Permies' members for 10% over my wholesale cost, and include diagrams and simple DIY instructions.  I am independent and have very little overhead.  Or I can even send you to some decently priced retailers.  (not spamming -- I am on this forum for personal reasons -- and hope to stick around and learn 

In the last 17 years I've done cabins, boats, islands, suburban homes, businesses, and municipal buildings -- and I get great deals on equipment.
If you have knowledge of basic electric and can connect a battery to a fuse and then a light and/or pump, you can do this.  If not, I don't think I can help you from afar.

If you need heat and a backup power system, consider a biomass gasifier/ biogas/biodiesel generator.  Only if you have appropriate engineering knowledge should you even consider steam power.  For power you have to count on, hook up some PV panels that will last you more than 30 years, and leave the more fringe technologies to hobby/tinkering as I do.

Lew
 
Fred Winsol
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Greennovator wrote:
I love the concept and efficiency of sterlings, and I hope to some day build a GEK gasifier, but I keep coming back to KISS (Keep It Simple Stupid).  You have to consider reliability, maintenance, complexity and the number of failure points, and cost effectiveness.  I've built all kinds of things in my lab (solar, wind, biogas, biodiesel, etc.), but what powers my house -- and a whole bunch of client's homes -- are regular PV panels.
Lew


I agree + disagree:  Borrowing from Europe's example, and given that we burn gazillion tons of biomass slash piles into open air, we need to get a small-medium scale biomass industry going and start tying our houses together - as in district/community energy sharing/distribution.

I guess your point, Lew, is that renewable energy in the USA is for 'dummies' and must be plug and play. I would put in a solar hot water system FIRST - way before PV... unless ya'll don't need a hot shower 

From where I sit the issue is education + consumer smarts.  Everyone need to educate themselves on some of the technical aspects of this - like a basic physics/electrical/mechanical trade school class

When it comes to the holy grail (LCA-life cycle assessment) of solar PV vs. biomass gasification (ala Euro Style) = it is lopsided in the favor of biomass for multi-unit housing.  Solar PV can't get close to 10-20KW for less than $10k.  Solar PV is good for single residential - but solar hot water would still be my first recommendation.
 
Lew Woodward
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winsol3 wrote:
I agree + disagree:  Borrowing from Europe's example, and given that we burn gazillion tons of biomass slash piles into open air, we need to get a small-medium scale biomass industry going and start tying our houses together - as in district/community energy sharing/distribution.

I guess your point, Lew, is that renewable energy in the USA is for 'dummies' and must be plug and play. I would put in a solar hot water system FIRST - way before PV... unless ya'll don't need a hot shower 

From where I sit the issue is education + consumer smarts.  Everyone need to educate themselves on some of the technical aspects of this - like a basic physics/electrical/mechanical trade school class. 

When it comes to the holy grail (LCA-life cycle assessment) of solar PV vs. biomass gasification (ala Euro Style) = it is lopsided in the favor of biomass for multi-unit housing.   Solar PV can't get close to 10-20KW for less than $10k.  Solar PV is good for single residential - but solar hot water would still be my first recommendation.



winsol3 ... I wasn't speaking about generalities or ideals, just to the practical (time and economic) issues that were being discussed.

If I'm not mistaken, this is a permaculture site with a lean towards independent living.  We are so far from individual self-sufficiency, so I thought I'd add some helpful advice that might help some get closer, given our realities.

The GEK is great .  For community scale I'd recommend http://www.eprida.com/home/index.php4 .  There's some serious promise in providing for larger solutions with their technology.  Why is it that the Chinese are investing in this and we are not [much]?

LCA of biomass gasification vs solar PV ... PULEASE!?!  When you factor in initial capital outlays, maintenance, fuel harvesting and transportation, etc., you need a fairly large project to justify the numbers.  And I am well aware that there is no magical crystal silicon tree .

Yes, this is about bigger picture stuff, but boiled down to smaller and doable solutions (at an individual level).  As an example, my brother-in-law is a master blacksmith/metal-worker and 'green' architect that chooses to use PV because it works best (search Lars Stanley, Austin TX).  He has the skills and knowledge to build GEKs or even steam-powered systems, but chooses PV for power.  If someone has the materials, knowledge, skill, time, and energy for it (pun intended), then go for it.  If you want to take the world on your shoulders, then I will build you a soap-box.  More power to you.  I was addressing practical issues.  Pardon me for assuming that most on this site would rather be in the garden than oiling up or scraping the creosote off of a clanking machine.

I'd be more than happy to discuss community sized solutions to energy needs at another time.  In the mean time, feel free to spend yours on consumer [citizen] education and skills.  Please keep me posted on how that goes.  I will remain a pragmatist.

BTW, I do SHW systems too.  Anything from evacuated-tube to 'bread-box' types (passive - for non freeze climates).  They are wonderful systems.  Most are not cheap.  I always recommend efficiency first.  "It is almost always easier/cheaper to save energy than it is to make it" Amory Lovins?  There are many ways to reduce resource consumption, but I'll leave that for another conversation.

Lew
 
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Greennovator wrote:
you can get it (with charge controller) for about $2 to $3 per Watt



2 to $3 per Watt?!?!?!?

I can even send you to some decently priced retailers.



That would be much appreciated. The best prices that I'm seeing, here in Ontario, Canada, are $6 to $7 per Watt (plus the sales taxes/etc).
 
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These guys monitor and publish pv prices, from real world suppliers that can deliver product.  Lots and lots of suppliers under two bucks a watt, not including balance of system components.:

http://www.ecobusinesslinks.com/solar_panels.htm

There are some canadian companies listed too.


Having assembled a machine shop and foundry, and having made some small sterling and steam engines, and having several of the best "small sterling" books out there, I would bet you my last pair of socks you cannot get anybody to make you a 4 hp sterling that has any decent durability, for a thousand bucks.  Even at two grand, I think you would be lucky and they would be doing you a favor.

That doesn't count cheapo/crapo conversion jobs from old air conditioner compressors and the like.  Poor efficiencies and durability questions.  It has to be purpose built to attain decent to good efficiencies.


Finest regards,

troy
 
Fred Winsol
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FredWalter wrote:
2 to $3 per Watt?!?!?!?

That would be much appreciated. The best prices that I'm seeing, here in Ontario, Canada, are $6 to $7 per Watt (plus the sales taxes/etc).



How about $1.80/watt?  for PV... check out  http://www.solar-electric.com/   I've had good luck with them over the last 10+years, very helpful and reputable.  They're located in Arizona, so I don't know about shipping costs to canada.

good luck
 
Lew Woodward
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winsol3 wrote:
How about $1.80/watt?  for PV... check out  http://www.solar-electric.com/   I've had good luck with them over the last 10+years, very helpful and reputable.  They're located in Arizona, so I don't know about shipping costs to canada.



Sure, I can find lots of panels for less than $1.50/Watt.  But to qualify for Ontario's FIT of 80.2 cents per kWh, the panels  have to be made in Ontario (and for sale there).  They charge a little more there (manufacturers taking advantage of the HUGE incentive) but one of my suppliers has a warehouse in Ontario, so that's what I was basing the $2 to $3 on.  There are too many different panels and charge controllers and possible configurations to list them all, so if you give me an idea of what you're looking for, I can put something together for you.

Lew
 
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Hello Peak Everything,

I being fellow travellor and well aquainted with the Stirling engine, can commisserate with yourself.  Some time ago we set to improove upon hot/cold cycling gas drive force.

We did this by using a turbine to halve act as a turbine providing energy to a shaft, and half acting as a centrifugal pump.

The entire device can be made by cut and join of pipe. One pipe of twice the diameter of the other.  The smaller pipe being cut legth ways to provide turbine vane which is affixed to peice of same size pipe thus creating the turbine runner and shaft. Which fits neatly into a peice of pipe twice the diameter. Please note that turbines require  an odd number of vanes to prevent the turbine stalling. Operation if using CO2 gas  requires ambient or other means of heat temperature above minus 40* Celsius, and for below 0*celius opperation the coolant in cooling tank needs be other than water.

The turbine can use any gas including air. Though we have choosen CO2 as it also is the Refrigerant R744. This provides excellant cooling as like in a fridge when its released from high pressure to low pressure it cools beyound attmospheric temperature.

The pricipal of working is very simple, as a turbine has duel function, (one) if used as a turbine a force is applied to the turbine vane causing it rotate the shaft and that shaft may be coupled to another mechanism, (two) if a force is applied externaly to the turbine shaft its called a centrifugal pump.

The manner of working is cool gas is allowed into the turbine vane cavity, then as the turbine runner (that disk with vanes attached) brings the vane holding the cool gas into contact with heat the gas expands providing a drive force causing the turbine runner to spin. What happens after the gas is heated and the turbine runner has travelled a distance is it passes through a water container. Water being water and gas being gas an interchange takes place, in that the gas rushes out of the turbine vane cavity and is replaced with water, this momemtarily turning the turbine from a turbine into a centrifugal pump which flings the water out close to the top of the turbine runner arc. The water now being flung out of the turbine vane through a pipe and into the water container that itself is attached to the lower arc of the turbine runner.

The hot gas which has entered the water container at the bottom of the turbine arc, cools as it rises up through the water (this being enhanced by the depressuration that similtianiosly having taken place) and then replaces the water being flung off again leaving the turbine vane cavity full of cool gas, and the process continues to repeat.

Cheers Peter

http://i1225.photobucket.com/albums/ee397/DaSEnergy/RROTARYDAS.jpg
 
Abe Connally
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Das - do you have photos of a working prototype?  Any specs on size and power generation?
 
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awesome... thank you
 
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that is a boatload of steps to take to make electricity..too many moving parts..wind turbine...PVa...done.

and as Troy said...finding a machinist who is capable of making a Stirling cycle engine of that size is a neat trick, let alone one capable of a MTBR needed in a reliable generation plant.

Twenty years in the Navy has made me a huge fan of KISS.
 
pollinator
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In my opinion, too many of us in the so-called "developed" countries automatically think of electricity when considering "alternative energy". This is so because we've come to use electricity for damn near everything (thanks to cheap grid power). If the desire is to cut the cord (i.e. go off grid), then electricity has to be greatly minimized compared to what the average U.S. home consumes (unless you're lucky to have exceptional energy resources in your location). In my opinion, if this is done properly, then most homes can get by with a modest PV array, then use direct solar thermal for most of their heating requirements. If you have good wind resources, then USE IT. A small hydro resource is even better. If you're surrounded by biomass, then this can also be a great alternative for both heat and electrical power generation. Now, if you want a/c, then you're probably gonna have to be a lot more creative.

Solar thermal power generation might become cost effective for small scale power generation on day, but only after suitable heat engines are mass produced. Interestingly, if this ever happens I expect it won't be a Stirling engine but a modern piston steam engine that wins that race.
 
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OK as a hobby machinist with a machine shop this trips my trigger. Even if it just for the steampunk gadget factor. I found an online video of a guy who made a Stirling engine large enough to run a go cart with it. I would think if you could get enough torque to run a go cart carrying a person you should be able to get decent torque to run a water pump or generator with a solar stirling. The problem I see is how large would you have to make the stirling to REALLY get a decent size generator going.

The tough part here is having the tools to make the engine since you can't just go down to wal-mart and buy one. I think the average handy man could learn to make the parts easy enough but having access to a decently accurate lathe the appropriate size will be the hard part. I would think the parabolic mirror would be as simple as finding a used satellite dish and lining it with mylar.

Actually I would be more interested in this in place of a ram pump where you don't have enough head to make a ram work. Use this to run a pump to fill your irrigation tanks. Again, not sure at what scale you would need things to actually be practically functional. My daughter is starting as a freshman at MIT this fall. She might get a kick out of helping dad out with some math and engineering on a project.
 
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SES scrapped a whole bunch of Stirling engines from the California power project. Evidently their bean counters decided it was not cost effective to maintain. Instead they replaced the whole installation with PV arrays.

This does point out one of the problems with trying to transfer technology and scaling it up or down to suit.
When you are doing maintenance on one unit its no big deal but when you have 500 or 1000 to do its a major effort. Multiple crews, trucks and workshops not to mention an inventory of spare parts.
I located one company in Switzerland that made a wood stove with a stirling engine mounted on top. It only produced 1 kW but this is adequate for a single family domicile. When I queries them I was told they would not sell into North America; no reason give so draw your own conclusion.
 
Lew Woodward
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How about this?...

http://www.ergenics.com/

... "Ergenics is developing a metal hydride heat engine that converts solar hot water into electricity for an estimated cost of less than 5¢ per kilowatt hour, much less than what we are paying for electricity today." ...

I memory serves, they got bought up a few years ago. Not sure what's going on with them lately but I always found their potential interesting.
 
arild jensen
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5 cents per kilowatt hour is more than the cost of hydro-electric power at 3.5 cents per kilowatt hour published by our local power utility.
Unfortunately neither source represents what actual end users will pay. What is not indicated is the capital cost of the equipment involved in harvesting the solar power.
 
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The BEST solar energy system? Well if by “best” you mean “does does the most good”, then the best specific example of a solar energy system is one that includes the following components: a school, a bio-gas generating sewage digester, an algae pond and a vegetable garden. I’ll explain.

I recently heard a lovely story about a school in a poor rural part of South Africa. It used to be a typically dismal third world community with hungry malnourished and sickly kids, no sanitation, polluted local water and a terrible shortage of cooking fuel.

Then a foreign charity funded a sewage processing system which captures the bio-gas (mostly methane) from the anaerobic decomposition of sewage in a digester vat similar to a septic tank. The water discharged from the vat, which is very rich in nutrients and also organic contaminants, is then fed into a series of shallow algae ponds. With all the nutrients and lots of sunlight the algae grows prolifically, capturing the energy of sunlight to create algae biomass. The algae is collected and fed back into the digester vat to create yet more bio-gas. Meanwhile the water that flow from the algae ponds is no longer polluted but still contains quite a lot of nutrients. This water is then used to irrigate and fertilize the school’s vegetable garden. Here more sunlight energy is captured to create nourishing healthy vegetables. These vegetables are cooked in the school kitchen, using stoves running on the bio-gas. And now they have healthy, happy kids with decent sewage, clean rivers and plenty to eat.
 
pollinator
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Robert Isted wrote:The BEST solar energy system? Well if by “best” you mean “does does the most good”, then the best specific example of a solar energy system is one that includes the following components: a school, a bio-gas generating sewage digester, an algae pond and a vegetable garden. I’ll explain.

I recently heard a lovely story about a school in a poor rural part of South Africa. It used to be a typically dismal third world community with hungry malnourished and sickly kids, no sanitation, polluted local water and a terrible shortage of cooking fuel.

Then a foreign charity funded a sewage processing system which captures the bio-gas (mostly methane) from the anaerobic decomposition of sewage in a digester vat similar to a septic tank. The water discharged from the vat, which is very rich in nutrients and also organic contaminants, is then fed into a series of shallow algae ponds. With all the nutrients and lots of sunlight the algae grows prolifically, capturing the energy of sunlight to create algae biomass. The algae is collected and fed back into the digester vat to create yet more bio-gas. Meanwhile the water that flow from the algae ponds is no longer polluted but still contains quite a lot of nutrients. This water is then used to irrigate and fertilize the school’s vegetable garden. Here more sunlight energy is captured to create nourishing healthy vegetables. These vegetables are cooked in the school kitchen, using stoves running on the bio-gas. And now they have healthy, happy kids with decent sewage, clean rivers and plenty to eat.



I LOVE these stories, but the test is if it will still be running in 1/5/10 years. Just like the "stupid consumer" in the US, you have to prove to anyone that it is worth their time. KISS

You can add an aquaponics cycle to that as well (cyclone separator to pull the major fish poo and put that in the methane digester, too) and add a protein source to a real food desert. But, that is even less KISS.
 
Marcos Buenijo
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Robert Isted wrote:The BEST solar energy system? Well if by “best” you mean “does does the most good”,....



Robert, please provide a link to where this project is described (if available)... that project sounds great to me, particularly the algae culture used to boost methane production.
 
Robert Isted
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Marcos,

I heard the story first hand from a friend who is one of the engineers behind the company that makes the biogas digester.
See www.biogaspro.com.

There’s a brief description of the project here:
http://biogaspro.com/download/case-studies-read-about-our-installations/item/school-three-crowns.html?category_id=2
 
Robert Isted
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Here’s another link to a description of the scheme.

http://ipsnews.net/news.asp?idnews=106927

In this article they state that the system does have an aquaponics cycle, with fish included into the scheme to provide improved filtration and more input for the digester.
 
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BEST SOLAR ENERGY

Wind energy is too expensive and it needs hundreds of petroleum originated lube oil to operate eah day, and the gearbox used for these things is immense and expensive. Also windmills screw up the environment both visually and practically.
Solar energy is free but there is no technology available to the public that gives more than 10-15% efficiency. It pays off but only in long term so unless you want to invest a decent capital in it forget about it.
Biomass is energy consuming because the process to refine the raw material into fuel is too expensive and not applicable at the moment for the broad mass.
Hydroelectric is good only where there are water falls or dams, but they also screw up the environment. E.g. if you cut off a river the whole nearby ecosystem collapses.

Power Plant Development | Technical Consulting Services
 
Abe Connally
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you can make your own wind turbine here: http://www.velacreations.com/energy/electrical-sources/wind-power/itemlist/category/21-chispito-wind-generator.html
wind for homes don't have to be expensive. They do not screw up the environment.

solar can pay for itself quite fast. To get the grid to my current property, it was going to cost $30K+. I have a solar system that cost me about $3,500, including the batteries. So, it paid for itself right off the bat. I bought solar 10 years ago for $5/watt. I purchase some panels this year for $1.50/watt. That's a 70% reduction in a decade. How much has your grid power dropped in that time?

You don't need to cut off a whole river to do hydro, just take a trench off the side. Hydro is used all over the world on an appropriate scale without harming the environment or water flows.

I love how people try and label the problems of MASS PRODUCTION on all all levels of production. It's like saying you shouldn't have a garden cause GM crops destroy the world.
 
And that's when I realized I wasn't wearing any pants. Maybe this tiny ad has pants:
Willow Feeder movie
https://permies.com/t/273181/Willow-Feeder-movie
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