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Interesting Renewable Energy System

 
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Potemkin Villager



Joined: 14 Mar 2006
Posts: 783
Location: Narnia

PostPosted: Mon May 08, 2017 12:37 pm    Post subject: Interesting Renewable Energy System Reply with quote

The good folk at Living Energy Farm in Virginia are putting into practice many of the ideas discussed on this topic including:-

DC no inverter system
Non battery energy storage
Modest capacity NiFe cell energy storage for LED lighting system

They make a good point that renewable energy systems do not have great sustainability prospects at the industrial and personal levels.

"Storing electricity is expensive. The national electrical grid is powered mostly by massive coal plants that run all day and night. Constantly generating electrical power means they dont have to store it. But that comes at enormous environmental costs. Off-grid houses, on the other hand, usually rely on PV and use large sets of lead-acid batteries which are toxic, explosive, and short-lived. That is a poor solution.

At LEF, we do not have lead-acid batteries to support our houses or agricultural buildings. At LEF, we do not have any AC outlets or inverters because we dont need them and because such outlets are too easily treated as free energy, and thus encourage excessive use of electronic gadgetry. A lot of off-grid designs fail when the users plug in too many gadgets."


http://www.geo.coop/story/what-energy-revolution-looks
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Pepperman



Joined: 10 Oct 2010
Posts: 759

PostPosted: Mon May 08, 2017 1:02 pm    Post subject: Reply with quote

Being DC only doesn't greatly restrict you on the gadget front given that most things either are DC powered already (e.g. most consumer electronics) or DC versions are available (e.g. fridges).

Their approach is a bit too purist for my liking but all power to them!
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emordnilap



Joined: 05 Sep 2007
Posts: 13974
Location: Houǝsʇlʎ' ᴉʇ,s ɹǝɐllʎ uoʇ ʍoɹʇɥ ʇɥǝ ǝɟɟoɹʇ' pou,ʇ ǝʌǝu qoʇɥǝɹ˙

PostPosted: Tue May 09, 2017 12:41 pm    Post subject: Re: Interesting Renewable Energy System Reply with quote

Potemkin Villager wrote:
http://www.geo.coop/story/what-energy-revolution-looks


The link doesn't work for me. Shame, I'd like to read the article. Laughing
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Potemkin Villager



Joined: 14 Mar 2006
Posts: 783
Location: Narnia

PostPosted: Tue May 09, 2017 2:25 pm    Post subject: Re: Interesting Renewable Energy System Reply with quote

emordnilap wrote:
Potemkin Villager wrote:
http://www.geo.coop/story/what-energy-revolution-looks


The link doesn't work for me. Shame, I'd like to read the article. Laughing


Yes it refuses to work for me too now!

Also at

http://www.resilience.org/stories/2017-04-18/what-an-energy-revolution-looks-like/
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emordnilap



Joined: 05 Sep 2007
Posts: 13974
Location: Houǝsʇlʎ' ᴉʇ,s ɹǝɐllʎ uoʇ ʍoɹʇɥ ʇɥǝ ǝɟɟoɹʇ' pou,ʇ ǝʌǝu qoʇɥǝɹ˙

PostPosted: Tue May 09, 2017 2:53 pm    Post subject: Reply with quote

Good article. Some inspiring and challenging insights.
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adam2
Site Admin


Joined: 02 Jul 2007
Posts: 6222
Location: North Somerset

PostPosted: Wed May 10, 2017 1:33 pm    Post subject: Reply with quote

An interesting report, thanks.

Use of a relatively high DC voltage has a lot to be said for it in view of the reduced losses.
Systems without a battery, or with only a very small battery for lighting, have the merits of simplicity and lower cost but suffer from a number of other drawbacks.
For PV modules to supply the greatest output they need to be operated at the correct voltage, with a higher or lower voltage the output declines significantly.
Charging a 12 volt battery from a PV module of 35 or 36 cells via a simple charge controller approximates to optimum conditions, use of a maximum power point tracker gives almost perfect matching between supply and load.

Most "no battery" systems waste a large proportion of the PV output. The widely varying system voltage is likely to kill all but the most loads such as simple motors.

Despite the costs of a battery it does give far more flexibility in use and maintains a roughly constant voltage.

For a large system I would favour a 120 volt nominal battery, many loads will work directly from this.
Lead acid batteries have their problems but are cheap, sold everywhere, relatively low tech, and no more explosive than the nickle iron batteries preferred by the author of the above article.

Lead is indeed toxic, but is valuable enough that it is recycled.

Take great care with DC voltages at this level, they are much more dangerous than AC mains in terms of fire risk, and some consider the electric shock risks to be greater also.
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Little John



Joined: 08 Mar 2008
Posts: 5667
Location: UK

PostPosted: Wed May 10, 2017 1:40 pm    Post subject: Re: Interesting Renewable Energy System Reply with quote

Potemkin Villager wrote:
emordnilap wrote:
Potemkin Villager wrote:
http://www.geo.coop/story/what-energy-revolution-looks


The link doesn't work for me. Shame, I'd like to read the article. Laughing


Yes it refuses to work for me too now!

Also at

http://www.resilience.org/stories/2017-04-18/what-an-energy-revolution-looks-like/
I like their attitude
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emordnilap



Joined: 05 Sep 2007
Posts: 13974
Location: Houǝsʇlʎ' ᴉʇ,s ɹǝɐllʎ uoʇ ʍoɹʇɥ ʇɥǝ ǝɟɟoɹʇ' pou,ʇ ǝʌǝu qoʇɥǝɹ˙

PostPosted: Wed May 10, 2017 2:11 pm    Post subject: Re: Interesting Renewable Energy System Reply with quote

Little John wrote:
I like their attitude


Yeah, me too. Sensible. They're probably blessed with a better climate than most of us here but what they're doing should really be commonplace. It will be one day.

It also can be fun, if you get on with your co-habitants. Shocked
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