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Economical things to do with excess off-grid solar electricity  RSS feed

 
gardener
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Location: Manitoba, Canada
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I am starting this thread after being inspired by the following quoted piece of William's excellent post in this thread: https://permies.com/t/85816

William Bronson wrote:What can we make to sell from any excess electric?
Compressed air? Nitrogen or oxygen extracted from.the air? Ice? Dry ice? Purified water? Milled lumber? Split firewood? Hydroponic weed? Hydroponic hops?
Hydroponic hops genetically engineered (!) to produce thc?
Server space?

Ok, I've spiraled out of control.
But many commercial better than organic growers have gotten their start by growing good food for themselves.

Maybe the problem of needing electric to get to work can be solved by providing electric for yourself and using the excess to make money. 



The scenario is this. Let's say that you have a bunch of extra electricity that you generated. Like maybe 10 kWh... for reasons. Let's ignore the obvious concern of why someone has so much excess in the first place. Let's step into the land of imagination where you have that big of a system and you can't sell it off and connecting to the grid is not possible. Your batteries are fully charged. Now what do you use the energy for? How can you use that excess in a way that generates a good return? Estimates of costs and benefits of each idea would be great!
 
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You could mine bitcoin. Not sure exactly what the system would look like but maybe you have your miner set to only run when there is power coming from your panels and the batteries are full. You could certainly build a modular mining computer so that it only drew as much energy as your panels were producing (all X CPUs would be rocking in late June when the batteries were full while only 1/2X CPUs would run in the same situation in December). I would imagine there are other big data type of computer applications that you could engage in but honestly, after pulling out 'CPU' I think I've exhausted my store of computer knowledge.
The only other thing that I can think of is you could use excess solar to pump water back to the top of a water battery. All summer you could be moving some large mass of water uphill during times of excess solar power and then in the winter you could run that water back down hill through a micro hydro set up to supplement your waning solar production. This is probably most applicable to folks living far from the equator, and especially folks who have a cloudy/rainy winter, where your solar might be half as effective or less in the depth of winter.
 
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Location: Boston, Massachusetts
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Here's a few ideas (assuming ones that can work without attention are best):

Water energy storage
Assuming your site has elevation changes, build (at least) two ponds (one high, one low) and a micro-hydro generator in between. Use excess power during the day to pump water uphill, water power is then available anytime to cover any shortage, or charge your EV at night.
You might already be planning to build ponds anyways...

Cold storage
Run an ice machine, have ice for food storage, cooling, slushy adult beverages...
If you had a spring, you could even make ice for sale, set up a roadside stand and make some cash.
Cool your house, the sunniest time coincidentally being the hottest...hmm. plus: A central A/C system with an "Ice Bear" cold storage system ice bear enrgy storage is designed to take advantage of off-peak energy prices... but time-shifting the generation of cold just the same...

Heat Storage
Keep a (larger/multiple?) electric hot water heater HOT for DHW
Supplement a SHW system, boosting a storage tank just a little hotter... (could work well in a stratified tank or cascade system to boost the hottest water temps)
hot water loop in your RMH bench, to make it warm without lighting it. (or run other heating like radiant floor heat, etc.)
Snow/ice melt system (not actually storage, just heat). Wake up/come home to "shoveled" paths and driveway. Both electric and HW systems are possible.

Cooking
Start planning a LOT of meals for your slow cooker. Start it in the morning when you leave, dinner is ready when you return.
Get one of those "bread machines" (I have no experience here, but seem to think there's some time (and possibly timer delay) involved)
(apologies if you are into gluten-free fast food ;-P)
 
pollinator
Posts: 574
Location: Southern Arizona. Zone 8b
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Every time I look into bitcoin these days, I come to the conclusion that even if your energy is free, you won't make a profit if you have to purchase the miners.

If you're willing to spend a 20-30 thousand or more on miners and have LOTS of free power, then maybe.

Cracking water into hydrogen is a possibility, but again the equipment is expensive and the profits are small.  If you don't care about efficiency (the energy is going to get wasted anyway) then you could build your own electrolyzer, but then the problem is compression the H2 for storage.  That part is dangerous and dozens, possibly hundreds, of people have killed themselves and others trying to do it.

If you make pottery, then running an electric kiln when you have surplus power might be a possibility.  Of if you do woodworking and metal working, then running the high draw equipment only when you have surplus power might work.
 
pollinator
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Does a good return mean turning it into cash? Or saving it for future energy? Big difference.

The cash side would be endless:

Aeration for compost teas.

Rock tumbler(slow and needs no human intervention)

Turn seawater to salt

Any food items (cookies, brownies, breads)

Run a kiln for pottery items for personal use or others.(Kiln time is hard to get in my area, i would participate in a drop off,pick up to get it done if it was offered)

Hydroponic lettuce under lights.

Make candles/lip balms from beeswax.

Running power tools for woodworking projects.

Those are homestead oriented, but it's literally endless. Anything a person can do to produce something is now done with free energy.

An electric sawmill would be AWESOME
 
pollinator
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Kenneth I think has the best solution and is what they do on large scales. There was a nuclear power plant that found they had excess power at night when people on the grid were asleep, so they used the power to pump water uphill to a huge dam and reservoir. During peak hours they let the water into pen stocks and powered turbines for additional power on the grid when it was not needed.

The system would be super simple, and super cheap to build making your return on investment good.
 
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Location: Western OK, avg rain 23" hazards: drought, tornado, wildfire
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In his original post, William Bronson mentioned purifying water. How do I find out how much electricity a reverse osmosis water filter uses? Also, what buzzwords do I use to search for this idea of small-scale water containment for making electricity when solar panels are not working?
Thanks!!
denise
 
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Location: Central NY, Eastern Edge of Oneida Co. ,Town of Trenton
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The amount of electricity used will depend on several things such as: how big of a pump you are using, what pressure your RO system is designed to operate at as well as the pressure your water system is already operating at, the size  of the membranes(more surface area= Less effort to pump) and, how old the membranes are (the old ones get clogged and make the pump work harder).

The water storage for electricity generation is called "Pumped-Storage Hydroelectric" and unfortunately it is anything but small... at least if you want to be able to run anything large/for a long time. now if you have a really large amount of head as well as an efficient turbine you might be able to provide enough for yourself from a small pond.

here is a wiki link to help https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity

*Fixed broken link*
 
Peter VanDerWal
pollinator
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denise ra wrote:lso, what buzzwords do I use to search for this idea of small-scale water containment for making electricity when solar panels are not working?
Thanks!!
denise



Define "small scale"?  How many acres? 

To store the same amount of energy as one golf cart battery would require a large swimming pool with 50 feet (5 stories) of head.  To run the average American house for 1 day would require a 1/4 acre pond with 50 feet of head.
 
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It is good that your solar system can produce excess energy as compared to your energy consumption needs. But it will be wasted if you don’t use it properly. Well, the blockchain technology could fix this problem. It allows you to traded energy with consumers. It is maintained by a network of computers. It is a public, shared, encrypted record that can track the ownership of electricity generated without disrupting the business of generating. And, these computers verify that tractions between the individual generator of a certified type and amount of power to a buyer or consumer. This blockchain technology is promising where the network of peers is connected via a grid and the grid depends on its shared data sets.
In Peer-to-peer energy sales, instead of selling your excess solar power to the grid, you sell directly to your neighbor instead. You still have the option to sell to the grid but it would be based on economics and would be a choice. If you are seeking some more information on the blockchain technology, then check out this blog: https://www.sunpowersource.com/peer-to-peer-energy-sales/
 
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I’ve been thinking about doing something like this with my excess solar.
https://qz.com/1355672/stacking-concrete-blocks-is-a-surprisingly-efficient-way-to-store-energy/
... basically with surplus energy they lift 55 gallon drums of sand with a crane and then when they want the energy they simply lower the barrels and recapture the energy.

Seems like something that could be done on a small scale with modified off the shelf parts, but I don’t know quite how yet.
 
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