What to do with large solar power excessive

JackB

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Sacramento, CA
I'm going to have 4k watt of solar on my boat, my batteries will be full after one day.
Now what? I've been trying to figure out a way to somehow store all this excess energy.
I would like to convert it to ethanol or some other high density liquid fuel to run an ICE,
any ideas?
 
JackB said:
I'm going to have 4k watt of solar on my boat, my batteries will be full after one day.
Now what? I've been trying to figure out a way to somehow store all this excessive energy.
I would like to convert it to ethanol or some other high density liquid fuel to run an ICE,
any ideas?

Excessive? You make ethanol from a biosource, but you could power your still electrically. What would you do with the ethanol once you had it?

I charge my celphone in the car or truck, the alternators produce more than enough electricity to run them. There's your best approach. What batteries you got that need charging?
 
What a great problem to have.

Maybe put half of the panels on your house? :)
 
hydrogen is the only way to do it

the problem is the massive amount of storage you need for it

or... you can compress it to high pressure (3000psi) - it's a massive waste of power compressing it like that.... but I guess it's no big deal when you have power to waste anyway



there's a video on youtube of a guy don't this, but he uses a dozen old lpg tanks (low pressure) but I can't find the link right now...


edit:
http://www.youtube.com/watch?v=mQEfTR3gw8c
 
hydrogen is too dangerous, storing it too difficult, containers too heavy.

Ideally I could make an ethanol like fuel to run in my gasoline engine.
UCLA has something in the lab like this.
http://newsroom.ucla.edu/portal/ucla/ucla-engineering-researchers-use-231103.aspx

But given the US government is funding many groups to research this kind of thing, I doubt I will
have something I can use on my yacht anytime soon. :(
So what are other practical alternatives?
 
neptronix said:
What a great problem to have.

Maybe put half of the panels on your house? :)

That's sort of what I was thinking. If you draw far too much power, unless you are hoping to compensate for an extremely cloudy short day, you could consider selling or re-purposing the panels else where.

I wonder if your boat uses an electric motor. I've wondered countless times why solar boats aren't extremely common.
 
bowlofsalad said:
neptronix said:
What a great problem to have.

Maybe put half of the panels on your house? :)

That's sort of what I was thinking. If you draw far too much power, unless you are hoping to compensate for an extremely cloudy short day, you could consider selling or re-purposing the panels else where.

I wonder if your boat uses an electric motor. I've wondered countless times why solar boats aren't extremely common.

Why I have such large solar panels is to generate the power to drive the boat's electric motors (or at least part of it, the rest comes from gasoline)
But once I have reached my destination, I have excess solar energy. I can't sell it, the boat is anchored offshore.

Flywheel was my first idea, but it is too heavy for a boat, particularly one powered by solar/electric power needs to be lightweight.
 
The Stig said:
Excess is good. You can have a fridge or cooler running or other systems/more power to the motors/less affected by clouds/acquire a few more cheap batteries
Haha, hey, that is a good idea. Make and sell ice!

The idea of having a purely solar boat is so awesome. You could go anywhere
 
hydrogen IS the only real way to store the power in your situation... you asked for ways to store it, not use it


best use of it is to have a big hot water tank and dump the power into there, so you can have a long hot shower with 'free' heat ;)
 
The excess electricity can be used to distill water into fresh, boil up an insulated tube, make a U-turn, and have it flow down exposed finned aluminum tubes to condense. Beware water that is too pure, you need electrolytes and other minerals.

Electrolysis has been mentioned. Its inefficient, but if you have excess energy, it doesn't hurt. H2 causes embrittlement and can seep out of conventional steel cyclinders, like 100-PSI propane tanks. You need to coat the insides with something that seals and protects the steel from H2. I don't remember what works for that. H2 can be used as a substitute for cooking gas and space heating. A leak and a spark can cause an explosion.

Get a propane carb and run it very rich to run a spark/piston engine (generator?) on H2. Just start looking, there is info on that around...
 
Dauntless said:
I charge my celphone in the car or truck, the alternators produce more than enough electricity to run them. There's your best approach. What batteries you got that need charging?


Do you have any clue how much energy 4kw is? I'm envisioning this is a large boat with a large solar array and I'm guessing at least 10-20kWh of battery on-board. If he just wanted to charge his cell phone, the energy he collects and stores in 20minutes would handle his entire year of all cell phone charging energy needs, and that would be a hardly noticeable change in pack SOC to do the entire year of cell phone charging.

The Stig said:
Excess is good. You can have a fridge or cooler running or other systems/more power to the motors/less affected by clouds/acquire a few more cheap batteries

A large full size, but modern and efficient fridge consumes about 450-500kWh/year to run. About 1-1.5kWh/day. He is likely producing about 20kWh of energy per day. It is substantial. Like the full usable capacity of a Nissan LEAF pack wasted each day if he doesn't find something useful for it.

knighty said:
hydrogen IS the only real way to store the power in your situation... you asked for ways to store it, not use it

I'm thinking he is floating in a giant ion bath called the ocean. There has to be some method to use the ocean as a component of your battery, and plate sodium metal onto something and let the reaction reverse to discharge so you're just putting the sodium ions back into the seawater.
 
Yeah the fridge was more of an example, but add a freezer and a typical marine desalination machine, electric grill/cookers and the boat could become way more livable and flexible and you get to use those extra kWh. I doubt you'll find much more cost effective storage than batteries...

We need pics!
 
My boat is still under construction. I need to plan for how to store its energy.
Lithium batteries are too expensive and too heavy to have a lot of them.
Here is pic of the 100ft $20M one that went around the world on solar power only, 93Kw and a lot of batteries.
DSC_00151.jpg


My cat/tri will be only 50ft. This 60ft boat has 10kw of solar, but crossed the atlantic on only solar.
Schiffportrait2w_10.jpg


Creating ICE is something I have considered, but can't really turn it back into electricity.
I will have a watermaker to create fresh water from sea water, but there is only so much water (and ice) I can use.
 
I think the answer is zinc. A Zinc-air battery can hold 4x the energy per weight than lithium.
Most non-rechargeable batteries are zinc-carbon. Problem is they can't be recharged.
But they can be recycled. The zinc-oxide can be converted back into zinc and oxygen,
and a new battery created. So I can use my solar energy to run a zinc battery factory.
Zinc is very inexpensive. So I should be able to store 4x the energy than lithium,
at 1/4 the cost.

Here is a paper on using thermal solar energy to recycle zinc-oxide:

http://pre.ethz.ch/publications/journals/full/j55.pdf
 
knighty said:
hydrogen is the only way to do it
Use it as resistive heating on biogas barrels and turn your food scraps/liquid to methane instead of hydrogen. If you have enough space methane stores nicer without compression, and is safer is relatively less oxygenated environments.
 
i would not get rid of the excess panels, god i am jealous of a boat like that, i want one!
im sure in time you will need that excess power, more appliances in the future, fridges over time can start to consume more if they start to fail also,
I would think of just adding more power to your boat motors tho, or something like that, that way you wont be wasting your harvest.
 
immersun...

http://www.navitron.org.uk/product_detail.php?proID=756&catID=127
 
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