What are some ways of storing "sun energy" that would be useful for power generation? Below are a few of the things I have read about.

Store the heat to keep the steam turbines going 24/7? Needing at least 4x the number of solar collectors to store enough energy to power the turbines for the 18+ non-solar hours? How is "heat" stored and then used?

Store the power being generated in batteries? This is awful expensive unless large scale battery cost is cheap or custom batteries can be made cheaply. Can you imagine the cost of a battery bank capable of storing 250,000 watt hours of power? How can large capacity batteries be made cheaply?

Convert the energy to compressed gas and use that compressed gas during the non-solar hours to run a pneumatic motor? Large air tanks at high pressure are scary IMO not to mention expensive. Can the tanks be made cheaply or large enough so that lower pressures can be stored?

If you can find the answers to these questions, you'll be at the forefront of the break thru in solar power conversion.

WHy do you think that solar power has not taken off like oil based power sources? Simply a Lack of development and lack of AFFORDABLE power conversion/storage potential

All these tree huggers and politicians look at solar energy conversion as some sort of panacea. It is and always has been a difficult power source to store and convert to useable WITH THE KNOWN SORAGE and CONVERSION DEVICES

THis is not so say that it can't be done, I"m just saying that none of the methods used so far are as cheap or effective or efficient as the inefficient fuel power energy conversion devices we use now.

It is funny that you mention this sort of thing. I had a similar question asked on/in a mechanical engineering final exam I had nearly 40 years ago. The more things change, the more some things stay the same - sp,e [rpgress jas beem ,ade bit mpt empigjt tp compete with $5 or even #100 per barrel crude..

http://www.sandia.gov/Renewable_Energy/solarthermal/NSTTF/salt.htm

I was reading the other day about a wind turbine system (of the large wind farm project type) that will drive an integrated compressor during periods of excess wind. The compressed air is stored in huge batteries of underground receivers and used to drive pneumatic motors which in turn drive the generators to make electricity during periods of lower then expected wind or periods of high electricity demand which of course rarely coincides with high winds. Sounds like a good, even if super-expensive idea however I wouldn't be at all surprised if it was just another one one of those: Press Release: We've developed blablabla... Investor: "Oh wow, that's going to be a hit, time to buy" so they do and those in the know who invested prior to the press release make a killing, device turns out to be all just "hot air" (excuse the punn) and the press release did exactly what it was supposed to do. Make a ton of money for a handfull of people. Gee, don't I sound cynical?

Gerry's link describes a storage system that I think has great potential except for a fatal flaw; if it is scaled up to become a significant part of the electric supply there will not be enough saltpeter available.

I think this same flaw exists for nearly all the proposed solar energy storage systems, there will not be enough of the raw materials available to scale them up to a significant level.

There is really only one solar energy storage system for which the raw material is in adequate supply and that is rain. However, even this one is limited because to be useful the rain has to fall on the top of high ground in a location where a dam can be built and this combination of weather and geography is in short supply.

P.S. Nitrates are also fertilizers so this salt solution storage idea has some similarities to bio-fuels in that it would probably have a serious effect on food crops if implemented on a large scale.


Skippy; There are two ways to pronounce *c*y*n*i*c*a*l*; one is "cynical", the other is "realistic".

Hi smertrios

You don't need to store the power you get from your solar cell you feed it back into the grid through a inverter it cuts your power bill down quite a bit like almost half if you have at least 3 good size cells also the water heating can be done with a solar water cell for further reduced power used

You can use the solar power also to charge your batteries in your electric/hybrid car
nothing is free but they pay you back in time

Dear Smertrios,

Your question "What are some ways of storing "sun energy" that would be useful for power generation?", has a dead cert. proven answer, but you may have to take a longer term view than you were considering.

Plant a few trees and wait. Photosynthesis will do the rest. Then after a few years you will have a good supply of logs to stuff into your local power plant. Of course, if you have more patience, you might eventually end up with some coal.

It might work..

Best wishes,

Martin

.....Plant a few trees and wait. Photosynthesis will do the rest. Then after a few years you will have a good supply....

I like your concept of "few years"'

Can I borrow a "few" pounds from you?

I promise I will pay you back in a "few" years (If you still exist). :D

I like your concept of "few years"'

Can I borrow a "few" pounds from you?



Dear Geof,

There seems to have been a bit of a misunderstanding about the direction in which funds might be moving.

I was actually thinking that you might like to buy some stock in my coal mine.

Best wishes,

Martin

I know this is off topic (sun energy). ;)

I think the best source of Alternate Energy is in ocean waves. Waves will never stop day or night, winter or summer!

The best design I have found is a Buoy (http://en.wikipedia.org/wiki/Buoy), think of one of those cheap flashlights that you shake, that don't use batteries, the bouy is anchored to the ocen floor with a cable & bobs on top of the waves, I watched a youtube video of one a while back, very simple in design, no pollution, no need to store the energy in batteries, etc,...

It's funny how folks can't see the energy, cause the waves are in the way (what a waste).

BTW, I'm no tree hugger (I drive a Jeep Cherokee) :)



Links:

http://en.wikipedia.org/wiki/Wave_power

http://www.youtube.com/results?search_query=wave+energy+buoy&search_type=&aq=f

http://www.youtube.com/results?search_query=wave+energy&search_type=&aq=f


.

I know this is off topic (sun energy). ;)...

Not off topic; wave energy is merely stored solar energy, inefficiently stored at that. Uneven solar heating of the Earth's surface and atmosphere, combined with the Earth's rotation creates wind; wind generates waves. I think it is less efficient than rain and suffers from the same problems, the need for a fortuitous combination of weather and geography.

I disagree,

We will have waves all day/night 24/7 tomorrow, that I will put my money on ;)

Will it be sunny or windy all day/night tomorrow (who knows)?



I think it is less efficient than rain and suffers from the same problems, the need for a fortuitous combination of weather and geography

Still disagree,

I vacation/live on the South Carolina coast, the waves look just as large to me, windy or not.

***************************************************

As far as geography, how far can a coal or nuclear power plant send energy down power lines?


.

I disagree,

We will have waves all day/night 24/7 tomorrow, that I will put my money on ;)

Will it be sunny or windy all day/night tomorrow (who knows)?





Still disagree,

I vacation/live on the South Carolina coast, the waves look just as large to me, windy or not.

***************************************************

As far as geography, how far can a coal or nuclear power plant send energy down power lines?


.

I was not comparing with wind, photovoltaic solar or nuclear, I was comparing hydroelectric solar energy, aka known as rain being trapped in dams, with wave energy. I would be surprised if more energy can be extracted from waves on a global scale than from rain and at lower cost.

Dear Switcher,

Ah, saltwater, that is the problem with most wave energy concepts.

Anybody who owns a small boat, a supertanker, a timber or RC dock, an oil rig or anything else that is dunked into the sea at the mercy of the waves knows that very few pieces of kit last very long. A few decades if you are very lucky.

I read somewhere , a long time ago, about the idea of using blow-holes at the foot of sea cliffs. The general idea is that the waves compress the air in the "cave" at sea level which then runs an air turbine higher up, and in no contact with salt water.

Is this a crazy idea that has no prospect of doing anything useful? If so, it will join a whole bunch of other bonkers ideas being proposed by the AGW industry.

Best wishes,

Martin

A few decades if you are very lucky.



That's not bad IMO, make em modular, replace when needed.

This link is more of the idea I am thinking of http://eecs.oregonstate.edu/wesrf/ , I think they have ran it at 10kW so far.

So it is being done, just needs to be on a larger scale.

http://eecs.oregonstate.edu/wesrf/projects/images/waveenergy-nonumbers.jpg


.

...This link is more of the idea I am thinking of http://eecs.oregonstate.edu/wesrf/ , I think they have ran it at 10kW so far.

So it is being done, just needs to be on a larger scale.

http://eecs.oregonstate.edu/wesrf/projects/images/waveenergy-nonumbers.jpg


.

Awe come on. If you think this sort of stuff has commercial viability I can probably show you a bridge for sale In Brooklyn or a bunch of desert property in Florida.

Awe come on. If you think this sort of stuff has commercial viability I can probably show you a bridge for sale In Brooklyn or a bunch of desert property in Florida.



Nice attitude. (nuts)

http://www.sandia.gov/Renewable_Energy/solarthermal/NSTTF/salt.htm

This looks like a good system but as was mentioned previously that is alot of melted $salt$. Any reason why the heat could not be stored in insulated containers filled with a solid like sand, rock, concrete or even dirt using the liquid salt to fill in the air pockets? Heat exchangers would be key!

....Heat exchangers would be key!

Yes the heat exchange would be important. Using something solid as you suggest puts two more heat exchange processes in the sequence and would reduce the efficiency. In addition rocks and sand, like most solids have a low heat capacity so you would need a much larger volume and it would need to be insulated.

or anything else that is dunked into the sea at the mercy of the waves knows that very few pieces of kit last very long

Sharks seem to have lasted a wee while. Even outlasted the dinosaurs by all accounts.

You're gonna say "yea, but sharks aint a bit of kit", but would you say that to one face to face? lol

All joking aside, what we should do is make big mirrors (concave) and stick them right near the sun to reflect the incident light and solar radiation back to a focus coincident with the sun's approximate centre. This will cause the sun to go nova (which it wouldn't normaly do) and create a lot of energy and a rather nice firework display...

*checks his notes for any flaws in the above hypothesis*... nope! seems ok to me!

...................I read somewhere , a long time ago, about the idea of using blow-holes at the foot of sea cliffs. The general idea is that the waves compress the air in the "cave" at sea level which then runs an air turbine higher up, and in no contact with salt water.

Is this a crazy idea that has no prospect of doing anything useful? If so, it will join a whole bunch of other bonkers ideas being proposed by the AGW industry.

Best wishes,

Martin

Hi Martin.
Might be worth having a look at Wavegen. In August last, they seemed to be upgrading their plant on the Scottish coast, so it might be said to be a reasonable proposition. ;)

Regards
John

Dear John,

OK, Wavegen have a 1000kW facility. I have no idea what it produces on average.

A whole 1000kW, that sounds really quite impressive really until you put it into some kind of perspective....

The power output from a single Porche Turbo sports car is about 310 kW.

BTW, who is paying for this enterprise North of the Border???

Answers on a postcard please....

Best wishes,

Martin

......
A whole 1000kW, that sounds really quite impressive really until you put it into some kind of perspective....
The power output from a single Porche Turbo sports car is about 310 kW.
........

Dear Martin,
An interesting illustration, but I'm not sure that it adds perspective.
I would think 10kw going into 100 cottages in the local village might be worthwhile.

.....
BTW, who is paying for this enterprise North of the Border???
Answers on a postcard please....


According to the website, if you read the Wavegen brochure .pdf, it's owned by Voith, a family company. I suppose the shareholders pay for it, but they also gain any profits to be made, and I have no problem with that.
Whatever the deal is, and whoever is paying or gaining, if the system brings power to places it wasn't available before, and without requiring petrol or similar to be added to the equation, I'm in favour.

Regards
John

I read somewhere (New Scientist possibly?) that there is a way to make hydrocarbon type fuel from algae. If it's possible I could see lots of benefits to using sunlight and, say, enclosed lakes to grow lots of algae. I would have said "lochs" since I'm Scottish, but there ain't enough sunlight in Scoland for it to be feasible imho.

[Edit]Here's one sample link

http://www.zimbio.com/Energy+and+the+Environment/articles/345/Sapphire+Energy+Making+petrol+algae

Google "Petrol from Algae" for lots more.

How about this:
Solar energy to power pumps to fill a reservoir with water, when the solar energy is gone run it as a hydro electrical dam. It may rain after the reservoirs are full, which would be a plus, but shield the lower reservoir from rain.

Here's the Wikipedia version of Greg's idea.
http://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity
Note the comment at the end stating that the wind energy could mechanically pump the water to the resovoir, eliminating the conversion to electrical energy, then electrical back to mechanical pumping. It also states that it can be a closed system.

EDIT - Wouldn't it be great if the system used wind powered archemedes screws to elivate the water... Just add a one way clutch so if the wind dies down it doesn't back-drive the windmills! I think a variable speed unit could be attached so that the gear ratio between the windmill and the auger would be matched to the power output of the windmill at given windspeeds.

Keith

.....Note the comment at the end stating that the wind energy could mechanically pump the water to the resovoir, eliminating the conversion to electrical energy, then electrical back to mechanical pumping. It also states that it can be a closed system.....Keith

I think the added mechanical complexity of direct driving water pumps from wind turbines and the fact that either a pump and lots of pipes would be needed to connect multiple turbines, or long drive shafts to do the same thing rules out direct drive.

A lot of things are theoretically possible but the people who propose them often do not look at the practical problems.

Actually with pumped storage it is not even necessary to have the water storage site anywhere close to the wind turbine site and the electrical transmission losses are not great. But finding suitable locations which do not involve destroying rivers, valley bottom land, or significant environmental damage is difficult. With pumped storage the lake(dam) levels fluctuate widely and this can causing slipping of the banks when the water is drawn down silting up the reservoir and potentially causing problems with the turbines.

Dear Greybeard et al

Here is a link to Denorwig, a pumped storage facility that used/uses conventionally generated electricity to utilise off-peak generating capacity, and deal with sudden demands. I have no idea what it actually achieves, and I do have an open mind.

http://www.ngfl-cymru.org.uk/cc-reducing-climate-change/cc-renewable-energy2/cc-hep/cc-pumped-storage-schemes.htm



Wavegen mentions a 1000kW facility. So do wind energy people. The actual output from UK windfarms is about 26% of the installed capacity. I have no idea how wave energy stacks up in comparison.

I guess another point that slightly worries me is that it might be a good idea to look at this with a dispassionate view, rather than directing information at school kids who have lapped up "An Inconvenient Truth".

Catch them at an early age...

Best wishes,

Martin

Google found www.hhoforums.com all they text about is HHO generators. Its almost all about "on demand" generators there is nothing about generators that keep the hydrogen and oxygen seperated so they can be stored more safely and used later.

One interesting thing I read was that some of the users with the good 316L SS plates are replacing the plates in the HHO generators after just a year. The HHO generators are expensive when "small" and made for cars, a large one for use as an alternative power souce could get very very expensive if that is always true.

As for car use and a 1 year lifespan I wonder if they could even be producing enough gas to support their replacement cost! This is crazyness but I mention this as it is another way of storing energy.

A great way to store that energy is from elements that exist on earth.
Mineral oil from the internals of the earth created by heat from sun and earth and pressure and elements. Or a tree, you can burn the wood. Yeah all those natural things that are here for us to use.

I haven't paid much attention to this since the early eighties, but as I recall you can use solar energy to heat water, heat eutetic salts, heat other solid objects, generate electricity from photovoltaic panels, etc.

However each is highly inefficient when you want to transition from passive to an active system. The capital outlay for anything active is quite high and the return on investment is probably quite outrageously low.

There has been little improvement in solar technology in the past couple of decades to make it commercially feasible on a large scale. Electricity sells for $0.08 per KWh in the US and is generated using natural gas, hydro, coal, fuel oil, etc.

So, the research dollars are mostly going to as well as commercial investment into "wind energy" farms.

Paul

There is a pumpback facility not too far from here that generates power during the peak demand times in the daytime then pumps back to the upper reservoir at night. They buy electricity during the night at a low $/Mw rate then sell it back during the day at a higher $/Mw rate. And they actually make money doing it.

The western plains were once populated with windmills to pump water out of the ground. You could use excess solar collection durnig the day to pump water out of a 100 ft deep well to a storage tank at ground level. Then durnig the night you dump the water from the tank back into the well and have almost 100 ft of head pressure for generation.

If you have a nice wide hillside you could run solar collection up the hill to generate steam running a turbine at the top. Condense the steam back to water to fill the reservoir at the top of the hill. Any excess generation could pump water up to the reservoir. Then drain the reservoir at night to gen the power needed at that time.

Hi All,

About 15 years ago, I had read about the possibility of putting mirrors into orbit, converting the energy into microwaves and sending it to receivers on Earth, Western USA desert areas. Supposedly, this would have produced many Megawatts of electricity. This was during the Carter administration. However, the Carter administration canceled the idea because the "PEOPLE" were afraid of the dangers of the microwave transmissions to Earth.

It was supposedly going to be a narrow beam that would not interfere with anything.

Anyone heard of or read of this?

Al

I perhaps would like to comment.

The idea of making cement lined tube sunk in the ground would not be to far fetched. In fact, if the companies wanted to store more energy then air in those tanks and there is a excess of energy being generated once way is to pipe the excess power into electrolyze to generate hydrogen. Store it in those tanks and make sure that thay are designed for hydrogen since hydrogen is the smallest molecule it can easily escape if not used over time.

Use a large wind/hydralic pump generator to drill those holes into the ground. No electricity needed except for support power for the equipment. But energy storage is a real issue when its needed at night. That, the cost of solar panels are costly hurdles that need to be overcome.

I remember reading somewhere about inertial storage,

Spin a large mass inside a vacuum with a motor that can be switched to a generator when the power is needed,

Slow it down quickly enough and you get massive power surges, slow it down slowly with large gear ratios and you get lower but more continuous power.

The benefit of this is I cant see many problems with scalability.

Serpah,
Here is a company that is doing this now.
YouTube - VYCON Flywheel Energy Storage

Google 'flywheel energy storage' or 'flywheel UPS' and you should find many links. It is being used commercially on a small scale; that is small compared to total consumption of electricity.

So I didn't dream that one then :).

Makes me wonder why this hasn't been scaled up, if its working on a "small" scale already surely the task shouldn't be insurmountable.

Perhaps cost is the limiting factor, I suppose magnetic bearings could become rather pricey pretty quick if they had to support several tonnes of spinning rotor?

.....Makes me wonder why this hasn't been scaled up, if its working on a "small" scale already surely the task shouldn't be insurmountable.....

I think one reason could be it simply does not sound sexy enough. You cannot use the prefix 'nano' in your grant application like you can when you are researching batteries and fuel cells.:)