Alternative to chemical storage of energy

[tz0c0s]

Hi All,
  I am sure I am not the first to think this & there are many reasons why it will not work.

I will explain the idea, please pick holes in it.

We are currently fixated in storing electrical energy in a chemical form ie batteries or heaven forbid hydrogen.
Larger systems use pumped storage of water ie Dinorwig.
Home based energy storage systems are expensive, battery based & have an annoying cycle life.

We are turning the corner of home generation during daylight hours but are not able to have anything stored at night without large reoccurring cost.
What would it take to construct a system that uses a largish mass raised to a height thus storing excess energy during the day.
This could be then released and regulated on demand to spin a small generator via a gearbox to take selected loads through the night?

I am hoping people much brighter than me could do a quick calculation of the mass & distance needed to have a reasonable amount of storage?

Regards Andy (thinking out of the box, into the canvas strappy jacket with the zip up the back)

[skyewright]

...a quick calculation of the mass & distance needed to have a reasonable amount of storage?

I'm guessing that you are thinking of a tank in the loft? If so that would be a medium or low head turbine.

I'm no expert, but I think it's a case of nice idea, but...

Pages http://www.navitron.org.uk/page.php?id=48&catId=70 & http://www.navitron.org.uk/page.php?id=49&catId=70 in Navitron's hydro section show the flow rates for a selection of turbines. You'd need a very big (and heavy) tank full of water to run any of those for even just a few minutes. 

I'd love to be wrong...

[Jonathan]

This is done regularly already by the power companies. They pump lots of water uphill, then let it trickle down again.

In a domestic environment, for just one house, how much do you want to store? Let's say 10kWh = (36,000,000 J) as a starting point. Suppose you use one of those one tonne sacks of sand from the DIY places - then how high would you need to raise it:

PE = mgh (Potential Energy (J) = mass (kg) x gravity constant (10) x height (m) ), or h = PE/g/m = 36,000,000/10/1000 = 3600m or 3.6km. That's quite high.

Ok, so what mass to raise from the ground floor to the roof to store 10kWh. Lets assume a 6m height rise

m = PE/g/h = 36,000,000/10/6 = 600 tonnes. Wow.

And this is all assuming 100% efficiency.

As I said, the power companies pump lots and lots of water up a very high hill.

regards Jonathan

P.S. OE&E - without the edit facility, we can't correct any of the above for any mistakes!

[biff]

dont worry andy,
               you are a long way off the straightjacket yet, they are quite comfortable you know !! .
    i did think one time of storing water in 1200ltr cage tanks at a height of 18ft and letting the full force of 10 tanks drive a little turbine, but the whole operation would take up so much room for so little return. then if the temp dropped and things froze it would be like walking under a waterfall in the thaw.
                                                      biff
     

[Justme]

Larger systems use pumped storage of water ie Dinorwig.

Dinorwig only works because of the price difference in cost between night time trade rate (I think they get it for less than 1p per unit) & peak demand rate (again I think they get paid hugely for this as its a balancing power so in excess of what you pay for day time units). If you or I did it using the same ratio of power used to power stored you would be in for a shock as its 4 used to even one stored (or that what they tell you on the tour). That is far far worse than lead acid batteries.

[djh]

We are turning the corner of home generation during daylight hours but are not able to have anything stored at night without large reoccurring cost.
What would it take to construct a system that uses a largish mass raised to a height thus storing excess energy during the day.
This could be then released and regulated on demand to spin a small generator via a gearbox to take selected loads through the night?

As people have already explained, you need a pretty big mass. Water is less efficient than a heavy metal block, but even so it would be a large block of metal. (Water is cheaper of course!). Another approach is to use flywheels. This http://www.beaconpower.com/products/smart-energy-25.asp seems to have about the right capacity, but I've no idea how big it is or how much it costs.

But the costs and the space required are the reasons why [almost] everybody who can uses the grid to balance the loadand twhy those who are off-grid use batteries. If there were better alternatives, everybody would be using them ...

[EccentricAnomaly]

Dinorwig's about 75% efficient (1 unit lost to every 4 stored; the other 3 are output).

[Baz]

Hydrogen looks the best bet for domestic storage. You can make it with electricity and get the electricity back with a generator fairly easily. Is there any other substance that works so well for this.
Electrolysis to produce lithium or sodium is possible which can generate hydrogen easily but is an awkward high temp process. Calcium carbide is also an awkward high temp process.
What is needed is the freeing up of the electricity distribution network from the current concept of a single supplier. Just as I can rent a phone line then make bidirectional contacts to anyone I choose so I should be able to rent pylon use and move power over it. I could contract with a local farmer to proivide daytime juice for his grain dryer, then buy back his biogas generated power overnight.

[tz0c0s]

Wow, lots of replies, thank you.

I too researched low & medium head turbines via the main site. A frightening volume of water is needed.
One was the equivalent of throwing the wife off the roof every second.............  

I was thinking more of a dry system being hoisted during the day. Allowing it to fall overnight. Like a grandfather clock.
Jonathan has my idea down to a tee, looks more like a sumo clock then. I knew there was a flaw in my cunning plan.

Is anyone able to peer review his calculations? one decimal point and digging a 6M hole would mean 30tonnes.... kind of possible. Reducing consumption yet again is sensible.

Biff, you know of a tailor to make these things comfortable? I am tired of my NHS one   IBC's would make a great store but the l/sec figures are frightening.

Smart energy 25 flywheel, wow, that's pretty hardcore stuff. I can't gauge easily any scale, they look sizeable & hard to spin up from a solar array.

Yes, I believe Dinorwig is for responding to the peaks in demand & absorbing off peak excess energy. It is I recall exceptionally fast in generation terms to come on stream. I did a project on it for my D of E Gold award in 1989. It was nice to meet the duck, Bob Holness & Sharon Davies.

I like the hydrogen idea, flexable but.... I am not going to hold my breath. The Big £££ companies will hold back on it until they find a way of transporting it to us for money. I like the idea of a hydrogen community, based around a lake (rain store) with fuel in tanks at the bottom, either simple plastic bags or low pressure tanks.

Andy

[mespilus]

Per haps we need domestic,
(basement stored?),
flow batteries?

[dhaslam]

The centrifuge idea has never really been developed.   While it is nice to have a high speed version running in a vacuum it might be possible to make something much more low tech.   Something like  a water filled or sand filled hollow  flywheel and several in parallel to make them smaller and easier to make. 

[Philip R]

The energy storage flywheel from beaconpower US was originally derived from uranium enrichment centrifuges, developed in the UK by BNFL/URENCO, Capenhurst, Cheshire. The original UK built device saw service on the New York subway.

When BNFL was broken up sold off by Gordon Brown, another good UK invention was effectively handed on a plate to the US.

[renewablejohn]

If you look at the process industry you will find that energy storage is with thermal oil because it is easily converted to process steam or electricity as well as high grade direct heating upto 280C.

[Justme]

Dinorwig's about 75% efficient (1 unit lost to every 4 stored; the other 3 are output).

I stand corrected.

They need to sort out there tour guides & get them giving the correct info out.

[dhaslam]

The usual figure given for large scale water storage is  50% made up of about 70%  pump efficiency and 70%  generation efficiency.