Author Topic: Energy storage by moving concrete blocks  (Read 5278 times)

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Offline Nominal Animal

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Re: Energy storage by moving concrete blocks
« Reply #50 on: January 22, 2019, 10:54:07 am »
Compressed sawdust brickets are actually really good for heating; beats typical firewood in energy density easily. (Anecdotal evidence only, but from a large house well north of Arctic Circle.)

Unsurprisingly, the main problem is manufacturers "accidentally" include quite a bit of sand and other non-burning debris in their brickets.  There is a significant difference between manufacturers and even batches; some produce a lot of ashy sand when burnt.  (Incomplete combustion is not the cause; the fireplaces used all had separate incoming cold air inlets beneath the fireplace.)

Sawdust/pellets are of course quite widely used for heating already, and are surprisingly clean tech (as long as good combustion is achieved).  Wood gas is even cleaner, though.
 

Offline DDunfield

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Re: Energy storage by moving concrete blocks
« Reply #51 on: January 22, 2019, 02:40:01 pm »
The video of the tower certainly looks nice ... but I don't think it quite makes sense.

Each block stores a potential energy based on it's starting height and ending height. in other words, energy increases with each layer of the tower:
Blocks at ground level store no energy.
Blocks at the top of the tower store the most energy.

So it actually stores quite a bit less energy then "first glance" might make you think (all those blocks)...

The video shows it basically building a wall around itself as it moves blocks from the top of the tower to the wall - but with each layer, the amount of energy retrieved lessens because the top of the tower is getting lower and the wall is getting higher.

The crane seems to have quite a long reach, and assuming the support structure is in place, counterweight would not be a problem as you could move the blocks in opposing pairs... so wouldn't it make sense to be building a large flat disk around the tower and not a wall?

 

Offline sibeen

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Re: Energy storage by moving concrete blocks
« Reply #52 on: January 23, 2019, 02:28:41 am »
Let's do back of the envelope calculations:
Great Pyramid of Giza weights 500.000 tonnes. It is 146 meter high. It's center of gravity is at 1/4 of it's hight, 36m. It's potential energy is about 50 MWh.
These guys claim that they can store 35MWh in their tower. Basically claiming that they can build the pyramid in a day and take it apart at night.

Just checking that it looks like you may be out by an order of magnitude. Apparently the pyramid masses approximately 5,200,000 tonnes.
 

Offline Doctorandus_P

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Re: Energy storage by moving concrete blocks
« Reply #53 on: January 23, 2019, 03:54:15 am »
So somebody found some footage of a gravel mine and made a bollocks story around it.
[sigh]
Efficiency of such a conveyor will be horribly low, and maintenance costs high. Far to many moving parts.

Churchbells have been driven for centuries on similar systems.
There have been some attempts by using a railroad track on a hill but pumped hydro is much simpler if you can find convenient places to store your water.
 

Offline Zero999

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Re: Energy storage by moving concrete blocks
« Reply #54 on: January 23, 2019, 10:46:07 am »
So you pyrolyze wood to make wood gas, burn that gas to get CO2, then invest energy to make methane which you can burn later on? Well sure, but why not use wood and wood gas directly?
Because using wood that way isn't "renewable"/"CO2 neutral" according to the climate agreements?

Actually, wood isn't very compact, so converting the wood gas to methane (which is already widely used in e.g. buses) would be simply a fuel refinement process.

I do know that CO2 sequestration from ambient air is nontrivial, and typical concentrations (0.04% per volume) are so low that the methane-generating processes cannot realistically rely on CO2 from ambient air.
Wood gas doesn't contain much CO2. It's mostly CO, H2, with a little CH4 and small amount of CO2. It can become unstable at high pressures, so needs to be converted to pure CH4, which is more than a bit than scrubbing and does involve some losses.

Whether it's renewable or carbon neutral or not, depends on how it's produced. It's ultimately more efficient to use solar panels and store the energy in pumped water.

Gasification is a good idea though and can be used to convert dry, organic waste such as nut shells or corn cobs, to a fuel which can be burnt to produce heat and electricity.
 

Offline EEVblog

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Re: Energy storage by moving concrete blocks
« Reply #55 on: January 23, 2019, 11:02:23 am »
Working prototype or bust.
 

Offline David Hess

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Re: Energy storage by moving concrete blocks
« Reply #56 on: January 23, 2019, 04:41:52 pm »
A pyramid is a relatively stable shape. The Egyptians were a fairly clever lot, so you can bet they realized a pile of sand settles in pretty much that shape because it's quite stable.

The Egyptians were clever enough for trial and error without testing; their first pyramids collapsed.

https://en.wikipedia.org/wiki/Bent_Pyramid

In 1974 Kurt Mendelssohn suggested the change of the angle to have been made as a security precaution in reaction to a catastrophic collapse of the Meidum Pyramid while it was still under construction.
 

Offline Nominal Animal

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Re: Energy storage by moving concrete blocks
« Reply #57 on: January 23, 2019, 05:12:48 pm »
Wood gas doesn't contain much CO2.
You missed the "burn that gas" bit.

Gasification is a good idea though and can be used to convert dry, organic waste such as nut shells or corn cobs, to a fuel which can be burnt to produce heat and electricity.
Wood gas was widely used in cars during the second world war in this part of the world, due to fuel shortages.  The downside was the size of the fuel, really, because the wood gas was generated in situ as needed. (In particular, that cylinder/"tank" you see in those vehicles is the generator; the gas itself is not stored at all.)

If, for some reason, we absolutely had to stop using gasoline and diesel for vehicles, switching to wood burning would not be that big of an issue.  "Mad Max" simply would not happen anywhere you got trees aplenty; people would just tinker a bit with their cars, add funky silly-looking gasification canisters, and go on with their lives.  Like they did here in Fennoscandia during the second world war.  Fuel use for a practical four-door sedan is 50 - 100 kg of firewood per 100 km travelled.

That said, you can burn even trash for heat and energy just fine.  Just look at Sweden, for example.
 

Offline NANDBlog

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Re: Energy storage by moving concrete blocks
« Reply #58 on: January 23, 2019, 05:26:01 pm »
Let's do back of the envelope calculations:
Great Pyramid of Giza weights 500.000 tonnes. It is 146 meter high. It's center of gravity is at 1/4 of it's hight, 36m. It's potential energy is about 50 MWh.
These guys claim that they can store 35MWh in their tower. Basically claiming that they can build the pyramid in a day and take it apart at night.

Just checking that it looks like you may be out by an order of magnitude. Apparently the pyramid masses approximately 5,200,000 tonnes.
True, the weight is 5 million tonnes. I am one order off.
 

Offline mariush

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Re: Energy storage by moving concrete blocks
« Reply #59 on: January 23, 2019, 06:20:57 pm »
My first though after seeing that was how would that system behave if there's powerful gusts of wind?

These may be used near wind turbine parks which obviously are in areas with wind.

What happens when one of those bricks is going down and suddenly there's powerful wind which starts moving the brink sideways as it goes down? Looks to me like those bricks must be accurately be placed down and lock together somehow to prevent them from falling off or losing the overall integrity.
 

Offline David Hess

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Re: Energy storage by moving concrete blocks
« Reply #60 on: January 23, 2019, 07:58:59 pm »
Another downside of wood gas (and producer gas) is that the CO content makes it deadly.  The whole thing about someone committing suicide by putting their head in their oven comes from wood gas and it was a major reason to replace it with natural gas.
 

Offline Nominal Animal

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Re: Energy storage by moving concrete blocks
« Reply #61 on: January 23, 2019, 08:18:56 pm »
Another downside of wood gas (and producer gas) is that the CO content makes it deadly.
Yup, carbon monoxide being odorless, tasteless, and slightly lighter than air makes it easy for one to die accidentally from it. (We have carbon monoxide detectors in all rooms with a fireplace for exactly that reason, and smoke detectors in other rooms.)

In vehicle use it was not a problem, because the amount of wood gas at any given point was very small: no tank, the gas was being produced as needed.  That said, I would *not* want to have a vehicle, or anything, with a tank for wood gas or producer gas, even if they were to add mercaptan or other odorants to detect leakage.  Too dangerous.  (However, I still think using wood, and wood gas as a precursor for better/safer fuels, like liquefied natural gas, makes sense even if some energy is wasted in the production.)
 

Offline sibeen

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Re: Energy storage by moving concrete blocks
« Reply #62 on: January 23, 2019, 09:49:41 pm »
Let's do back of the envelope calculations:
Great Pyramid of Giza weights 500.000 tonnes. It is 146 meter high. It's center of gravity is at 1/4 of it's hight, 36m. It's potential energy is about 50 MWh.
These guys claim that they can store 35MWh in their tower. Basically claiming that they can build the pyramid in a day and take it apart at night.

Just checking that it looks like you may be out by an order of magnitude. Apparently the pyramid masses approximately 5,200,000 tonnes.
True, the weight is 5 million tonnes. I am one order off.

You, Sir, are a true engineer :)
 

Offline Zero999

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Re: Energy storage by moving concrete blocks
« Reply #63 on: January 24, 2019, 12:39:56 pm »
Power to gas uses power to do this reaction:
2 CO2 + 4 H2O = 2 CH4 + 3O2
Natural gas is mostly methane.
Power to gas (P2G) is not done in the industrial scale, but there is a 100 MW plant being built in Germany. I think others will follow. And methane can be used in many other ways than just power generation. My favorite part about P2G is that it is actually reverses the CO2 emissions and global warming.
Where does it get the CO2 from?
Wood gas doesn't contain much CO2.
You missed the "burn that gas" bit.
Oh so you mean make wood gas, burn it, presumably to generate energy and use that to convert the CO2 generated and water to methane and oxygen? That would result in less energy than simply burning the wood gas in the first place, as it will take energy to convert the CO2 to methane.

Quote
Quote
Gasification is a good idea though and can be used to convert dry, organic waste such as nut shells or corn cobs, to a fuel which can be burnt to produce heat and electricity.
Wood gas was widely used in cars during the second world war in this part of the world, due to fuel shortages.  The downside was the size of the fuel, really, because the wood gas was generated in situ as needed. (In particular, that cylinder/"tank" you see in those vehicles is the generator; the gas itself is not stored at all.)

If, for some reason, we absolutely had to stop using gasoline and diesel for vehicles, switching to wood burning would not be that big of an issue.  "Mad Max" simply would not happen anywhere you got trees aplenty; people would just tinker a bit with their cars, add funky silly-looking gasification canisters, and go on with their lives.  Like they did here in Fennoscandia during the second world war.  Fuel use for a practical four-door sedan is 50 - 100 kg of firewood per 100 km travelled.

That said, you can burn even trash for heat and energy just fine.  Just look at Sweden, for example.
Yes, wood gas used in the war, instead of petrol to power cars, but not very many people had cars back then. It's impractical to use on a large scale and is very inconvenient. The wood gas generator needs to be fired up for awhile before starting the car and properly shut down afterwards, making it unsuitable for short journeys. We'd soon run out of trees, as there aren't enough of them to use sustainably. It would make far more sense to go electric instead. Modern gasification technology can convert wood, waste biomass and hydrocarbons to electricity much more efficiently, than vehicle mounted wood gas generators.
 

Online coppice

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Re: Energy storage by moving concrete blocks
« Reply #64 on: January 24, 2019, 12:45:04 pm »
That said, you can burn even trash for heat and energy just fine.  Just look at Sweden, for example.
Many countries burn their trash to make electricity. Others use the trash for land fill, cap the land fill and collect methane from it. Then they burn the methane to make electricity.
 

Offline Zero999

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Re: Energy storage by moving concrete blocks
« Reply #65 on: January 24, 2019, 01:46:30 pm »
Burning biogas will give less energy, than just burning the rubbish, since only biodegradable material will produce methane and burning the rubbish will use all of the organic material. The only advantage of biogas is it doesn't release so much carbon dioxide, as the carbon in the buried non-biodegradable matter remains their for all eternity.
 

Online coppice

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Re: Energy storage by moving concrete blocks
« Reply #66 on: January 24, 2019, 01:52:09 pm »
Burning biogas will give less energy, than just burning the rubbish, since only biodegradable material will produce methane and burning the rubbish will use all of the organic material. The only advantage of biogas is it doesn't release so much carbon dioxide, as the carbon in the buried non-biodegradable matter remains their for all eternity.
Burning the rubbish requires complex capture mechanisms to avoid a whole bunch of nasty things in the trash being emitted from the flue, so there is a tradeoff.
 

Offline Zero999

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Re: Energy storage by moving concrete blocks
« Reply #67 on: January 24, 2019, 02:59:10 pm »
Burning biogas will give less energy, than just burning the rubbish, since only biodegradable material will produce methane and burning the rubbish will use all of the organic material. The only advantage of biogas is it doesn't release so much carbon dioxide, as the carbon in the buried non-biodegradable matter remains their for all eternity.
Burning the rubbish requires complex capture mechanisms to avoid a whole bunch of nasty things in the trash being emitted from the flue, so there is a tradeoff.
Biogas also requires scrubbing before it can be burnt to produce energy.

Gasification can also be used, rather than simply burning the rubbish, as it's easier to clean a smaller volume of producer gas, than a larger volume of flue gas.

Taking gas from landfill and extracting the biogas or burning/gasifying all the rubbish are both sub optimal. The waste should be separated into recyclable, biodegradable and non-biodegradable first. The biodegradable waste is then better fermented to produce biogas and fertiliser and the non-biodegradable waste gasified to produce electricity and heat.
 

Offline Nominal Animal

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Re: Energy storage by moving concrete blocks
« Reply #68 on: January 24, 2019, 03:50:54 pm »
Oh so you mean make wood gas, burn it, presumably to generate energy and use that to convert the CO2 generated and water to methane and oxygen? That would result in less energy than simply burning the wood gas in the first place, as it will take energy to convert the CO2 to methane.
Yes. The issue is that you don't want to store wood gas.

In the vehicles where wood gas was used, it was produced as needed, not stored.  The production process wastes about 30% of the energy in the wood.

Yes, wood gas used in the war, instead of petrol to power cars, but not very many people had cars back then.
About 46 000 between 1939 and 1946 in Finland, for a population of about 3.6 million.

I am kind of inclined to argue that people already have too many cars, so that if a sudden shift away from petrol were to occur, it would mostly be a shift away from personal cars, and not so much a shift away from transportation in general.  Buses, not Mad Max.

It would make far more sense to go electric instead.
As long as you have a practical, sensible way to store the energy, I have no arguments there.

Liquid fuels are generally easy to manage, which means some losses are acceptable for ease of use.

The waste should be separated into recyclable, biodegradable and non-biodegradable first.
Problem is, sorting garbage is Somebody Elses Problem.  Just look at how difficult it is to get people to dispose of batteries and electronics properly, for example.
 

Offline Kasper

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Re: Energy storage by moving concrete blocks
« Reply #69 on: January 27, 2019, 08:50:04 am »
Why has no one mentioned the ramp rates when comparing potential energy storage to chemical energy storage?

Potential energy generally has a much faster ramp rate than chemical. Open the dam and the turbine output ramps up way faster than turn up the heat and wait for boiler to heat up.

Around 5pm when solar panels stop generating and people arrive home, plug in their cars and cook dinner, the amount of stored energy that needs to be converted to electricity ramps up quickly.  The more solar we have and the more electric cars we have, the bigger problem we have (in regards to utilities providing stable voltages).

If utilities have access to potential energy storage then they should be more accepting of electric vehicals and renewables and their inconsistent, unreliable usage.

Utilities that rely on chemical energy burn off a lot of energy when loads are low just so they are ready for when loads are high.

Look up "duck curve" for more info.
 

Offline dmills

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Re: Energy storage by moving concrete blocks
« Reply #70 on: February 01, 2019, 10:43:33 pm »
A fast start on a combined cycle turbine is actually very efficient as long as you then keep it running for long enough to get meaningful power out of the steam part of the cycle. 

In fact the part of the cycle where you are recovering heat into basically cold water in the steam generator is actually the most efficient part, it is just that you cannot get that energy back until you have run long enough to get reasonable steam pressure.

Where those things suck is "startup, run for an hour, shutdown" because the heat recovery cycle does not have time to warm up to produce reasonable amounts of power, you loose the energy stored in the boiler when you shutdown for obvious reasons.

This actually makes a combined cycle gas turbine a reasonable choice for a spinning reserve as it throttles quickly and as long as idle is sufficient to keep the steam generator warm... 

Regards, Dan.
 

Offline CCitizenTO

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Re: Energy storage by moving concrete blocks
« Reply #71 on: February 15, 2019, 01:08:12 am »
OK. Apply a minimum of "thought" and see if you can propose a design that might work.
This or a variant of it self centres when roughly placed and is already designed to be hard to break and fit while worn.
Try stacking those 150m high, when they start to get beaten up a bit, and see how far the stack tilts.

They look like giant concrete lego blocks. I'm imagining it'll nest decently into recesses in the bottom... That said you could minimize potential for breaking and such by having a hole in either side and running a cable through them to help keep them straight and lined up.

Might be better to have a metal shell on the outside as concrete/cement is prone to chipping. Metal just gets little dings and dents. Would be more expensive but last much longer and still be cheaper than metal blocks while providing a huge amount of weight/mass to store energy with.
 

Offline timelessbeing

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Re: Energy storage by moving concrete blocks
« Reply #72 on: February 15, 2019, 10:04:20 am »
it reminds me of this

 
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Offline electromotive

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Re: Energy storage by moving concrete blocks
« Reply #73 on: February 28, 2019, 02:58:00 am »
"As an IdeaLab founded portfolio company..."

Maybe they should rename it "BadIdeaLab". Their eSolar startup was a colossal flop that only generated ~12.6% of the predicted output of its Sierra SunTower project (now defunct).
 

Offline EEVblog

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Re: Energy storage by moving concrete blocks
« Reply #74 on: August 06, 2019, 06:27:11 am »
 
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