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Engineering is heading towards perpetual motion machines
2

Engineering is heading towards perpetual motion machines

Engineering is heading towards perpetual motion machines

(OP)
Perhaps the writer of this newspaper article missed a key part of the plan to build this facility, but it sounds like they are going to try to get a net energy gain out of a closed loop system:

http://www.intelligencer.ca/ArticleDisplay.aspx?e=3167065

My step dad made a very good point on why they may want to go ahead with this. If they get a "green energy" incentive they may use energy from the grid to lift the water during off peak hours (cheaper electricity prices), then feed some energy back to the grid during on peak hours at the higher "green energy" price therefore netting a profit.

 

RE: Engineering is heading towards perpetual motion machines

Pumped storage for demand peaks is nothing new and a really good use of disused mines.

The only bit of that article that disappointed me was the name "Hastings".  Why can't these people think of new names for places?

- Steve

RE: Engineering is heading towards perpetual motion machines

(OP)
I probably should have worded that more clearly, here is the particular paragraph from the article that sounds off:

"The pumped storage facility would generate about 400 megawatts of electricity by allowing water to flow through a turbine system from the reservoir to the open-pit mine, and, vice-versa, use power generated by the down flow to pump the water back up to the reservoir to be reused and recycled through the system."

And they seem to be calling this a "green" project. While I understand that this helps the efficiency of fossil fuel plants etc to help them run at a more constant rate, it's my understanding that storage facilities still work at a loss of 20-25% (they are 75-80% efficient). Maybe I'm missing something about the definition of "green technology"?

RE: Engineering is heading towards perpetual motion machines

There is definitely a net loss in this system, as neither the pumping or generating is 100% efficient.  However, as pointed out, it can allow the existing plants to be more constantly loaded and more efficient and is an excellent way to peak shave within building another fossil fueled plant.

RE: Engineering is heading towards perpetual motion machines

75 - 80% efficient?

From fundamentals it should be obvious that pumped storage must operate at a negative efficiency.

It sort of makes sense where there is an over supply of electricity produced by big thermal plants that can't be turned on and off at the flick of a switch, or can't be turned down at off-peak times without serious repercussions on efficiency or emissions.

They are "green" because the term has no meaning, and people don't understand how pumped storage works within a larger system.
 

RE: Engineering is heading towards perpetual motion machines

OK yeah, the line you high light sounds a bit off.  Even if they meant net power (shouldn't it be energy?) put into the network what is returned later to pump the water back up then there's still a big efficiency loss they ignore.

Pump store is very useful for peak shaving etc. and as such can help with the overall efficiency and even 'greenness' of the electrical network.  While they do tend to pump the water up when there is surplus power, I don't think that's how they'd make their money as such.

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RE: Engineering is heading towards perpetual motion machines

I wonder if they've considered the following:
Evaporation loss vs Precipitation Recharge
Potential contamination of water due to leachating of minerals in mine
 

RE: Engineering is heading towards perpetual motion machines

Is this style of Pumped storage more efficient/economic than above ground reservoirs? I would imagine it is much easier to overcome environmental hurdles by using disused mine shafts but do the technical difficulties incurred by operating underground outweigh the political benefits?  

Comprehension is not understanding. Understanding is not wisdom. And it is wisdom that gives us the ability to apply what we know, to our real world situations

RE: Engineering is heading towards perpetual motion machines

Based upon this statement: "Mantenuto explained Northland plans to build a massive water reservoir above the mine utilizing more than 70 million tons of rock already present at the site." they're using an above ground reservoir.

RE: Engineering is heading towards perpetual motion machines

Pesky laws of physics, ruins everything.  

These guys must be coming out of the woodwork lately, green flavor of the day, one would suppose.  I looked at a project down by Houston a year ago that purports to do nearly the same thing, only using wave action in holding ponds.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

RE: Engineering is heading towards perpetual motion machines

It looked to me (trying to read between the lines of journalism school dropout lingo) like the pit was to become the lower reservoir, and a second, upper reservoir was to be constructed using on-hand tailings as ballast.  

Using tailings for ballast (dam walls) may be a surface-water contamination issue, depending on how well/reliably it gets sealed.  Can't really see how the pit being filled with water would be any more of a groundwater contamination issue than it already is.

RE: Engineering is heading towards perpetual motion machines

The efficiency of the hydro part is negative, but that doesn't matter.  The hydro storage makes the entire generating system more effective.  Works a treat when combined with a continuously running nuclear plant.

RE: Engineering is heading towards perpetual motion machines

A similar mixture of wind and water will soon be providing an abundant supply of energy for the 11,000 inhabitants of El Hierro (Canary Islands, Spain). In 2000 Unesco made the island a biosphere reserve. This meant that the wind farm had to meet strict requirements: the site is exposed to the prevailing wind but well out of sight, and all the pipes and buildings were either painted camouflage green or buried.

http://www.storiesproject.eu/docs/El_Hierro_Project_-_Estoril_26.03.2010_G._Piernavieja.pdf

http://notonlybridges.blogspot.com/2009/08/wind-water-power-perfect-match.html

http://NotOnlyBridges.blogspot.com

RE: Engineering is heading towards perpetual motion machines

All well and good so long as UNESCO buys the green paint and pitches in with the shovelling.

RE: Engineering is heading towards perpetual motion machines

I'm seeing a lot of interest in attaching wind turbines to the output of air conditioning vents to capture otherwise wasted energy.

It's a cool idea, but the idea of harvesting energy from an electric motor is one of the types of a perpetual motion machine.

RE: Engineering is heading towards perpetual motion machines

Its only PM if you use the wind turbine to run the air conditioner to run the wind turbine to run the...:)

RE: Engineering is heading towards perpetual motion machines

I actually think that Kacarrol opens a very urgent question. An abondonned mine may still contain a lot of heavy elements, arsenic and other contaminants.

Best regards

Morten

RE: Engineering is heading towards perpetual motion machines

(OP)
It was zelgar and btrueblood who brought up the contamination issue, they just reminded me that I had read an article on contamination at a mine site near Marmora a long time ago.

I really do hope that the project gets the go ahead, Marmora and area could use the jobs. My pet peeve lies with journalists who are incapable of getting the facts straight. I also get a little annoyed with everyone labeling their projects as green, but that's a minor beef.

RE: Engineering is heading towards perpetual motion machines

soo... maybe I haven't read carefully enough, or thought enough about the comments above to understand what's meant by a negative efficiency...

RE: Engineering is heading towards perpetual motion machines

"Agenda much?"

Sorry, Greg, but yes.  Poorly planned use of crappy sites is what does in a lot of projects, usually way too late to do much about it.  Too often, the current owner is just looking for any available dodge to get out from under EPA/Bureau of Mines or whatever your country's equivalent laws regarding mine reclamation are.

No huhu from me about pumped hydro storage, frankly it's the best megawatt storage idea I've seen with any merit and will, implemented properly, be an enabling technology for solar, wind and other renewable source energy production schemes.

 

RE: Engineering is heading towards perpetual motion machines

Negative efficiency.  It's a pretty simple concept really.  I'm surprised it needs any explanation.

You see on the one hand you've got your energy in.  And on the other hand you've got your energy out.

Then you see.....uhm....well the ratio or energy out to energy in.....errr.....

And of course there are losses inherent in the process that ..... ahhhh.....

And anyway, lot's of numbers less than 1 are negative.  Yeah, that's it.

RE: Engineering is heading towards perpetual motion machines

Btb, yes that's a reasonable comment, mine was aimed at the OP who seems to be looking for any stick with which  to bash the project. When people pointed out that pumped water electricity storage is actually a good idea he then went off on another tack.  

Cheers

Greg Locock


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RE: Engineering is heading towards perpetual motion machines

Dunno, I personally wouldn't be pumping vast quantities of water anywhere near a project with arsenic contamination.  The water will go places it shouldn't- rain and snow will ensure that.

Properly designed and implemented, I have no problem with pumped water storage.  The trouble with using an old mine site is that the temptation to do this wrong to save money and get a quicker payback will be great.

RE: Engineering is heading towards perpetual motion machines

I don't think the OP was trying to "bash the project", just correct the falicy in the article that this project would be generating more energy than it was consuming.  I was the first to indicate that there may be potential issues of using a mine for water storage (e.g., potential contamination issues).  I didn't have any "Agenda" other than to bring up a potential issue that should be considered in this design.

I think a lot of current environmental problems could have been prevented if someone had taken a little time to consider the environmental impacts during the design phase.  

---

A thought just occurred to me.  Could there be potential structural problems associated with filling the mine with water?  Depending upon the characteristics of the geology and the structural support of the mine itself, could flooding of the mine result in problems?

RE: Engineering is heading towards perpetual motion machines

molten,

Don't disagree with that, but if the pit is currently open, and the tailings uncapped, then a good thing can be accomplished.  First adding sealing to the pit, and building a berm from tailing pile and capping it, could remediate the site and provide a pumped hydro storage project in a single go, which accomplishes two good things from what was a bad one.

RE: Engineering is heading towards perpetual motion machines

btrueblood:  true enough- provided the project is designed AND implemented properly.  The trouble is, the more money you spend on doing those good things, the longer the payback on the project will be.  The temptation to cut corners will be very high indeed.

RE: Engineering is heading towards perpetual motion machines

Maybe I missed something, but are you proposing to seal the mine?
I believe an old mine will emit gas, which must be allowed to escape.

Filling an old mine with water will allow the gas to escape, but the water usually won't stay in the mine. It will seep to other places, unless there is a containment in the mine, which at the volumes of water you are talking about can be quite expencive.

RE: Engineering is heading towards perpetual motion machines

(OP)
Ha ha! Thanks Yagonyonok I needed a laugh, that was fantastic.  

RE: Engineering is heading towards perpetual motion machines

Ah yes, fuel less flight.  They actually have some interesting points on buoyancy when you look into it, I just think they don't seem to properly take into account the energy used to alter the buoyancy.

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RE: Engineering is heading towards perpetual motion machines

of course there are gravity powered airplanes ... the space shuttle, gliders, B767s and A330s (on occassion), ... the energy tends to be pretty easy to spend, but expensive to buy, and problems sometimes arise when you run out of it ... you're either at your arrival gate or at the bottom of a smoking hole.

RE: Engineering is heading towards perpetual motion machines

Cranky,

Yes, seal the mine, via a clay seal layer, concrete, geo-membrane, something impermeable to water so you don't get mine-contaminated water leaching to places you wouldn't want it.  Also keeps the water where you do want, i.e. inside the reservoir.  Your question makes it seem that you think this is a shaft mine, but it's an open pit according to the op.  Quite a bit simpler to seal.

Old mines (and construction sites too) "generate gas" mostly due to oxidation of exposed rocks.  Stop the oxygen, you stop (most) of the noxious gas formation.  Some mines (esp. coal) also seep natural gas, but this happens most quickly when the mine is first dug, and decays over time.  Some coal mine reclamation includes a gas vent system, but more commonly the gas is left to find its own way out.  Once the coal is mined out, there really isn't much natural gas left anyway.

RE: Engineering is heading towards perpetual motion machines

Thanks for updating me. I have heard of salt mines that were sealed, exploding, then imploding (exploding as in seapage turning to gas exit). Open pit would be easer to seal, and a water feature would be much than building houses on it (like I have seen also). It would also keep rain water from collecting the minerals and washing them into the water table.

I actually thought mines produce gas because of gas movement in the rocks. But it makes since that the decay of coal, however I don't know where the hydrogen comes from.

RE: Engineering is heading towards perpetual motion machines

(OP)
Cranky108,

Just a guess, but it could be that hydrogen comes from iron and water becoming rust:

Fe2+ + 2 H2O ⇌ Fe(OH)2 + 2 H+
Fe3+ + 3 H2O ⇌ Fe(OH)3 + 3 H+

It comes to mind because I read a lessons learned on how a confined space may become oxygen depleted from the rapid formation of rust (slightly different reaction but a reminder of chemical processes).

RE: Engineering is heading towards perpetual motion machines

My question wasen't the chemical processes so much, but I was thinking coal mines as being dry, and therefore a lack of water to react. (under ground mines). This true of salt mines, as the salt would become moble if hydrated.

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