🎉 Hoodie Giveaway Winners 🎉

Thanks to everyone who took part – I’ve now randomly selected the 10 winners:

@lorenzoventura7701
@neilgarcia9127
@mikaellinberger6645
@angelaanderson2662
@marsupialdungbucket
@annieellison2046
@joshMorland
@catherinegreen8440
@rivmey
@michaelreid2329

If you’re on this list, congratulations! Please email me at daveb@justhaveathink.com within 28 days, quoting your YouTube handle, so I can arrange delivery.

Thanks again to everyone who entered – really appreciate the support for the channel 👍

I was a mining engineer in the UK coal industry for a while, and can add a bit of detail.  1) a lot of coal mines have salinity (geological water much saltier than seawater) or acidity (due to varioius factors, mainly pyrites) issues that corrode steel very quickly and the idea of somehow puming water in and out of an old coal mine just on this basis alone is a bit crazy.  2) There are also issues with methane production - which in certain ranges is highly explosive - and so pumping air into old workings can easily dilute the accumulated gases into explosive range.  Then you mix the fresh air with methane and low/zero oxygen air and it is a big safety hazard when it's released back out again.   3) most old coal mines in the UK have had their shafts infilled, capped and sealed - and are not retrievable.  Maybe a few of the newer concrete shafts such as at Maltby might be in good enough condition or be capable of refurbishment to be suitable for gravity systems - I'm guessing at about 20 remaining shafts..?  Just from a geological perspective, I would be looking more at Boulby (if it ever closes as a mine) or deep salt mines - which are far more common in Europe.  I was quite excited when I saw gravity storage in old mine shafts being proposed recently, but the fact is the UK doesn't have many sites left that would suit.  4) If you pump compressed air into an old coal mine, it's as like as not going to push polluting water into places you don't want it to go.  Compressed air into cornish (hard rock) mines will as like as not just exit in the next valley through another abandoned mine or forgotten verntilation shaft.  Underground stone mines might be good for low pressure compressed air (they are mostly too shallow for medium or high pressure) - but are also used as office space for the armed forces, and so I'm not sure how much (if any) would be available.  It's only old hard rock mines (mainly cornwall) and old stone mines (mainly round Bath) or old lead mines (such as speedwell cavern or maybe the old mine at Strontian) that allow even the slightest possibility of someone going in and doing work away from the shaft.

I like that this channel gives factual information instead of hype, thank you.

Oh my! 700K, congratulations sir!

Was always totally bonkers. Living in an area that has lots of old mines they are all capped, uncapping them is a nightmare because of gas emissions and water entry causing a whole new load of pollution.

Flooding abandoned coal mines in West Virginia has resulted in contaminated ground water and streams..

As a mechanical/aerospace engineer I think it would be really helpful for folks to have at least a very basic understanding of the energy content of things, especially fluids, so they can grasp the difficulties of any mechanical thing or heat engine. Especially when we are talking about compressing and expanding gasses.  The concept of enthalpy and how it relates to a gas’s temperature and pressure and the ability to get work out of it is super important.
People also need to know about losses. The amount of energy lost in just two meshing gears is very non-zero. Add a whole bunch of them and it is almost trivial to lose 10% of input power to waste heat.  The same goes for things like chain drives, rubber belts, gas seals, not to mention the power demands of the systems to remove this heat. When you look at and compare how different systems generate waste heat across their whole life cycle the variations are truly astonishing. Just moving oil from the ground to the refinery is a huge loss. The losses at refineries are also staggering.  The overall transport energy for even pipelines is pretty amazing. But it’s invisible.  

We should all know that anything that forces a whole bunch of mechanisms, pumps, turbines, heat engines of any kind, shafting, bearings, coolants, lube systems, and compels sustained long distance transport of anything at scale is inherently something to avoid. It should be seen as a short term compromise and nothing you want to do forever.  Depending on end use you might be seeing an end energy utility fraction below 10%. I know this sounds way too low but consider the overall end function. Most IC engines get 25% efficiency when operated at ideal conditions.  On a great day you might break 35%.  But this is almost never the case.  Much of the time you are halted and efficiency is zero. And there’s a drive train to consider. Complex multimesh transmissions, differential gearing, bearing losses, hysteresis in elastomers and parasitic loads that have nothing to do with moving your mass from A to B.  And behind all this is a huge infrastructure of spare parts manufacturing, distribution, warehousing and maintenance.  And that’s for a car. The costs and complexity to keep one jet aircraft running safely is astonishing. And don’t even ask how much cobalt there is in a modern high bypass turbofan engine. Your guilt at having an EV with a few kg will be at least slightly assuaged.
One of the most depressing moments as a student engineer is being first confronted with the Carnot efficiency.  It’s just so annoying. But, like poverty, it should focus the mind. At least a little bit. We should all internalize a bit of this stuff so we recognize the astonishing tools we do have with renewables.
We finished converting our 120 year old house and two cars to all electric/ induction/ geothermal heat pump and maxed out our solar and are ramping up our battery storage from 20 to 50 kWh. This utterly changes the energy landscape for us. Our energy costs are now pocket change. I wish everyone could access this technology.  The more of us that demand this the cheaper it’s gonna get. And that’s at least one step out of this hole we’ve dug.

Pumped hydro is a very old idea. The first steam engine used at a cotton mill in Manchester, so around 1780-90 was used as a pump for a pumped hydro system.  The pump took water from the basin below the mill’s water wheel and move it up to the header mill pond. When there was plenty of water in the river the mill ran on pure water power but the engine could keep sufficient head of water to power the mill in a summer dry spell.

A 10,000kg weight with 100m raised height only has 2.73kwh of potential energy.

In real life it would be even less with friction, generator inefficiency etc

I find it irritating that many countries give HUGE subsidies to fossil fuels and if they stopped that "100 year old continuously increasing habit" and put even half of those subsidies into coal mines as batteries and many other sustainable technologies, I suspect they would become far more feasible. Why should these newer technologies have to go it alone when disgustingly profitable industries have support in the region of billions of dollars EVERY year?

I feel a burning desire to help the algorithmic side of things.  Best wishes to you, JHaT.

If the energy of clicks could just be utilized...

There is a small geothermal industrial park sitting on top of old coal mines in Springhill, Nova Scotia, Canada.  The water that has filled the old mines is apparently quite warm, so buildings in the area can get cheap heating with ground source heat pumps.

I may be having a knee jerk reaction to repurposed coal mines but I think it’s worth mentioning that in addition to fouling the air, the extraction of coal also fouled the groundwater and in the case of strip mines, surface water as well. The potential for instability under new stresses such as the methods mentioned here sounds like a recipe for disaster frankly.

Among all the gravity solutions, it seems like the only tried-and-true one is pumped hydro. Still, gravity is a constant force, a constant source of energy, and it only makes sense to tap into it.

In the USA which is not so densely populated, there is plenty of potential for classic pumping hydro storage. No need for fancy extra solutions.

If this technology gets used to any significant extent it won't be in old coal mines. They are often in areas of unstable geology and are often full of dangerous gasses. Old coal mines usually have their shafts backfilled very soon after closure to make them safe so although there are a lot of them you would be hard pressed to find one that is realistically accessable.Old mines for some types of stone or ores are more likely to be cut into hard rock and are less prone to be full of dangerous gas, though many metals are toxic. Yes, this is going to be very site specific, so while I can envision this being used, it will remain a rareity.

A great follow up video could be comparing the efficiency of each system and looking at pump efficiency losses of pumped hydro; heat loss from compressed air; and motor loss from gravity storage. Then compare to battery charge/discharge.

Germany has a plan to use lignite opencast mines as pumped hydro reservoirs. The for just one (Garzweiler IIRC) ist estimated to be 0,5 TWh. And we have a lot more lignite opencast mines

"The therodynamics are pretty unforgiving" Nicely put!