Comments by "mpetersen6" (@mpetersen6) on "Dunkelflaute: No Wind, No Sun, Now What?" video.

For all the hype about battery banks etc I find I am more in favor of mechanical storage systems. One reason is they are already developed. These break down into two types. The first is flywheels. I'm sure there is room for improving efficiency but they are a currently (no pun intended) available technology. The second is gravity batteries. Today this mostly means pumped hydro. But pumped hydro isn't going to work in all locations. Either because of the topography. Or simply because the excess water might not be available. Another type of gravity battery is simply a large mass turning a generator as it falls. And no I do not mean that idiotic idea they were demonstrating in Switzerland. Instead have a tower enclosing 4 vertical shafts. In the shafts you have a box containing say 500 metric tons of sand. 1 million kg. That's around 1600kg per cubic meter. 625 cubic meters of sand. In a box 8.5 meters on a side. Build your tower whatever height you want. Install your motor/generator set not at the top of the shaft as in an elevator installation. But at or bear ground level. It just makes servicing easier. OK, you now you have four shafts grouped together in a square 20 to 30 meters on a side. If you build this in an urban center wrap the tower with office space, shops, apartments, what ever. These offer rental income. Is it elegant? Maybe not. But at say 50% efficiency I could live with that. Hell, even at 25% it looks attractive. How much energy would be stored in 500 metric tons raised to a height of 100 meters. The only other potential battery system I can see that is possible to put into widespread use is some sort of Thermal Battery. For home or individual apartment energy storage one idea that sounds good provided it works out is the iron/air battery. It offers the possibility of an individual battery about the size of a standard washing machine being able to provide power for up to 60 hours.
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The best way to reduce demand is through increased efficiency. Telling or forcing people to reduce their standard of living can cause a certain amount of pushback. Plus this is a problem we need to solve. Energy usage in developing countries is going to increase. Or do we tell those people. Sorry its eternal poverty for you.
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@31ofranz The only reliable ways to decrease a societies energy usage in all forms is either through 1) an absolute dictatorship or 2) population reduction. There are ways we should be reducing our energy usage. Number one is efficiency. But there is only so much to gain there in terms of electricity use. And as more and more EVs get registered electricity needs will go up. If a region has rolling brownouts or blackouts now. It doesn't take a genius to understand what happens when you add EVs into the mix. The other major energy field where we can see reduced energy usage is in structure heating and or cooling. Any one who owns their own home or has rental property where they are paying the bill even if the renters covers covers the cost. They are foolish if they don't do more to weatherize their homes. Personally I think building codes should be changed to require new construction to be built to such standards that heating and cooling costs are reduced.
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@RaphaelBraun The energy required for mining and processing materials. One figure I've seen is for a 1000 lbs battery pack for an EV you need to process about 500,000 lbs of raw materials.
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@hubbsllc Worth doing? Hell, I dont know. Can we realistically build enough actual battery storage facilities along with all of the batteries that would be required to replace all of the current ICE powered cars and trucks. Is society willing to accept the mining that might be needed to supply all the rare earth materials required. If we go full on renewables are we going to be willing to devote the required space to the Solaror wind farms needed. I suspect that if you proposed a very large Solar facility in the deserts of the American Southwest there would be some group willing to file lawsuits to stop it. In reality we do not suffer from a lack of available energy sources. I would prefer to see us move away from fossil fuels as it becomes feasible.
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I'm going to throw out why aren't we using more geothermal. Pretty much inexhaustable on a geologic timeline. Also in terms of Solar what about Ocean Thermal facilities that use the temperature differential between surface and deeper water to generate power. If we don't use them for onshore power what about using it for desalination plants?
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Pumped hydro is great in the right setting. In reality is nothing but a hydro electric facility were you fill it during low demand hours. But you need the right topography (and the water). In some settings it might require enclosed basins. In areas along sea coasts or even large inland bodies of water water is not an issue. I think the idea of gravity batteries has merit. And that's what pumped hydro is. A gravity battery. While the idea of massive banks of chemical batteries sounds elegant. To me it sounds like an environmental disaster from the production and recycling standpoint. Plus what would the operating life be? Myself I would rather see a brute force approach using simple technologies. Using standardized designs would allow a gravity battery employing large masses. Say 500 metric tons of sand. Doing so would mean we could build these basically on an assembly line using modular components. 500 metric tons of sand is a cube roughly 8.55 meters on a side (1). Sand is cheap (any readily available mass could used). Steel is relatively cheap. Enclose the box containing the sand in basically an elevator shaft. Group four shafts together. Install the lifting motor and generators at ground level. It makes servicing easier. The four shafts form a square say 20 meters on a side. If built in or near an urban area wrap the exterior with office space, shops or living space. This provides an extra revenue source. Is this the most efficient thing we could do. Maybe not. But what would the potential operating life of such a system be.
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@hubbsllc The main point I was driving at (poorly) was if we were to use gravity batteries include them into structures we are already building. Or could be building.
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For a solid mass driven gravity battery it would make far more sense to use a moderate to higher density material in large box in an enclosed shaft. 500 metric tons of sand would fit in a cube roughly 8.55 meters on a side. The idea with all the individual blocks is idiotic. Sand is 1520 to 1680 kg per cubic meter. Install your gravity batteries in the interior of urban high rises. Say four per building. Wrap the exterior with office space, shops and residential. You get an extra income stream from the exterior space. The lifting and generating machinery you install at or near ground level. It makes servicing easier.
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