111–118 of 118 posts
Earlier quoted context omitted.
I took those things m, and I’m a successful software engineer and founder with an exit. I can never remember anything but joules for energy. Which I think doesn’t matter? And my RV has amp-hours? No fucking idea.
But are you writing articles about the topic?
Earlier quoted context omitted.
> Potential energy, U = mgh. So the energy required to raise 1m^3 of sand 1400m is 1600 x 1400 x 9.8 = 22MJ = 6.1kWh If you lowered 10 m^3 of sand (61kWh of potential energy), to generate the minimum 100kW power to participate in grid stabilization markets, you'd have to drop that 16000kg of sand for 61kWh/100kW = 0.61hr = 2196 sec. 1400 meters in 2196 seconds is 0.64 m/sec. That seems reasonable, but you'd need a lo…
I've participated in grid stabilization in Switzerland (ancillary services), and 100kW is absolutely nothing. As far as I recall, 10 years ago, the minimum needed to become a participant was 10MW
However, having the lower minimum has the advantage of allowing smaller firms to participate (i.e. companies controlling 100s of electric water heaters), instead of just massive utilities.
Earlier quoted context omitted.
Exactly one reservoir (or a number of tiny ones not worth mentioning), because even all the way from Richland to Portland there is hardly any elevation drop.
PS: oh, you meant reservoirs in contributory valleys left and right of the main river. Sorry about the misread, "above and along" should have been clear enough.
This is because dams are very expensive, have height limitations, and some inherent risk. Hover dam is only ~200 meters high. The big hydro storage projects have height changes ~400 meters.
Isn't there a better article? - 2 MW of energy MW is a unit of power not energy, maybe they mean 2 MWh, but if that's the case, it is a joke. That's like 30 Teslas cars, or half of a Tesla Megapack, which is a shipping container sized battery. 2 MW of power is not that big either, that's about what you get from a typical wind turbine. - 70TWh of energy At least, we have a proper unit, but I wish they tell us a bit mo…
>Future GraviStores will store more than 20MWh https://www.marketscreener.com/quote/stock/ABB-LTD-9365000/n...
Another completely misleading article on gravity batteries. All the solid weight stuff is bunk, probably designed to suck out money from naive investors / corrupt state officials. Moving solid weights gives only a very small electric power, so building the proposed solid weight batteries gives units of MW at most, which is uneconomical. Unless it transports a large lake of water up and down a hill like in pumped-stor…
Isn't there a better article? - 2 MW of energy MW is a unit of power not energy, maybe they mean 2 MWh, but if that's the case, it is a joke. That's like 30 Teslas cars, or half of a Tesla Megapack, which is a shipping container sized battery. 2 MW of power is not that big either, that's about what you get from a typical wind turbine. - 70TWh of energy At least, we have a proper unit, but I wish they tell us a bit mo…
>Isn't there a better article? >maybe they mean 2 MWh, but if that's the case, it is a joke. There are tons of equally bad articles about this story, which is sad to see. Quality journalism might not be dead but it sure is outnumbered! However, reading about the proposed mechanism I might charitably interpret it as being able to deliver 2MW peak power, for however long it has available sand. So an interesting aspect…
Were going to read how this is an unsuccessful endeavor in about 5 years. I haven't seen a lot of great reports on gravity batteries. I wish something like this was highly viable and succesful. Seems like a great simple solution.
Earlier quoted context omitted.
There was recently an article here about an electric truck that never needs charging. It drives up a hill, collects a load of rock from the mine there, and by the time it has driven back down with the heavy load, regenerative breaking has recharged the battery.
While that makes perfect sense, I have read journalists claiming that Teslas were 110% efficient because of regenerative braking.