This is either one of those ideas so breathtakingly simple it's mental than no-one has done it already, or it's got some 'orrible fundamental flaw.
Essentially, the Gravitricity system is a huge ‘clock weight’. A cylindrical weight of up to 3000 tonnes is suspended in a deep shaft by a number of synthetic ropes each of which is engaged with a winch capable of lifting its share of the weight. Electrical power is then absorbed or generated by raising or lowering the weight. The weight is guided by a system of tensioned guide wires (patents applied for) to prevent it from swinging and damaging the shaft. The winch system can be accurately controlled through the electrical drives to keep the weight stable in the hole.
The key requirement is a deep hole in the ground; it can be a disused mineshaft brought back into use, or a purpose-sunk shaft. Shaft depths can be from 150m for new shafts down to 1500m for existing mines. The biggest single cost is the hole, and initially we will prove the technology using existing mine shafts. As our technology costs decrease, the costs of drilling will reduce significantly, opening the opportunity for purpose-built shafts.
Sounds like a much better use of the Boring Company's resources than hyperloops or flamethrowers.
Over the 12 months from January 2018 we will be undertaking sub-system design and deploying a 250kW concept demonstrator. We aim to trial our first full-scale prototype in 2019 or 2020 at a disused mine in the UK.
https://www.gravitricity.com/
Well, the big question is that hole in the ground. Similar systems use rail cars running along rails above ground on an incline. Same basic principle, but without the expense of digging a deep hole in the ground.
ReplyDeleteinterestingengineering.com - These Concrete Gravity Trains May Solve the Energy Storage Problem
This is a simple extension of the pumping of water up the hill into a reservoir, then letting it flow back down, past a turbine.
ReplyDeleteen.wikipedia.org - Pumped-storage hydroelectricity - Wikipedia
There have been all sorts of variations on this scheme, over the years.
They themselves are pretty clear what the big disadvantage is: Response time "<1s". Fast response means a lot of strain on the cables. The other is that it's storage only; A hydroelectric plant is both storage and production, so in a place with stable supply might not see a lot of use during its 50 year life span. But this is changing with more solar and wind power.
ReplyDeleteIt occurs to me that the amount of digging required could be vastly reduced by using a narrow shaft, possibly with a larger diameter hole at the bottom. That way, a weight chain could "pool" at the bottom.
ReplyDeleteI wonder if it could be combined with the hot rocks idea, at least for a few decades ? Seems to me that a narrow shaft is going to have a much smaller impact than rails or hydro.
ReplyDeleteRhys Taylor I'm not sure any mechanical system can achieve the efficiency of a battery recharging scheme. We've looked at the equations, it's really tough.
ReplyDeleteWhen my father and I were doing solar panel work in the Sahel, we worked out this scheme as follows:
The sun comes up, the solar panels run a DC motor at the bottom of a covered well, filling an elevated water tank. A float valve shunts the current to a charging unit, recharging a number of deep cycle truck/marine batteries wired up in series. When the batteries are charged, the current shunts to ground. A water distiller provided water to keep the batteries topped up.
The alpha rationale for this setup was to keep vaccines cold. Maintaining a cold chain. The batteries lit a schoolroom at night: people would come in from the farm work, especially children, and get an education.
There's a whole family of electrical appliances built to run on this sort of setup with DC power, but you can also put on an inverter and run AC appliances.
We did have one setup which failed: despite training the people, they forgot to keep the batteries topped up with distilled water. Africa's like that....
I've often wondered if I could do a molten salt storage setup, that looks pretty good, with the new MIT barrier, but that's a big undertaking, about which I know nothing.
Check out a company called 1414 degrees from Adelaide who are doing a molten substance energy storage.
ReplyDeleteYou can get a gravtricity powered light at Wallmart.
ReplyDeletehttps://www.walmart.com/ip/GravityLight-Self-Powered-Portable-Hanging-Lamp/601441565
walmart.com - GravityLight Self Powered Portable Hanging Lamp