Live data from Hacker News

MIT engineers create an energy-storing supercapacitor from ancient materials

news.mit.edu

21–30 of 101 posts

Re: MIT engineers create an energy-storing supercapacitor from ancient materials

#21
post #6

So i get the electrolyte, but how does this polarize?

By splitting the cube in 2 :) But that would kind of ruin the press release so it's not mentioned. Also, the paper itself mentions no houses nor foundations nor other shit like that. That's only in the press release.

Re: MIT engineers create an energy-storing supercapacitor from ancient materials

#22
> The team calculated that a block of nanocarbon-black-doped concrete that is 45 cubic meters (or yards) in size — equivalent to a cube about 3.5 meters across — would have enough capacity to store about 10 kilowatt-hours of energy, which is considered the average daily electricity usage for a household.

Edit: 10kwh/3.5³m³ ≈ 0.233 Wh/l

> Besides its ability to store energy in the form of supercapacitors, the same kind of concrete mixture can be used as a heating system, by simply applying electricity to the carbon-laced concrete.

Re: MIT engineers create an energy-storing supercapacitor from ancient materials

#23
post #22

> The team calculated that a block of nanocarbon-black-doped concrete that is 45 cubic meters (or yards) in size — equivalent to a cube about 3.5 meters across — would have enough capacity to store about 10 kilowatt-hours of energy, which is considered the average daily electricity usage for a household. Edit: 10kwh/3.5³m³ ≈ 0.233 Wh/l > Besides its ability to store energy in the form of supercapacitors, the same kin…

> 10 kilowatt-hours of energy, which is considered the average daily electricity usage for a household.

Excluding heating.

Re: MIT engineers create an energy-storing supercapacitor from ancient materials

#25
post #16

Earlier quoted context omitted.

It isn't. Even with pumping water up hill and letting it flow down, which is far easier and more efficient, there just isn't the land, elevation, and water for the scale we need.

This is one of those sort-of hyperbolic put downs which goes to "we need" encompassing the entire western worlds power requirements. No, you can't replace all existing power sources now and into the future by pumped hydro. Pumped hydro has a massive role to play in power supply, time shifting electricity from renewable sources, providing system resiliency, black start, inductive and inertial load, you-name-it. It als…

I’ve always wanted to ask someone who knew something about this stuff if this idea is feasible:

Imagine a giant empty bucket held high in the air. As it rains, the bucket fills and using a counter-weight it slowly lowers down to ground level. Now the bucket is covered and the water is slowly drained causing the counter-weight to lower to the ground and the bucket to rise in the air again.

If this were geared properly, could energy be generated in any meaningful amount?

Re: MIT engineers create an energy-storing supercapacitor from ancient materials

#26
post #19
post #13

Typical university press release: this technology can revolutionize our energy grid by storing energy in a building’s foundation, because we powered an LED with some tiny cells we made.

I thought the same thing, so I went and looked at the paper, and unfortunately, the paper itself has some of these kind of speculative claims as well.

Unpopular opinion, most of MIT's research claims are preposterous and can be safely ignored. Their undergraduate education is quite good, but the research output is quite shoddy. The only exception is their computational photography group (Fredo Durand) is pretty legit.

Re: MIT engineers create an energy-storing supercapacitor from ancient materials

#27
Harnessing the entropic properties of bulk matter, easily ending up with molecular self assembly, without the need for micromanaging the process--genius!

The team calculated that a block of nanocarbon-black-doped concrete that is 45 cubic meters (or yards) in size — equivalent to a cube about 3.5 meters across — would have enough capacity to store about 10 kilowatt-hours of energy, which is considered the average daily electricity usage for a household. Since the concrete would retain its strength, a house with a foundation made of this material could store a day’s worth of energy produced by solar panels or windmills and allow it to be used whenever it’s needed. And, supercapacitors can be charged and discharged much more rapidly than batteries.

What I'm wondering is how to create a lightning battery with this? Unless my math is wrong (probably is) 1 lightning strike is

  1 zeus = 1 billion joules = 300 kwh. 

  1 big-cube = 45m^3 = 10 kwh

  density = 10/45 kwh/m^3

  volume needed to bottle lightning = 300kwh * 45/10m^3/kwh  = 1350m^3

  cube of sides 12m. or sphere of diameter 14m
So, what I'm proposing is, we get a 60m high copper pole, stick it in a 14m diameter sphere of this, and put it in a rainstorm.

Bottle of lightning?

Re: MIT engineers create an energy-storing supercapacitor from ancient materials

#28

Seems to me that the potential of simply lifting a weight up (storage) and down (generation) beats these fancy engineering goals for cost and practicality. Especially if the weight being lifted is a container full of rocks. At first glance there are plenty of those everywhere. No hills or reservoirs needed either. Of course, no papers need to be published ... that may be the goal.

Unfortunately lifting weights is extremely efficient and low energy endeavor. So it makes a really shitty density wise storage.

Re: MIT engineers create an energy-storing supercapacitor from ancient materials

#29

Seems to me that the potential of simply lifting a weight up (storage) and down (generation) beats these fancy engineering goals for cost and practicality. Especially if the weight being lifted is a container full of rocks. At first glance there are plenty of those everywhere. No hills or reservoirs needed either. Of course, no papers need to be published ... that may be the goal.

To estimate the cost and practicality, assume you build a tower 120 meters tall and machinery able to lift 60 tons block of concrete to the top, then retrieve the stored energy by lowering it to the ground level. Think for a moment how much that would cost. Then calculate: mgh = 60000kg x 120m x 10m/s^2 (assume acceleration of gravity is 10m/s^2 for simplicity, no energy losses due to friction etc). The result is 72 million joules. That is 20 kilowatt-hours, about two days of a single household electricity usage.

Re: MIT engineers create an energy-storing supercapacitor from ancient materials

#30
post #16

Earlier quoted context omitted.

This is one of those sort-of hyperbolic put downs which goes to "we need" encompassing the entire western worlds power requirements. No, you can't replace all existing power sources now and into the future by pumped hydro. Pumped hydro has a massive role to play in power supply, time shifting electricity from renewable sources, providing system resiliency, black start, inductive and inertial load, you-name-it. It als…

I’ve always wanted to ask someone who knew something about this stuff if this idea is feasible: Imagine a giant empty bucket held high in the air. As it rains, the bucket fills and using a counter-weight it slowly lowers down to ground level. Now the bucket is covered and the water is slowly drained causing the counter-weight to lower to the ground and the bucket to rise in the air again. If this were geared properly…

Nowhere rains enough for that; hydro dams only manage it by having a huge catchment area nobody needs to build.

Highest rainfall in a year:

> 26,470 mm (1,042 in); Cherrapunji, Meghalaya, India, 1860–1861

https://en.wikipedia.org/wiki/List_of_weather_records

26.4 tons * 1km * 9.8m/s/s / 1 year = 7.4 watts

Post reply on HN