111–120 of 135 posts
Why not use excess energy to lift millions of tons of worthless rock off the ground and then when power source fails, use the winding down via gravity to turn generators? Gravity is never going away and never going to run out.
More details: http://physics.ucsd.edu/do-the-math/2011/11/pump-up-the-stor...
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When you cool the air by mixing it with water spray, a good portion of the energy is now spent producing low temperature water vapour. So... how do you recover that energy? You'd need to condense the water vapour to get at the latent heat. And if you do recover the heat by condensing this vapour, it is low grade heat, which CANNOT be efficiently converted back to mechanical power or electricity. Your web site claims…
Sorry! This is a very subtle process. If you analyze it superficially, it makes sense, dig deeper and it's confusing, and then dig still deeper and it makes sense again. When you cool the air by mixing it with water spray, a good portion of the energy is now spent producing low temperature water vapour. So... how do you recover that energy? You'd need to condense the water vapour to get at the latent heat. You're rig…
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As I read it, in the proposed system the heat generated during compression is stored, and then recovered, hence the advantage over the plain old air compression. But I'm going to be that guy who says it will not work, and cannot work, based on fundamental thermodynamic theory. Here goes: 1. The best efficiency of a thermodynamic cycle is 1-TL/TH, where TL is the temperature of heat rejection from the cycle, and TH is…
Consider a big Carnot cycle. It's 100% reversible -- as efficient as you can get. No losses. And it's 100% reversible no matter what temperature it operates at. The Carnot cycle is: 1. Isothermal compression (T_c) 2. Adiabatic compression (T_c -> T_h) 3. Isothermal expansion (T_h) 4. Adiabatic expansion. (T_h -> T_c) The adiabatic compression and expansion processes are just to get between the two temperatures, T_hot…
Earlier quoted context omitted.
When you cool the air by mixing it with water spray, a good portion of the energy is now spent producing low temperature water vapour. So... how do you recover that energy? You'd need to condense the water vapour to get at the latent heat. And if you do recover the heat by condensing this vapour, it is low grade heat, which CANNOT be efficiently converted back to mechanical power or electricity. Your web site claims…
Sorry! This is a very subtle process. If you analyze it superficially, it makes sense, dig deeper and it's confusing, and then dig still deeper and it makes sense again. When you cool the air by mixing it with water spray, a good portion of the energy is now spent producing low temperature water vapour. So... how do you recover that energy? You'd need to condense the water vapour to get at the latent heat. You're rig…
This seems like a really smart feat of thermodynamical engineering, but it does not reference explicitly any technology that would not have been available 30 years ago. I could imagine that being hidden in the subtitles of getting the process efficient enough - e.g. in computer-based component design and CFD simulations.
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Here's one: http://daniellefong.com/2010/02/11/how-law-shapes-the-busine...
I'm surprised at the difficulty I have in convincing people that eliminating the FDA is a good idea. The FDA makes the build-compile-run cycle in medicine 10x longer and more expensive. That's a mighty brake on technological progress.
I just don't see how we can circumvent RCTs as the burden of proof for efficacy and safety. Probably, yes, we could slash a lot of fat from the FDA, and trim a lot of processes... But do away with it entirely?
I would be interested to hear what your alternatives are
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> Once you exit the software bubble, almost everything, especially new technology, becomes a lot "harder" and takes a lot longer. I've done hardware in spades, so I'm well aware of the differences. In hardware, Series D was either a Mezzanine round or a something-has-gone-wrong = inside/major-dilution round Maybe the world has changed, but having no product at D is not a sign that things are going well on the biz sid…
If you are a consumer hardware company, yes. If you're on the edges of what we as humans know to be possible, it can take far beyond Series D to get there. If you look at the early telecoms, they were essentially series Z with the government before becoming accessible. If you're talking about anything that has impact on utility scale power or anything else on a massive scale, series D is just the beginning. LightSail…
No I was referring to enterprise, and when it comes down to it, pretty much all VC funded operations. The nuts and bolts of the way VC funds are structured make it necessary to pretty much have the company investment resolved in about 8 years. (Typical funds are LLCs limited to 10 year frames.) Each round should last 1.5-2 yrs. If you are at D with no product, then your A round is up a creek.
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I'm surprised at the difficulty I have in convincing people that eliminating the FDA is a good idea. The FDA makes the build-compile-run cycle in medicine 10x longer and more expensive. That's a mighty brake on technological progress.
It's one thing to say that the FDA stands in the way of progress in medicine, however what regulatory framework would you suggest be put in its place to protect consumers if it was removed? I would argue that the break is not on technological progress, (I could scarcely imagine it possible that 10, or even 5 years of current progress could be achieved in 1, as you imply) - but in the practical application of these ad…
1) Opt-out. Allow anyone to opt-out of the FDA. That is, allow terminal patients/early adopters/test pilots to voluntarily buy products from companies before the FDA certifies them as safe and effective. For example, people might decide that they will use drugs that have cleared Phase I trials and proven safe, and use their own judgment for whether the drug is effective. Essentially this is a rollback of cases like Cowan vs. United States, a 1998 case in which the FDA sued to prevent a terminal AIDS patient from using a drug that they had not yet approved:
2) Multiple regulators. The purpose of sites like Metacritic or Rotten Tomatoes is that any one reviewer is flawed, but an aggregate will usually be better. But for most drugs and devices, only a very small number of people within the FDA plus perhaps a 15 person expert panel are involved. FDA does not have the internal expertise to evaluate all fields of medicine, so frequently gets outside experts from Harvard Medical School, the Mayo Clinic, and the like to serve on its panels. Here is an example where the chair is from Mayo:
The multiple regulators concept would allow any of these institutions to certify drugs and devices, just as we allow multiple medical schools to certify MDs. As another analogy, a company rejected by one regulator can get a second opinion from another, just as academics can submit to multiple journals if the first one rejects a paper. Indeed, much FDA review is already subcontracted out to expert panels from these institutions anyway. In return for doing approvals, Harvard Med or Mayo would get the user fees authorized under PDUFA/MDUFA that would otherwise go to FDA. People could wait for a drug to be approved by the FDA, or they could take a drug which had Harvard Medical School's stamp of approval.
These two proposals - opt-out and multiple regulators - are relatively simple to implement yet will cause huge changes in the system.
Right now we have a crude version of both in that a wealthy patient can opt-out of the FDA by flying to Europe, and a company can to some extent have multiple regulators by going for the EU's CE Mark first rather than the FDA. Indeed, within the medical devices space they now say "Europe first" just like internet startups today say "mobile first".
But it would be better if a patient could opt-out without flying to another country, and a company could get a second opinion from a different regulator without launching outside the US.
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> Your calculations appear be within an order of magnitude of correct Being within an order of magnitude is absolutely fantastic for a quick set of calcs with unverified data pulled out of various 'net sites! So, about 6,000psi for 1m^3 ? I was just looking at this: http://www.nuvair.com/storage-storagetank.shtml Their NUVT6000 tanks will do it. Specs: Outside diameter: 9.4in Height: 52in Weight (empty): 195lbs. Air…
We get a higher energy density per m^3 of air at higher pressures. We were aiming at 4500 psi eventually. We aim for it not to be noisy -- any noise from high pressure air rushing out represents wasted energy. Sonic booms from exhaust have this problem in automobile engines, we avoid it. Lithium ion is indeed much more dense :-) Consider that every car has a gasoline tank, many houses have fuel oil, and we undergird…
There's a reason most (recreational) scuba tanks stop around 3000 - 3500 PSI max working pressure: you fairly quickly stop getting linear gains, at the expense of additional tank wall thickness and stronger valves required.
Edit: Nevermind, it appears that 4500 PSI/300 BAR is semi-standard in Compressed Air Powered cars, so I guess there is value in going to that pressure (storage density I guess).