Nuclear weapons aside (60-year-old technology that they are), our pinpoint weapons have allowed this "war" to be prosecuted with a lot fewer deaths on both sides than could have been done as recently as 1990. War with WPD (weapons of point destruction) is less deadly, and the only thing which would make it more so is a return to the WMD of the past.
One of the things preventing us from eliminating Iran and N. Korea as nuclear threats is the inability to neutralize their facilities without throwing up large amounts of fallout and killing many thousands downwind (not all of them enemy nationals either). If we were in a position to blow a hole in the ground and destroy their centrifuges and machine shops without contaminating the area with fission products, we'd be able to force the Teheran regime to blink.
My concern is that we use wisdom in the race to build bigger and better weapons. Do we REALLY need a weapon like this?
It's actually a smaller and better weapon, and I believe the answer is yes. Look at the difference between the damage in the bombing in Serbia and Iraq. Between those two we got the Joint Direct Attack Munition (JDAM), and our ability to put explosives onto a target with pinpoint accuracy got so good we could use one bomb where we used to need ten. We even got so good some folks found we could dispense with the explosive and just drop a steel shell full of concrete to kill a target like a tank.
I doubt we're going to see antimatter cheap enough to be more than a research material for decades, but when we can turn it into devices which make it impossible for anyone to field an army it essentially makes conventional warfare into suicide. Isn't that what you wanted?
Yes, but can you imagine putting a piston through the head because of overspeed... at 120 RPM? (I know you're kidding, but I want to make a point.)
That engine has a top speed of 102 RPM because it's direct drive. Direct drive eliminates the need for motor-generator sets and all the bulk, weight and cost people have been talking about above, but it also cuts the power output and increases the required size of the engine.
Other marine diesels seem to be designed to run at 600-1000 RPM. An engine running at 6x the speed can move 6x the air and fuel per unit of displacement, and thus could be about 1/6 the size and weight for the same power. This becomes even more lopsided for gas turbines; an 85 MW GE gas turbine is a tiny fraction of the size of the diesel of the same power, and an even tinier fraction of the weight.
I... concur that battery-powered vehicles are feasable when their role is limited to city commuting.
Then you read something I didn't say. I said this:
CalCars has been suggesting "depletion-mode" hybrids, which carry batteries both for surge power and regenerative braking as well as short-distance driving without using any fuel at all. If the average daily commute is 20 miles round trip, a mere 20 miles range on electricity would serve to eliminate petroleum consumption on a large fraction of all driving and take a big bite out of the fuel needs for the rest.
Note that this is potentially the first 20 or so miles of driving after every stop, whether on short trips or long, in cities or across Wyoming. There are people whose driving is mostly long trips, but they are outliers; a very large fraction of all driving is the first few tens of miles after a period of parking. All of the fuel consumed in that is potentially replaceable by electricity.
Your proposal in that Blade Runner discussion, however, is an efficiency play (in my previous efficiency/substitution taxonomy) whereas mine is more like a substitution.
Electric propulsion from overhead lines isn't substitution? It's also emissions and noise reduction, but that doesn't make it any less of the other things.
I would dispute that, because passenger vehicles consume most of the oil, that we should attack their consumption first. By that reasoning, word processors should have preceded mainframes, because typewriters vastly outnumbered corporate accounting offices in 1950.
Perhaps I was taking too much knowledge for granted, but I believe my proposal holds up in light of technological reality where yours does not. In 1950, it would have taken the cost of hundreds of typists to equal that of one computer. Today, hybrids are nearly economical at the US retail price of fuel and are no-brainers given most of the attempts to account for the fuel's full cost. Next, you can easily put the batteries for the typical 20-mile commute into a car without changing it much, but you can't do the same for even a 100-mile delivery in a semi let alone cross-country. Last, electrifying highways requires large infrastructure additions before it's useful and creates hazards and height restrictions which currently don't exist, and putting trucks on rails presents many similar challenges. Plug-in hybrid cars can be added one by one without changes beyond buying an extension cord.
I say a more appropriate figure of merit is how much oil we save per dollar of capital cost.
Why not TCO? I agree with your general concept but I doubt that the facts support your conclusion. We consume about 3.5 times as much gasoline as diesel, so even if you could substitute electricity for 100% of the diesel you still wouldn't achieve as much as you would with a 50% substitution of gasoline; the law of diminishing returns supports a push for passenger vehicles first.
I can't see how superconductors would change that equation at all.
Power/volume is proportional to dB/dt. The lower the frequency, the higher B(peak) has to be to get the same dB/dt. Superconductors can maintain a higher B field under the conditions (heat dissipation, etc.) of large motors, so you can get more power out of them.
Even if the superconductor carries more current, the magnetic material has the same basic flux energy storage capacity.
Superconductors let you run with air cores; even iron isn't much help once it has passed saturation. (The reason you use a core is to lower the resistance of the magnetic circuit and get a greater B field for a given amount of coil current. At saturation, that stops happening.)
... superconductors tend to lose superconductivity in strong magnetic fields.
They do; IIRC it's called "quenching". You just design your motor not to run at such high field strengths that it's a problem. MRI designers have the same issues, and they've solved them.
The Navy doesn't like diesels because they're too noisy for vehicles which chase submarines. The alternative is a gas turbine, which spins fast enough that you can make an acceptably small and light alternator without going to extreme materials; only when you need to drive a low-speed propellor do you really need the high-current capabilities of superconductors.
The technical explanation is that you can transfer a lot of power with a small, rapidly-varying magnetic field (like the itty-bitty toroid in your computer's power supply, running at 100 KHz instead of the 60 Hz power line frequency), but to transfer the same amount of power with a slowly-varying field needs a much bigger field, bigger currents and bigger losses. Superconductors get rid of the losses and can sustain bigger fields in a smaller package.
It's easier to get an eviction order and restraining order with a police report in your hand than a baseball bat. Also easier to sue for damages, etc.; if you use the bat on the wrong thing, you could find the tables turned on you.
There may be other uses for a baseball bat in the resolution of this matter, but I would not presume to offer advice. I'm sure our imaginations are up to the task.
In most places I've heard of, invasion of privacy is a crime; there have been numerous news items about people (mostly men) being prosecuted for putting cameras in restrooms and changing rooms. So go to the cops first. At the very least you'll get a police report out of it.
When we look at the capital costs changing infrastructure, the prospect of electrifying the transportation network doesn't look so bad. We can start with the railroads.
Which have you been reading, my comments or my blog? I wrote on that months ago, though from a somewhat different angle (plug-in hybrids rather than heavy transport) and again on the Blade Runner discussion. Passenger cars and light trucks use about twice as much fuel as heavy trucks, so it makes sense to hit cars first and hardest; however, as a means of getting rid of congestion on the roads, moving trucks onto electrified rails for all but local travel has big payoffs.
What you do is look at the things which will affect it and try to reproduce their effects. You can confirm your results by examining things which have been around for thousands or millions of years and see how the same influences have affected them; to the extent that they are similar to your test materials you can use them to confirm the results of your tests, and you can take un-aged specimens of the same stuff and subject them to your accelerated testing program to see how well it reproduces the results of time.
You still don't get it, there's no way to predict anything will be anything 200,000 years from now.
Earth will still be here, and the Sun will still be shining on it. Jupiter and Venus will still be some of the brightest objects in the night sky. And all intelligent life will still have nay-sayers with them.
(Yes, I'm going after misconceptions today. Don't interrupt, I'm on a roll.)
A hundred nuclear fission plants using the safer pebble technology and a really solid waste storage approach would go a long way to weaning the U.S. and its allies off the Wahhabi oil machine. They could generate hydrogen....
I keep seeing this misconception going around among technophiles, and I hate it. Hydrogen is more easily and cheaply generated from fossil fuels (natural gas or even coal) than it is from nuclear power, and hydrogen is extraordinarily difficult to use as a vehicle fuel. So difficult, AAMOF, that I'm certain that the Bush administration killed the PNGV and started the hydrogen car initiative just to make certain that nothing would be in a position to challenge oil in the next couple of decades (or at least nothing arising from US government programs). Then you have the problem of creating a big fraction of a trillion dollars of hydrogen infrastructure... you get the idea.
To use nuclear (and solar, and wind) power to displace oil, you need some way to use electricity in vehicles. Batteries and their cousins, regenerative fuel cells, are the best prospects for this; hydrogen is a waste of effort. For my musings on this, see my blog:
Our vehicles use less than 200 GW average at the wheels; if we can generate the energy where we do now, we can easily move the required power using the existing electrical grid. See You find you get what you need
Uranium is not a compound you find all over the place. It's very scarce.
I'm sorry, that's just wrong. Uranium is all over the place; anywhere you have issues with radon, you've got uranium in the soil. I've read that ordinary granite is sufficiently rich in uranium that it contains more potential energy than the same weight of coal.
High-grade uranium deposits are another matter, but don't go around with the misconception that our current prices and extraction technology define the limit of reserves... of anything.
... breeder reactors must use molten sodium metal as the primary coolant.
Wrong. A fast breeder reactor can use anything with a low neutron absorption cross-section and low moderation capability (to keep the neutrons fast); the Soviets were looking at lead-bismuth for the purpose. Second, that only applies if you are breeding Pu-239 from U-238; if you are trying to make U-233 from Th-232, light water will do just fine.
Second, breeders require reprocessing-- PUREX, plutonium/uranium extraction-- to be useful.
That's water-based chemistry; there are now alternatives based on electrolysis of molten salt solutions. Google "Integral Fast Reactor" and "pyroprocessing" for enlightenment. (The IFR would have sealed all of its fuel in the reactor building, and the only thing that would have left the building would have been extracted fission products in vitrified form ready for final disposal. Further, the re-refined fuel would have had sufficient contamination from fission products that it would have been nearly impossible to steal without killing the people trying to steal it. There goes your proliferation threat.)
Wouldn't it make more sense to just throw the equivalent of the mass of paint required at the asteroid to drive it slightly off course?
It depends how much lead time you have. An impact is a discrete event; you will have one (very small) change in velocity and that's it. The change in thrust from changing the radiative characteristics is long-term, and the delta-V builds up over time.
Besides, if you spray the paint on in a fly-by (or even an impact) maneuver, you'll get that same initial delta-V anyway. It's the addition of the paint that is "the gift that keeps on giving".
The chunks of ejecta from a lunar impact will almost certainly be much smaller than the original body, and very few of them would actually hit Earth. The ones which did might well be spread out over time, also. Faced with a choice between braving a 3-mile asteroid impact on Earth and the debris coming to Earth from impact of the same on the moon, I'll let it hit the moon.
We do have some meteorites which are known to have come from the moon, so it's proven that stuff kicked off of there can wind up here. It's also pretty obvious that the pieces that wind up here are nowhere near as big as what smacked the moon in the first place.
For defense, you want to kick the rocks heading for Earth no matter how slowly, or quickly, they'd hit. For capture, you want to find a rock with small delta-V requirements no matter how far away its closest approach is right now. Two different selection criteria.
Besides, you probably want to get your shielding material sooner rather than later, and not wait for the approach of a dangerous rock to set your schedule.
Even if you could somehow take a guidance system designed for putting a warhead just above a target on the ground and destroying it and use it to make a far faster approach to a much, much smaller object and still go off with the required accuracy of timing, you wouldn't be accomplishing much except to add radioactive fallout to the considerable blast, heat and tsunami damage.
ICBMs typically reach velocities of about 15,000 MPH for their sub-orbital trajectories. Getting into orbit requires about 18,000 MPH, and getting away from Earth to intercept a ways out (days) would require an escape trajectory and 25,000 MPH or more of delta-V. You are not going to get this from an ICBM without very heavy modifications... and that's without the new guidance system. Not trivial.
There are a few matters of physics that you have to know for this to make sense:
Both solar and thermal radiation exert pressure.
The incoming solar radiation pushes away from the Sun, but the thermal re-radiation from the asteroid pushes away from the hottest parts.
Asteroids rotate, so the thermal-radiation pressure is not directly away from the Sun but away from the "afternoon" part. The lower the albedo (darker) and the greater the thermal conductivity (lag between peak insolation and peak temperature), the greater the difference between the direction to the Sun and the thrust vector.
By painting the asteroid whiter (or, in theory, darker) you change the amount of heat absorbed and thus the ratio between the thrust from the reflected light (tracks exactly with incoming light) and the thrust from the radiated heat. Given enough time this will let you change the orbit of the rock enough to miss (or possibly hit) what you want it to. This works best with smaller bodies and long (very long) lead times.
Name the styles of device which can withstand impact into a target at even ICBM velocities and still detonate correctly. Can't list even one? Want to bet civilization on it working? Me either.
If you use a stand-off weapon you can apply a shove (by vaporizing a layer off the asteroid surface and expanding it into space) on any side, even a quartering part of the back side. This lets you apply a shove in the direction optimal for making the rock miss the Earth, or crash into something else (like the Moon, if you're lucky enough to have exactly the right configuration).
The real problem is that we do not have the ready launch vehicles and nuclear devices to perform such a trajectory change on short notice. This is the thing I fear the most: our search programs turn up a dangerous rock on an impact orbit in ~6 months, and there is nothing we can do to fix the problem in time.
I'll bet that hypochlorite winds up as chloride just from reacting with organic stuff. Dunno what you are asking about phosphates, and I will be the first to admit that I don't know what happens to them in the thermal depolymerization process. The articles I've seen would appear to suggest that they wind up among the solids.
Anaerobic digestion doesn't like bleach (kills the bugs) and will pass the phosphate through the system. You'll still have to dispose of it, but letting bugs convert the organics into methane will reduce the bulk and make it more concentrated.
Based on what you've said, I suspect that the most economical scheme for municipalities dealing with sewage sludge is thermal depolymerization; the market for sludge-derived products is small, contaminants such as heavy metals strongly indicate its disposal other than on cropland, and the processing time for TDP is much shorter than any bacterial process. The flip side of the coin is that digestion is a simpler process than TDP with lower capital costs and no patent barriers.
Even if you were talking about sludge, we can manage to get enough storage together for a few days.
Even if you arrange it vertically? If your solids fraction is 3% and your current residence time is 8 hours, adding the same volume again in methane digesters would allow you to hold the material for about 11 days. That may be enough for the thermophilic bugs to run the reaction close to completion and get rid of most of the BOD of the material.
... you're still looking at an extremely large and potentially dangerous storage problem (from the explosive gas it would produce).
You're storing the slurry. The gas is not explosive unless mixed with air, and you neither allow that to happen nor have more than small amount on hand at any time (the "head space" in the digester tanks). If I were designing such a plant (I'm not a civil engineer, so take with a truckload of salt) I'd use as much gas on-site as was required to run the plant and heat the digester tanks, and any excess would either be burned for additional power or sold to nearby industrial customers to help displace the need for natural gas.
If that's the sort of organic vapor these folks are talking about, it's going to cost an awful lot of that energy they produce to safely get rid of these things.
In the case of anaerobic digestion, the organic vapors are part of the fuel gas; they don't have to be "afterburned" because they're burned the first time. In the case of thermal depolymerization, any combustible gases go to provide process heat.
You could do the same with human waste if it was guaranteed not to have any non-organic nastiness (like other chemicals or heavy metals) in it.
If your town has even one plating plant or other manufacturing operation in it, good luck. You'd need separate sewer systems for domestic and industrial, and guarantee that nobody dumps anything nasty down either a domestic sewer or a storm drain. I see this having two chances: slim and none.
This is one reason why I think thermal depolymerization has a bright future for cities. It reduces the inputs to water, combustible gas, hydrocarbon liquids and a solid fraction of carbon and ash. If you can guarantee that e.g. heavy metals will wind up in the solid fraction, you've reduced it to a compact and stable form which can be landfilled much more safely than most other possibilities.
Reprocessing is the chemical separation of fissionables from fission products in spent fuel. None of that is going on; the fissionables came from the warheads in pure form (metal), have already been converted to ceramic (oxide), and could probably be mixed into partially-enriched uranium oxide and sintered into fuel pellets right here. I am aware of no legal barrier to this (which does not mean there is not one).
I suspect that the real barrier is the refusal of publicity- and litigation-shy US nuclear plant operators to have anything to do with nuclear weapons, even their ultimate and permanent disposal. By the end of a fuel cycle, conventional PWRs are deriving a majority of their power from fission of Pu-239 bred from the U-238 in the fuel pellets. Despite that fact, "environmentalists" can still panic the ignorant public with talk of power from plutonium.
Slashdot Mirror
One of the things preventing us from eliminating Iran and N. Korea as nuclear threats is the inability to neutralize their facilities without throwing up large amounts of fallout and killing many thousands downwind (not all of them enemy nationals either). If we were in a position to blow a hole in the ground and destroy their centrifuges and machine shops without contaminating the area with fission products, we'd be able to force the Teheran regime to blink.
I doubt we're going to see antimatter cheap enough to be more than a research material for decades, but when we can turn it into devices which make it impossible for anyone to field an army it essentially makes conventional warfare into suicide. Isn't that what you wanted?
That engine has a top speed of 102 RPM because it's direct drive. Direct drive eliminates the need for motor-generator sets and all the bulk, weight and cost people have been talking about above, but it also cuts the power output and increases the required size of the engine.
Other marine diesels seem to be designed to run at 600-1000 RPM. An engine running at 6x the speed can move 6x the air and fuel per unit of displacement, and thus could be about 1/6 the size and weight for the same power. This becomes even more lopsided for gas turbines; an 85 MW GE gas turbine is a tiny fraction of the size of the diesel of the same power, and an even tinier fraction of the weight.
The technical explanation is that you can transfer a lot of power with a small, rapidly-varying magnetic field (like the itty-bitty toroid in your computer's power supply, running at 100 KHz instead of the 60 Hz power line frequency), but to transfer the same amount of power with a slowly-varying field needs a much bigger field, bigger currents and bigger losses. Superconductors get rid of the losses and can sustain bigger fields in a smaller package.
There may be other uses for a baseball bat in the resolution of this matter, but I would not presume to offer advice. I'm sure our imaginations are up to the task.
In most places I've heard of, invasion of privacy is a crime; there have been numerous news items about people (mostly men) being prosecuted for putting cameras in restrooms and changing rooms. So go to the cops first. At the very least you'll get a police report out of it.
To use nuclear (and solar, and wind) power to displace oil, you need some way to use electricity in vehicles. Batteries and their cousins, regenerative fuel cells, are the best prospects for this; hydrogen is a waste of effort. For my musings on this, see my blog:
Starving the Beast
Our vehicles use less than 200 GW average at the wheels; if we can generate the energy where we do now, we can easily move the required power using the existing electrical grid. See You find you get what you need
High-grade uranium deposits are another matter, but don't go around with the misconception that our current prices and extraction technology define the limit of reserves... of anything.
Besides, if you spray the paint on in a fly-by (or even an impact) maneuver, you'll get that same initial delta-V anyway. It's the addition of the paint that is "the gift that keeps on giving".
It's a pity that we don't get to see the thing he's going to be talking about; there is nothing informative on the page.
We do have some meteorites which are known to have come from the moon, so it's proven that stuff kicked off of there can wind up here. It's also pretty obvious that the pieces that wind up here are nowhere near as big as what smacked the moon in the first place.
Besides, you probably want to get your shielding material sooner rather than later, and not wait for the approach of a dangerous rock to set your schedule.
Tunguska.
ICBMs typically reach velocities of about 15,000 MPH for their sub-orbital trajectories. Getting into orbit requires about 18,000 MPH, and getting away from Earth to intercept a ways out (days) would require an escape trajectory and 25,000 MPH or more of delta-V. You are not going to get this from an ICBM without very heavy modifications... and that's without the new guidance system. Not trivial.
- Both solar and thermal radiation exert pressure.
- The incoming solar radiation pushes away from the Sun, but the thermal re-radiation from the asteroid pushes away from the hottest parts.
- Asteroids rotate, so the thermal-radiation pressure is not directly away from the Sun but away from the "afternoon" part. The lower the albedo (darker) and the greater the thermal conductivity (lag between peak insolation and peak temperature), the greater the difference between the direction to the Sun and the thrust vector.
By painting the asteroid whiter (or, in theory, darker) you change the amount of heat absorbed and thus the ratio between the thrust from the reflected light (tracks exactly with incoming light) and the thrust from the radiated heat. Given enough time this will let you change the orbit of the rock enough to miss (or possibly hit) what you want it to. This works best with smaller bodies and long (very long) lead times.- Name the styles of device which can withstand impact into a target at even ICBM velocities and still detonate correctly. Can't list even one? Want to bet civilization on it working? Me either.
- If you use a stand-off weapon you can apply a shove (by vaporizing a layer off the asteroid surface and expanding it into space) on any side, even a quartering part of the back side. This lets you apply a shove in the direction optimal for making the rock miss the Earth, or crash into something else (like the Moon, if you're lucky enough to have exactly the right configuration).
The real problem is that we do not have the ready launch vehicles and nuclear devices to perform such a trajectory change on short notice. This is the thing I fear the most: our search programs turn up a dangerous rock on an impact orbit in ~6 months, and there is nothing we can do to fix the problem in time.Anaerobic digestion doesn't like bleach (kills the bugs) and will pass the phosphate through the system. You'll still have to dispose of it, but letting bugs convert the organics into methane will reduce the bulk and make it more concentrated.
Based on what you've said, I suspect that the most economical scheme for municipalities dealing with sewage sludge is thermal depolymerization; the market for sludge-derived products is small, contaminants such as heavy metals strongly indicate its disposal other than on cropland, and the processing time for TDP is much shorter than any bacterial process. The flip side of the coin is that digestion is a simpler process than TDP with lower capital costs and no patent barriers.
Even if you arrange it vertically? If your solids fraction is 3% and your current residence time is 8 hours, adding the same volume again in methane digesters would allow you to hold the material for about 11 days. That may be enough for the thermophilic bugs to run the reaction close to completion and get rid of most of the BOD of the material. You're storing the slurry. The gas is not explosive unless mixed with air, and you neither allow that to happen nor have more than small amount on hand at any time (the "head space" in the digester tanks). If I were designing such a plant (I'm not a civil engineer, so take with a truckload of salt) I'd use as much gas on-site as was required to run the plant and heat the digester tanks, and any excess would either be burned for additional power or sold to nearby industrial customers to help displace the need for natural gas. In the case of anaerobic digestion, the organic vapors are part of the fuel gas; they don't have to be "afterburned" because they're burned the first time. In the case of thermal depolymerization, any combustible gases go to provide process heat.This is one reason why I think thermal depolymerization has a bright future for cities. It reduces the inputs to water, combustible gas, hydrocarbon liquids and a solid fraction of carbon and ash. If you can guarantee that e.g. heavy metals will wind up in the solid fraction, you've reduced it to a compact and stable form which can be landfilled much more safely than most other possibilities.
I suspect that the real barrier is the refusal of publicity- and litigation-shy US nuclear plant operators to have anything to do with nuclear weapons, even their ultimate and permanent disposal. By the end of a fuel cycle, conventional PWRs are deriving a majority of their power from fission of Pu-239 bred from the U-238 in the fuel pellets. Despite that fact, "environmentalists" can still panic the ignorant public with talk of power from plutonium.