Even if salt doesn't have high efficiency, it's salt! Just use more. Salt is cheap and widely available...On the other hand batteries degrade over time, they are more complex, and have a lifetime (except for the most exotic designs) measured in a small number of years. Also batteries can short out or catch fire.
I chose a battery type for comparison that's made of dirt-cheap materials, which is highly reliable and very simple. (Far simpler than molten salt plumbing. Just imagine designing valves and pumps to carry a liquid that freezes unless the pipes are glowing red-hot.) You're right that batteries can short out and catch fire, but molten salt is basically on fire all the time, so I'm not sure it's a win.
Ultimately the engineers at this site chose a molten salt design. I think I'll trust their judgment over yours.
These guys aren't general electrical engineers picking the best of all options, it's a solar-thermal company filled with solar-thermal engineers who cut their teeth doing solar-thermal experimental projects, and are out to prove that solar-thermal can work. And sure, they might be right, but the fact that every solar thermal plant up until now has been unable to compete against other renewables and fossils doesn't give me hope.
Thermal energy capacity: 0.13 kWh/kg Electrical conversion efficiency: 25% at best Electrical storage capacity: 0.03 kWh/kg Amount of mass to store 12 kWH (one household overnight): 400 kg Amount of mass to power a large city overnight (1 million households): 1 Empire State Building
Sodium-sulfur battery electrical storage capacity: 0.5 kWh/kg Charge/discharge efficiency: 80% Useful storage capacity: 0.4 kWh/kg Amount of mass to store 12 kWh (one household overnight): 30 kg Amount of mass to power a large city overnight (1 million households): 1 large submarine
Both systems use cheap, common materials, both systems are proven reliable over decades, but you get about 10 times as much energy storage when you use chemistry.
This is about as useful as arguing about the most important person of the 20th century. The refrigerator was huge. So was the mass-produced automobile, the atomic bomb, the television, the transistor, digital communications, the list goes on. And all of these things enabled and depended on each other, so singling out one as the key to everything is stupid.
I do agree that refrigeration deserves more attention, though.
Yeah, this scandal is going to make VW rethink its plans to sell the new VW Smug, which was which was to be powered entirely by the driver's condescending attitude.
The hydrogen engine *has* to be smaller and *has* to use less fuel, because if it carried enough fuel to match the power and range of a gasoline engine, the fuel tank would be as big as the car. (And that's not an exaggeration. OK not much. I did the math.)
Hydrogen has great energy per mass, but its energy per *volume* is terrible -- about equal to lithium batteries. Rather than dealing with synthesizing, transporting, storing, and burning an explosive super-pressurized gas, it's much easier to just use electricity.
Magnesium hydride doesn't help: since it stores only about 8% by weight of hydrogen gas, its energy per mass and per volume are both worse than compressed H2 gas. It might be safer, but it's not gonna solve the fuel tank problem.
What's the difference? I classify the "diesel electric" system used on trains, in which the engine turns a generator but delivers no direct power to the wheels, as just another sort of hybrid. An inferior sort, since directly powering the wheels can be more efficient at some points on the speed/power curve, so it's better to have that option.
I did an obsessive amount of research on VW's clean diesel technology, and the engineering issues that motivated their decision to cheat. Going hybrid would solve all their problems. Well, the technical ones anyway.
The problem is that their patented "clean NOx trap" pollution control technology involves storing NOx pollution in a zeolite "molecular sponge". The sponge needs to be cleaned out periodically by changing the engine fuel-to-air ratio: when that happens (for a few seconds every minute or two), engine performance is drastically reduced. VW's engine computer tries to keep this from happening while the driver is accelerating, but apparently it wasn't good enough, so they programmed the computer to not bother with trap cleaning unless it's being tested in an EPA lab.
With a full hybrid system, the engine can run at optimum efficiency at all times, and can take a break to clean the NOx trap whenever it wants: the electric motor and batteries can take over.
You should pay for some sort of news outlet. New York Times, Washington Post, NPR, I don't care which: you need to make sure that the place you're getting your information from is beholden to its readers, not just to its advertisers and owners. You know the old saying: if you're not paying for it, you're not the customer, you're the product.
Diesels do use catalytic converters. The problem is that ordinary gas engines destroy NOx by reacting it with very small amounts of unburned fuel. This doesn't work with diesels because their exhaust has lots of oxygen, so any unburned fuel just reacts with the oxygen rather than the NOx. So diesels need extra equipment to make their catalytic converters work properly despite the oxygen.
Hi. I'm mostly a Mac and Linux guy, but I have a Windows box I use for gaming. Windows 10 is a fine product: it's a nice extension of the Windows 7 experience, with better security, good speed, and some nice features. As you say you're not going to be able to get your family off Windows, they should be running 10, with all the updates. Trying to stick with 7 (or god forbid, XP), they'll have more incompatibility issues going forward rather than less, and picking and choosing Windows updates is more trouble than it's worth.
If you tell them to buck the trend and set up something weird, they're going to ask you to deal with the consequences.
The EPA considers the specific ECU software that deactivates the emissions control system to be a "defeat device", and points out that "device" includes "any element of design", not just physical hardware, according to the definitions in the Clean Air Act.
Read the EPA's complaint. Seriously. It's a master-course in anticipating the arguments of rules-lawyering pedants like you.
Yeah, that's been my best guess too. But (10,000 miles / (40 miles/gallon diesel)) * 2% urea/ diesel = 5 gallons urea per service interval. Passat has a 5-gallon urea tank, which is just the right size.
So they're not skimping on size/weight of the tank. The only explanations left that I can see: either the urea system puts some performance limits on the engine that I haven't figured out yet, or else they just want to save some money on urea (since they pay for it for the first 30,000 miles.) But risking billion-dollar fines and your company's entire reputation to save $20 worth of chemical? No way. Volkswagen may be unethical but they're not that stupid.
Anyhow, I think the problem was VW didn't want to use an AdBlue style system.
But they *do* also use an AdBlue system on their larger vehicles (notably, the Passat), and the EPA claims they were cheating on the Passat too. Quite frankly, I have no idea why.
Read the EPA complaint: it anticipates the "but they passed the test!" argument and goes into great detail about what the "defeat device" is in this context. And in any case, since VW has admitted wrongdoing, hair-splitting is pointless.
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Dear SXSW:
Grow some balls.
I chose a battery type for comparison that's made of dirt-cheap materials, which is highly reliable and very simple. (Far simpler than molten salt plumbing. Just imagine designing valves and pumps to carry a liquid that freezes unless the pipes are glowing red-hot.) You're right that batteries can short out and catch fire, but molten salt is basically on fire all the time, so I'm not sure it's a win.
These guys aren't general electrical engineers picking the best of all options, it's a solar-thermal company filled with solar-thermal engineers who cut their teeth doing solar-thermal experimental projects, and are out to prove that solar-thermal can work. And sure, they might be right, but the fact that every solar thermal plant up until now has been unable to compete against other renewables and fossils doesn't give me hope.
Molten salt is terrible for electricity storage.
Thermal energy capacity: 0.13 kWh/kg
Electrical conversion efficiency: 25% at best
Electrical storage capacity: 0.03 kWh/kg
Amount of mass to store 12 kWH (one household overnight): 400 kg
Amount of mass to power a large city overnight (1 million households): 1 Empire State Building
Sodium-sulfur battery electrical storage capacity: 0.5 kWh/kg
Charge/discharge efficiency: 80%
Useful storage capacity: 0.4 kWh/kg
Amount of mass to store 12 kWh (one household overnight): 30 kg
Amount of mass to power a large city overnight (1 million households): 1 large submarine
Both systems use cheap, common materials, both systems are proven reliable over decades, but you get about 10 times as much energy storage when you use chemistry.
This is about as useful as arguing about the most important person of the 20th century. The refrigerator was huge. So was the mass-produced automobile, the atomic bomb, the television, the transistor, digital communications, the list goes on. And all of these things enabled and depended on each other, so singling out one as the key to everything is stupid.
I do agree that refrigeration deserves more attention, though.
Yeah, this scandal is going to make VW rethink its plans to sell the new VW Smug, which was which was to be powered entirely by the driver's condescending attitude.
Hydrogen is stupid.
The hydrogen engine *has* to be smaller and *has* to use less fuel, because if it carried enough fuel to match the power and range of a gasoline engine, the fuel tank would be as big as the car. (And that's not an exaggeration. OK not much. I did the math.)
Hydrogen has great energy per mass, but its energy per *volume* is terrible -- about equal to lithium batteries. Rather than dealing with synthesizing, transporting, storing, and burning an explosive super-pressurized gas, it's much easier to just use electricity.
Magnesium hydride doesn't help: since it stores only about 8% by weight of hydrogen gas, its energy per mass and per volume are both worse than compressed H2 gas. It might be safer, but it's not gonna solve the fuel tank problem.
Given that Iceland has nearly unlimited geothermal and hydroelectric power, electric vehicles seem like an obvious choice.
What's the difference? I classify the "diesel electric" system used on trains, in which the engine turns a generator but delivers no direct power to the wheels, as just another sort of hybrid. An inferior sort, since directly powering the wheels can be more efficient at some points on the speed/power curve, so it's better to have that option.
I did an obsessive amount of research on VW's clean diesel technology, and the engineering issues that motivated their decision to cheat. Going hybrid would solve all their problems. Well, the technical ones anyway.
The problem is that their patented "clean NOx trap" pollution control technology involves storing NOx pollution in a zeolite "molecular sponge". The sponge needs to be cleaned out periodically by changing the engine fuel-to-air ratio: when that happens (for a few seconds every minute or two), engine performance is drastically reduced. VW's engine computer tries to keep this from happening while the driver is accelerating, but apparently it wasn't good enough, so they programmed the computer to not bother with trap cleaning unless it's being tested in an EPA lab.
With a full hybrid system, the engine can run at optimum efficiency at all times, and can take a break to clean the NOx trap whenever it wants: the electric motor and batteries can take over.
Their design is a problem everywhere, but it's only(*) illegal in the US.
Looks like deadtree circulation for the Times is about a million, roughly equal to online-only subscriptions.
http://www.nytimes.com/2009/10...
Yup, paying for stuff is necessary, but not sufficient. The NY Times gets about 1/4 of its revenue from subscriptions, which is hopefully enough.
Most 21st century newspapers would kill for a circulation of 12.5% of their population. Los Angeles Times, for example, is about 5%.
Nobody's saying that the New York Times is a massive success, but it is turning a profit.
You should pay for some sort of news outlet. New York Times, Washington Post, NPR, I don't care which: you need to make sure that the place you're getting your information from is beholden to its readers, not just to its advertisers and owners. You know the old saying: if you're not paying for it, you're not the customer, you're the product.
I dunno. If I had to choose between negotiating with Steve Jobs or Vladimir Putin, I think I'd pick Putin as the safer choice.
The college professors of the world say "Ha ha, now let's see how much YOU like being secretly judged!"
Diesels do use catalytic converters. The problem is that ordinary gas engines destroy NOx by reacting it with very small amounts of unburned fuel. This doesn't work with diesels because their exhaust has lots of oxygen, so any unburned fuel just reacts with the oxygen rather than the NOx. So diesels need extra equipment to make their catalytic converters work properly despite the oxygen.
It was a joke. Same key ingredient, but actually making it out of urine would be ridiculous, hence the humor. C'mon, keep up.
Hi. I'm mostly a Mac and Linux guy, but I have a Windows box I use for gaming. Windows 10 is a fine product: it's a nice extension of the Windows 7 experience, with better security, good speed, and some nice features. As you say you're not going to be able to get your family off Windows, they should be running 10, with all the updates. Trying to stick with 7 (or god forbid, XP), they'll have more incompatibility issues going forward rather than less, and picking and choosing Windows updates is more trouble than it's worth.
If you tell them to buck the trend and set up something weird, they're going to ask you to deal with the consequences.
I think the logic is: thanks to the Peter Principle, managers will always be incompetent. So why not just hire incompetent people from the get-go?
The EPA considers the specific ECU software that deactivates the emissions control system to be a "defeat device", and points out that "device" includes "any element of design", not just physical hardware, according to the definitions in the Clean Air Act.
Read the EPA's complaint. Seriously. It's a master-course in anticipating the arguments of rules-lawyering pedants like you.
Yeah, that's been my best guess too. But (10,000 miles / (40 miles/gallon diesel)) * 2% urea/ diesel = 5 gallons urea per service interval. Passat has a 5-gallon urea tank, which is just the right size.
So they're not skimping on size/weight of the tank. The only explanations left that I can see: either the urea system puts some performance limits on the engine that I haven't figured out yet, or else they just want to save some money on urea (since they pay for it for the first 30,000 miles.) But risking billion-dollar fines and your company's entire reputation to save $20 worth of chemical? No way. Volkswagen may be unethical but they're not that stupid.
But they *do* also use an AdBlue system on their larger vehicles (notably, the Passat), and the EPA claims they were cheating on the Passat too. Quite frankly, I have no idea why.
It decomposes if mixed before burning.
Read the EPA complaint: it anticipates the "but they passed the test!" argument and goes into great detail about what the "defeat device" is in this context. And in any case, since VW has admitted wrongdoing, hair-splitting is pointless.