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Denmark Faces a Tricky Transition To 100 Percent Renewable Energy

wagnerrp Re:Use the money you save (488 comments)

Like I use energy to lift a stone, and I get 100% of that energy back if the stone drops.

No body is fully elastic. You will have infinitesimally small energy losses due to changing internal stresses in the two bodies. You get very very close to 100% recovery, but not 100% recovery. The energy is still there. It hasn't escaped your hypothetical closed system. It is simply not recoverable in a useful form. It is disordered. Reversible processes are those "special cases".

about a week ago
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The Downside to Low Gas Prices

wagnerrp Re:Stupid, trucks cause the problem (554 comments)

Of course doing so has the side effect that no one will give you loans because your currency is too unstable to be of any international value.

about two weeks ago
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The Downside to Low Gas Prices

wagnerrp Re: so why specifically target drivers? (554 comments)

Those numbers already take into account the difference in traffic volume. An individual loaded tractor trailer causes several thousand times the damage as a single sedan. In other words, there would have to be 80x the volume of passenger traffic on the road to cause the same amount of damage as present truck traffic.

about two weeks ago
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The Downside to Low Gas Prices

wagnerrp Re: so why specifically target drivers? (554 comments)

Doesn't matter much, it's the same people that drive their cars that also buy supplies that require trucking.

So what? You're artificially buoying up industries that perhaps shouldn't be. Nearly all of our shipping is done over the road, due to cost and convenience. Make roadway shipping pay to repair its fair share of damage done to the roadway. Initially, shipping costs will rise. Costs for all products would rise across the board as those increased operating costs trickle down to consumers. Over time, those companies will find new ways to reduce costs. Money would be pumped into the rail system, expanding and modernizing it to improve speed and throughput. Manufacturing would become more regionally diverse so less has to be shipped across the country. Fewer vehicles on the road means lower traffic congestion. Less roadway maintenance further means lower traffic congestion. Locomotives are more efficient per unit of shipped material are more easily managed in terms of emissions. Fixed, limited access railways can be more easily converted to electric.

The trucking industry would suffer, unquestionably, but it's a much more complicated issue than you give it credit for, and perhaps the advantages in other areas outweigh those effects.

about two weeks ago
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The Downside to Low Gas Prices

wagnerrp Re: so why specifically target drivers? (554 comments)

Semis burn 5x more fuel yet cause 80x more damage.

Is that taking into account traffic volume, as a typical loaded tractor trailer is going to cause several thousand times the damage as a typical sedan.

about two weeks ago
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Boeing Readies For First Ever Conjoined Satellite Launch

wagnerrp Re:So, ion drive or something??? (67 comments)

You would need a nuclear reactor to provide enough power to land on the Moon using an arcjet.

about two weeks ago
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Denmark Faces a Tricky Transition To 100 Percent Renewable Energy

wagnerrp Re:Use the money you save (488 comments)

Electrolysis has nothing to do with thermodynamics

By that, you actually mean everything has to do with thermodynamics. You're adding energy to disassociate a molecule. Thermodynamics dictates that you cannot recover that same amount of energy by letting the constituent elements recombine. Tyr07's uncertain belief coincides with one of the fundamental principles at play in any real world system.

Fuel cell efficiency varies greatly, it goes up to 85% for current marketed high temperature hydrogen fuel cells.

No it doesn't. The only way you could hope to achieve anywhere near that is through some combined cycle process that scavenges waste heat from the fuel cell. You might find some experimental units pushing 70%, but anything commercially available is going to be under 60%.

Total cycle efficiency is going to be under 25%. That is complete nonsense, you must be bad in math.

Assuming realistic values for electrolysis and fuel cells, you're already well under 40%. Depending on your compression ratio, you're only likely to recover 50-60% of the energy spent compressing the hydrogen for storage, so that's either higher losses, or higher capital costs for storage volume. Tack on a couple percent for leakage, and 25% is very reasonable.

about two weeks ago
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Denmark Faces a Tricky Transition To 100 Percent Renewable Energy

wagnerrp Re:Use the money you save (488 comments)

The energy required to compress and cool the hydrogen into a liquid in the first place, as opposed to just larger, less insulated, high pressure gas tanks, would more than offset any gains made by using the boiloff to cool your data center.

about two weeks ago
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Denmark Faces a Tricky Transition To 100 Percent Renewable Energy

wagnerrp Re:Use the money you save (488 comments)

conversion ratio wise I believe it takes more power to produce the hydrogen than it returns so there is a loss

Yes. Electrolysis does not violate the laws of thermodynamics. What I assume you were getting at, electrolysis usually runs around 50-60% efficiency and fuel cells range from 30-70% depending on the chemistry, and in practice since you have to store it, you also have to factor in compression losses, hydrogen leakage, and burners to bring your decompressed gas back up to the operating temperature of your fuel cell. Total cycle efficiency is going to be under 25%.

about two weeks ago
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Denmark Faces a Tricky Transition To 100 Percent Renewable Energy

wagnerrp Re:Are renewable energy generators up to task ? (488 comments)

You can expect about 900kWh yearly per 1kW of typical solar panel installed in Denmark. Therefore it takes an installed capacity of 240GW of solar panels to cover Denmark.

That makes the assumption that your daily average production and consumption is anywhere close to your yearly average, or that you have an absolutely massive energy storage system capable of storing hundreds of petajoules to last the winter months.

about two weeks ago
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New Atomic Clock Reaches the Boundaries of Timekeeping

wagnerrp Re: Old saying (249 comments)

Because it would be meaningless to "compensate" for the time difference between clocks moving and accelerating differently. Time literally moves at different rates in different reference frames. The clocks are correct; the problem is that the concept of similtaneity is fundamentally flawed.

I'll admit, I don't understand why the arbitrary reference time we use currently is any less valuable now that we have surface clocks whose real time is measurably changing due to relativistic effects.

about three weeks ago
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New Atomic Clock Reaches the Boundaries of Timekeeping

wagnerrp Re:Old saying (249 comments)

Why can't we compute what the relativistic slew rate between two different locations will be and compensate?

about three weeks ago
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Virgin Galactic SpaceShipTwo Crashes

wagnerrp Re:Not a good week... (445 comments)

So someone who straps a couple homemade AP motors to the side of an ultralight qualifies as well? (One could argue doing such a thing would preclude them classification as an ultralight...)

They're daring, sure, but they're not pioneering new territory, as we did this over 50 years ago; they're just making it cheaper. Even when they do get there and make it cheaper, there's no way to expand upon its capabilities without a complete from-scratch redesign. They're not enabling anything further. Unless they directly expand science, industry, or medicine, or indirectly provide the tools for others to do so, they're not benefiting society, just themselves personally. Being a hero implies acting for the benefit of someone other than one's self.

about three weeks ago
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Virgin Galactic SpaceShipTwo Crashes

wagnerrp Re:Using NASA's dictionary (445 comments)

To be fair, we already reached that specific frontier over 50 years ago.

about three weeks ago
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Virgin Galactic SpaceShipTwo Crashes

wagnerrp Re:Not a good week... (445 comments)

The guys (and woman) who died in Challenger were heroes. The casualties from this crash were like the people who died building the Empire State Building.

- you know you are an actual asshole, right? What, the difference between people that are flying space ships for private business and for NASA or whatever agency is that in private business they are billionaires? Nope. The owner of the company is, the people flying the fucking rockets are heroes even before they blow up.

The NASA astronauts were working to expand our breadth of knowledge. Orbital Sciences, SpaceX, Bigelow Aerospace, Blue Origin, while ultimately working for profit, are building technologies that enable the expansion of expand science and civilization. Virgin Galactic and XCOR Aerospace exist to provide entertainment. Their designs cannot be scaled to actually reach orbit. Their designs cannot be scaled to provide practical transportation. It's for entertainment, and while entertainment is important, it's just a distraction to fill down time.

about three weeks ago
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Virgin Galactic SpaceShipTwo Crashes

wagnerrp Re:Not a good week... (445 comments)

That's right. People risk their lives to do adventures like this because it's worth it.

This is spaceflight in definition only. It's nowhere near orbit. It's not even useful as a suborbital transportation system. If you want to perform tests in rarefied atmosphere or vacuum, sounding rockets are vastly cheaper and offer better performance. This exists for tourism, for people who want a few minutes of weightlessness all at once, rather than a several arches in a "vomit comet" a dozen seconds at a time, and for people who want to claim they technically went to space, even though most people expect that means you actually stayed there for more than a few seconds.

This isn't worth it.

about three weeks ago
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What It Took For SpaceX To Become a Serious Space Company

wagnerrp Re:Blah blah Elon call me when (96 comments)

Considering no one has ever done that, are you saying the last half century of spaceflight has just been amateur hour?

about a month ago
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What It Took For SpaceX To Become a Serious Space Company

wagnerrp Re:Skylon (96 comments)

The real cost of any (liquid fueled) launch is in the vehicle, rather than the fuel. Thus, the ultimate goal of cheap spaceflight is to recover and reuse that launch vehicle. Whether you achieve that with an extremely elaborate multi-mode gas turbine engine on an SSTO spaceplane, or a traditional staged rocket whose boosters abort and return for a powered landing back at the launch facility, you get the same end result. The question simply becomes which one is cheaper to design and maintain.

about a month ago
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What It Took For SpaceX To Become a Serious Space Company

wagnerrp Re:they should get Nasa to use them (96 comments)

At $4,653/kg to LEO it would cost rought 400K to push an average human to LEO

Don't forget your life support and re-entry systems.

about a month ago
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DHS Investigates 24 Potentially Lethal IoT Medical Devices

wagnerrp Re:Well ... duh! (79 comments)

The same goes for my thermostat. And my lights. And my stove. And my freezer. If you're not taking security seriously, I'm not taking your fscking product seriously.

The entire industrial control world is completely indifferent to security. Things like HMI applications may implement user-level restrictions, but ultimately the hardware they interface with is usually just open access over OPC or HTML. This works in general when you're on an isolated industrial network, of course these networks are typically not completely isolated, allowing remote access for maintenance and support. Even when completely isolated, you still have the issue of operators connecting infected hardware to the network, as seen with stuxnet.

The problem with IoT is that the same embedded and controls engineers are just applying the same methodology to this as industrial applications, and assuming someone upstream will handle the security issue. Security is a double edged sword. While it's necessary at some level, it's going to add considerable overhead and latency, and is all but unusable if you intend to do real time control. The isolated, open network is the only sensible approach. Now IoT parts could completely embrace the industrial methodology, and while the typical controls engineer might think nothing of running ethernet or RS-485 drops throughout their home with a central secured gateway for access, the typical consumer user is enamored will all things wireless. On the other hand IoT parts are not doing any form of real time control over their remote interfaces, so there's no reason for them to be externally behaving like industrial hardware, and programmers stuck in that mindset should not be left in charge of building those interfaces.

about a month ago

Submissions

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MythTV 0.24 Released

wagnerrp wagnerrp writes  |  about 4 years ago

wagnerrp (1305589) writes "Following with the accelerated development schedule, MythTV 0.24 is now available six months after the release of 0.23. MythTV is a distributed Linux-based PVR and home theater application. Highlights of this release include a brand new theme-able playback OSD, playback of HD audio formats, multichannel and 24/32-bit audio output, Bluray playback, and multi-angle DVD playback. A full listing of changes is available on the MythTV wiki."

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