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* Posts by Excoriator

10 publicly visible posts • joined 15 Feb 2008

Russia could chop vital undersea web cables, warns Brit military chief

Excoriator

Unconvincing threat

As I understand it, the Internet is designed to withstand damaged cables, and simply reroutes the traffic. Unless they can cut them ALL, I can't see it making a lot of difference. It's worth noting that cables fail for many reasons, and they are simply repaired by a specialised cable repair ship.

It is also worth noting that at this time of the year, defence spending is reviewed, and I suspect this has more to do with the defence industry worrying about further cuts! A good scare story often appears at this time of the year, and apart from the entertainment they give are best ignored.

The 'threat' was originally invented by a right-wing 'think tank' called "The Policy Exchange" and seems to have been got up by a conservative MP whose name I have forgotten. He seems to be non-technical and has an MBA which according to his profile is his only qualification. I imagine the think tank is reflecting the industrial sector of the UK's military-industrial complex, with the General representing the military bit.

As threats go, this one is about as convincing as a nine-bob note!

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Tesla unveils battery-swapping tech for fast car charging

Excoriator

Ok, Ok excoriator. We get you don't like electric cars. But ffs, stop the forum carpet bombing. You are repeating yourself.

OK CCCP. It would be nice to see an end to the hype about these things too. Now that most certainly IS repeated time after time after time.

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Excoriator

Its worth noting that this idea has been tried - extensively - in the past. A hundred years ago they were quite popular because you didn't need to crank them to get them going. The invention of the self-starter destroyed that advantage and a in a straight battle with the internal combustion engine it quickly became apparent that the batteries simply weren't up to the job.

A hundred years later and here we are. The batteries STILL aren't up to the job!

I think it is a very telling point that if you look at any conventional car, the battery in it is invariably lead-acid. It is substantially unchanged 150 years after it was invented but is still the cheapest, most rugged, battery around. Forget the much hyped Lithium cells. They don't meet the spec half as well as the old Lead acid battery.

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Excoriator
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Re: @excoriator

Your point about not needing 1MWh is correct. I think modern diesels are about half the efficiency of an electric car so for equivalent range x performance about 500kWh is about right. However I think my point stands even at this rate Our grid was not designed for every house to take a 60kW load for hours overnight. from a significant percentage of the population. The cost of domestic electricity (about £0.12/kWh) would make it an expensive recharge too. Probably not significantly cheaper than diesel. Incidentally, I'm sure a 3-phase supply is not expensive, but a 50 to 100kW charger to convert it to DC certainly would be.

But there are other downsides too. Battery capacity falls with temperature, so you can expect poorer millage in cold weather. If you don't have a battery swap car, then you are probably going to have to buy a new battery in a few years, and they are not cheap.Also, if you do get it wrong and leave the car uncharged whilst you go on holiday it is likely that the battery will not survive. The cells used do not like being left undischarged for long. Also if the worse DOES happen and you run out of juice I don't see much alternative to a tow-back. You can't easily pour a gallon of electricity into the thing.

There are 30 million cars on UK roads. Supplying them all with electricity in the quantities needed is simply not on. Lets assume 10% of them draw a 50kW load simultaneously (overnight say) That's 150GW, which is more than twice the total capability of our existing national grid.

If you do a few simply sums you realise what a crackpot idea it is. I think it's essentially motivated by politicians wanting to do something 'Green' and seeing the grants given to bankrupt motor companies for 'green' technology as more politically acceptable than a hand-out.

Anyway, I'm pleased that the general public is not as easily fooled as the cheering crowd selected by Mr Musk for his show.

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Excoriator

Why so much negativity about electric cars? Because they are a totally idiotic idea.

A conventional car can easily contain a megawatt hour of energy in its tank, with a negligible weight penalty. It can be 'recharged' in a couple of minutes, safely and easily. Battery energy density is about 1% of this, and there is little prospect of it increasing much in the foreseeable future.

There is a more serious problem though:

Even if batteries capable of being tucked under the boot and storing a megawatt hour existed, charging them in two minutes would require a power level of 30 MegaWatts, enough to supply a town of some 30,000 inhabitants!. A filling station with ten 'pumps' would consume about a third of the output of a typical power station.

Want to charge your 1 MWh electric car overnight at home? Fine! You can do it over 8 hours at a power level of 125kW. - thats about 42 3kW electric heaters going full tilt . You'll have to pay the power company to install three-phase power at an appropriate level at home of course, and that will probably cost more than the car. There is also the minor problem that very many city dwellers have no garage and park on the streets, often some distance from their homes anyway.

I have no idea why the industry is pushing these daft things. They remain deeply unpopular with the car buying public, and no wonder. I find it deeply gratifying that even when the Government is subsidising them to the tune of £5.000 in the UK,. that the the British public are sufficiently intelligent to see through the hype and say a firm NO to them.

With the existing generation of batteries trying to make a decent electric car is as idiotic a project as an internal combustion powered hearing aid!

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Excoriator

You have to store a lot of energy for a car, and the best way is oil (petrol or diesel). Batteries, by comparison are hopeless. They store only about 1% on the energy weight for weight..It is not exactly advertised by the likes of Tesla, but if you want to stay warm on a cold day and turn the heater on, this can have a dramatic impact on your range. In a conventional car it makes no difference.

Note that the oil need not come from petrochemicals, Oil can be synthesised in many ways from a variety of primary energy sources. One of the most interesting is Joule unlimited which does it from non-potable water, waste CO2, and sunlight..It's worth noting, too, that most of the world's electricity comes from thermal power plants which produce it at the appalling efficiency level of around 30%!

Its important to distinguish between an ENERGY crisis (which we do not have) and an OIL crisis (which we probably will have) Whether cars are powered by oil of electricity is not at all relevant to to primary energy source.

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Excoriator
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Re: and let's also add...

No. Once underground it is safe.

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Excoriator
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The problems are:

1. It is unreliable. A seized or cross threaded bolt could stop the process halfway through leaving you marooned at the filling station. There are numerous other ways this could happen

2. You have to recharge more often than you have to fill your tank. At least twice as often and possibly more so depending on what size battery you buy.

3. It costs about the same as filling your tank for far less range.

4. Batteries degrade with use. The range is likely to be unpredictable depending on the age of the battery you get.

5. Recharging the batteries takes time wherever it happens. Although you can recharge in 30 minutes, this reduces the life of the battery. If you recharge over - say 4 hours - and the swap station is doing swaps at the rate of 30 an hour, this implies a stock of 120 batteries undergoing charge at each swap station.

6. 120 80kWh batteries undergoing charge over four hours adds up to 2.4 Megawatts. Fifty such swap stations consume the full output of a medium sized nuclear power station. Better build more power stations PDQ!

7. Swapping batteries on stage with everything brand new clean and dry is one thing. Doing it with cars off the street which could be filthy and covered in salt spray in winter is quite another. Charging batteries covers in salty water sounds a recipe for disaster to me.

8. Battery swapping stations have been tried before in Israel, where they proved to be commercial failures. There is every reason to suppose these will suffer the same fate.

It doesn't sound at all practical to me. If you are going to have to visit a filling station (you have to on a long trip - the range is far less than a modern diesel for instance) you might as well buy a conventional petrol or diesel car. It is likely to be a lot cheaper and a lot better too.

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OnlineTV recorder TVCatchup.com shut down

Excoriator

Voluntary suspension?

The TVCatchup site now displays a notice claiming that they were closed down 'presumably' at the request of the broadcasters, but have decided to stay off the air until the matter is resolved.

I think it's much more likely that the bandwidth demands have proved too much for their ISP, and it has nothing to do with the broadcasters who are much more likely to serve an injunction on them than ask the ISP to shut them down.

They claim to be sending at a rate of about 512 kbits/sec. which is why its a bit jerky and the definition is less than perfect, so you can work out what a few thousand independently timed copies of the latest simpsons episode going out simultaneously is likely to involve, as well as the ISPs problems in handling such a load.

I think this problem is the achilles heel that will kill the idea.

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Excoriator

Why it was pulled

As I understand it, the site was pulled not because of its legality or otherwise, but because the bandwidth demand was too great for their ISP to handle.

I think this is a serious flaw in the idea, and I can't see any other ISPs queueing up for the privilege of having their systems crashed by too much data either.

No doubt there are ways round this, but they probably involve multiple ISPs or multiple sites but this will involve hugely more hassle and expense. My guess is that it has gone for a long time, probably forever.

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