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- CommentAuthorJoiner
- CommentTimeAug 4th 2012
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- CommentAuthorEd Davies
- CommentTimeAug 4th 2012
12 kWh for 87p sounds like a good deal - I wonder if it's a conversion of US prices or something. Other than that, is there anything interesting or surprising in that article at all?
Credibility check: the rough rule of thumb is £1/W·a (watt·year). That an iPad, averaged over all time including when it's not in use, and allowing for charging inefficiencies would use a bit less than 1 W sounds about right. -
- CommentAuthorJoiner
- CommentTimeAug 4th 2012
It's a UK-based internet publication, Ed.
And it saves having to work it all out yourself, so marginally useful and possibly interesting to some.
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- CommentAuthorFred56
- CommentTimeAug 4th 2012
A few years back I was listening to a Radio 4 piece about the power consumption of DAB radios. The BBC spokesperson explained, without any recognition of the significance, that a DAB radio consumed between 12 and 20 times the energy of an analogue radio. Hmm. Just think about all those batteries.
It got me thinking. Have you considered all the energy consumed by all those extra set-top boxes tagged onto or TVs. The government want to sell the spectrum currently occupied by analgue but just what does that cost in extra generation.
It's not just old TVs. We have a very recent (less than 2 years LED TV). It has built in Freeview as well as analogue tuners. However, it turns out that this is not a HD Freeview tuner despite the fact that it is a full HD TV. As it happens we use a Freesat HD box because it is just better than Freeview. So every time we switch on, we fire up three tuners. -
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CommentAuthorDamonHD
- CommentTimeAug 4th 2012
Our (oldish) cable box takes 15W and effectively has no standby. Our ancient 16" CRT TV takes ~60W; a new LED-lit LCD 26" TV will take between 30W and 40W if we get a good one. So even though it's not good the set-top box is not horrible (~40kWh/y or ~3% of out total electricity consumption).
Rgds
Damon -
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- CommentAuthorRobL
- CommentTimeAug 4th 2012
I think the addition of radio to freeview was a mistake - how many tellies get left on just so you can "tune in" ?
Our telly is a rather embarrasing plasma (takin an evil 250W), but the set top box is good - a genuine 1W on standby. Lots of set top boxes take 15-25W in "standby". At long last, set top boxes can be as low power standby as those VHS recorders of yester-year ! I think the high standby is because manufacturers use software* based solutions, allowing them to omit a cheap seperate timer chip to allow it to start from standby for timer-record.
*generally linux, but not really it's fault -
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CommentAuthorSteamyTea
- CommentTimeAug 4th 2012
I believe the early DAB radios where a bit power hungry, mine did not last long enough to for me to find out.
Was rubbish anyway and I am led to believe that the DAB standard is changing sometime anyway.
I went back to my old Freeplay Ranger (that is the original solar and wind up one), must be ten years old now and still good on the FM, much better than the newer Freeplay Sherpa one that has a torch in it, the sound quality is just rubbish, it is also half the size and mass so easily knocked about.
The Ranger is still on the original battery as well, last a week between charges if not left in the sun (tis on about 18 hours a day). -
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- CommentAuthorJoiner
- CommentTimeAug 5th 2012
Last night I set the freesat to record a film we wanted to watch later. Hmmm. On Friday we decided that we would start to turn off the TV and all related boxes at the plug and stop leaving it all on standby, so as we got up to go to bed I did the righteous thing.
Bugger!
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CommentAuthorSteamyTea
- CommentTimeAug 6th 2012
iPlayer (or equivalent) or an illigal download
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- CommentAuthordjh
- CommentTimeAug 8th 2012
Posted By: JoinerIt's a UK-based internet publication, Ed.
But the Electric Power Research Institute that they're quoting is American, so Ed is probably right. -
- CommentAuthorJoiner
- CommentTimeAug 8th 2012
Forget the price, look at the consumption...
"The research shows that each Ipad consumes less than 12kWh of electricity annually" -
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CommentAuthorfostertom
- CommentTimeAug 8th 2012
How many cubic miles of water lifted how high is that? -
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- CommentAuthorJoiner
- CommentTimeAug 8th 2012
Stirrer!
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CommentAuthorSteamyTea
- CommentTimeAug 8th 2012 edited
12 tonnes 36 km
or
432 tonnes 1 km
or
1296 from the nearest coast to me to the nearest sizeable carne near me
But allowing for 75% efficiency that will be 1620 tonnes. -
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- CommentAuthorJoiner
- CommentTimeAug 8th 2012
Don't believe you.
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CommentAuthorSteamyTea
- CommentTimeAug 8th 2012 edited
Me neither.
PE=mgh (J)
Edited from earlier as too tired
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- CommentAuthorEd Davies
- CommentTimeAug 9th 2012
PE = 12 kWh × 3.6e6 J/kWh = 43.2e6 J.
g = 10 N/kg.
43.2e6 J = m × 10 N/kg × h.
mh = 43.2e6 J·kg / 10 N = 4.32e6 kg·m.
For m = 12 tonnes = 12e3 kg, h = 4.32e6 kg·m / 12e3 kg = 360 m.
For m = 432 tonnes, h = 4.32e6 kg·m / 4.32e5 kg = 10 m.
So, unless I've made a similar blunder, I think ST's numbers are 100 times too large.
Still, 12 tonnes 360 metres up shows just how much umph there really is in such a 'trivial' amount of electricity. -
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CommentAuthorDamonHD
- CommentTimeAug 9th 2012
I looked it up today on the infallible Wikipedia: the potential energy of lifting 1kg up to geosynchronous orbit only seems to be about 15kWh or £2 of electricity!
Rgds
Damon -
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- CommentAuthorJoiner
- CommentTimeAug 9th 2012
Don't encourage him, Damon!
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CommentAuthorDamonHD
- CommentTimeAug 9th 2012
(I think that if ST manages to raise 1kg to geosync orbit, then while he's not looking I'll sell on the service as the space elevator at a nice little mark-up: move over Space X!) -
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CommentAuthorSteamyTea
- CommentTimeAug 9th 2012
I must stop doing sums in my head and find my pencil and paper.
August is my busy month and never really think straight, roll on September when the Emmets are gone and the sun comes out
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- CommentAuthorJoiner
- CommentTimeAug 10th 2012
This emmet might be heading your way in the first week.
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- CommentAuthordjh
- CommentTimeAug 10th 2012
Posted By: DamonHDI looked it up today on the infallible Wikipedia: the potential energy of lifting 1kg up to geosynchronous orbit only seems to be about 15kWh or £2 of electricity!
When you (or Wikipedia) say 'potential energy' does that mean you also need to add a huge amount of 'kinetic energy' to actually get it into orbit? I think you might find you have to supply the 'kinetic' energy as the payload goes up your space elevator. -
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CommentAuthorfostertom
- CommentTimeAug 10th 2012
No - the point about a space elevator to geosynchronous orbit is that centrifugal force does the lifting. Innit?
The problem is that the force is applied at the top, so a lifting cable has to be dropped down to the surface - and the weight of that length of cable is so vast that it wd have to be impossibly huge in cross sect area to support its own weight. -
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- CommentAuthorSeret
- CommentTimeAug 10th 2012
Posted By: fostertomNo - the point about a space elevator to geosynchronous orbit is that centrifugal force does the lifting. Innit?
No, the centre of mass of the elevator is at geosync. Everything up to there has to be lifted (although less so as you go up). The big advantage is that you (possibly) get to leave your engines and fuel on the ground. Which is why NASA are funding competitions for cable-climbing machines powered by laser energy beamed from the ground. -
- CommentAuthorJoiner
- CommentTimeAug 10th 2012
Why not just tether the weight to a load of pigs and get them to fly it into orbit.
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- CommentAuthorSeret
- CommentTimeAug 10th 2012
I'll run that one by Dr Julius Strangepork and see what he says. -
- CommentAuthordjh
- CommentTimeAug 10th 2012 edited
Posted By: fostertomNo - the point about a space elevator to geosynchronous orbit is that centrifugal force does the lifting. Innit?
The problem is that the force is applied at the top, so a lifting cable has to be dropped down to the surface - and the weight of that length of cable is so vast that it wd have to be impossibly huge in cross sect area to support its own weight.
No, the fact that, as you point out, the lifting cable is dropped from above shows that objects still have weight as they track up the cable. The weight and strength are not beyond the theoretical reach of materials made from carbon (or boron-nitride) nanotubes, as I understand it. It's "just" an engineering problem now. The advantage of a cable is that you don't have to supply power to hold an object wherever it is, only to move it against the force of gravity. A rocket has to expend power just to hover. A stick can support the weight of a rock with much less energy use than if you hold the rock up yourself.Posted By: DamonHDI looked it up today on the infallible Wikipedia: the potential energy of lifting 1kg up to geosynchronous orbit only seems to be about 15kWh or £2 of electricity
OK, I agree with Wikipedia now. The figure I have is 60 MJ/kg or 16.67 kWh/kg. Impressively low. -
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CommentAuthorSteamyTea
- CommentTimeAug 10th 2012 edited
Posted By: JoinerThis emmet might be heading your way in the first week
Better tell Tom to get the roof of the FIAT
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CommentAuthorfostertom
- CommentTimeAug 10th 2012
Let's ALL go and visit ST next week! -
