OT: More National Grid woes

[newshound]

Presumably they will need longer runways, in case when you land you don't have enough energy left for reverse thrust.

[Jane]

I bet it doesn?t when we get our act into gear with nukes once fossil fuels become significantly more expensive.

[The Natural Philosopher]

It's still an issue.

But yes, a nuclear electric society is one possible future.

All - or mostly - nuclear is economically viable as France shows.

That leaves you with two problems:

1: Off grid transport. 2: Replacing coal and gas as chemical reducing agents.

Synthetic fuel for both is possible, but way too expensive at the moment.

However if off peak electricity were turned into hydrocarbon fuel, you might say that fuel cost was essentially zero as the opportunity cost of keeping a nuke going flat out rather than throttled back is almost zero.

[Jane]

There is only much of that with aircraft and it will always be possible to make petrol, gas and diesel using nukes.

No need to when nukes mean that those are still available.

Yes, but viable once the price of those hike. But it will be a long time before that happens with shale oil and CSG etc.

And then it can be used in cars and planes.

[The Natural Philosopher]

They will always 'still be available' but at some point too expensive to compete with synfuels.

Read the linked paper

The problem with hydrocarbon fuels is not really CO2, but things like injecting H2O high in the atmosphere, and or NOx at ground level.

This suggests that people would prefer BEVS for city use where car density is high.

And electric aircraft if possible. Electric transatlantic flight is absolutely on the limits of *theoretical* lithium air technology.

Like fusion its all possible, if only someone knew how to solve the technical problems...

I'd give it a 50/50 in the next 30 years.

[Jane]

What I said.

Did that.

No evidence that that is a real problem.

Yes, but I was commenting on your off grid. Those arent.

The next 30 years isn't a problem with hydrocarbon fuels.

[The Natural Philosopher]

No, it is not.

Considerable evidence that aircraft contrails are far more of a climate modifier than CO2 is.

Considerable eveidence that Nitrogen oxides are serious causers of smog and other pollution hazards and are extremely corrosive to human airways.

They are at the point of use.

*arent't* a problem.

That depends. On who has the hydrocarbon reserves and what they want in exchange.

If islamification of Europe, or sovietisation, is the price for Arab Oil, I'd rather have nukes.

[Tim Streater]

And fracking.

[AnthonyL]

Samsung is a non-issue for flights - Emirates (and others) will not take the Galaxy Note 7 on board either as carry-on or checked in.

Current aircraft have to jettison fuel if having to make a prematurely early landing (as in an emergency). Beware falling batteries over major cities. If Landing weight is to equal take off weight there will be a massive reduction in payload.

[The Natural Philosopher]

They do not do that to reduce weight.

They do that to reduce fire risk.

[Roger Hayter]

No, they need some reserve fuel anyway despite the fire risk. They do it to reduce weight, to make landing safer or, in some cases, possible on available runways.

[The Natural Philosopher]

O am glad you accept that there is a fire risk and that it is reduced by fuel.

It doesnt make that much difference.

From a quick google it looks like airframe weight:fuel:payload is about

1:1:1.

So the very most you could reduce the all up weight by dumping fuel would be 30% or so, and since stall speed varies as the square root of wind loading thats only about a 17% reduction in landing speed.

An electric aircraft with fully charged batteries would in any case be lighter at takeoff than a fully fuelled one. Since its going to get heavier as it flies.

[Roger Hayter]

A few percent of the take off weight is quite a large chunk of the revenue-earning payload. And many airliners are certified for a maximum legal take off weight significantly higher than the maximum legal landing weight. Following certification rules is of course a legal obligation as well as safer.

Yet another disadvantage of electric planes.

[Fredxx]

What batteries do you have in mind that increase their weight significantly when discharged?

[Chris Hogg]

?

[Fredxx]

Yes, I did see that link and others to proposed research on the topic, but to date no commercial Lithium-air battery exists.

[Steve Walker]

For each aircraft type and runway length/altitude there is a maximum takeoff weight and a maximum landing weight. They dump fuel specifically to get below the maximum landing weight.

SteveW

[charles]

so, they'll make a low pas over the airfield and drop part of the battery load by parachute, then come round again and land.

[Max Demian]

Einstein says a charged battery is heavier that a discharged one.

[The Natural Philosopher]

Lithium air.

Start off with pure lithium, end up with lithium oxide.