UK coal and N. Sea

Tarrel · Post by **Tarrel** » 12 Dec 2012, 21:04

UndercoverElephant wrote:
Tarrel wrote:
What I cannot imagine happening is for cold human beings in places like Russia and North America leaving burnable, recoverable coal in the ground
An interesting thought-experiment; if you found yourself marooned in such a climate for the winter, in a cabin on the edge of the tree-line, with enough frozen seal-meat to keep you going for a few months, and someone had thoughtfully left a tonne of coal in there, would you burn it? (Assume wood is available, but in limited supply, and would require expenditure of large numbers of calories to fell and process it.)
Of course I would, but I'm not sure what is interesting about the thought experiment.

The scenario is a metaphor for the idea that we take the path of least resistance to fulfilling the basic needs that we have (in this case, heat). In the cabin you have an alternative, which is to expend a lot of effort in procuring the wood supply. What's interesting is that you immediately went for the alternative that was most readily to hand (the low hanging fruit, if you will), as would I have done. It's human nature to do so. Multiply that up several billion times and you have the situation we are in now.

RenewableCandy · Post by **RenewableCandy** » 12 Dec 2012, 23:01

I'd use the wood when well, and the coal when ill or injured.

vtsnowedin · Post by **vtsnowedin** » 13 Dec 2012, 00:51

biffvernon wrote:Electricity can be used for pretty much everything - coal is much more awkward.

A couple of exceptions come to mind. Electric aircraft? Commercial ships? Ag tractors?

Post by **adam2** » 13 Dec 2012, 08:57

vtsnowedin wrote:
biffvernon wrote:Electricity can be used for pretty much everything - coal is much more awkward.
A couple of exceptions come to mind. Electric aircraft? Commercial ships? Ag tractors?

Indeed, all of the above are just about possible in a very limited way, but dont seem viable for general use.
Hydrogen produced from electricity is a possible alternative but innvolves considerable costs and complications and appears unlikely to be much used.

biffvernon · Post by **biffvernon** » 13 Dec 2012, 09:11

vtsnowedin wrote:
biffvernon wrote:Electricity can be used for pretty much everything - coal is much more awkward.
A couple of exceptions come to mind. Electric aircraft? Commercial ships? Ag tractors?

Electric tractors are easy - never travel far from a charging point and the heavy batteries can displace those lumps of iron they hang on the front to balance the rear payloads. Electric aircraft are about as impossible as coal-fired aircraft. Don't fly. Sail a ship.

Post by **adam2** » 13 Dec 2012, 10:15

Battery electric tractors certainly exist but only in small sizes AFAIK, suitable for large gardens, smallholdings, public parks and the like.
Mains powered tractors that use a long power cable have been tried with only partial success. During WW11 when oil was in very short supply, several countries tried them. They had to be hauled to the worksite by horses or a steam engine.

I suspect that we may soon see electricly powered light aircraft, a prototype has flown succesfuly.
An electric jumbo jet seems most unlikely.

Electric ships are a distinct possibility for short regular voyages such as ferry routes.

Sailing ships with auxillary electric power are certainly possible, but an ocean crossing under battery power seems very unlikely.

Post by **clv101** » 13 Dec 2012, 10:29

For electric tractors, surely the trick is to get rid of the tractor? Just winch equipment across the field from the edge.

emordnilap · Post by **emordnilap** » 13 Dec 2012, 10:36

biffvernon wrote:Electricity can be used for pretty much everything - coal is much more awkward.

For everything we really need, yes. The problem is getting others to see this, which is why all fossil fuels will be burnt.

Tarrel · Post by **Tarrel** » 13 Dec 2012, 12:37

Electric ships are a distinct possibility for short regular voyages such as ferry routes.

Yep, CalMac are introducing them next year on some of the shorter inter-island crossings in Scotland.

Tarrel · Post by **Tarrel** » 13 Dec 2012, 12:40

biffvernon wrote:
vtsnowedin wrote:
biffvernon wrote:Electricity can be used for pretty much everything - coal is much more awkward.
A couple of exceptions come to mind. Electric aircraft? Commercial ships? Ag tractors?
Electric tractors are easy - never travel far from a charging point and the heavy batteries can displace those lumps of iron they hang on the front to balance the rear payloads. Electric aircraft are about as impossible as coal-fired aircraft. Don't fly. Sail a ship.

I wonder if electric airships may be more viable than aircraft. The power is then only needed for forward propulsion and manoeuvring, and not for lift.

Post by **clv101** » 13 Dec 2012, 12:54

Flight (airships or jets) isn't really about energy required for lift. It's all about air resistance. Yes airships float for 'free' but try pushing their bulk at any kind of speed, or against the wind and they soon become energy hogs.

Tarrel · Post by **Tarrel** » 13 Dec 2012, 15:37

clv101 wrote:Flight (airships or jets) isn't really about energy required for lift. It's all about air resistance. Yes airships float for 'free' but try pushing their bulk at any kind of speed, or against the wind and they soon become energy hogs.

Well, yes, you need the speed in order to create the lift, which brings you up against the air resistance problem you mention. But an airship doesn't need speed to stay up in the air. It can travel much slower than an aircraft (but faster than a ship) and therefore use much less energy. (Drag increases with the square of speed. Halve the speed and you quarter the air resistance to be overcome.) Admittedly, there is a rather large bulk to be moved through the air compared to a conventional aircraft.

The problem would probably be the weight of the batteries needed to provide any kind of decent range.

PS_RalphW · Post by **PS_RalphW** » 13 Dec 2012, 15:55

Just fill it with hydrogen and power the engines using fuel cells !

Tarrel · Post by **Tarrel** » 13 Dec 2012, 22:20

RalphW wrote:Just fill it with hydrogen and power the engines using fuel cells !

Makes sense.

I seem to remember reading somewhere you were at Imperial? I was there '77-80 (Mech Eng). There was an interesting project going on at the time, using hydrogen directly in internal combustion engines. It runs them just fine. The problem, as ever, was how to transport the hydrogen. IIRC, they were looking at holding the hydrogen as lithium hydride crystals, which can be stored in a regular (non-pressurised) container, thus saving weight. Heating apparently releases the hydrogen.

Dr. Laming, who was there at the time, was a real airship fan. Had a small consultancy firm going, looking at medium-scale freight transportation by airship, IIRC.

PS_RalphW · Post by **PS_RalphW** » 14 Dec 2012, 13:40

I did Chemistry 80 -83. At that time zeolites where the new storage option - they can adsorb large quantities of gas at relatively low presures. I think they needed heating to release the gas agin.

I wouldn't want Lithium hydride in my 'gas' tank. Chemically it sounds a little to much like rocket fuel!

wikipedia

As discussed above, LiH reacts explosively with water to give hydrogen gas and LiOH, which is caustic. Consequently, LiH dust can explode in humid air, or even in dry air due to static electricity. At concentrations of 5–55 mg/m3 in air the dust is extremely irritating to the mucous membranes and skin and may cause an allergic reaction. Because of the irritation, LiH is normally rejected rather than accumulated by the body