The climate change debate continues.

[spacesailor]

WHY ARE WE WASTING A FUEL SOUCE.

 

A polytarp will collect methane & poly pipes can transport it.

 

Not a lot of outlay to get that FREE methane fuel to a commercial plant for industry.

 

spacesailor

 

 

[facthunter]

I reckon the methane off my dam would power the house. Landfill is a source. Nev

 

 

[Marty_d]

If every house and every factory roof in Sydney was fitted with solar panels, maybe the daytime level of power generation from "old technology" might be reduced to a trickle, but as soon as the Sun drops below the horizon, and we want to use our electrical equipment, what is going to take up the load? 

 

Living in a non-urban area for a long time makes one lose sight of the massive amounts of power a metropolitan area like Sydney uses. Last night it was cloudy over Sydney, but the urban light reflected by those clouds made it as bright as a 3/4 Moon. And as I drove home at 1:00 am from work, I saw large areas lit by street lights where 10 years ago, or less, there were only paddocks. In the CBD, multi-storey buildings have lights working on every floor, and no doubt air conditioning plants and a million computers, servers and routers.

 

 

 

Smart grids are one answer, at least to household power.

 

During the day when both parents are out working and the kids are at school, power from the PV goes into the battery.  In afternoon / evening when everyone turns on Netflix, batteries supply the power.  In a smart grid the houses not using energy at night can sell their power to neighbours whose batteries run dry - automatically.

 

Helped by smart appliances, solar hot water, energy efficient design and sensible landscaping.

 

If high rises were sensibly designed instead of slapped up for the least outlay by developers, A/C would almost become a thing of the past.   Automatic shading, windows that open allowing cross-breezes, roof/side gardens - there's a multitude of design concepts that make buildings more sustainable, efficient, and healthier to work / live in.

 

 

[facthunter]

Marty, Airconditioners ARE the future.  Get in fast while stocks last..When it's impossible to go outside you create the only liveable space available for yourself until the power poles burn & the screen says "GAME OVER" and the supermarket shelves are empty. . This can happen in a matter of days, as we have found out. Nev

 

 

[willedoo]

If high rises were sensibly designed instead of slapped up for the least outlay by developers, A/C would almost become a thing of the past.   Automatic shading, windows that open allowing cross-breezes, roof/side gardens - there's a multitude of design concepts that make buildings more sustainable, efficient, and healthier to work / live in.

 

There's some interesting designs proposed for future city building. As EV's take over, the prospect of rooftop/balcony vegetable gardens becomes more viable as the pollutants reduce. I can see a future where internal combustion vehicles are banned from city centres.

 

 

[Old Koreelah]

2M of evaporation is probably on the low side. the "lake " NE of Mt ISA is 11 M deep and evaporation has made it useless.

 

    The water evaporated  from Lake Eyre won't form cloud till it reaches saturation which might be over the south island of New Zealand. Nev

 

Nev your logic is okey, but assumes air masses are moving rapidly across our continent. If not, surely rainfall downwind of all that water would increase.

 

Perhaps we could see the likely impact of a permanently-full L. Eyre basin on nearby climate by examining past weather records during the times the lake has filled. I wonder if anyone has done that research.

 

 

[Old Koreelah]

The Snowy Scheme civil engineering works would be completed sooner today simply because we now have larger, more efficient earthmoving and tunneling equipment. 

 

Maybe we need a Gunpowder Plot to rid ourselves of political prostitutes (apologies to sex workers)...

 

 

 

 

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[facthunter]

OK there's NO clouds till the rel humidity reaches 100% anywhere. Deserts exist on many shores in the world where quite extensive Oceans abut .. The prevailing winds have to be over water for a long time and preferably warm water where the actual humidity is high (Airmass is tropical maritime,) THEN a bit more moisture( Low pressure system circulation) OR some cooling (orographic uplift) and hey presto... Clouds and RAIN. Nev

 

 

[Old Koreelah]

Yes Nev, I'm pretty familiar with all that, physical geography being my specialty.

 

What interests me is if there has been any change in weather patterns downwind of L Eyre while it's got water in it.

 

 

[old man emu]

The geological record indicates that back before Lake Eyre and Central Australia started to dry out, the area surrounding the lake was quite lush. How far east that extended, I don't know.

 

If you look at the country from Lake Eyre to Port Augusta, you can theorise that Lake Eyre drained into Lake Torrens, then into the ocean near Port Augusta. Without checking a topo map, there seems to be high ground which would prevent water passing from Lake Eyre to Lake Torrens. Maybe we could open a channel through that area, and from and the coast to Lake Torrens an inundate all that central area. 

 

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[Old Koreelah]

I just checked the 1:250k map on OzRunways. I was surprised that the surface of Lake Eyre is not particularly level; it varies by a few metres, the deepest being about 14m below sea level. The country between there and Lake Frome is higher and Frome is just a poofteenth above sea level, so I doubt it played a part in any ancient drainage to the sea.

 

 

[old man emu]

What if you had a device that made use of the heat introduced to a building by sunlight, operation of electrical equipment, and human metabolism to drive an electricity generator? I'm not talking of a perpetual motion machine, which anyone with a modicum of thermodynamic knowledge would reject out of hand. I'm talking about a machine that has an efficiency of up to 50%, and, while not producing all the electricity needed in the building, could make a goodly contribution to the demand.

 

Here is an interesting video about such a machine the concept of which was discovered in the early 19th Century. 

 

 

[facthunter]

 OK I doubt the effect is very marked. Till condensation occurs, not much is going to be evident. Probably just a miniscule increase in Rel humidity which a small ambient variation could cause anyhow. Like a clear night might cause local thin fog in a small low lying area. Nev

 

 

[old man emu]

There is no condensation involved. The device operates as a result of the different temperatures above and below the separator.

 

The operation can be described by the Combined Gas Law:

 

The volume of a given amount of gas is proportional to the ratio of its Kelvin temperature and its pressure.  

 

PV / T = C

 

A constant © can be put in that is unique to each environment.

 

Although the pure science expresses the Law in terms of temperatures measured in degrees kelvin. For practical use, calculations can be carried out using measurements made using the Celsius scale since the graduations in both scales are of the same size. The kelvin is the primary unit of temperature measurement in the physical sciences. Zero degrees Celsius is 275.15 kelvin.

 

As the pressure goes up, the volume changes and the temperature also goes up, and vice-versa. Also same as before, initial and final volumes and temperatures under constant pressure can be calculated.

 

P1V1 / T1 = P2V2 / T2 

 

If T1 and T2 are different, then the pressure in the container will change, and because the separator can move, the volume on the "hot" side can change, in a similar fashion to the movement of a piston in an internal combustion engine. A diesel engine operates on the same principle, with the exception that in a diesel engine, a combustible material is injected when the increase in pressure caused by reducing the volume of the cylinder has caused the temperature to rise high enough to cause the combustible material to ignite. This device does not require a combustible material, so does not use any fuel, nor does it produce pollutants. Also, since there is no rapid combustion, there is no "bang". The device runs silently, except for noise generated by power transmission components.

 

 

[Old Koreelah]

OME I think Nev was talking about L Eyre and impact on climate.

 

 

[facthunter]

Yes I was. A friend of mine has a stirling engine and we've run it a few times It does run but agreed it would not make very significant power as a motor running at any real revs It could probably lift water though (without rotating) through the night with Diurnal variation and at very little cost. Bearing in mind the lift of water is only around 30 feet when you have a perfect vaccuum and you will always have some water vapour pressure.  Large and slow might be the go. Big diaphragm with linkage. Nev

 

 

[Yenn]

One of the big users of power is air conditioning.

 

I remember in the days when I was building reinforced concrete chimneys that even on the hottest of days we would be fairly cool, due to the chimney beneath us heating up and drawing air in at the base, which could get to quite a strong force as the chimney got higher.

 

The theory could be used to cool buildings, just have a black painted chimney above the building to draw air in.

 

 

[old man emu]

OK, Nev - crossed conversations.

 

I wonder what effect depth of water would have on the measured evaporation rate.

 

Evaporation is measured using the Class A evaporation pan, a cylinder with a diameter of 47.5 in (120.7 cm) that has a depth of 10 in (25 cm). That gives a surface area of (2.pi.r = 2 x pi x 120.7 = 241.4 x pi = 758 sq cm or 7.5% of one square metre. We all know that if you dive into a swimming pool that hasn't been used during a sunny day, you go through a warm layer into a cold layer underneath.

 

So, isn't it logical that the evaporation from a deep body of water would only occur from, say the first metre of depth?  

 

Regarding the Stirling motor, didn't you watch the video? In it, the presenter tells that these motors are being used to propel submarines underwater. The motor utilises the thermal difference between the temperature inside the hull and the seawater on the outside. They have an advantage in submarines in that the motors do not make noise as they produce motion. Silence is a godsend for submarines.

 

 

[Litespeed]

OME,

 

That would be the Swedish hybrid sub that snuck up on the US fleet in exercises and said " bang" you are all dead.

 

The Yanks are very unimpressed. If you can sneak up on a highly protected fleet with sub's hunting you, you are a very deadly hunter.

 

Amazing use of old tech.

 

Love it when Uncle Sam gets a blood nose.

 

 

[old man emu]

Not so much "old tech" as further development of an established principle.

 

Yes, it was the Swedish sub that not only "sank" the US "Ronald Regan", after it had eluded the US Navy for twelve months of continuous war-gaming. The Yanks rented the sub from the Swedes for a year after that while they tried to develop systems for locating this type of sub.

 

The Swedes built three of these subs, and plan to bring an improved type on line in 2025. The cost of one of these Swedish subs is the same as the cost of one fancy Yankee fighter plane ($100M).

 

 

[Bruce]

OME, the trouble with using a small difference in temperature to drive a heat engine is that the efficiency is also very small. This is a consequence of the second law. It explains why diesel engines are more efficient than petrol engines. They combust at a higher temperature. It is a fundamental limitation not effected by the quality of the engine.

 

And Nev is right about what would happen if lake Eyre were filled according to a commission of met men. The evaporated water would need to be lifted somehow to condensation levels to even get a cloud. Most of the time, not even this would happen.

 

There was a theory in about 1890 about how " the rain would follow the plough " and it was believed by enough optimists that it became accepted wisdom. Lots of people went broke as a result of expanding the wheat areas too much.  They thought that ploughing the ground would cause more transpiration and therefore more rainfall.

 

 

[old man emu]

In the 19th century, the "rain follows the plow" myth was used to justify settlement of the Great Plains. The cultivation of semi-arid to arid land was said to increase rainfall by moistening the soil and humidifying the atmosphere. Subsequent research debunked the myth, though large discrepancies still existed between model representations and actual observations. In addition to, and partly motivated by, the "rain follows the plow" myth, many scientific papers have been published with conflicting results: wet soil would increase, decrease or not change precipitation in different papers. A couple of years ago, a Doctoral student in Arizona researched the topic. His goal was to resolve this controversy. His research of climate data found that morning soil moisture can affect afternoon rain accumulations over the Southern Great Plains during the warm season and the impact differs based on atmospheric conditions. On days when the wind brings limited moisture to the region, drier soils enhance afternoon rain. But when the wind brings greater moisture to the region, wetter soils increase afternoon rain. So the myth seems to depend on whether plowing holds soil moisture or lets it dry out. The other big factor is the humidity of the air mass brought in as wind.

 

Found the video! 

 

How's this for an aero engine? 

 

I see that these engines still have a few problems in regard to pollution. It appears that to get constant operation at relatively high revs, a fuel has to be burnt. I wonder what sort of torque these motors can generate.

 

Also, there does not appear to be a method for controlling the speed of the motor. That factor would suggest that a Stirling motor would be OK as a stationary motor, used to spin electrical generators or other shaft driven equipment, but not practical in a vehicle.  

 

 

[facthunter]

OME evaporation only really happens right at the boundary of the water surface Molecules vibrate  (faster as they get hotter) and some escape into the air at well below boiling point..  This evaporation even happens with metals although to a much lesser extent. Nev

 

 

[old man emu]

evaporation only really happens right at the boundary of the water surface Molecules vibrate  (faster as they get hotter) and some escape into the air at well below boiling point.

 

 

 

That's correct.  It is due to the Surface Tension of the material. Generally we talk about the surface tension of a liquid. It's hard to imagine molecules of a solid having enough energy to overcome inter-molecular bonds.

 

The cohesive forces between molecules down into a liquid are shared with all neighboring atoms. Those on the surface have no neighboring atoms above, and exhibit stronger attractive forces upon their nearest neighbors on the surface. This enhancement of the intermolecular attractive forces at the surface is called surface tension. Surface tension results from the greater attraction of liquid molecules to each other (due to cohesion) than to the molecules in the air (due to adhesion). The net effect is an inward force at its surface that causes the liquid to behave as if its surface were covered with a stretched elastic membrane

 

 

The surface tension of water is 72 dynes/cm at 25°C . A dyne is a unit of force that, acting on a mass of one gram, increases its velocity by one centimetre per second every second. A dyne is a minuscule amount of force. It would take a force of 72 dynes to break a surface film of water 1 cm long. The surface tension of water decreases significantly with temperature as shown in the graph.

 

 

So, the hotter the few top centimetres of the body of water becomes, the more of the water will escape from the surface. The question as to the rate of drying of the a filled lake seems to depend on the depth of the hot surface layer.

 

 

[willedoo]

OME,

 

That would be the Swedish hybrid sub that snuck up on the US fleet in exercises and said " bang" you are all dead.

 

The Yanks are very unimpressed. If you can sneak up on a highly protected fleet with sub's hunting you, you are a very deadly hunter.

 

Amazing use of old tech.

 

Love it when Uncle Sam gets a blood nose.

 

Litespeed, are you thinking of the time our Collins Class sub did exactly that. In Hawaii I think it was. They sneaked through under an overhanging rock ledge from memory. Then got the carrier in range and broadcast the 'bang, you're dead' thing. I think they were banished to the boonies for the rest of the exercise.