Cheap, efficient solar

[Richard]

Originally Posted by Jim Franklin

Now when that energy is absorbed by solar panels, it is converted for our use, yes a small proportion is reradiated back as thermal energy (Infra-Red), but the bulk of that absorbed is used up as losses in the system and as electricity for our use, and that means that the energy that would have been given to the planet, either by heating the ground or the atmosphere is lost, therefore the heating does not occur.

This is the main flaw in your argument IMO. Just about all the energy utilised by humanity ends up back in the environment as low-level waste heat. There may be a time delay as compared to that heat simply being radiated off a roof if it's turned into electricity and used to power, say, a washing machine. But it still ends up in the environment as waste heat sooner or later (and it would most likely be sooner rather than later in case your counter-argument is that we might store vast amounts of energy in batteries for decades, or something. )

[Jim Franklin]

Good posts everyone...I have only just got home (00:25hrs!!) and am in no fit state mentally to do a long post.

I am just leaving this to let you know I have not cut and run..simply trying to live in the real world!!

Anyway, I will try to address the issues you all highlight, they are all valid arguments, but I think I can address all of them in a way that you guys/gals willunderstanbd and be able to absord..whether you still agree afterwards I do not know though

[imp]

Originally Posted by Jim Franklin

Nature, please don't take this comment as condescending as it is not meant to be, but I think I understand the physics of the atmosphere better than you do.

As well as being a sparky, I have a HNC in Electrical Engineering, a first class honours in Astonomy and have been readin text books on Nuclear/Geo and Astro physics since I was about 12 years old.

You forget that the energy absorbed during the day does not go away, about 30% is reradiated back into the atmosphere during daylight hours, and another 25% during darkness, which is why the globe doesn't freeze at night. This is true for the ocean to the ocean occurs during the night.

Now when that energy is absorbed by solar panels, it is converted for our use, yes a small proportion is reradiated back as thermal energy (Infra-Red), but the bulk of that absorbed is used up as losses in the system and as electricity for our use, and that means that the energy that would have been given to the planet, either by heating the ground or the atmosphere is lost, therefore the heating does not occur.

On a small scale this is negligable, but on the massive scale some speak of it will have an impact as the energy the atmosphere uses to drive the weather systems will be diminished.

It is too early in the morning for a long post on the energy budget of the planet, but I will do one tomorrow with accurate figures if I can locate them in time from my notes and reference material.

P=I^2R => rate of energy flow back to the environment from all electrical equipment

[Jim Franklin]

Originally Posted by imp

P=I^2R => rate of energy flow back to the environment from all electrical equipment

hehehehehe..nice try Imp..P=I²R is the power used by an electrical circuit. That is total energy (not taking into account power factor) used in the circuit, the amount that may be reradiated back into the environment due to losses, or intent of the machine, will vary from machine to machine and circuit to circuit.

Quick example. Electrical circuit has a resistance of 20 Ohms and uses 12A at 230V

Therefore I² = 12*12 = 144

So 144*20 = 2880W of energy

Oddly enough that is approximately the resistance of the everage 2.8kW household kettle!!

Now a kettle is a great example as the elements in them are about 60% efficient, that is about 60% of the energy they consume goes to heating the water, the rest is lost heating the element, the metalwork and plastic of the kettle, the electrical connections and the air immediatly surrounding the kettle to a lesser degree..

The other reason I picked a kettle is because it is one of only a few forms of energy use that puts the majority of energy BACK into the environment in the form of Infra-Red radiation (heat).

When I have some time I will give you some instances later, of domestic white goods, that are terrible for the environment...most we all know of already..

[Green Giant]

Consider: the Earth's surface is currently about 3% urbanised, with 5/8's of the Earth's surface covered in water. So this gives about 1.1% of the total surface of the Earth as urbanised. As an extreme case, lets assume that all roofs in the world are covered completely with solar panels and that 50% of all urban areas are roofs (vast overestimation, but let's just assume). This gives an area of the world's surface covered by solar panels of 0.56% (i.e. a fraction of 1%).

Exactly what I was thinking Richard. Well said!

Out of interest do we know how much energy the sun throws at the Earth? I'm sure the amount that we would remove through solar energy would be a fraction of that. (which granted might still have an effect on the weather..)

[Gerbil Rebellion]

Whilst I agree with the point that the reradiated heat of solar panels is less and thus going to effect the overall energy in the system, a point I was shot down for a while ago, When you talk about the kettle (or other appliances) then the enrgy transfer has to include the energy that goes through us when we drink or eat the product heated. there are a few other factors if we are going to get finicky about it but I hope this opens the picture a bit wider for everyone.

[Jim Franklin]

I think the problem is that the atmosphere is such a big thing and difficult to understand many people have great difficulty in believing we can effect weather patterns..OH hang on..isn't that the whole argument about climate change....

Anyway, get some information together for you all..had a mare of a day..main computer died over night last night so lost internet connection. The laptop has it's own wireless but would not let this machine connect via the network due to a corrupted winsock installation..so I have installed the wireless 54G card in this and am in the process of backing up the laptop so I can do a reinstall. The main machine will be back tomorrow when I install a new motherboard as that is what died...goit!!

Just gonna fry the atmosphere burning some gas for food (cooking with it not eating Gas!!) anf then will be back here.

Just to keep things going though, for those who are curious, the total amount of energy that hits the Earth's surface is 24 hours (one period of rotation) is 1.5 × 10²² Joules (4.16 × 10E14 kW/hr)

Now the total surface area of the globe is 510100000²km (Oceans and Land) so if you divide 1.5 x 10²² by 510100000 you get end up (after conversion) with 80890442kW/hrs per square km per 24hrs or 3370425kW per hour per square km of the surface.

[Series2]

Originally Posted by Green Giant

Out of interest do we know how much energy the sun throws at the Earth?

The total amount of energy hitting the earth is 1.740×10^17 W.

As the earth rotates, this is equivalent to an average of 342 W/m² (known as "insolation" - Wikipedia article).

I'm siding with Claire on this one, I think. Almost all of the energy generated by the solar panels is going to end up as heat eventually - which is what would have happened if the solar panels weren't there and the incoming radiation hit plants, rocks or earth instead.

And if you used fossil fuels to generate the electricity, instead of sunlight - then you would simply be generating extra warming.

If you paved the whole of Nevada with solar panels and shipped the electricity to Detroit, then I guess you would affect thermal gradients enough to affect the local climates. Detroit wouldn't be any warmer, but Nevada could be colder. Same thing if you paved the Sahara and piped the electricity to Northern Europe. But (to date) all solar panels provide electricity on a very local level.

I think imp's point is also valid. I really don't understand Jim's kettle argument - I can't think of any "domestic white good" that doesn't put back almost all of it's input energy back into the environment as heat.

[Gerbil Rebellion]

Funny thing about humans though, we are the most arrogant and stupid creatures on the planet, almost all other animals use as little an amount of energy to get energy from their foods and yet we are probably using 100 times more than we need to per person, in agriculture, transport, retailers and finally when we get it home and cook it.

(edit)

Not just food either, we don't move with the climes we are meant to and some stupid idiots long ago thought it would be good to have country's and borders to stop movement of people, DUH!!!!

[Jim Franklin]

Originally Posted by Gerbil Rebellion

Not just food either, we don't move with the climes we are meant to and some stupid idiots long ago thought it would be good to have country's and borders to stop movement of people, DUH!!!!

Gerbil, I presume you don't know too much about nature then by that comment.

Humans are a territorial predatory omnivore, even in the natural world we had territories, just as lion's tigers, bears, wolves and 99.9% of all animals do. National boundaries are simply manifestations of this phenomena on a massive scale in some instances.

Unlike other groups of animals, our tribes have learnt that banding together against common threats works in our favour, thus a small tribal territory expanded over time, and yes I do recognise that on a number of occasions this expansion of territory has been done by violent means. But all territorial animals do this, humans simply do it on a scale we see nowhere else on this planet.