comments on my signature...

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quasi said:


Oops didn't see this, hope I'm not too late.

I read in a technical journal a few years ago (sorry can't remember which one) that from a pure energy conversion point of view a solar system with associated electronics and batteries using current technologies cannot ever repay the energy required.

Taken into account was the energy required to mine or create the raw materials, convert them (glass, aluminium, cells, lead, plastics, copper etc.) process them and manufacture the bits required.

When adding up all this energy and factoring in replacing the batteries every 5-7 years or so then the system never pays for itself in terms of energy used to energy returned.

This may not be true in financial terms which explains why solar systems are appearing on rooftops (even here though the payback in Australia is 10+ years), but in terms of what the planet provides to what it gets back solar cell and battery systems are worse for the environment than other forms of energy production (wind, hydro, nuclear).

This means that to scale production of solar systems to provide city size energy requirements could be really bad for the planet.

Cheers

I might add that the same is true for wind turines. I have not updated my knowledge on the subject for a few years, so they may have crossed the "break even" state by now, but it sure is lately if they have.
When mentioning wind turbines, another issue have been added within the last couple of years. Now the blades are partly made of carbon fibre, which is perhaps the worst environmental issue we will see in the next 50 years, as there is AFAIK no reasonably environmentally friendly way of getting rid of carbon fibre constructions. Up till now that have not presented any major problems, as carbon fibre have been relatively expensive, so it was limited to small objects like fishing rods and the like, but now even relatively low budget cars include that stuff in relatively large amounts, as well as wind turbine blades and a load of other large ithems.

Magura:)
 
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