What is green and how to measure it

This blog is motivated by the Nobel prize awarded to Al Gore and the IPCC.

While I do not have sufficient expertise to comment on global warming and its effects, I have a few questions on the solutions being proposed.

Take solar energy for instance. For water heating, one only needs a simple collector and a tank to store the hot water. As most houses (at least in the developed countries) have a tank it is reasonably clear that for water heating using solar energy is good for the environment.

However for electricity generation the situtation is not so clear. The amount of energy that is required to create a solar panel is not insignificant. currently they are all made using "conventional energy". The question is that does the solar panel generate more energy that was required to manufacture it? If the panel does not generate enough energy to cover its manufacture how can it be green?

The situation is similar for wind energy. The poles, the turbines, etc. are all constructed using carbon based energy. Similarly, transporting the items to a wind farm is usually on trucks etc. which run on diesel. I am not convinced that the energy from a windfarm is more than the energy used to set it up.

The reason oil, coal etc. are excellent sources of energy is that the amount of energy required to be invested in extracting it, transporting it is lower than the energy obtained by burning it. Hence it is worthwhile using such resources as energy sources.

I will be convinced that solar is sustainable only when the panels can be made from other solar panels and we also have surplus energy for other activities.

My argument is not based on economics (cost) as costs are often skewed by taxation, subsidies etc. My view is purely from a energy accounting activity.

We should continue to research alternate sources of energy. But until we can show that they are really sustainable, we cannot claim solar, wind, tidal energy to be green.