Artful Dodger:

> How much steel and land do “environmentally friendly” energy technologies use? Is this “sustainable”?

Every industrial activity (even the "Green" industries) consume land, natural resources and energy. It is a given.

Wind turbines require steel, aluminium, lubricants, wiring, electronics, etc. Pollution is generated from the manufacture of wind turbines.

Solar panels are not much better. Refining silicon wafers is very energy intensive. There there is copper, plastics, metal, glass, etc.

If wind turbines use land, so do oil wells and drilling rigs. If wind turbines use steel, so do oil wells, drilling platforms, pump jacks, etc.

One must look at the sum total of energy spent during manufacture and energy generated during consumption. Oil wins at the moment because the amount of energy used during extraction, transportation and refining is relatively low compared to the amount extracted when oil products are burned. This is why oil is cheaper than wind turbines.

One must also look at the amount of pollution generated during manufacture, production, transporation, consumption, accidental spills, etc. Oil production can be very messy when spills occurr. Oil releases a lot of carbon dioxide when burned. There is also nitrogen oxides, ozone and other pollutants generated during combustion. Windmills and solar panels win on the pollution side because once they are manufactured and installed, they generate almost no pollution. That is what makes renewable energy sources attractive.

Then we have to remember that is most of the energy comes from renewable sources, then a more ecologically balanced manufacture or wind turbines and solar panels is possible. The raw materaials can come from recycled steel, aluminium, plastics, glass, etc. The energy comes from a renewable source, so less fossil fuels are used during manufacture.

Slowly, the renewable side can add up leading to a decrease of our dependance on oil. The problem is that people want a solution right now. People don't want to wait 30 years for renewable energy to become viable.