Should we be concerned with conserving non-renewable fuels? Can renewable energy help us become better stewards of God's creation? If the world is really under God's control, should we really put all our time into these renewable sources?

A company claims to have solved the problem of storing energy from renewable sources using giant gravel batteries:

http://www.guardian.co.uk/environment/2010/apr/26/gravel-batteries-renewable-energy-storage

What do you think?

I have to give a speech for a class where i have to persuade the audience to vote for a bill which requires all energy providers in the US to have at least certain percentage of its energy source from renewable sources. I need to know how much they use now, so that i have an idea of how much the required percent would be reasonable. If you know any representative who has proposed a similar bill, please let me know.

I understand that at present if our economy were to suddenly adjust to a green economy, there would be a serious crisis. For one, renewable energy sources are not very reliable, and may need to be subsidized similar to how ethanol is subsidized. But with sufficient research and development, could the US economy remain strong or become even stronger runnng almost exclusively on renewable sources?