So I am pretty new to bitcoin, but I am concerned with energy usage of the system.

I estimate that the bitcoin system is running on well over 400 kW in pure computation power. This figure only includes GPU/CPU power and not any other component. I saw a figure that shows that Slush's pool accounts for about 1/4 of the total blocks found and has about 208 Ghash/s capacity. If we assume that the entire network is using highly efficient GPUs we could expect around 2 Mhash/J, but I feel that this is generous. total power=(slush capacity)/[(slush fraction of total)*efficiency] = 208 Ghash/s / (0.25 * 2 Mhash/J) = 416 kW.

Thats quite a bit of power. The other concern is we can throw more and more power into solving the blocks, but we have fixed the rate at which blocks will be found to be constant. So we add more power, then difficulty increases. Is there any way that we can make this a more environmentally friendly idea?

My plan is to mine over winter and use the heat generated to heat my apartment. I was also thinking about adding in some solar panels. Doing those things would make me feel better about the mining, but I am still not 100% comfortable with the idea of being a part of the system which is energy intensive as a whole. I understand that this may not be a concern for many people, but I thought I would throw it out there and see what people are thinking. Thanks for your input.