When you look at fuel sources, I think that’s where you answer the sustainability question. What fuel source is sustainable? I feel like coal is sustainable for 200-300 years. Some people talk about biomass and wood as being sustainable. I’m nervous about that one. You’re cutting down trees, cutting down forests. I’m not sure sustainability fits in that. Now, switch grass, a crop that you can renew every year is sustainable. I think the fuel has to be there long term or somewhat renewable to be sustainable.