not competitive with, say, natural gas, electricity production. now, in a narrow sense, they will be competitive. that is, during the middle of the day when the sun is shining. but when you buy power, what you're really buying is reliability. you want 24-hour-a-day, even if it's been cloudy for four or five days, you want your hospital to have electricity. you want somebody in an apartment building not to freeze to death. and so taking these intermittent sources and adding them in means that we either need peakers, things that come in supplementing, or we need massive storage. and so we do not have an economic way of converting the energy system to a zero co2 system. only through big innovation in storage and so getting the costs down will we have that. that's what we need. and it could come from solar. it could come from nuclear.