The Senate was debating energy policy and amendments to establish a national renewable portfolio standard. Such a standard would require utilities to generate a certain percentage of electricity from renewable sources like wind and solar. While supporters argue it promotes green energy, critics say it would increase costs for consumers, pick winners and losers in the energy market, and function as a form of economic protectionism for states with existing renewable investments. A national renewable standard could also pave the way for broader climate change policies like a cap-and-trade program in the future.