He says the government is responsible for protecting clean air, not protecting old and dirty power stations.

他表示，政府有责任保护清洁的空气，而不是保护老旧肮脏的发电站。

Here are the results.In fields from Iowa to Texas, wind power is now cheaper than dirtier, conventional power.

下面就是其结果，从爱荷华到德克萨斯的发电站，风力比肮脏、传统的电力要廉价。

Wind turbines and solar panels provide power only intermittently; for now, dirtier power plants are needed as back up.

风力涡轮机和太阳能电池板只能间歇性地提供电力；目前，需要更脏的发电厂作为后备。