But new wind turbines and solar cells are joining an infrastructure with coal-fired power plants that seem to run more hours every year and that are multiplying as well.

• 不过，要用新建的风力发电机组或太阳能电池，往往必须与燃煤发电厂组成电力网，但后者的运转时间更长，而且数目也正快速增加中。