I think the argument (not sure how true it is because I don't know the facts) is that we can do more to (in the future) reduce carbon emissions from power plant

I think the argument (not sure how true it is because I don't know the facts) is that we can do more to (in the future) reduce carbon emissions from power plants and that we will get benefits of scale when we move burning fossil fuels to bigger plants as opposed to doing so in every car.