Why does Dr. Johnson suggest building a greenhouse near a power station? Which of the following can be used as fertilizer?

Hello, every one, and I’m so pleased that you’ve decided to tunein to our weekly program "Science around US". Today, let’s look at a new idea of building a special greenhouse in Massachusetts. Green houses in cold climates need a lot of heating. This is expensive. Power stations produce a lot of hot air that is dumped to the atmosphere. This is wasteful. Doctor Berd Johnson, a researcher of Massachusetts Institute of Technology, has connected these two facts and proposes to do something about them. He observes that power stations tend to be built far from cities and to be surrounded by wasteland. He suggests building greenhouses on this land and pumping in the exhaust from the power station. Such greenhouses could be used to grow fruit, vegetables and flowers cheaply. Not only will the exhausts keep the plants warm, it might also fertilize them. Carbon dioxide, the results of burning fuel is, together with water and sunlight, the raw material of photosynthesis. More of it in the air makes plants grow faster. Dr. Johnson is working on the idea in collaboration with Cowpift cooperation, a power company based in San Jose California. Cowpift has a great delight in building pilot greenhouse. Next one of it is natural gas power generating plants, probably, the one in Dayton Massachusetts. The exhaust will be mixed with normal air to cool it from 130 degrees centigrade, the temperature at which it leaves the power station to about 20 degrees centigrade. The temperatures are preferred by tomatoes. Dr. Jonson wants to use a gasbuming rather than a coal or oil-burning plant because the exhaust produced by burning natural gas is free from sulfur dioxide, which plants hate. If this idea works, the term "greenhouse gas" may take on a whole new meaning. Electricity companies could soon be growing tomatoes as a sideline.