While my manufacturing experience is limited, what I have seen, and what you can see on YouTube or the History Channel are not exactly energy friendly processing. Watch the forging process in action in Asia. The problem is that things need to be heated up to very hot temperatures. In the case of steels this is 800-1100 Celsius or 1500 to 2000 Fahrenheit. Keep in mind that heavy things and larger things take more energy to heat up. So the main problem in my mind is heating this stuff up.
Some processes, like carburizing, can be heated electrically in a vacuum and thus save the trouble of heating up lots of air or burning hydrocarbons. Heating processes that take place at one atmosphere (open to the air) are more energy intensive because of the air that has to be heated up. Additionally, heat is often created by burning oil. So there is an exhaust component as well that leaves all sorts of carbon dioxide and other chemicals to be cleaned up.
Induction heating holds a whole lot of promise. It requires a whole bunch of energy, but compared to burning things can be more environmentally friendly. Now energy that we typically use to run our electronics comes from power plants that are burning things. Fortunately, this is not always the case. Wind energy, solar energy, tidal energy, wave energy, hydroelectricity, and hopefully fusion someday present the possibility of nearly zero emission electricity. Since all of those energy releasing systems first need to be produced and manufactured there will always be some emissions that occur in the product lifestyle. The hope being that we can have emissions for all aspects of our life that are less than the Earth's ability to use those emissions through photosynthesis and other processes.