Cogeneration means all energy is recycled as efficintly as possible. An example of this is-

A gas generator produces power, but it also produces heat. In Cogeneration, that heat is used to "do work" like heat water, air or other beneficial use.

When designing your alcohol production system, you will want to take advantage of all the energy produced from any source you can to maximize the production so (for us) it might look like this:

The mash is fermented in a solar "hot-house" and periodically, when the mash is ready, a wood fired system will heat it to separate the alcohol from the moisture. Heat will come off the chimney on the wood burner and can be used to heat sand under the mash (which will help with fermentation). Heat will also come from the steam produced from the alcohol separation process and can be stored in the next tank to ferment and it will get off to a good start since it has a higher temperature.

Cogeneration can happen almost everywhere energy is used. In looking for cogeneration on the internet you will find washers & dishwashers that hold the water until its cold to keep from sending the heat down the drain; dryers that recycle the heat, and more. How efficient this is - is questionable. But once you see a total system like the Brazilian model of ethanol production or the Swedish model, which uses sugar beets, you begin to see how sensible setting up your system for long-term is.