thoughtfully wrote:@drunken: maybe power that didn't come from a power company? That doesn't mean it didn't cost money, you know. Solar cells cost money, too. Your "free energy" could be more expensive than what comes from the power company, since they get economies of scale. The cheapest "free energy" is conservation, anyway.
In terms of physical quantities, its all the same. Its an economic distinction, not a scientific one.
What you say is true but the problem is not that the economic world and the scientific world are nicely seperate and contained. In fact they are the same world, and while living in them I often talk to people who use the scientific term 'free energy' and also many other people who like to save money. I can't stop scientists from giving me evil looks and thinking I am an idiot when I use the scientific term in the economic meaning. Given that the economic meaning is much older than the scientific meaning it is really not my problem if I cause confusion using the same term for both. I want a new less ambiguous term for the scientific meaning, or a new equally unambiguous term for the economic meaning. A wikipedia search for 'free energy' gives the following:
* Thermodynamic free energy, the total amount of energy in a physical system that can be converted to do work, in particular:
o Helmholtz free energy, the amount of thermodynamic energy in a system that can be converted into work at a constant temperature and volume (called work content in chemistry)
o Gibbs free energy, the amount of thermodynamic energy in a system that can be converted into work at a constant temperature and pressure
+ Free-energy relationship (or linear Gibbs energy relation) help understanding the reaction mechanism for a chemical reaction and makes it possible to predict reaction rates and equilibrium constants.
* Free energy perturbation, is a method based on statistical mechanics that is used in computational chemistry for computing free energy differences from molecular dynamics or Metropolis Monte Carlo simulations.
* Free energy suppression, the notion that special interest groups deliberately suppress technologies that may provide energy at very little cost
So it seems relatively simple to me: unless one of the terms 'thermodynamic free energy' 'Helmoltz free energy' 'Gibbs free energy' or 'free energy pertubation' or some similar scientific quantifier then we can assume that the speaker is referring to the economic/social concept of energy that costs nothing to harvest. A lot of people confuse this with cheap energy but that is something else again.
edit (@oxoiron): I already gave examples. Here is another. I am lying on the ground, I am cold, I need energy to get warmer. Then the sun comes out from behind a cloud and I am warmed. Where is the cost?
PS I am going to leave this now I feel like I am derailing what looks like a very useful thread. If I think of more things to say I'll make a new thread and link it here