It is not the energy released from fossil fuels that is the main contributor of global warming. What is creating the warming is the trapping of energy from the sun due to the insulating properties of the gases that are released from that burning.
"Given that energy is only converted, never destroyed, it is questionable that capturing that 'sunlight' and repurposing it would have any impact at least on a global basis."
If we're collecting that energy with solar panels on earth, I would agree. As long as the amount is down in the noise level, so it aren't darken huge expanses of our planet, the rest of the ecosystem should be mostly unaffected.
But if we're collecting that energy with solar panels on the moon, or asteroids, and then beam it down to earth somehow or other, that's a different matter. If releasing the energy that was previously trapped in fossil fuels is creating appreciable global warming, imagine what happens if humans start to believe that shipping in extra energy from extra-terrestrial sources constitutes "free energy."
Except it is highly unlikely we would ever need to capture a large portion of the solar energy that hits the earth. On the magnitude of 0.01%. Given that energy is only converted, never destroyed, it is questionable that capturing that "sunlight" and repurposing it would have any impact at least on a global basis. If anything, we are more likely to capture more energy that would be reflected, so the effects would be similar to burning fossil fuels ... i.e. adding energy.
In terms of energy and power, Engineers know the difference and only get hung up on the semantics of which is the right term when it matters for the most part and always when formal writing.
Energy and power normally gets interchanged in casual conversation unless we have technical datasheets reference. In a project team there are individuals with different educational backgrounds so quite possible. Problem happens when in design phase data gets calculated wrongly espcially when the product have crossfuntional areas like mechanical, software and electronics.
Good point--solar arrays occupy lots of land (unless they are on the roof). That land can't be used for food or habitation. Some of the solar setups in the desert are huge, makes it hard for native flora and fauna to succeed, they have evolved to live in that environment.
"Perhaps we should do the harvesting on the moon, then find some safe way to bring that power to earth."
Hmmm. Even that idea is full of risk, come to think of it. Even if the human contribution to global warming is ambiguous now, the human contribution would be much more obvious if we bring down energy from other celestial bodies, eh?
That's why I think demanding ever increasing efficiencies from our machines makes a lot of sense, even if global warming is not primarily our own doing, as of now.
Harvesting power from the sun follows the same model as harvesting power from RF sources. If you expect to harvest a large percentage, you're going to destroy whatever system is using that power now. In the case of solar, you can't come close to harvesting all of the solar energy impinging on the planet, if you expect the ecosystem to continue to function!
Ditto with any other "renewable" source. Power harvesting only makes sense if its impact is "in the noise."
Perhaps we should do the harvesting on the moon, then find some safe way to bring that power to earth.
I suppose you can think of oil etc as solar energy collected over the eons, converted to biomass, then tranformed into fuel.
Consider how much solar energy flux and solar power impinges on Earth--that's an upper limit of what we can get from most renewable sources (not counting geothermal, for example, which is likely due to radioactive decay deep within the Earth and is solar-independent). The Wikipedia entry is a starting point at http://en.wikipedia.org/wiki/Solar_energy, Warning: I don't know how good those numbers are--but they do make you stop and think.
In a sense, that's what "sustainable energy" is all about.
Most of our sources of energy have used long term, low power "charging" in developing themselves, and we are depleting them a lot faster than it took to build up that energy content.
Battery-powered EVs are a less dramatic example of the same phenomenon. The power needed to move vehicles is quite a bit higher than the power available in battery charging circuits, which means that the battery is depleted a lot faster than it can be replenished. But the delta time is not close to being as dramatic as it is for making coal, oil, or natural gas.
To bring this back to harvesting RF power for your smartphone, since smartphones tend to be on most of the day, and RF harvesting yields very low power in most environments suitable for human habitation (unless you render that RF system useless by capturing most or all of its energy with large, encompassing receive antennas), I don't think it's a practical solution.