> How are renewable and environmentally friendly power sources* MUCH worse?

Because you need enormous quantities of the machinery used to harvest the power. Hundreds if not thousands of times as much as you would need in a nuclear reactor.

Show me an environmentally friendly energy source with anywhere near the EROEI of the environmentally unfriendly ones.

The real solution is gradual powerdown and, eventually, population reduction.

Hydro wins:

http://en.wikipedia.org/wiki/File:EROI_-_Ratio_of_Energy_Ret...

I guess it is highly unfriendly to the local environment though (on the other hand, we already did most of the damage in the good spots).

There is also the "high enough" factor. If things got awkward, we could run a civilization on solar PV, and even devote some of the energy production to increasing the total energy production.

(I sort of expect the cost curve on solar to start to bend quite a lot faster in the next few years; it's reached the point where it almost beats the grid without subsidies)

Going to hydro is exactly what the parent poster says - gradual powerdown and/or population reduction. There's just so much hydro potential around, we're already using almost all of the good spots, and there's not nearly enough capacity on this planet for our current use.

I thought they were claiming that EROI makes alternative energy sources intractable. That isn't true. The oil/coal preference is all about cost and convenience.

(The 'hydro wins' was just the sort of fun/obnoxious way to link to the chart showing that lots of systems have a net EROI, which is almost all you need)

EROEI does not take into account time which is where renewables really shine. Renewables are the solution, they are infinite unlike all the others. Reducing our consumption is needed, I can agree with that.

The inputs are infinite. The harvesting equipment has a limited operational lifetime. I'm pro -renewable, but but it's not a silver bullet, which is why I'm also pro nuclear. Renewables are also a long way from taking up the slack of fossil fuels just yet, so you can't just say 'renewables!' and call it done.