Yesterday I wrote a post about how expensive car batteries are. Today Brad Plumer has a post about clean energy subsidies and how they're fading out. These two things together reminded me about an energy factoid that's always struck me as slightly odd: virtually every form of energy seems to be almost as efficient as burning oil, but not quite.
For example, on either a power/weight basis or a cost basis, batteries are maybe 2x or 3x bigger and less efficient than an internal combustion engine. Not 50x or 100x. Just barely less efficient. And you see the same thing in electricity generation. Depending on how you do the accounting, nuclear power is maybe about as efficient as an oil-fired plant, or maybe 2x or 3x less efficient. Ditto for solar. And for wind. And geothermal. And tidal power.
I'm just noodling vaguely here. Maybe there's an obvious thermodynamic explanation that I'm missing. It's just that I wouldn't be surprised if there were lots of ways of generating energy that were all over the map efficiency-wise. But why are there lots of ways of generating energy that are all surprisingly similar efficiency-wise? In the great scheme of things, a difference of 2x or 3x is practically invisible.
It's tantalizing as hell, too. It doesn't seem like there ought to be a reason that during a century of looking we haven't been able to find a single energy source more efficient than either water wheels or burning oil, but we haven't. I think God is playing games with us.