One thing is readily apparent: we use energy in three distinct ways. One is for electricity generation, and the major fossil fuel used in that instance is coal, with some contribution from natural gas. Another is for heat generation for home and industry, which splits evenly between petroleum and natural gas. The last is transportation, which is mostly petroleum.
The thing to realize is that if we were to replace all of our non-fossil-fuel energy with other, more sustainable sources, we'd have to generate a hell of a lot more power. The numbers haven't changed much. We will need to generate seventeen times as much energy as we do now to make up the entire shortfall. [UPDATE: Major error -- it's actually more like five or six. See comments.] More to the point, we will have to transition to an all-electric economy.
The question is, how?
Part of the problem comes down to energy storage. It's hard to beat petroleum as an energy storage medium. Petroleum and its distillates are liquid over a large temperature range, which makes them very easy to store, and very easy to move. Replacing petroleum will require us to find energy storage devices that are about as good. Battery technology is getting better all the time, which helps us out some.
Another part of the problem is that significant parts of the economy rely on direct heat, for which petroleum and natural gas are very useful. Ease of storage and movement are important here, but also important is the fact that you can burn hydrocarbons and get large amounts of instant heat. This is important in the steel business for blast furnaces, but it's also important for the Mongolian place down on the corner that uses that big, circular gas-fired grill. Replacing these with electrically-powered devices is possible, but not without a significant capital expense.
Lastly, the largest part of the problem is simply where will we find a five- or six-fold increase in power? Basically, we'll have to find it wherever we can.
Aside from burning things, we have five basic sources of energy here on Planet Earth:
(1) Fusion energy, arriving in the form of radiation from the Sun;
(2) Heat from radioactive decay deep within the Earth;
(3) The angular momentum of the Earth-Moon system;
(4) Nuclear fission, which amounts to making (2) above happen much faster;
(5) Nuclear fusion, which amounts to duplicating (1) above down here on Earth.
I don't like the term "renewable energy." The Second Law of Thermodynamics tells me that no such thing exists. Every time you convert energy from one form to another, you lose a little bit to waste heat, no matter where you get it from. But the term is out there, and there's nothing I can do about it. What renewable energy is all about is tapping into a flow of energy that's there for the taking, whether you use it or not. The Sun is shining down on you anyway, why not use it? (There's even some poetic justice in using sun-power to run your air conditioning.) The wind is blowing anyway, why not use it? The tides will run in and out no matter what we do, so why not put them to work?
One thing to be aware of, though: extracting energy from these systems is liable to have some blow-back. If you extract too much energy from the wind, there could be some knock-on effects on weather patterns, and we just don't know enough about those dynamics yet to predict what could happen. And that's just one example. (The exception is solar power. I can't really think of any down-side to collecting sunlight.)
That said ... renewable energy taps sources (1) through (3) above, and there's a practical upper limit to how much of that we can get. If our experience with oil has taught is anything, it's that no energy source is truly inexhaustible. So, what else do we have to do?
At the risk of repeating myself, I'll point out something readily apparent near the top of the picture above: two-thirds of the electrical power we generate is wasted between the point of generation and the consumer. Presently there's not a whole lot we can do about that. Joule heating scales with current, and high-voltage power lines carry a whole lot of current. But, every year brings a better understanding of superconductivity, and every year the temperature at which this effect can be made to work climbs a little bit. There's also some really promising work on conductive carbon nanotubes. If we were able to re-engineer our power grid such that we cut the resistance of those high-power lines by 80%, that cuts our power loss to only a fifth of what it is today ... which, at a stroke, nearly triples our deliverable power. That cuts a seventeen-fold increase down to only about six-fold: still a formidable amount of power production to build out, but that's an easier task to accomplish.
We will also, at least in the short run, have to make use of nuclear power. It's got its problems to be sure, but those problems are well-understood and manageable. Nuclear power is good for providing large amounts of always-available electrical power, and we'll need large amounts of always-available power if we're going to switch all of our transportation infrastructure over to fully-electric power.
But the holy grail remains controlled nuclear fusion. The reason is simple. We will eventually deplete our supplies of oil, gas, even elements like uranium. But given that hydrogen is the most abundant chemical element in the entire Universe, I'm going to guess that we'll not run short of it for quite a long time, and by "quite a long time" I mean some billions of years. There's a lot of exciting work going on in this area. The next year and a half is liable to tell us which approaches will work, and which ones may not. If things work out like I'm hoping they do, we could have working power plants within fifteen to twenty years.
It's easy to despair, given the constant drum-beat of the news from the Gulf coast. But despair is a sin. The answers to our dilemma are coming together. We just need to hold things together a little bit longer ... then, we can enjoy the spectacle of BP's executives looking on in befuddlement as the world passes them by.
Living well is, after all, the best revenge.
