A lot of concerned people emailed me to say that we MUST be running out of energy, because so many authoritative-looking people say so on TV. Here’s the result of ten minutes of Googling (it will take longer if you beer-Google) on "World Energy Reserves":
Conventional fossil fuels (from British Petroleum, "reserves available at existing economic and operational conditions," i.e. not oil shales or other more expensive petroleum ores):
Oil: 161.9 billion tonnes (annual use 3.8 billion tonnes)
Natural Gas: 179.5 trillion cubic meters (annual use 2.7 trillion cubic meters)
Coal: 909 billion tonnes (annual use 2.8 billion tonnes)
Nuclear fission (from DOE estimates):
Uranium: ~11.5 million tonnes
Thorium: ~34.5 million tonnes
One metric ton (tonne) of uranium completely fissioned equals approximately 2 million tonnes of oil. So our 46 million tonnes of currently available nuclear fuel is roughly equal to 92 trillion tonnes of oil, or 24,000 years of world oil usage. (Or perhaps “hydrogen usage”, or “beamed-energy usage” would be more accurate; while nuclear energy could be used to make gasoline out of coal or oil shale, if we do it for a thousand years we shall find ourselves running low on oxygen!)
These are just the reserves available with our current technology at our current prices (actually, with 1970s technology… the US hasn’t started construction of any reactors since 1978). It does assume that we actually recycle the nuclear fuel efficiently, instead of continuing Jimmy Carter’s policy of forcing the power companies to declare the uranium and plutonium in fuel rods to be "waste." Currently, US nuclear power plants are forced to operate at 0.5 % fuel efficiency, and do not breed more fuel out of thorium. Then the enforced inefficiency (and potential danger, from piles of unrecycled fuel) is used to justify the 12-billion-dollar boondoggle called Yucca Mountain.
It is just possible that nuclear power might get a teensy bit cheaper as time went on if some of the plants were allowed to be 150% efficient 21st-century fast-neutron breeders instead of 0.5% efficient 1970s relics. It is also possible that electric power might be cheaper if it were produced by competing free-market companies instead of government-granted monopolies. Of course this would lead to the inherent problems of unrestricted capitalism. For instance, if there had been competing electric companies in New Orleans during Katrina, it would have caused terrible inequalities. Not everyone’s power would have gone off and stayed off for months (in fact no one’s power would have stayed off for months, because they would have switched companies). The same would be true in wartime or other emergency; the inefficient duplications of capitalism would mean that not all power would be knocked out in a city at the same time. Unthinkable, of course (though in the early days of electric power, there were no monopolies, and users often owned the wires and bought power from competing power plants…).
Fusion: ah, now the concerned emails start flowing in earnest. "We don’t know how to use fusion, and it’s impossible for mere humans to invent a way." Wrong. There is already an operational fusion reactor powering the global economy, and it produces 28 trillion times more raw energy than all man-made energy sources combined. So even if some future "UN NRC" forever bans the helium-3 + deuterium reactor, we can still expand our energy use by a factor of 28 trillion, and maintain it for the next five billion years or so.
Yes, it would be incredibly inefficient compared to artificial fusion reactors, but using 1960s nuclear rocket technology we could surround the Sun with orbiting solar collectors by the time we run out of uranium on the Earth (there’s the small problem of finding enough silicon for the solar cells, but the fusion reactors can make it out of Jupiter’s hydrogen… oh, right, we’re pretending that fusion can’t be done. We would have to settle for a few million times the present world energy output if we restrict ourselves to using the asteroid belt and minor planets. But only if the "Leif Erickson gene" is lost and we never leave this particular natural fusion reactor to visit others…).
Even today a few percent of the world’s electric power comes from the sun’s fusion energy, at such sites as Three Gorges Dam and European windmill farms. And much as I love to tease solar cell enthusiasts (especially at night), solar cells get better almost as fast as computers. They’ll be ready for prime time by the time we have to use the monoliths to make the silicon out of Jupiter…
There are already thousands of cost-effective, mass-produced man-made fusion reactors as well; they are fueled by lithium deuteride. Unfortunately, they are all owned by governments (or perhaps government-funded "terrorist groups"), and they are sitting on top of missiles or in bombers, waiting to slaughter millions of people apiece at the whim of various politicians. But these fusion reactors (popularly know as "H-bombs") are not intrinsically evil. While they are not suited to steady production of electric power, they can be used for many valuable, even life-saving industrial purposes.
One of the essential requirements for successful environmental stewardship is to keep the ecology from being blown up by asteroid impacts. The existing 25-megaton city-killers would be quite suitable for deflecting extinction asteroids. They would also be useful for forcing asteroids and comets to hit the CO2 polar caps of Mars and induce Global Warming there. If all the CO2 polar caps on Mars were sublimated, the little planet would have an atmosphere half as thick as Earth’s. That’s plenty good for green plants (which will quickly convert much of the CO2 to oxygen, of course), so you Luddites who don’t think that anyone can invent a fusion reactor will have somewhere to build your log cabins and plow behind your genetically-altered Mars Mules. (The Earth will long have been 99% powered by He-3 fusion reactors, so you’ll have to move to maintain your belief system.)
But enough "no-technological-progress-ever" nonsense. The fact is that the world is full of young engineers, and new energy sources are being constructed all the time. The Russians are using new fuel designs to beat their nuclear swords into economic plowshares (and breed fuel out of abundant thorium at the same time). The Chinese, Indians, Koreans, Japanese, etc. etc. are all into improved nuclear power technologies. Almost the only nations not likely to build new-technology nuclear plants on a large scale are the US foreign-aid dictatorships in Africa, and the US itself. Even oil-rich Iran is moving into nuclear energy as fast as it can.
The US political class can (and does) make energy vastly more expensive for Americans. They can invade oil-producing nations like Iraq and shut down their oil industry. They can (and have) prevent Americans from building any new oil refineries or nuclear reactors for decades. But they can’t alter the geology of the Earth, or the laws of physics, and they can’t stop people in rogue states that really do have WMDs from doing anything they damn well please.
A quick look at the world’s nuclear research programs shows that there are many nations that have breeder reactor technology in commercial prototypes already… and several of these countries are fresh out of socialist economic nonexistence. A few more years of even the most tainted capitalism, and they’ll have nuclear reactors that are at least 60-70% fuel-efficient, compared with our 0.5% "Jimmy Carter Specials." The nations that want energy will get energy, whether the US political class approves or not.
This all assumes, too, that no one ever invents any new energy sources. This assumes that we know everything about Physics, mining technology, transportation systems, nuclear reactor design, etc. After all, we’ve had nuclear power for… less than a human lifetime. Surely we know everything by now, right?
The truth is that Googling can’t find most "World Energy Reserves." Energy reserves are created by human minds out of the raw materials of nature. Most of these reserves will be the creations of the minds of people that aren’t even born yet. All we can do on Google is find out the rock-bottom LOWER limit for our energy reserves. The lower limit is enough to build interstellar civilizations and go on to find the "World Energy Reserves" of the Milky Way. I wonder where the real upper limit is?