In the real world, barring a massive buildup of nuclear plants, reducing carbon dioxide emissions means consuming less energy and that means raising prices a lot, either directly with a tax or indirectly with a cap-and-trade permitting system.
Elsewhere, Sean Carrol determines that biofuels are a crappy source of solar energy, and that nuclear fission is the way to go:
As an uneducated guess, I would imagine that in the medium run the world will have to turn to (Earth-based!) nuclear power for its energy needs. In the longer run, solar will be the way to go, although the amount of solar power we can reasonably collect here on Earth is somewhat limited. We’ll likely have to solve the problem of how to efficiently beam power down from orbit, after which we can build big million-square-kilometer solar power collectors in space. Not in my lifetime, I would bet.
Biofuels have been getting a bad rap recently, generally because – in the US, at least – “biofuel” is a synonym for “corn ethanol”, which has long been considered a technology with very limited promise, and is the only “alternative fuel” (aside from, one could argue, nuclear) which has ever received any significant federal investment. Compare to, for example, biodiesel from algae:
“If you replaced all the diesel in the U.S. with soy biodiesel, it would take half the land mass of the U.S. to grow those soybeans,” says Matt Caspari, chief executive of Aurora Biofuels, a Berkeley, Calif.-based private firm that specializes in algae oil technology. On the other hand, the Energy Department estimates that if algae fuel replaced all the petroleum fuel in the United States, it would require 15,000 square miles, which is a few thousand miles larger than Maryland.
Which sounds like a lot of real estate, but is only 1/7th the land area used for corn production in 2000 (last two links and 1/7th stat via Wikipedia. And could this 15,000 mi^2 be on the ocean? The ocean doesn’t vote.) Biofuels can also be extracted from agricultural and industrial waste. In practice, none of these technologies are actually ‘carbon neutral’, but they are tremendous improvements over fossil fuels, and there is no fundamental reason why, as the technology matures, it couldn’t be brought arbitrarily close to carbon neutrality. In addition, it is designed to work with our current fossil fuel infrastructure, which is an often-overlooked point when discussing alternative fuel options. The electric motor is a wonderful thing with endless advantages over internal combustion, but replacing every V-6 on the road with an all-electric engine would cost a great deal of money and energy, and would probably be a very hard sell to the world’s #1 CO2 producer, where per capita income is less than $2000/year.
All bio/fossil fuels are stored solar energy. Solar energy is, on any non-astronomical timescale, constant and inexhaustible. My namesakes at Scientific American gives us a sense of how much energy we’re talking about:
Solar energy’s potential is off the chart. The energy in sunlight striking the earth for 40 minutes is equivalent to global energy consumption for a year. The U.S. is lucky to be endowed with a vast resource; at least 250,000 square miles of land in the Southwest alone are suitable for constructing solar power plants, and that land receives more than 4,500 quadrillion British thermal units (Btu) of solar radiation a year. Converting only 2.5 percent of that radiation into electricity would match the nation’s total energy consumption in 2006.
That 2.5% is 10,000 mi^2 at 100% efficiency, comparable to the estimated 15,000 mi^2 needed for domestic petroleum replacement. In addition to this unimaginably huge natural supply of solar energy (which includes wind, bio/fossil fuels, etc.), there is energy from nuclear fission, hydroelectric/geothermal energy (a combination of Earth’s gravitational and naturally-occurring fission), tidal energy (essentially derived from the Earth’s rotational momentum), and eventually perhaps controlled nuclear fusion. None of these are without drawbacks – some create waste, some require large land areas, and so on. But the potential energy available is, for all intents and purposes, infinite. And extracting it is, fundamentally, not a very difficult problem. So a couple of things:
1. All non-fossil fuel technologies are, at this point, immature, so judging classes of them as failures at this point is very, very premature. (As would be judging them successes – all 15,000mi^2 figures are to be viewed with considerable skepticism until actually delivered.) If you were handicapping the technologies available to the horseless carriages 100 years ago, you would be fully justified in favoring the simpler electric or the proven coal-powered steam engine over the newfangled gas-o-leen that the Chardonnay-sipping elitists in Detroit were trying to foist on you. Now, however, you’d look like a mustache-waxing prick in amusing period dress for saying this, but do you ever learn? No you never do, you mustache-twirling, stovepipe hat-wearing ass. It is remarkable what a good idea and a few trillion R&D dollars can do towards making you look the fool.
2. There is no answer, and there is no end state. We have always used a mix of energy sources, and that mix has always varied over time, in response to economic and technological circumstance. That’s history fact. Fundamentally, there is no limit to available energy, nor is there any essential connection between energy and carbon dioxide, or any form of pollution. That’s science fact. As technologies mature, some will show more promise in certain applications, others will disappear, and still more will be discovered. If anyone knew any of the particulars of how this process will play out over the next 10-20 years, they’d be trillionaires already.
3. This evolution can be greatly expedited by broad and deep public spending on R&D, and not very much by cooing sweet libertarian nothings about the Invisible Hand while generously subsidizing corn ethanol and oil drilling. Rather than prove this in the conventional way, I will merely note that Ron Bailey has already written an opinion to the contrary, and then ask you to remind me of the last time Ron Bailey was remotely right about anything. Exactly. Indeed, I will suggest to you that the only way to fully appreciate the magnitude of my Rightness here, you have to read the entire Ron Bailey article, for only then will you truly know. Better you than me, anyway.