Thursday, June 19, 2008

Oil: How will we ever do without it?

Oil, and the price, supply, and demand thereof, is all in the news today, thanks mainly to Bush's declaration that the US should lift its moratorium on outer shelf drilling. This has led to a groundswell of talk about oil and gasoline prices, American dependence on foreign oil (note polling methodology used), alternative fuels, and all sorts of other things.

The problem is that virtually all of this talk is rearranging deck chairs on the Titanic. Unless you're one of those crazy people who believes in the abiogenic theory of oil origin (which asserts that the Earth contains secret, unlimited supplies of hydrocarbons if you just drill deep enough; while it may be the case that some subcrustal hydrocarbons are of nonbiological origin, that fact will not somehow make their supply limitless), there's no way of escaping the fact that the amount of available oil on the planet is either fixed or increasing very slowly, and that we're drawing down that finite supply at an alarming rate. A 2007 report puts world reserves of crude oil at between 1119 and 1317 billion barrels. Meanwhile, the world consumption of oil (per OPEC in 2006) was 78.3 million barrels a day, or 28.6 billion barrels a year. That means we have between 39 and 46 years of oil left at our current consumption rate, after which we will be out.

Now, many people, especially in the oil industry (and government people friendly to these people) seem willing to hang their hats on the idea that we'll find more oil before we run out in 2054. But even the most optimistic estimates for finding new sources of oil only push the sunset back a few decades more, or rely on the discovery of techniques that seem thermodynamically infeasible today, such as extracting oil from oil sands, which currently cannot be meaningfully done because it takes the equivalent energy of two barrels of oil to get one barrel of oil out, which is something we'd only do if we wanted the oil for nonenergy uses.

And there are certainly nonenergy uses for oil. We make all sorts of things out of crude oil. Plastics, pharmaceuticals, dyes, even food. Many of these will be hard to do without, which might happen if we squander all of our oil for energy. Some of the feedstock demand for these substances can be met from oil sands or from biological sources, but at higher costs (both in terms of dollars and, more importantly, in terms of energy). As we draw down our finite supply of oil, we will find that the price of "cheap" plastic will suddenly not be so cheap, as energy uses increasingly compete with industrial feedstocks for the declining supply of petrochemicals. Wood furniture is looking better every day, isn't it?

So, we need to reduce our consumption of oil as an energy source, and do it fast, before we run out entirely. There are two ways to do this: find alternative sources of energy that can substitute for oil and its derivatives, and reduce our demand for oil and its derivatives by changing how we live. It's clear that we must do both. By far our largest use of oil-derived energy in the United States is to support our extensive transportation system. The problem with transportation systems is that they need a means to store energy in a portable manner, typically as a combustible chemical (fuel), as electrochemical potential (battery), or as electrostatic charge (supercapacitor). The main restriction is that the entire energy source for a given trip has to be mobile with the transport vehicle; that is, no tethers. (Some forms of mass transit use centrally-generated electricity, and are exempt from this issue.) This imposes pretty rigorous energy density requirements, for which there are relatively few options. We currently use gasoline because it's just about the densest available option that isn't dangerously explosive or hazardously toxic. Let's first explore the options for substitute forms of energy storage, then talk about how we can cut demand.

Biological sources of combustible fuel such as ethanol are of no value here; it takes 1.29 barrels of oil to make one barrel-equivalent of ethanol from corn. Switchgrass is worse: 1.50 barrels per barrel-equivalent. Those of you using E85 in your "alternative fuel vehicles" are actually using more oil every time you fill up than if you just put plain old gas in the car. There are advantages to ethanol-fortified gasoline fuels, but they have nothing to do with controlling oil demand. So, we must reluctantly reject biofuels as a solution to this problem. However, as a lot of the energy consumed in farming goes into the production of fertilizer and in the operation of mechanized farm equipment, it remains possible that we might be able to develop farming methods that do not consume more energy than they produce. We must continue research in this area (not only because it will benefit the potential for viable energy production, but also because it will reduce the energy costs of food production), but it seems unlikely to me that this will reap sufficient reward in a timeframe short enough to avoid the impending doom. Similar analysis also deepsixes most form of biodiesel. The one positive of biofuels is that they are theoretically carbon-neutral; that is, they take as much carbon out of the atmosphere as they add to it.

What about hydrogen, George W. Bush's pet solution? Sorry, no. There's two main ways to produce hydrogen in bulk. One of them is from petrochemical stock, which just inserts another step in the chain; the second law of thermodynamics means this is a net loss overall. The other is by electrolysis from water. Since the cracking process is thermodynamically the exact reverse of the reaction involved in burning hydrogen, the energy required to do it is not less than the energy that will be yielded by burning it; another net loss overall. Basically all we're doing by producing hydrogen is storing energy from another source as hydrogen. The problem with this is that hydrogen is not a particularly good medium for storing energy; hydrogen is an explosive gas with a very low boiling point and with a very low density at standard temperature and pressure, requiring complex, expensive, and heavy containment systems to be safely used in a vehicle. There may be niche applications where hydrogen combustion is useful, and hydrogen fueled vehicles do have other benefits (such as theoretical carbon neutrality), but again (as with ethanol) these benefits have nothing to do with controlling oil demand. Hydrogen will eventually become very important, but that day is quite some time off.

Virtually all other available combustible fluids are similarly derived from petrochemicals. The main exceptions are liquified natural gas (LNG) and gasified coal. We have about ten times as much available energy in coal reserves as we do in oil reserves. Of course, coal will run out eventually too, but that date (even if we switched all our oil consumption to coal) is somewhere between 2200 and 2500. There are several problems with coal. A lot of effort (and therefore energy) has to be spent to make it not dirty, and to put it into a form that we can use in cars. There's been ongoing research in coal gasification for years, but the process has not yet been made cheap enough to displace the production of hydrocarbon fuel from crude oil. Eventually the economics of spiraling oil prices will make coal gasification an economically viable alternative even without market tweaking, but it would be a good idea to further incent this behavior now. Also, both LNG and coal are not carbon neutral, and their use will contribute to global warming (assuming you believe in global warming). In any case, increased use of coal will almost certainly be a major part of our middle-term plan as we move to a combination of renewable and fusion power in the future, simply because it's unlikely that we will develop efficient fusion power before the oil runs out.

An examination of the capabilities of the various electric cars on the market today demonstrates why we're not using electric cars. Simply put, the energy storage capabilities of a battery aren't even close to being on a par with what is offered by chemical fuels. The best all-electric car you can find today has a range of perhaps 50 miles at speeds far below what we have come to expect in a car. Electric cars are not today, and quite likely will not in any short time become, a drop-and-go replacement for gasoline-powered cars. Hybrids help some here, in that they use less fuel than nonhybrids, but even doubling the fuel efficiency of the entire vehicle fleet only pushes back the sunset a few decades at most. Plug-in electrics at least allow us to use central power generation, which is an area where we can use renewable sources.

Fundamentally, what has to happen to avoid the oil doom is to rethink our transportation system. And that means more dependence on centrally-powered mass transit, but even more so it means eliminating the need to travel long distances on a regular basis. We can get some gain by making it easier for people to commute to work by light rail or overhead-powered buses, but we get even more if we make it possible for people to walk to work, or to use small electric-powered personal vehicles that can be easily recharged while at the office.

The problem is that our cities have grown up around the car, and around the highway. We have structured our urban environments and our culture on cheap gas. It's a real pain now that gas isn't cheap, and it's going to get even more expensive. (Plaintive cries to the government to do something about the price of gas are about as realistic as asking Congress to lower the gravitational constant. Gas is expensive because we're running out. The government cannot make a naturally limited resource become unlimited.) We can either see the writing on the wall and make deliberate plans to change our way of life gradually, or we can ignore the obvious and let the Titanic slam headlong into the iceberg. Your choice, America.