Dear Science,

Why can't we get away from oil? Didn't it quadruple in price in about a year? Where are all the alternatives? I can't believe this is all just one gigantic conspiracy. Help me, Science! Light my world. Heat my house. Just do it without oil!

Eco Hog

Why oil? Because it's a really excellent way to store, transport, and use energy. Petroleum holds huge amounts of energy in small volumes and masses—making it one of densest sources of energy. The energy stored is incredibly stable—lasting for millennia without loss—making it easier for us to store or transport. The stored energy is readily useable, as fossil-fueled machines are less complex than machines using most other energy sources.

Any one alternative can't do all of these things. Let's talk numbers, comparing the equivalent amount of energy stored in batteries to a gallon of gas. It takes about 2,000 fully charged NiMH D batteries to store the same energy contained in one gallon of gasoline. The 2,000 batteries weigh about 57 kilograms; the gallon of gas weighs about 3 kilograms. Making batteries requires toxic metals and complex chemistry; a gas tank can be made by pressing common metals or molding plastic. The batteries weigh the same charged or empty, while the gas tank gets lighter as the energy is used up. If you're picking an energy source for a car, which would be your choice?

How about building a power plant? With a fossil-fueled plant, you have to consider both the initial (capital) costs to build the plant as well as the operating costs to buy the fuel. Yes, you have to buy the coal, oil, or gas to run the plant, but at least this cost is spread out over years. If you want to build a solar- or wind-powered plant, almost all the costs are up-front capital costs. If the wind doesn't blow or the sun doesn't shine where you chose to build your plants, you're totally out of luck. By concentrating the costs right at the start, the risks of building an alternative-power plant are higher. If you're an investor—and given the financial turmoil right now, you're probably a little skittish as an investor—what kind of plant would you rather have your money tied up in?

But we must replace petroleum. All of the fossil fuel consumed in just one year of our global society is about equal to half a millennium of the plant and animal growth of ancient earth. Replacing oil will take the combination of several different technologies to overcome the relative deficiencies in the available alternates. Or it will require us to develop an alternative—perhaps through bioengineering—that matches petroleum. In either case, science is optimistic.

Substitutingly Yours,